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Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities (2023)

Chapter: 7 Applications of Recycled Plastics in Other Infrastructure

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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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Suggested Citation:"7 Applications of Recycled Plastics in Other Infrastructure." National Academies of Sciences, Engineering, and Medicine. 2023. Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities. Washington, DC: The National Academies Press. doi: 10.17226/27172.
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133 7 Applications of Recycled Plastics in Other Infrastructure As part of a larger effort to reduce plastics waste in landfills and the envi- ronment, plastics waste has been and continues to be the subject of inves- tigation as feedstock for plastic materials and products across a myriad of infrastructure applications. Due to the perceived widespread availability of recycled plastics, fluctuations in virgin plastic pricing, and consumer and manufacturer interest in products with improved environmental impacts, demand for infrastructure applications that include recycled plastics has increased. Virgin plastics have been used extensively in buildings and construction (Di et al. 2021; Heller et al. 2020) for years and have a wide range of uses in infrastructure. For certain applications, composite or all-plastic products have proven to be an attractive alternative to traditional metal and wood materials that are vulnerable to corrosion and rot (e.g., stormwater drain- age piping and plastic decking). The incorporation of recycled plastics into such infrastructure products, then, relies on demonstrating performance comparable to products made with virgin plastic feedstock. New plastic products for infrastructure applications such as composite utility poles or plastic bike paths, for example, are attracting interest but will require fur- ther development and testing before widespread industry acceptance, irre- spective of whether the plastic is virgin or recycled. Long-term performance and environmental impact data are needed for many plastic products being considered for infrastructure applications. This chapter examines the current state of research, development, and deployment of recycled plastics in infrastructure applications other than as highway pavements. The maturity and overall acceptance of these

134 RECYCLED PLASTICS IN INFRASTRUCTURE applications depends not only on the performance of plastics, particularly recycled plastics, but also industry and state government motivation to develop new standards that accommodate their use. As one speaker shared with the committee, until these standards and specifications are established, the use of recycled plastics in certain industries will remain largely innova- tive. Consideration is given to how some industry practices affect the pace of inclusion of recycled plastics in infrastructure. The following is not meant to be an exhaustive survey of the use of recycled plastics in infrastructure. A wide array of manufacturers has devel- oped pioneering and sometimes niche products for infrastructure applica- tion that are in varying stages of development and for which information and data may be proprietary; it was not possible to survey them all. Instead, the chapter discusses a representative selection of products that underscore the opportunities for and barriers to incorporating recycled plastics in non– highway pavement infrastructure. PRODUCTS AND APPLICATIONS Lumber Applications Wood–Plastic Composites Wood–plastic composites (WPCs) are mixtures of plastic and wood prod- ucts, typically 50/50 plastic and wood (though certain products may have a larger percentage of wood) (Ibach 2010). The most common plastics found in WPCs include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), and polystyrene (Najafi 2013). The Framework for Assessment of Recycle Potential Applied to Plastics reported that high-density polyethyl- ene (HDPE) milk containers and polyethylene terephthalate (PET) beverage containers are the most effective in wood–plastic composites (Barlaz et al. 1993). Numerous studies have evaluated the use of blends, single types of plastics, and recycled or virgin plastics or mixtures thereof with varying results. While virgin and recycled plastics theoretically demonstrate similar melting points, different plastics may melt at different temperatures; there- fore, plastics waste mixtures may result in inconsistent melting points and fail to produce homogeneous mixtures. Similarly, the presence of impurities in recycled plastics waste may also increase the immiscibility of the blend. As a result, compatibilizers are often necessary when blending different types of plastics and/or a recycled plastics mixture. Performance of WPCs depends on the blend of plastics, whether there are recycled materials, and what type(s) of compatibilizers are added. The properties of blends may be inconsistent due to contaminants, deg- radation of the plastic, and different grades and colors in the supply.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 135 Cross-linking can be used to modify the thermoplastic properties of a product, such as the melt flow index or creep resistance. Plastics that have been cross-linked, however, cannot be recycled again through melting. In a 2012 survey of WPCs made with recycled plastics, most literature indi- cated that they demonstrated lower impact strength than products made with virgin plastics (Barlaz et al. 1993). Results for flexural modulus and tensile strength vary by study (Barlaz et al. 1993). Some publications in- dicate that WPCs made with recycled materials have lower strength and stiffness (Youngquist et al. 1995), higher flexural modulus and strength (Kamdem et al. 2004; Najafi et al. 2009), or perform comparably to WPCs made with virgin materials (Lei et al. 2007; Najafi et al. 2006; Selke and Wichman 2004). Numerous studies suggest that water absorption and thickness swelling were worse for recycled materials than for virgin materials (Najafi et al. 2007a, 2007b, 2008). Other works demonstrate comparable swelling and absorption relative to virgin materials (Adhikary et al. 2008b), but these properties can be improved with the addition of a coupling agent (Adhikary et al. 2008a). WPCs offer some advantages over traditional lumber materials. They are generally lower maintenance, more resistant to termites, require less frequent replacement, and are not treated with potentially toxic materials. However, like lumber, the wood particles in WPCs are vulnerable to fungi. Additionally, WPCs suffer from polymer degradation because of ultravio- let (UV) light exposure unless photostabilizers are added. One area that requires further exploration is the potential to recycle WPCs themselves. Recycling WPC materials has been found to yield material more susceptible to degradation and reduced performance (Petchwattana et al. 2012). Wood is degraded during the recycling process, and recycled WPCs demonstrate lower tensile strength, lower flexural strength, and greater water absorption relative to new WPCs (Shahi et al. 2012). Finally, wood–plastic composites can require a prohibitive upfront investment, despite potential long-term gains due to reduced replacement and maintenance. Barlaz, Haynie, and Overcash (1993) note that lumber produced using plastic is two to four times the cost of virgin lumber. Despite these challenges, WPCs have been widely adopted for various products and applications, including decking (see the case study in Box 7-1), siding, and fencing. WPCs had an estimated market size of around US$5.5 billion in 2021 (ARC 2023). Further aiding the adoption of WPC products are the numerous standards surrounding their use and production, including but not limited to the following stan- dards and specification: • ASTM D7032, Standard Specification for Establishing Performance Ratings for Wood-Plastic Composite and Plastic Lumber Deck Boards, Stair Treads, Guards, and Handrails (ASTM 2021a);

136 RECYCLED PLASTICS IN INFRASTRUCTURE • ASTM D7031, Standard Guide for Evaluating Mechanical and Physical Properties of Wood-Plastic Composite Products (ASTM 2019a); and • ISO 20819-1, Wood-Plastic Recycled Composites (WPRC)—Part 1: Specification (ISO 2020). Plastic Lumber Plastic lumber refers here to lumber developed from plastic feedstock and without wood additives. Plastic lumber may include glass fibers or other additives and stabilizers, however. Plastic lumber offers many of the same advantages and disadvantages of WPC lumber. Compared to traditional ma- terials, it is lower maintenance, moisture resistant, and resistant to rot, cor- rosion, and insect attacks (Krishnaswamy and Francini 1998). Additionally, BOX 7-1 Fiber Composite Decking: A Case Study A typical deck requires approximately 11 trees, notes the Fiberon website.a Fiber Composites, LLC develops Fiberon composite decking as an alternative to traditional lumber materials, and much of the product line is manufactured with recycled wood and recycled plastics. Most of these products are 25 to 30 percent polyethylene, 10 to 12 percent polyvinyl chloride, and 51 to 53 percent wood.b A subset of Fiberon decking products underwent a life-cycle assessment conducted by SCS Global Services in compliance with ISO 14044 (Environmental Management—Lifecycle Assessment) and other ISO standards, which led to the development of an environmental product declaration.c These products have a minimum of 94 percent recycled content, including PE and wood fibers.d Fiberon products result in the recycling of 100 million pounds of plastic each year, using approximately 2000 plastic bags in a single board of decking. The products meet ASTM standards for specific gravity (ASTM D792), modulus of elasticity (ASTM D6109), and the linear coefficient of expansion (ASTM D6341), among others. a Fiberon Balance. https://balance.fiberondecking.com. b Fiber Composites, LLC. “Environmental Product Declaration: Fiberon | Composite Decking Systems.” In an email sent to staff, Brittany Segundo, from John Woestman of the Composite Lumber Manufacturers Association on March 18, 2022. c SCS Global Services. “Life Cycle Assessment of Composite Decking Systems.” In an email sent to staff, Brittany Segundo, from John Woestman of the Composite Lumber Manu- facturers Association on March 18, 2022. d SCS Global Services. “Recycled Content Certification for Fiber Composites, LLC.” In an email sent to staff, Brittany Segundo, from John Woestman of the Composite Lumber Manufacturers Association on March 18, 2022.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 137 plastic lumber is free of the chemicals used to treat wood lumber. However, plastic materials are vulnerable to weathering and degradation because of UV radiation (Breslin et al. 1998). Using recycled plastics waste may result in the inclusion of plastic that has already undergone degradation, further exacerbating the impact on the lumber’s material properties. Plastic lumber commands a higher initial cost than alternative materials, but its reduced maintenance costs indicate potential for lower costs over the service life of the product. Results on the compressive strength of plastic lumber are mixed and dependent on the plastic mixture and composition. Breslin et al. (1998) re- ported that the compressive strength of wood is two to three times greater than that of plastic lumber. Smith and Kyanka (1994) demonstrated that the compressive strength decreased with temperature increases, and wood had a compressive strength five times that of plastic lumber. By contrast, Lampo et al. (1998) observed that the compressive strength of plastic lumber samples was similar to or even greater than that of wood. The modulus of elasticity for plastic lumber products is much lower than that of wood (Breslin et al. 1998; Lampo et al. 1998). As a result of plastic’s viscoelastic properties, plastic lumber also undergoes significantly more creep and deflection, particularly under sustained loads and elevated temperatures (Krishnaswamy and Francini 1998; Lampo et al. 1998; Smith and Kyanka 1994). Moreover, one study found significant variation in the physical properties of plastic lumber samples from a single manufacturer, perhaps due to the heterogeneity of the material (Breslin et al. 1998). Re- searchers have evaluated the use of additives, such as fiberglass, as well as plastic composites, on plastic lumber performance (Ness et al. 2001; Nosker 1989; Nosker et al. n.d.). Oriented glass fibers may improve creep performance (Ness et al. 2001), but even samples of lumber with these ad- ditives are limited by a modulus of elasticity that is significantly lower than wood lumber’s modulus (Breslin et al. 1998). Given the reduced mechanical performance of plastic lumber, it is most appropriate for applications with small, infrequent loadings (Levie 1993). Plastic lumber is commonly used in decking, fencing, and waterfront ap- plications, such as pier decking and marine pilings. In applications such as decking, the material needs to be supported by wood framing, larger cross- sections, and/or joists and columns that are more tightly spaced than in the case of wooden decking. Plastic lumber’s upfront cost may make more sense in environments where wood is not an ideal material, such as in areas with lots of water (Lampo et al. 1998). Projects with plastic lumber are guided by multiple established ASTM standards: • ASTM D6108, Standard Test Method for Compressive Properties of Plastic Lumber and Shapes (ASTM 2019b);

138 RECYCLED PLASTICS IN INFRASTRUCTURE • ASTM D6109, Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and Related Products (ASTM 2019c); • ASTM D6111, Standard Test Method for Bulk Density and Specific Gravity of Plastic Lumber and Shapes by Displacement (ASTM 2019d); • ASTM D6112, Standard Test Methods for Compressive and Flexural Creep and Creep-Rupture of Plastic Lumber and Shapes (ASTM 2013); and • ASTM D6117, Standard Test Methods for Mechanical Fasteners in Plastic Lumber and Shapes (ASTM 2018a). A dearth of long-term performance data makes it challenging to evalu- ate manufacturer claims of durability and environmental impact of these products. Pilings for Port and Coastal Infrastructure Plastic lumber (or plastic timber) is well suited for marine piling and related marine applications. In a report by researchers from the U.S. Army Corps of Engineers and Rutgers University, Lampo et al. (2003b) detail different installations of recycled plastic lumber across various marine applications such as recreational pier, staging platforms, a boardwalk, and marine pilings. Plastic fendering and piles for port and marine applications are used widely. The Port of Los Angeles installed a prototype plastic pile in 1987 (Iskander and Hanna 2003) and since then it has used plastic fender piles and protective front-row piles in many construction projects (Los Angeles Harbor Department 2012). Although high initial cost has been a barrier to widespread deployment (Iskander 2012), the use of these products has grown in recent years. One of the larger installations of marine materials made with plastic pilings is at the Port of Hueneme, California, where these products were installed in 2018 as part of a harbor-deepening project. Plastic timber and pilings have been used as well in a fendering system at Port Newark in collaboration with the Port Authority of New York and New Jersey. The U.S. Army Corps of Engineers also used these products to build guide walls at Bayou Boeuf and Port Allen in Louisiana. Other installations of pilings and fenders fabricated with recycled plastic include, for example, Port Arkansas in Texas, and Oakland Bay Bridge in Califor- nia. Figure 7-1 illustrates the replacement, by the Florida Department of Transportation (DOT) in 2020, of a deteriorated wood fendering with a new fendering system fabricated with recycled plastics at a bridge located on the St. Lucie River.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 139 Plastic pilings are typically made from HDPE (Guades et al. 2010; Iskander 2012) and often reinforced with steel core, steel rebar, and/or fiberglass core, grid, or fibers. Because of their fabrication with multiple materials, they are also referred to as composite plastic piles. Since compos- ite plastic piles are typically manufactured with a minimum of 40 percent post-consumer recycled plastic content, Marc Hollahan of Tangent stated that one 20-ft. composite pile uses the recycled plastic generated from the waste of approximately 8,500 milk jugs. The Port of Hueneme installation mentioned above used recycled HDPE equivalent to 8.2 million milk jugs.1 Untreated wood lumber is vulnerable to marine borers. Wood treated with chromated copper arsenate, creosote, or other chemical preservatives can incur significant disposal costs when removed owing to regulatory re- strictions (USEPA 2023). By comparison, plastic piling is recyclable, even with reinforcement materials. Steel pilings are prone to corrosion, and concrete is sensitive to sodium and calcium chloride, which leads to cracks and potential corrosion of the interior reinforcement. While the initial cost 1 As presented to the study committee by Marc Hollahan on November 18, 2022. FIGURE 7-1 Replacement of wooden fender with HDPE structural fender system at the Martin Downs Blvd (SR-714) Bridge over the South Fork of the St. Lucie River in Stuart, Florida. SOURCE: Tangent Materials.

140 RECYCLED PLASTICS IN INFRASTRUCTURE of plastic pilings is two to three times the amount of pilings made of wood (Heinz 1993), Marc Hollahan of Tangent shared that the costs are recouped in approximately 8 to 12 years because of the reduced maintenance require- ments of plastic pilings.2 Composite plastic piles, as with all plastic lumber, are appropriately used only in environments with small, infrequent loading (Levie 1993). These piles demonstrate inferior drivability (i.e., during construction) and creep performance compared to wooden piles (Iskander 2012). Creep can be exacerbated with high temperatures and sun exposure (USEPA 1993). Understanding about their long-term performance and the environmental impact is limited by a dearth of published long-term performance data (Iskander 2012; Zyka and Mohajerani 2016). Reviews indicate the need for durability testing emulating saline marine conditions to assess the effectiveness of epoxies, evaluation of possible reinforcing arrangements to prevent lateral deflections, and full-scale field research to develop guidelines for driving composite plastic piles (Iskander 2012; Zyka and Mohajerani 2016). However, representatives from Tangent reported that plastic pilings perform competitively when it comes to cyclical loading and impact. Plastic pile development is guided by numerous ASTM specifications, including but not limited to the following standards: • ASTM D6109, Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and Related Products (ASTM 2019c); • ASTM D256, Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics (ASTM 2018b); • ASTM D570, Standard Test Method for Water Absorption of Plas- tics (ASTM 2018c); and • ASTM D4329, Standard Practice for Fluorescent Ultraviolet Lamp Apparatus Exposure of Plastics (ASTM 2021b). Railroad Ties According to the Association of American Railroads (AAR), in 2023 U.S. freight railroads own and maintain nearly 140,000 miles of rail track (AAR 2023). Maintaining this vast track network requires routine replacement of the approximately 450 million railroad ties, also known as crossties, in the system (RTA 2022). The Railway Tie Association (RTA) reports that in 2018, U.S. railroads installed and replaced about 16.1 million railroad ties (RTA 2022) (see Table 7-1). 2 Ibid.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 141 Traditionally, railroad ties have been manufactured from wood. Wood has shock absorption properties that reduce wear and tear of the rails and rolling stock. Wood also has the advantage of being an electrical insulator, thus preventing interference between the ties and electric rail monitoring equipment (Smith 2022). Wood ties have been treated with creosote since the mid-1800s. Creosote, a wood preservative derived from the distillation of tar from wood or coal, is used to protect wood from termites, fungi, and other pests. The U.S. Environmental Protection Agency (USEPA) states that creosote poses concerns for workers who handle it (OSHA 2023; USEPA 2022a). Loading conditions (high tonnage versus low tonnage), track geometry (straight versus curved), and climate (wet versus dry) affect the longevity of railroad ties, but it is generally accepted that the service life of creosote- treated wood ties is about 20 to 25 years (Bolin and Smith 2013; Vollin 2021). That life span is generally shorter in high-humidity environments and longer in arid climates. Although not as popular as creosote-treated wood ties, alternative tie materials include concrete, steel, and plastic composite ties. Manufacturers began experimenting with rail ties made from HDPE in the 1990s (Lampo et al. 2003a). Commonly known as composite ties, these products are manufactured from proprietary blends of recycled plastics and other materials, such as glass fiber. The manufacturers typically prefer high-quality recycled HDPE for railroad tie production,3 but railroad ties have been manufactured from other kinds of recycled materials, including shredded fiberglass–epoxy plastic composite material from end-of-life wind turbine blades (Jacoby 2022). Plastic composite and wood ties each weigh more than 200 pounds; thus, they could be used interchangeably (Macha- laba 2004). A particular advantage of composite ties is that they do not rot or degrade in wet and humid conditions and offer longer life cycles than wooden ties in those environments. 3 As presented to the study committee by William Mainwaring from SICUT on June 9, 2022. TABLE 7-1 Railroad Tie Installations (as Part of Capital Projects as Well as Maintenance) in the United States in 2018 New Wood Ties (thousands) Secondhand Wood Ties (thousands) New Ties Other Than Wood (thousands) Class I Railroads 13,389 111 279 Regional and Short Line Railroads 2,101 259 6 Total 15,490 370 285 SOURCE: Data obtained from RTA 2022.

142 RECYCLED PLASTICS IN INFRASTRUCTURE Although composite railroad ties made from recycled plastics have been deployed successfully in select projects, they have an uneven performance and deployment history (McHenry et al. 2018). Mechanical performance issues, handling considerations (i.e., storage and installation), and economic factors have contributed to limited deployments. With regard to mechanical performance, plastic composite ties have exhibited two primary types of structural failures that have delayed their routine use: cracks at the center span of the tie and fatigue cracks at the pike hole where the rail is fastened to the tie (McHenry et al. 2018). The coefficient of thermal expansion of composite ties, which is much higher than that of wood, is also a factor that needs to be considered.4 Because of their higher coefficient compared with that of wood, composite ties will expand and contract in size more than their wooden equivalents. Test re- sults indicate that tracks could experience up to 0.25-in. gage difference in a single day. While this gage difference is not a significant deterrent for the use of composite ties, it does merit further testing and monitoring owing to the potential for increased regular maintenance from railroad owners and operators (Gao and McHenry 2021). MxV Rail, a prominent rail field test facility, is investigating the thermal effects of composite ties to support specifications drafting by the American Railway Engineering and Maintenance-of-Way Association. The following characteristics are being investigated: required coefficient of thermal expansion and thermal conduc- tivity values in accordance with track class and acceptable gage widening, the appropriate ambient environment(s) (i.e., temperature, humidity condi- tions) necessary for installation, and best practices for accommodating the thermal influence of railroad track with plastic composite ties (Gao 2022). Plastic composite railroad ties have exhibited inconsistent performance depending on the batch of recycled plastic used in their manufacturing. Quality assurance could potentially address this issue. The Federal Railroad Administration (FRA) conducted testing in 2012 and concluded that some manufacturers’ plastic composite ties exhibited higher variation in me- chanical properties, such as bending stiffness and energy absorption, than others (FRA 2012). These variations in mechanical properties are further exacerbated by weathering, storing, or aging, resulting in different stiffness of some ties (FRA 2012). More recently, staff from Union Pacific stated that issues related to quality variations depending on the batch of ties have been addressed through continued process control by vendors and rigorous testing prior to entering the market (Beck 2021). From the perspective of construction, unlike wooden ties, composite plastic ties must be predrilled prior to installation in order to avoid cracking 4 The coefficient of thermal expansion of HDPE is between 6 × 10–5 and 11 × 10–5 in./in./°F. The coefficient of thermal expansion of wood, parallel to the grain, is 0.17 × 10–5 in./in./°F.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 143 of the tie at the location of the spike hole. Predrilling adds an extra step in the field in comparison to wooden ties. The extra step adds to the time and complexity of installation. Because of their durability, plastic composite railroad ties offer the opportunity of longer life cycles than wooden ties, especially in high- humidity environments, where wood is susceptible to rot. With the goal of minimizing the maintenance and replacement of ties, railroads and transit agencies are conducting evaluation studies of these materials and installing them in select projects. For example, in 2016, after Hurricane Sandy, the Metropolitan Transportation Authority used 7,500 composite ties in the re- construction of the Staten Island Railway terminal (Nunez 2016). In 2020, Union Pacific Railroad commissioned field and physical testing of polymer composite railroad ties to evaluate mechanical and thermal performance to industry specifications (Beck 2021; ESi 2020). The results of the ongoing evaluations are being used to update internal Union Pacific specifications and processes for railroad ties (ESi 2020). The U.S. Department of Defense (USDOD) has also taken an interest in the use of recycled plastics and composite ties for military rail infra- structure. For example, in 2018 a USDOD railroad tie replacement project was completed using recycled plastic and composite crossties at a cost of approximately US$3.4 million (Stewart et al. 2023). Inspections carried out a year later exposed tight gage problems (i.e., less gage than the standard) related to these ties. As a result, researchers from the U.S. Army Corps of Engineers and Mississippi State University have conducted studies to evalu- ate the use of recycled plastic and composite railroad ties for military rail infrastructure (Stewart et al. 2023). Stewart et al. (2023) concluded from an evaluation of published lit- erature that recycled plastic railroad ties could possibly be used in military rail infrastructure, but they identified significant impediments for their acceptance and systemic deployment by the military. Laboratory and full-scale testing conducted by Stewart et al. (2023) uncovered problems related to variability in the performance of recycled plastic ties, as well as changes both in dimension and in material properties with temperature (i.e., seasonal variation in gage and temperature-dependent ductility), and lower load-carrying capacity than wooden ties. The investigators also concluded that the use of recycled plastic railroad ties would not reduce maintenance or increase reliability of USDOD rail infrastructure. In their assessment, in order to avoid post-installation track problems that would adversely impact military readiness, the development of performance specifications is needed (Stewart et al. 2023). Performance-based speci- fications could help address performance shortcomings revealed during in-field testing.

144 RECYCLED PLASTICS IN INFRASTRUCTURE Life-Cycle Analyses Plastic ties could lead to increased environmental benefits from these prod- ucts. For example, according to composite rail tie manufacturers, 1.8 million metric tons of recycled plastics could be incorporated into the near 20 mil- lion railroad ties needed annually.5 However, there are no published life-cycle analyses to verify the claim. Bolin and Smith (2013) conducted compara- tive environmental life-cycle assessments of plastic composite railroad ties, creosote-treated wooden ties, and concrete ties and concluded that the use of plastic composite ties results in higher fossil fuel and water use and higher en- vironmental impacts (with the exception of the eutrophication impact6 indica- tor) than creosote-treated wooden ties. Based on the analysis, the use of plastic composite ties instead of wooden ties resulted in 2.5 times more fossil fuel use and 11 times more water use, and results in emissions with the potential to cause 5.0 times more greenhouse gases, 72 times more acid rain, and 1.1 times more smog. On the other hand, creosote-treated wooden railroad ties resulted in approximately 1.4 times more eutrophication impact than plastic railroad ties. Bolin and Smith (2013) note that their life-cycle inventory for plastic composite ties was designed to be representative of the product category, and therefore might not be accurate for a specific product brand. Overall, composite plastic ties provide a promising application of re- cycled plastics, but long-term performance data are needed. Further explo- ration of the service life, mechanical properties that are altered due to aging, and environmental impacts over the course of plastic tie use are needed. Composite Plastic Utility Poles There are an estimated 160 million timber utility poles in use in the United States (Zabel and Morrell 2020). Timber poles are impregnated with pre- servatives to mitigate decay that weakens the material properties of the structure, but the preservatives can pose health risks to workers in wood treatment facilities, and there are also environmental concerns (USEPA 2022a, 2022b). Timber pole service life estimates vary; one survey of the public indicated that most people assume a service life of 30-40 years (Mor- rell 2016), while another source suggested that the life is closer to 45 years (Bowmer 2021). However, in the same survey it was revealed that many poles are actually in service well beyond these estimates, with some poles still in active use after 90 years. Like wooden railroad ties, the service life 5 Information from William Mainwaring, SICUT North America Inc., during a public brief- ing to the committee, June 9, 2022. 6 Eutrophication impact is a critical part of a life-cycle assessment that measures the runoff of excess nutrients in local bodies of water, which can result in harmful and toxic algal blooms (USEPA 1993).

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 145 of wooden poles is determined in part by regional climate and other factors that affect the rates of decay. While timber poles are the dominant type of utility pole, poles may also be made from galvanized steel, concrete, and fiber-reinforced polymer (FRP) composite. Steel poles are stronger, lighter weight, and more resistant to decay. They have the added benefit of being completely recyclable (Love et al. 2021). Steel, however, is more expensive than timber and is prone to corrosion. Concrete poles are also strong, consistent in properties, and resistant to rot, decay, fire, and termites, as well as ice. Because they are less prone to corrosion, concrete poles are often employed for marine and wetland environments. A more recent development in utility pole construction is FRP compos- ites. Fibers are applied to a resin matrix through two common methods: filament winding and protrusion (Rigby 2008). The most common types of fiber include carbon, Kevlar, spectra, and glass. Matrices are typically made from polymers, though metals, carbon, ceramics, and concrete may also be used. The polymers used are either thermosets or thermoplastics. Thermoset polymers are considered better for the matrix because of their cost, stiffness, strength, fatigue life, and viscosity (Rigby 2008). Acceptable thermosets include unsaturated polyester, vinylester, phenolics, and epoxies. These products are not currently recyclable, as the cross-linked chemical structure of thermosets prevents them from being remelted. The first FRP pole was installed in Hawaii during the 1960s in a low- voltage environment. The installation lasted approximately 45 years but ultimately had to be removed due to UV-light-induced degradation (EPRI 2021). Since then, additives that provide resistance to UV degradation have improved the service life of composite poles. Manufacturers claim service lives ranging from 40 to 80 years (EPRI 2021; Rigby 2008). FRP composite poles can have higher initial cost than timber poles but offer performance advantages. They are resistant to corrosion, termites, and woodpeckers. The poles are high strength, relatively low weight, and low maintenance. Because of their relatively low weight, the poles are well suited for installation/replacement in difficult terrain, such as in mountain- ous or marshy regions (Barone et al. 2017). Additionally, FRP composite materials can be engineered to absorb the energy from vehicle impact. Ten percent of all fatal crashes with fixed objects are accidents with utility poles, and significant work has been done to develop poles with breakaway fea- tures (Foedinger et al. 2003). Such an approach has been piloted in New Jersey (FHWA 2016). Because FRP utility poles do not absorb water like timber poles, they perform well in areas with extreme weather and heavy storms. FRP poles have been observed to outperform noncomposite poles under severe weather (Coughlin 2018).

146 RECYCLED PLASTICS IN INFRASTRUCTURE Composite poles experience higher deflections due to wind and other lateral loads than steel or concrete (Barone et al. 2017; EPRI 2021). How- ever, composite utility poles may have more potential in rural settings, where lateral deflection is less of a concern. Utility poles are typically spaced around 125 feet apart in urban settings and 300 feet apart in rural environments. Composite poles can have a higher per-unit cost than alternatives, as their production is manufacturing-intensive. Due to their lower weight, however, the installation costs may be lower. Additionally, given manu- facturer claims for longer lifetimes, their life-cycle costs may be lower than those for timber, concrete, and steel poles (Barone et al. 2017; EPRI 2021). Specifications for utility pole load requirements are defined by the National Electric Safety Code (NESC). NESC CR-2007 includes guidance for FRP poles and compares them favorably to steel (IEEE 2006). Industry recommendations for composite utility pole manufacturing include ASTM D4923-92, Standard Specification for Reinforced Thermosetting Plastic Poles (ASTM 1992), and ANSI C136.20, Standard for FRP Lighting Poles (ANSI 2012). In 2003, the American Society of Civil Engineers (ASCE) developed, and updated in 2019, a comprehensive manual of practice for design, construction, monitoring, testing, and maintenance of FRP utility poles (ASCE 2019). Beyond the promising developments in FRP utility poles that incor- porate virgin polymers, there is little to no research on the use of recycled plastics in their production. Further research is needed in this area to de- termine the barriers to using recycled plastic as a source for the composite materials in FRP poles. There has been some investigation of structural reuse of FRP composite wind turbine blades as utility poles and towers (Alshannaq et al. 2022). Pipes Pipes for Stormwater, Sanitary Sewer, and Land Drainage Concrete, PVC, and PE are the most common materials for stormwater and irrigation drainage pipes. While completely inflexible, concrete pipes are used in projects and situations that demand high pipe-wall strength and can provide a complementary exterior shell for drainage pipes of another material that is weaker or more vulnerable to the environment or load (eSUB 2020). PVC is a commonly used material for drainage pipes. PVC exhibits strength properties that make it useful for drainage situa- tions where the water and environment exert a great deal of pressure and

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 147 weight. PVC pipes are manufactured in a wide range of sizes. PE pipes are the most flexible and light of the plastic pipe types, enabling rapid instal- lation and making them an optimal choice for projects that require piping and water to be transferred in small spaces and/or along routes with many turns (eSUB 2020). Drainage pipes are often made of HDPE and are used for storm sewers, culverts, and land drainage applications. They are usually manufactured in 4- to 60-inch diameters and in 20-foot lengths, with corrugated ribbing to provide strength for support of overlying soil. These products are an attractive alternative to other materials for drainage applications because they are relatively lightweight and easy to transport and handle on site, and because of their durability and resistance to corrosion and abrasion.7 According to the Association of Plastic Recyclers and the Northeast Re- cycling Council, the plastic drainage pipe industry is the largest user of non- food-grade, post-consumer HDPE (NERC and APR 2022). Using recycled plastic for HDPE pipes offers life-cycle benefits (e.g., increased durability, increased performance, and reduced pollution), as well as cost benefits. Additionally, there are no restrictions on the color of the recycled plastic used, since the end product—the pipe—is black. Also, the use of blending in the manufacture of plastic drainage pipes allows for use of recycled HDPE plastics with a wide range of properties. Virgin HDPE can be included in the blends to achieve desired properties. According to manufacturers of recycled HDPE corrugated pipe, these products are 20 percent more cost effective than using traditional materials, primarily because of their ease in installation, which is about three times faster and allows the use of lighter construction equipment.8 Until recently highway standards have traditionally required that plastic drainage pipes be manufactured from 100 percent virgin plastic (NERC and APR 2022).9 To evaluate the potential use of corrugated pipes manufactured with both post-consumer and post-industrial recycled HDPE, the National Cooperative Highway Research Program (NCHRP) conducted research over the past decade (NASEM 2018; TRB 2011). The NCHRP research concluded that recycled materials could be incorporated into American Association of State Highway and Transportation Officials (AASHTO) standards, provided the final material blends meet specific re- quirements. The research produced a draft revision to AASHTO M-294 to include the incorporation of corrugated pipes manufactured with recycled 7 Presentation by Michael Pluimer from the University of Minnesota Duluth to the study committee on June 9, 2022. 8 Presentation by Daniel Figola and Gregg Bohn from ADS to the study committee on June 9, 2022. 9 Presentation by Michael Pluimer from the University of Minnesota Duluth to the study committee on June 9, 2022.

148 RECYCLED PLASTICS IN INFRASTRUCTURE HDPE, draft revisions to AASHTO Bridge Design Specifications to include material properties for pipes manufactures with recycled content, and an ASTM test method F3181 for evaluating crack stress of these materials (ASTM 2016). Supported by the research, the revised AASHTO M-294 published in 2018 allowed the use of HDPE drainage pipes with recycled content. A year later, in 2019, AASHTO published the new Standard Recommended Practice for Service Life Determination of Corrugated HDPE Pipes Manu- factured with Recycled Material. Per AASHTO M-294, corrugated PE pipes are required to meet the 100-year service life required for this application regardless of the source material (AASHTO 2021). The adoption of these standards has been a catalyst to the deployment of drainage pipes manufactured with post-consumer recycled HDPE for drainage applications in transportation projects (AASHTO 2018). Today there are numerous companies that produce corrugated pipes manufactured with recycled HDPE that meet the AASHTO and ASTM standards. Box 7-2 presents a case study of corrugated pipe manufactured with recycled plastics. BOX 7-2 Corrugated Pipe Manufactured with Recycled HDPE: A Case Study ADS Recycling is the largest HDPE plastics waste recycler in North America. It has nine facilities in the United States and Canada. Today, more than 50 percent of the HDPE plastic purchased by ADS is recycled plastic, which amounts to more than 600 million pounds of recycled HDPE plastic. The company’s goal is to recycle 1 billion pounds of plastic per year by 2032. ADS purchases recycled HDPE plastic in various formats: post-consumer bales of mixed-color HDPE, post-industrial bottles, shipping materials and sup- plies made of HDPE plastic, post-industrial scrap, and used solid and corrugated HDPE pipe that has reached the end of its service life. The purchased post- industrial and post-consumer HDPE plastics are sorted and separated (either at an ADS plant or by one of its mobile operations), washed, and pelletized by ADS Recycling. The pellets are then taken to the ADS pipe manufacturing facil- ity for corrugated HDPE drainage pipe production. During production a series of material tests is conducted (e.g., moisture analysis, infrared spectroscopy, strand testing, and melt index analysis) to ensure quality control.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 149 BOX 7-2 Continued The pipes produced meet the ASTM and AASHTO specifications for land drainage applications (ASTM F2648),a for storm sewer applications (ASTM F2306 and AASHTO M 294),b,c and for sanitary sewer applications (ASTM F2947).d a ASTM F2648/F2648M-22, Standard Specification for 50 mm to 1500 mm [2 in. to 60 in.] Annular Corrugated Profile Wall Polyethylene (PE) Pipe and Fittings for Land Drainage Applications. https://www.astm.org/f2648_f2648m-22.html. b ASTM F2306/F2306M-21, Standard Specification for 300 mm to 1500 mm [12 in. to 60 in.] Annular Corrugated Profile-Wall Polyethylene (PE) Pipe and Fittings for Non-Pressure Gravity-Flow Storm Sewer and Subsurface Drainage Applications. https://www.astm.org/ f2306_f2306m-21.html. c AASHTO M 294-21, Standard Specification for Corrugated Polyethylene Pipe, 300- to 1500-mm (12- to 60-in.) Diameter. AASHTO Materials Specification. Washington, DC. d ASTM F2947/F2947M-21, Standard Specification for 150 to 1500 mm [6 to 60 in.] Annular Corrugated Profile-Wall Polyethylene (PE) Pipe and Fittings for Sanitary Sewer Ap- plications. https://www.astm.org/f2947_f2947m-21a.html.

150 RECYCLED PLASTICS IN INFRASTRUCTURE Natural Gas Pipelines HDPE and PVC plastic pipes have been used in the natural gas industry since the late 1950s. While most natural gas gathering (i.e., upstream dis- tribution) and transmission pipelines are constructed of steel, most down- stream distribution pipelines (e.g., customer service lines)—which represent the largest amount of pipeline mileage in the United States—are constructed predominantly of plastic pipe (USDOT 2015). The Pipeline and Hazard- ous Materials Safety Administration reports that in 2021, 805,000 miles of main distribution lines and 730,000 miles of service lines in the United States were made of plastic. These mileages correspond to 60 and 76 per- cent of the total number of main and service pipeline miles, respectively (USDOT 2022). ASTM and American Society of Mechanical Engineers standards exist for PE plastic pipe (USDOT 2015). While research, standards development, and market-driven manufac- turing exist for nonpressurized applications, such as drainage pipes, as discussed in the previous section, the potential use of recycled plastics in pipes for high-pressure applications, such as gas distribution or water distri- bution, still lacks robust examination and evidence for its deployment. The Plastics Industry Pipe Association of Australia (PIPA) states that standards for pressure pipes exclude the use of recycled plastics because pre- and post-consumer material in the waste stream is highly variable and its char- acteristics are impractical to assess (PIPA 2022). Recent research by Juan et al. (2020) indicates promising results for the use of recycled PP in pressure pipes. The same research concluded that the use of recycled PE in pressure pipes is highly dependent on the quality and degree of contamination of the recycled materials (Juan et al. 2020). Once conclusive evidence-based research is completed in support of the use of recycled plastics in high- pressure pipes, standards will need to be drafted and adopted to bring this application to market.10 Plastic Bike Paths While road infrastructure for heavy vehicles relies on traditional materi- als such as Portland cement concrete and asphalt, an all-plastic bike path surface produced from 100 percent recycled PP was constructed in 2018 in the Netherlands. Known as PlasticRoad, the project—a 100-foot bike path—was constructed as a collaborative pilot between the province of Overijssel and the municipality of Zwolle, as a solution for a location prone to recurring flooding (PlasticRoad 2022). The modular components of the PlasticRoad are designed with water storage capacity in the hollow 10 Panel discussion with committee during public meeting session on June 9, 2022.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 151 space under the bike path deck, allowing water to drain away from the bike path surface even in extreme rain and later gradually infiltrate into the lo- cal subsoil. Figure 7-2 presents a bike path sign in Zwolle illustrating the water drainage feature of the PlasticRoad. The manufacturer reports that at the highest water level experienced to date, only 48 percent of the water storage was needed. The hollow substructure of the PlasticRoad modules also provides access for installing sensors and accommodating cables for utility services. The PlasticRoad bike path in Zwolle used the equivalent of 218,000 re- cycled plastic cups (PlasticRoad 2022). From the perspective of greenhouse gases, the manufacturer indicates that with this construction, the project achieved carbon savings of at least 52 percent compared to a traditional FIGURE 7-2 Sign in Zwolle, the Netherlands, illustrating the cross-section of PlasticRoad panels. SOURCE: Randy West.

152 RECYCLED PLASTICS IN INFRASTRUCTURE bicycle path. A second pilot, in Giethoorn (the Netherlands), is evaluating an improved installation process to overcome subsoil issues. While the current range of applications is limited to light-loading environments, such as bike paths, schoolyards, and parking spaces, the manufacturer suggests that the PlasticRoad could potentially be used for automobile and truck roads in the future. However, to achieve that, fur- ther research, development, and testing is needed to understand and ensure adequate performance. Highway Sound Barriers Highway sound barriers are constructed for new highway construction and existing highway improvements mainly for noise abatement to residential communities and other noise-sensitive areas. The latest sound barrier inven- tory, maintained by the Federal Highway Administration (FHWA), indicates that, from 1963 (when the first sound barrier was built [FHWA 2017a]) to 2019, 3,537 linear miles of barriers were constructed in the United States totaling more than 269 million square feet (FHWA 2021). Barrier height varies by state from 7 feet to 18 feet and is 14 feet on average. The use of sound barriers grew substantially starting in the 1970s after several legislative acts including the National Environmental Policy Act (NEPA) of 1969, which provided broad authority and responsibility for evaluating and mitigating adverse environmental effects such as highway traffic noise, and the Federal-Aid Highway Act of 1970, which mandates that FHWA develop noise standards for mitigating highway traffic noise. Traditionally, sound barriers are made from precast or cast-in-place concrete sections. However, other types of materials are used in sound barrier construction. The sound barrier inventory indicates barriers con- structed with a single material make up 84 percent of all barriers; the remaining 16 percent of all barriers are constructed with a combination of materials (FHWA 2021). Figure 7-3 illustrates the percentage of barriers constructed with single materials or a combination. The FHWA regulations for mitigation of highway traffic noise in the plan- ning and design of federally aided highways are contained in 23 Code of Federal Regulations (CFR) 772. The regulations require the following during the planning and design of a highway project: (1) identification of traffic noise impacts, (2) examination of potential mitigation measures, (3) the incorporation of reasonable and feasible noise mitigation measures into the highway project, and (4) coordination with local officials to provide helpful information on compatible land use planning and control. Compliance with the noise regula- tions contained in 23 CFR 772, “Procedures for Abatement of Highway Traffic Noise and Construction Noise,” is a prerequisite for the granting of federal-aid highway funds for construction or reconstruction of a highway (FHWA 2017b).

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 153 FHWA’s 1995 Highway Traffic Noise Analysis and Abatement Policy and Guidance allows the state DOTs flexibility in creating State Noise Abatement Policies, and this flexibility has carried over into noise barrier design (Office of Environment and Planning Noise and Air Quality Branch 1995). Most state DOTs that have been building sound barriers have their own specific requirements for barrier construction, and these affect the costs and materi- als, durability, ability to satisfy aesthetic desires of the public including the nearby residents and localities, and other environmental considerations. For structural design, states follow the guidance in the Noise Barrier Design Handbook (FHWA 2021) and the AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications, Section 15, “Design of Sounds Barriers” (AASHTO 2022).11 Various types of plastic walls have been put into service as a replace- ment for concrete or steel panels or wood inserted between steel or concrete frames. However, as the sound barrier wall inventory indicates, the use of 11 The Guide Specifications for Structural Design of Sounds Barriers from 2002, which were issued as a standalone publication, were incorporated into the current edition of the LRFD Bridge Design Specifications. FIGURE 7-3 Main materials used in sound barriers in the United States. NOTE: The category “Single material construction: other materials” comprises acrylic, carsonite, composites, undefined concrete, fiberglass, plastics, and other unspecified materials. SOURCE: Created with data from FHWA 2021.

154 RECYCLED PLASTICS IN INFRASTRUCTURE plastic walls is minor. Fewer than 1 percent of single-material walls in the United States are manufactured with plastics (see “Single-material construc- tion: other materials” in Figure 7-3). For walls fabricated with a combi- nation of materials, recycled plastics might be one of several components (e.g., polymer composite or aluminum shell filled with adsorptive material such as recycled PET, tire scrap, or other material or solid panels gener- ally made from proprietary blends of recycled HDPE and LDPE and other materials, such as glass fiber). In general, wall panels are manufactured from a recycled plastic composite that is extruded into tongue-and-groove structural planks that can, during construction, be stacked within a frame. Box 7-3 presents a case study of HDPE noise wall panels in Victoria, Australia, where these panels are being deployed as part of Victoria’s ecologiQ initiative to integrate recycled content across transportation in- frastructure (Victoria’s Big Build 2022a). Acceptance and regular use of innovative products in infrastructure benefits from the development and adoption of performance-based speci- fications. Victoria’s Big Build initiative adopted performance-based speci- fications in 2021, which enabled the deployment of plastic sound barriers discussed in Box 7-3 (Australia HeavyQuip Journal 2021; Victoria’s Big Build 2022b). Additionally, when surveyed about choosing sound barrier material (Ernst et al. 2008), state DOTs indicated that durability informa- tion, material specification information, material costs, and issues with con- struction specification not being achieved were very important. The novelty and unfamiliarity with these new products and their performance may limit the rate of acceptance by infrastructure owners in the United States. As with other infrastructure components made with recycled plastics, plastic sound barriers are vulnerable to weathering and degradation due to UV radiation, thus necessitating the use of a UV compatibilizer. They are, however, less vulnerable to rot and insect attacks than barriers made of wood. Plastic sound barriers are more prone to warping and creep due to the material’s viscoelastic properties, especially in elevated temperatures (Krishnaswami and Francini 1998; Lampo et al. 1998; Roschke and Esche 1999; Smith and Kyanka 1994) and are therefore likely to be framed by wood and/or steel supports. In one particular configuration of plastic bar- riers, the researchers found that, after 1 year, the material deflections fell within an acceptable tolerance, and they concluded that any deformation would likely not impact the service life (Roschke and Esche 1999). Plastics are less stiff than concrete and masonry block barriers. As a result, they pose more challenges in sound barrier applications where the barriers also serve as an impact barrier for vehicles (Roschke and Esche 1999). Plastics or wood–plastic composites may be used for sound barriers, but plastics with- out wood fibers perform better over the course of multiple freeze-and-thaw

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 155 BOX 7-3 HDPE Noise Wall Panel: A Case Study Along the Mordialloc Freeway in Victoria, Australia, 32,000 square meters of noise wall panels manufactured with recycled HDPE were successfully installed in 2021 as a pilot project for the state’s Recycle First policy. Rotationally molded plastic panels were formed from 570 tons of hard and soft recycled HDPE plas- tics. Because they were rotationally molded, the panels could be designed to any shape, color, and pattern. This design flexibility allowed them to match aesthetic considerations of the locality. A new performance specification was developed in Victoria to support the installation of plastic noise walls with up to 100 percent recycled plastic. The walls, developed as part of the ecologiQ initiative, use a novel configuration with rotationally molded panels that aids in superior acoustic performance. They currently are 75 percent recycled plastic and use up to 570 tons of soft and hard HDPE sourced from post-consumer household waste. These noise walls also meet technical requirements around UV stability, fire performance, thermal expansion, and light reflection, among others, and they are easier and safer to install. Based on laboratory testing, the supplier estimates that the service life of these sound barriers will be two to three times that of wooden walls and likely similar to those made of concrete. SOURCE: Presentation to the study committee by Scott Taylor and Alexis Davison of Major Road Project Victoria and Tony Aloisio of ecologiQ on July 20, 2022.

156 RECYCLED PLASTICS IN INFRASTRUCTURE cycles, which can impact the strength and stiffness of the material (Saadegh- vaziri and MacBain 1998). One benefit of using plastic lumber or extruded plastics in sound barriers is that the material is graffiti-resistant, a desirable characteristic for transportation agencies (Ernst et al. 2008). Most importantly, the limited data on plastic sound barriers indicate that they perform comparably or may even exceed sound reduction stan- dards. In one study, the prototype sound barrier exhibited noise reduction of around 17 dBA, which exceeded the state agency standards (Roschke and Esche 1999). Another paper posited that the higher density of plastic will lead to increased noise inhibition over wood materials (Hag-Elsafi et al. 1999). One configuration of recycled plastic barriers demonstrated a noise reduction coefficient that was higher than concrete and the same as 4.4 cm of wood, though all three materials fell below the threshold required for “sound absorptive” materials (Saadeghavaziri and MacBain 1998). The sound transmission class, determined in accordance with ASTM E90-90 and E413-87, of the prototype was slightly higher than that of wood, but much lower than that of concrete. Saadeghavaziri and MacBain note that their results are not representative of the holistic acoustic performance and do not capture the varied performance at different frequencies. Geosynthetics Geosynthetics are plastic products used to contain liquids, stabilize and strengthen soils, prevent erosion, and perform other geo-environmental func- tions (Koerner 2012).12 Because geosynthetics are buried—underground, underwater, or within retaining walls—these materials are protected from weathering and UV light damage, making them a durable and cost-effective solution for terrain stabilization and leakage control. The main markets for geosynthetics are the civil engineering and geotechnical industries, for example in the construction of roads, airfields, embankments, canals, dams, and landfill liners (Koerner 2012). Geosynthetic products are used during all construction stages to strengthen infrastructure, limiting erosion, controlling evaporation, and increasing the longevity, resilience, and safety of structures. Koerner (2012) lists seven types of geosynthetic products—geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, and geocomposites—manufactured for a wide range of applications (see Figure 7-4).13 While their structure (e.g., grid versus membrane) and material composition vary depending on their purpose, all of them are typically manufactured from thermoplastic polymers, mainly PE or PP. 12 The information for this paragraph builds on information from GeoSolutions (2021). 13 Presentation to the study committee from Fred Chuck, Executive Director of the Geosyn- thetic Materials Association, on June 7, 2022.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 157 Geosynthetics are highly engineered, durable products with a potential design life of more than 100 years.14 Additionally, they typically do not contain harmful chemicals, and their constituent polymers are not easily lost into the environment. Geosynthetics are thermoplastics and can be recycled at the end of their design life. While, historically, geosynthetics have been manufactured from virgin polymers, innovation in the use of recycled plastics has moved forward in the past few years. For example, in 2020 the largest manufacturer of geo- synthetics in Australia increased the use of recycled plastics in its products, creating a product line of geotextile rolls that uses 100 percent recycled packaging, flat drainage pipe made from 100 percent recycled HDPE, and nonwoven paving fabrics made from recycled PET (International Geosyn- thetics Society 2021; Roads & Infrastructure 2021). Reported estimates indicated that during 2020 this Australian company used plastics from 11 million recycled PET bottles (Roads & Infrastructure 2021). The company also indicates that since 2020, its initiatives diverted nearly 1.5 percent of the annual amount of plastics disposed of in Australia. While several U.S. geosynthetic products made from recycled plastics exist in the market (see Table 7-2), their use and acceptance in the United States is not as established. 14 Ibid. FIGURE 7-4 Nonwoven geotextile being installed at road construction site. SOURCE: Cherokee MFG, LLC.

158 RECYCLED PLASTICS IN INFRASTRUCTURE Recycled plastics might also be employed in the form of pins for slope stabilization (Bowders et al. 2003; Islam et al. 2021)15 and, in conjunction with geosynthetics, offer an alternative to traditional concrete piles (Islam et al. 2022). According to the Geosynthetic Materials Association, there are several impediments to widespread use of recycled plastics in the manufacture of geosynthetics. A primary obstacle is the ability to obtain the materi- als in sufficient quantities that meet the material consistency and quality requirements to ensure the quality and performance of the manufactured geosynthetics.16 15 Bowders et al. (2003) evaluated the performance of recycled plastic pins (RPPs) at five different sites. RPPs are made of various materials, typically HDPE or LDPE that is compres- sion molded or extruded. 16 Presentation to the study committee by Fred Chuck from the Geosynthetic Material As- sociation on June 7, 2022. TABLE 7-2 Available Geosynthetic Products in the United States and Manufactured with Recycled Plastic Suppliers Products Product Type Raw Materials Application Huesker Fortrac Eco Geogrid 100% recycled PET Soil reinforcement Basetrac Eco Geogrid 100% recycled PET Road base and subbase reinforcement California Green Paving Ecoraster E30 Geogrid 100% recycled LDPE Subbase reinforcement and slope stabilization Landscape Discount NDS EZ Roll Gravel Pavers Geogrid 100% recycled HDPE High-traffic gravel areas that are normally covered with asphalt or concrete Boom Environmental Products Green Geotextiles® Geotextile 100% recycled plastic bottles Increase soil stability, provide erosion control or aid in drainage Cable Ties and More GeoGrid Permeable Ground Stabilization Paver Geogrid 100% recycled HDPE Geogrid paver for driveways and parking areas SOURCE: Dr. Halil Ceylan, information-gathering session on June 9, 2022.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 159 Concrete Additives and Aggregates Concrete is a mixture of water, cement, fine aggregate, and coarse aggre- gate, with aggregate as the predominant component. Water and cement react chemically to create a paste binder for the aggregate. The quality of concrete is based on the quality of the paste, aggregate, and the bond between paste and aggregate. In a presentation to the committee, Rick Bohan, senior vice president of sustainability for the Portland Cement As- sociation, described concrete’s long history with experimental additives.17 Bohan noted that thousands of papers have been published on the use of recycled plastics and byproducts in concrete, but there is a dearth of practical research and experience in the field. Most of the work, he said, is academic and not currently scalable. One potential use for recycled plastics is as a fine aggregate or fiber in concrete. Khalid et al. (2018) mechanically recycled PET bottles to produce differently shaped fibers, which were then incorporated into concrete beams. They showed that the tensile strength and strength of first crack were improved with certain fibers. Ring-shaped PET fibers on concrete performed comparably to concrete beams with com- mercial synthetic fibers. Numerous other research papers explore the use of recycled plastics as a partial replacement for sand as a fine aggregate in concrete. Kou et al. (2009) used scrapped PVC pipe granules in conjunction with river sand as fine aggregate in a concrete mixture with Portland cement and expanded clay. The concrete prepared with PVC was lighter and more ductile, and had lower drying shrinkage and higher resistance to chloride ion penetra- tion. However, inclusion of PVC granules also led to decreased workability, compressive strength, and tensile splitting strength. Similarly, Nodehi and Taghvaee (2022) concluded that the use of recycled plastics in concrete results in improved impact resistance, abrasion resistance, and insulation characteristics, but it reduced the mechanical properties of the final product. Mustafa et al. (2019) experimented with recycled polycarbonate plastic particles as a partial replacement for sand as a fine aggregate in concrete beams. Incorporating recycled plastics decreased strength under static load but increased strength under impact load. Slump values and compressive strength of the concrete decreased as plastic content increased. Flexural energy increased with 20 percent recycled plastics under impact load. Tayeh et al. (2021) used PET and PE from industrial tanks and bottles to partially replace uncrushed natural sand as a fine aggregate. The plas- tic was cleaned with pressurized water and ground by blade mill and then combined with Portland cement and different coarse aggregates for 17 Presentation to the study committee by Rick Bohan of the Portland Cement Association on June 7, 2022.

160 RECYCLED PLASTICS IN INFRASTRUCTURE experimentation. The authors found that plastic reduced the weight of concrete samples and reduced strength metrics. However, the inclusion of plastic improved impact resistance. In general, sound insulation and ther- mal insulation, as well as density, improve with the inclusion of recycled plastics in concrete (Almohana et al. 2022; Siddique 2008). Field trials with recycled plastic as an aggregate in concrete have been limited in number.18 The amount of plastics included in some of these field trials is marginal compared to that of control samples. There is a lack of practical research and experience using recycled plastics in concrete and cement. Bohan noted that the impact of the inclusion of recycled plastics on longevity and durability of concrete is an open question and depends on how the plastic is used. Plastic could potentially be incorporated as filler for aesthetics, plastic rebar for reinforcement, or fibers for secondary reinforcement. More research is being done to see if recycled plastic fibers can be used as primary reinforcements. For the concrete industry to consider incorporating any material into concrete mixes as aggregate and/or for strength, it must make economic sense (is there a consistent and regular supply), the material needs to be physically and chemically inert, the material must have consistent physical and chemical characteristics, and it must have a consistent impact on fresh and hardened concrete properties. Plastic feedstock would need to be tested and free of organic materials prior to incorporating into concrete. Use of recycled plastics in concrete would require large amounts of clean plastic to be reliably available. During his presentation to the committee, Bohan remarked that the use of plastics in concrete will be experimental until ASTM specifications are developed to support their addition. Voluntary consensus standard-devel- oping bodies would need to develop taxonomy for use of recycled plastics, the American Concrete Institute would need to develop specifications for concrete waste, and code authorities such as the International Code Council would need to reference these specifications when updating design codes. Because this process could pose an obstacle to large-scale innovation, Bo- han stated that the Portland Cement Association and similar organizations favor expedited standard development when appropriate. Bricks Earth-Mix Bricks Experimental work has explored the use of recycled plastics in earth-mix bricks for building. Akinwumi et al. (2019) crushed PET bottles into two 18 Ibid.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 161 differently sized particles that were then compacted and heated. The PET particles were mixed with a disturbed soil sample of clayey sand to form compressed earth bricks. The authors found that erosion rates increased with the inclusion of recycled plastics, so a binder and finer plastic particles may improve performance. Results of this work indicate that bricks con- taining 1 percent shredded PET bottles may be used for non-load-bearing or lightly loaded walls but would require stabilization for heavily loaded walls. Another paper explored using LDPE with sand to form sand blocks (Kumi-Larbi et al. 2018). The authors report that these sand blocks are used in roads, pavements, and “hard standing areas.” Decreased sand par- ticle size led to increased density and compressive strength, and the blocks behaved similarly to asphalt in compression but failed in shear. Their results suggest that, due to compressive strength comparable to that of C20/25 concrete, the blocks could be used in buildings, such as in roofing tiles and partitioning walls. Gjenge Makers in Kenya used post-industrial recycled plastics to pro- duce bricks that are “almost five to seven times stronger than concrete” (Waita 2021). The bricks have been used in the Mukuru Slums Develop- ment Project as well as in sidewalks in the Nairobi business district (Joe 2021). Limited and inconclusive data are available on the long-term perfor- mance and environmental impact of such products. Plastic Bricks A company called ByFusion developed a steam and compression process to produce recycled-plastic bricks (ByFusion 2022a) (see Figure 7-5). From the infrastructure perspective, the application of this product is limited to low load-carrying capacity applications, such as bus shelters, park settings or sound barriers, and sheds. Each recycled-plastic brick called a ByBlock uses approximately 22 pounds of unsorted plastic (i.e., sensitivity to plastic type and/or impu- rities is not a critical factor for its manufacturing process and product performance) and requires no additives or fillers. The building blocks do not require mortar or glue for installation, but instead are held together using post-tension, reinforced with rebar installed into base footing. For applications where the blocks are directly exposed to the elements, a UV sealer is necessary to prevent degradation. Likewise, fire-resistant barriers (e.g., drywall) and materials would need to be used in order to meet any building requirements. ByFusion’s process can accommodate almost all plastics without limit, except for polystyrene and similar plastics made with foam. According to the manufacturer, these blocks emit 83 percent less carbon, and they are

162 RECYCLED PLASTICS IN INFRASTRUCTURE FIGURE 7-5 Photo of a ByFusion block. SOURCE: Chris Piotrowski, ByFusion. lightweight as compared to concrete (ByFusion 2022b). Because the blocks do not require mortar or any special skills for installation, the company es- timates that the cost of building projects will be 54 percent less and take 65 percent less time than comparable projects using concrete. The long-term performance and environmental impact of these products remain untested. Flooring Tiles and Panels There are some early-stage efforts to investigate the use of recycled plastic to form flooring tiles. One group formed tiles from mixtures of LDPE and flame retardant at varying levels to demonstrate that, at specific levels of each, flammability was reduced and tensile strength was improved (Dhawan et al. 2019). LDPE plastics bags were cleaned, shredded, and mixed with filler materials. Afterward, a screw extruder formed the material into wires that were then cut into pellets, heated in an oven, and the resulting mate- rial compression molded into tiles. The authors state that these tiles could potentially be used as pavers or structural floor tiles. Global Fiberglass Solutions has developed a process to recycle com- posite fiberglass–plastic material from end-of-life wind turbine blades (Ja- coby 2022). Wind turbine blades are about 30 percent thermoset plastics by weight, with various epoxies, polyesters, and vinyl esters used to bind

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 163 together the reinforcing fibers. The blades are cut and shredded to produce small pellets, which are then processed to produce construction and flooring panels (Jacoby 2022). Two-Way Hollow Structural Slabs By insertion of hollow plastic spheres into structural slabs for buildings, the amount of concrete required for the slab can be reduced, speeding construction, lowering costs, and reducing loads for building foundations to support. This is the basis of BubbleDeck, a patented technology that links the use of air, steel, plastic, and concrete (BubbleDeck 2023). The hollow plastic spheres are held in place by reinforcing steel, as illustrated in Figure 7-6. For a majority of BubbleDeck projects, the plastic spheres are manufactured with 100 percent post-industrial plastic.19 HDPE is used for the smaller spheres employed in slabs from 9 to 24 inches thick, while polypropylene is used for larger spheres in slabs with thicknesses greater 19 Email correspondence of David Dzombak with Jerry Clarke Ames, BubbleDeck Canada Ltd., January 10-11, 2023. FIGURE 7-6 BubbleDeck hollow HDPE plastic spheres installed in a floor slab prior to pouring of concrete. SOURCE: BubbleDeck.

164 RECYCLED PLASTICS IN INFRASTRUCTURE than 16 inches.20 The HDPE spheres are manufactured via blow molding, while injection molding is used for the polypropylene spheres. Post-indus- trial plastics, such as HDPE from ground-up, off-specification kayaks, are used as feedstock to ensure product quality and avoid the manufacturing problems that can ensue from the presence of contamination, especially for the blow molding process.21 ROLE OF PUBLIC AGENCIES AND OTHER INFRASTRUCTURE OWNERS The use and value of recycled plastics in infrastructure components need to be understood by the various stakeholders of the infrastructure ecosystem, including public agencies, private infrastructure owners, designers and contractors, procurement professionals, and the general public. There are common themes that impede the widespread adoption of recycled plastics use in infrastructure: 1. Amount and depth of research on the other uses of recycled plastics in infrastructure. Most of the uses of recycled plastics in nonpave- ment infrastructure products presented in this chapter have been limited or are still in their nascent stage. 2. Design criteria, guidelines, and standards. Professionals rely on de- sign criteria, guidelines, and standards for the design, construction, and operations and maintenance of infrastructure. This assures them of understood and predictable performance and safety of the built infrastructure. Absent accepted design criteria, guidelines, and standards for the use of recycled plastics in infrastructure, there is an unavoidable skepticism on the feasibility of recycled plastics use in infrastructure. 3. Knowledge gap and disconnect between research literature and field. Research work from bench to pilot has been conducted for many years on the use of recycled plastics in the asphalt pavement industry, in railroad ties, and in some other applications. As dis- cussed in this chapter, there are some owners and designers who have explored the possibility of using materials manufactured with recycled plastics in other infrastructure. However, in most cases, applications that consider a more expansive temporal and spatial scale beyond a pilot have been very limited. 4. Uncertainty in costs and cost effectiveness over the life cycle of the use of recycled plastics in infrastructure. As discussed in Chapter 4, 20 Ibid. 21 Ibid.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 165 Life-Cycle Considerations, there are special considerations to make in the emerging uses of recycled plastics in infrastructure. Those considerations vary relative to programmatic or project-level life- cycle cost and cost-benefit analysis. Complicating this uncertainty are the social, economic, and environmental issues related to indi- vidual infrastructure system assets in which materials incorporating recycled plastics might be deployed. 5. Reconciling public awareness and effective use of recycled plastics in infrastructure. There is significant value in bridging the gap between public perception of what could be done with recycled plastics as well as the feasibility of building infrastructure using re- cycled plastics. Procurement strategies need to be explored through a review of project requirements and can serve to bring perception and feasibility closer together. The examples provided in this chapter about use of recycled plastics in infrastructure components indicate that relatively few public agencies and asset owners have been working on use of recycled plastics in infrastructure (see also Appendix D), but there has been some progress. The reasons vary, but this progress has provided a foundation for growth of innovative use of recycled plastics in infrastructure, even with the constraints associated with established engineering practices. Standards and policies can accelerate this innovation. An example of a supportive policy, other than those already presented in Chapter 5, is California Assembly Bill No. 2953 (California AB 2953, 2022). The statute requires the California Department of Trans- portation and local transportation agencies to use recycled materials in construction projects. There is a generic reference to recycled materials for use in highways but it could possibly include recycled plastics. Standards related to use of recycled plastics in infrastructure will also help advance use of recycled plastics and can precede statutes. FINDINGS • Using recycled plastics in infrastructure has been studied and evalu- ated for decades for certain applications but with limited success in deployment in the United States. Only one application, drainage pipe, has generated significant demand from infrastructure owners. • A number of other applications have attracted commercial inter- est to varying degrees. The factors that are inhibiting demand by infrastructure owners differ by application. While some products, such as marine pilings/fenders and railroad ties, are starting to gain interest among infrastructure owners who are incorporat- ing them into select projects, acceptance of these applications has

166 RECYCLED PLASTICS IN INFRASTRUCTURE been inhibited by factors that include high material and installa- tion costs, uncertainties about long-term performance and environ- mental impacts, and general lack of familiarity with the products. Other applications, such as plastic bricks, are a recent market development and, as such, there are no historical data regarding their engineering and environmental performance. • Although there is an absence of long-term testing related to the performance and environmental impact of many infrastructure products incorporating recycled plastics, these materials gener- ally present advantages in corrosive and humid/wet environments where—due to material properties—plastics excel but traditional materials experience higher rates of degradation due to rot and saltwater. • Many of the products manufactured with recycled plastics and marketed for infrastructure applications involve proprietary mate- rial formulations and manufacturing processes. • Market expansion of infrastructure-related products manufactured with recycled plastics depends on feedstock recycled plastics that are reliably available, in sufficient quantity, at sufficient quality, and at prices competitive with virgin plastics. • Thermoplastic polymers HDPE, LDPE, linear low-density polyeth- ylene, and PET are the most commonly used recycled plastics in the infrastructure applications surveyed here. Recycled PP is also being used in a more limited number of infrastructure applications. • Products for specific infrastructure applications have varying levels of sensitivity to plastic blend and impurities in the recycled plastics feedstock. For applications sensitive to plastic blends and impuri- ties, such as concrete aggregate, a well-sorted, clean supply of recycled plastics is required for successful scalability. Applications where performance is less sensitive to plastic blend and impurities (e.g., steam-compressed plastic bricks) may be viable for lower- quality supply chains of recycled plastics. • Other applications of recycled plastics in infrastructure (e.g., recy- cled plastics in Portland cement concrete) have shown inconclusive results in laboratory testing—for example, revealing improvements in some mechanical properties and deterioration in others—and therefore would need further research and development, including field testing at scale, economic and environmental life-cycle assess- ments to support confirmation of performance, development of standards, reduction of costs, and acceptance by owners and the public. • The development of specifications and standards is critical to scal- ing the use of recycled plastics in infrastructure. While standards

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 167 and specifications exist for the use of recycled plastics in some applications (e.g., drainage pipes and plastic lumber), others will need to be developed or incorporated into existing specifications and standards for the remaining applications. REFERENCES Acumen Research and Consulting (ARC). 2023. Wood Plastic Composites Market Analy- sis—Global Industry Size, Share, Trends and Forecast 2022-2030. https://www.acumen- researchandconsulting.com/wood-plastic-composites-market Adhikary, K. B., Pang, S., and Staiger, M. P. 2008a. Dimensional stability and mechanical behaviour of wood–plastic composites based on recycled and virgin high-density poly- ethylene (HDPE). Composites Part B: Engineering 39(5):807-815. –––. 2008b. Long-term moisture absorption and thickness swelling behaviour of recycled thermoplastics reinforced with Pinus radiata sawdust. Chemical Engineering Journal 142(2):190-198. Akinwumi, I. I., Domo-Spiff, A. H., and Salami, A. 2019. Marine plastic pollution and af- fordable housing challenge: Shredded waste plastic stabilized soil for producing com- pressed earth bricks. Case Studies in Construction Materials 11. https://doi.org/10.1016/j. cscm.2019.e00241 Almohana, A. A., Abdulwahid, M. Y., Galobardes, I., Mushtaq, J., and Almojil, S. F. 2022. Producing sustainable concrete with plastics waste: A review. Environmental Challenges 9. https://doi.org/10.1016/j.envc.2022.100626 Alshannaq, A., Bank, L. C., Scott, D., Pye, J., Bermek, M., and Gentry, R. 2022. FRP com- posite wind turbine blades as power-line utility poles and towers. In 10th International Conference on FRP Composites in Civil Engineering (CICE 2021), edited by A. Ilki, M. Ispir, and P. Inci. Lecture Notes in Civil Engineering, Vol. 198. Springer. https://doi. org/10.1007/978-3-030-88166-5_10 American Association of State Highway and Transportation Officials (AASHTO). 2018. Committee on Materials & Pavements. Technical Subcommittee 4b, Flexible and Me- tallic Pipe. Mid-Year Meeting. https://materials.transportation.org/wp-content/uploads/ sites/24/2018/02/COMP-TS-4b-Mid-Year-Meeting-01_03_2018-Minutes.pdf –––. 2021. Standard Specification for Corrugated Polyethylene Pipe, 300- to 1500-mm (12- to 60-in.) Diameter. AASHTO Materials Specification M 294-21. Washington, DC. –––. 2022. AASHTO LRFD Bridge Design Specifications, 9th Edition. Customary U.S. Units. American Association of State Highway and Transportation Officials. American National Standards Institute (ANSI). 2012. American National Standard for Road- way Lighting Equipment—Fiber-Reinforced Composite (FRC) Lighting Poles. ANSI C136.20-2012 (R2021). https://webstore.ansi.org/standards/nema/ansic136202012 American Society of Civil Engineers (ASCE). 2019. Recommended Practice for Fiber-Rein- forced Polymer Products for Overhead Utility Line Structures, 2nd edition. MOP 104. Reston, VA: American Society of Civil Engineers. Association of American Railroads (AAR). 2023. U.S. Freight Railroads. https://www.aar. org/wp-content/uploads/2023/01/AAR-Railroad-101-Freight-Railroads-2023-Congress- Fact-Sheet.pdf ASTM. 1992. Standard Specification for Reinforced Thermosetting Plastic Poles. ASTM D4923-92. https://www.astm.org/d4923-92.html –––. 2013. Standard Test Methods for Compressive and Flexural Creep and Creep-Rupture of Plastic Lumber and Shapes. ASTM D6112-13. https://www.astm.org/d6112-13.html

168 RECYCLED PLASTICS IN INFRASTRUCTURE –––. 2016. Standard Test Method for the Un-notched, Constant Ligament Stress Crack Test (UCLS) for HDPE Materials Containing Post-Consumer Recycled HDPE. ASTM F3181- 16. https://www.astm.org/f3181-16.html –––. 2018a. Standard Test Methods for Mechanical Fasteners in Plastic Lumber and Shapes. ASTM D6117-18. https://www.astm.org/d6117-18.html –––. 2018b. Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics. ASTM D256-10(2018). https://www.astm.org/d0256-10r18.html –––. 2018c. Standard Test Method for Water Absorption of Plastics. ASTM D570-98(2018). https://www.astm.org/d0570-98r18.html –––. 2019a. Standard Guide for Evaluating Mechanical and Physical Properties of Wood- Plastic Composite Products. ASTM D703-11(2019). https://www.astm.org/d7031-11r19. html –––. 2019b. Standard Test Method for Compressive Properties of Plastic Lumber and Shapes. ASTM D6108-19. https://www.astm.org/d6108-19.html –––. 2019c. Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and Related Products. ASTM D6109-19. https://www.astm.org/d6109- 19.html –––. 2019d. Standard Test Method for Bulk Density and Specific Gravity of Plastic Lumber and Shapes by Displacement. ASTM D6111-19a. https://www.astm.org/d6111-19a.html –––. 2021a. Standard Specification for Establishing Performance Ratings for Wood-Plastic Composite and Plastic Lumber Deck Boards, Stair Treads, Guards, and Handrails. ASTM D70032-21. https://www.astm.org/d7032-21.html –––. 2021b. Standard Practice for Fluorescent Ultraviolet Lamp Apparatus Exposure of Plas- tics. ASTM D4329. https://www.astm.org/d4329-21.html Australia HeavyQuip Journal. 2021. Recycled Plastic Noise Walls Get the Approval for Victorian Road Projects. https://www.australiahqj.com/2021/11/18/recycled-plastic- noise-walls-get-the-approval-for-victorian-road-projects Barlaz, M. A, Haynie, F. H., and Overcash, M. F. 1993. Framework for assessment of recycle potential applied to plastics. Journal of Environmental Engineering 119(5):798-810. Barone, S., Cucinotta, F., and Sfravara, F. 2017. A comparative life cycle assessment of utility poles manufactured with different materials and dimensions. In Advances on Mechan- ics, Design Engineering and Manufacturing  (pp. 91-99). Cham: Springer. https://doi. org/10.1061/(ASCE)0733-9372(1993)119:5(798) Beck, R. 2021. Union Pacific Composite Tie Strategies. 2021 Virtual International Crosstie & Fastening System Symposium. https://www.youtube.com/watch?v=jE_zPdDPBk0 Bolin, C., and Smith, S. 2013. Life cycle assessment of creosote-treated wooden railroad crossties in the U.S. with comparison to concrete and plastic composite railroad cross- ties. Journal of Transportation Technologies 3:149-161. https://www.researchgate.net/ publication/273745081_Life_Cycle_Assessment_of_Creosote-Treated_Wooden_ Railroad_Crossties_in_the_US_with_Comparisons_to_Concrete_and_Plastic_Composite_ Railroad_Crossties Bowders, J. J., Loehr, J. E., Salim, H., and Chen, C. 2003. Engineering properties of recycled plastic pins for slope stabilization. Transportation Research Record 1849(1):39-46. https://doi.org/10.3141/1849-05 Bowmer, T. 2021. Maintaining and inspecting wood poles: The “big picture” and prac- tical approaches. IAEI Magazine. https://www.iaei.org/page/2021-01-Beyond-the- Service-Point-Wooden-Poles Breslin, V. T., Senturk, U., and Berndt, C. C. 1998. Long-term engineering properties of re- cycled plastic lumber used in pier construction. Resources, Conservation and Recycling 23(4):243-258. https://doi.org/10.1016/S0921-3449(98)00024-X

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 169 BubbleDeck. 2023. BubbleDeck North America LLC—Advancing Concrete Design and Con- struction. https://bbdna.com/ ByFusion. 2022a. Byblock—Build a Better Future. https://www.byfusion.com/byblock –––. 2022b. Byblock Product Data Sheet. https://www.byfusion.com/wp-content/ uploads/2021/01/ByBlock%C2%AE-Product-Data-Sheet_2021.3-1.pdf California AB 2953. 2022. Department of Transportation and Local Agencies: Streets and Highways: Recycled Materials. https://leginfo.legislature.ca.gov/faces/billNavClient. xhtml?bill_id=202120220AB2953 Coughlin, D. 2018. Weathering the weather: The benefits of composite utility poles in storm zones. EET&D Magazine. https://electricenergyonline.com/energy/magazine/1148/article/ Weathering-the-Weather-The-Benefits-of-Composite-Utility-Poles-in-Storm-Zones.htm Dhawan, R., Bisht, B. M. S., Kumar, R., Kumari, S., and Dhawan, S. K. 2019. Recycling of plastic waste into tiles with reduced flammability and improved tensile strength. Process Safety and Environmental Protection 124:299-307. https://doi.org/10.1016/j. psep.2019.02.018 Di, J., Reck, B. K., Miatto, A., and Graedel, T. E. 2021. United States plastics: Large flows, short lifetimes, and negligible recycling. Resources, Conservation and Recycling 167:105440. Electric Power Research Institute (EPRI). 2021. Management of Composite Structures. https:// www.epri.com/research/products/000000003002020576 Ernst, D., Biton, L., Reichenbacher, S., Zgola, M., and Adkins, C. 2008. Guidelines for Selec- tion and Approval of Noise Barrier Products. NCHRP Project 25-25, Task 40. ESi. 2020. Composite Railroad Tie Evaluation Study. https://www.engsys.com/media/1047- esi-case-study-composite-railroad-tie-evaluation.pdf eSUB. 2020. Different Types of Drainage Pipe and When to Use Them. https://esub.com/blog/ different-types-of-drainage-pipe-and-when-to-use-them Federal Highway Administration (FHWA). 2016. Appendix H: Utility Pole Management in New Jersey. https://safety.fhwa.dot.gov/roadway_dept/horicurves/fhwasa15084/apph. cfm –––. 2017a. Noise Barrier Design Handbook. https://www.fhwa.dot.gov/Environment/noise/ noise_barriers/design_construction/design/design01.cfm –––. 2017b. Highway Traffic Noise Analysis and Abetment Policy and Guidance Legisla- tion. https://www.fhwa.dot.gov/environMent/noise/regulations_and_guidance/polguide/ polguide01.cfm –––. 2021. Summary of Noise Barriers Constructed by December 31, 2019. https://www.fhwa. dot.gov/environment/noise/noise_barriers/inventory Federal Railroad Administration (FRA). 2012. Cracking and Impact Performance Character- istics of Plastic Composite Ties. https://railroads.dot.gov/sites/fra.dot.gov/files/fra_net/87/ TR_Cracking_Impact_Plastic_Composite_Ties_final.pdf Foedinger, R., Boozer, J. F., Bronstad, M. E., and Davidson, J. W. 2003. Development of energy-absorbing composite utility pole. Transportation Research Record 1851(1):149- 157. https://doi.org/10.3141/1851-15 Gao, Y. 2022. Thermal Effect on Engineered Polymer Composite Ties. Denver, CO: AREMA. Gao, Y., and McHenry, M. 2021. Thermal effects on track gage of engineered polymer com- posite ties. Technology Digest TD21-014. Pueblo, CO: AAR/TTCI. GeoSolutions. 2021. What Are Geosynthetics? https://www.geosolutionsinc.com/blog/what- are-geosynthetics.html Guades, E. J., Aravinthan, T., and Islam, M. M. 2010. An overview on the application of FRP composites in piling system. In Proceedings of the Southern Region Engineer- ing Conference (SREC 2010), edited by S. C. Goh and H. Wang. Canberra, Aus- tralia: University of Southern Queensland. https://research.usq.edu.au/download/9c 9770e70fb6891eb006b07eb3efb7edfbb48384aa1dc5229c0c59024f068133/422086/ Guades_Aravinthan_Islam_AV.pdf

170 RECYCLED PLASTICS IN INFRASTRUCTURE Hag-Elsafi, O., Elwell, D. J., Glath, G., and Hiris, M. 1999. Noise barriers using recy- cled-plastic lumber. Transportation Research Record 1670(1):49-58. https://doi. org/10.3141/1670-07 Heinz, R. 1993. Plastic piling. Civil Engineering 64(4):63. https://www.proquest.com/docvi ew/228451417?parentSessionId=AScPfptrqMoOcQfkIAyW6udmCi3WrQ%2Bi1yNib4 W5cCw%3D Heller, M. C., Mazor, M. H., and Keoleian, G. A. 2020. Plastics in the US: Toward a material flow characterization of production, markets, and end of life. Environmental Research Letters 15:094034. Ibach, R. 2010. Durability of wood plastic composite lumber. McGraw-Hill Yearbook of Sci- ence and Technology, pp. 113-116. IEEE. 2006. National Electrical Safety Code, C2-2007. http://villanobos.weebly.com/ uploads/2/3/2/6/23268366/national_electrical_safety.pdf International Geosynthetics Society. 2021. Spotlight on Sustainable Initiatives in Geosynthetics. https://www.geosyntheticssociety.org/spotlight-on-sustainable-initiatives-in-geosynthetics International Organization for Standardization (ISO). 2020. Wood-Plastic Recycled Com- posites (WPRC)—Part 1: Specification. ISO 20819-1:2020. https://www.iso.org/ standard/77445.html Iskander, M. G. 2012. Sustainable piling made of recycled polymers: State of the art re- view. Journal of ASTM International 9(2). https://www.researchgate.net/profile/ Magued-Iskander/publication/300766078_Sustainable_Piling_Made_of_Recycled_ Polymers_State_of_the_Art_Review/links/5f8473d592851c14bcc18527/Sustainable- Piling-Made-of-Recycled-Polymers-State-of-the-Art-Review.pdf Iskander, M., and Hanna, S. 2003. Engineering Performance of FRP Composite Pilings. TRB 2002 Session on Fiber Reinforced Polymer Piles. https://s18798.pcdn.co/plasticpiles/wp- content/uploads/sites/4030/2016/05/TRB2003-000959.pdf Islam, A., Hossain, S., Badhon, F. F., and Bhandari, P. 2021. Performance evaluation of recycled-plastic-pin-supported embankment over soft soil. Journal of Geotechnical and Geoenvironmental Engineering 147(6). https://ascelibrary.org/doi/abs/10.1061/%28AS CE%29GT.1943-5606.0002528 –––. 2022. Numerical study of recycled-plastic-pin- and geosynthetic-platform-supported embankment over soft soil. Transportation Research Record 2676(9):159-171. https:// doi.org/10.1177/03611981221086624 Jacoby, M. 2022. Recycling wind turbine blades. Chemical & Engineering News August:26-30. Joe, T. 2021. Nzambi Matee Transforms Kenya’s Plastic Waste into Building Bricks. Green Queen. https://www.reuters.com/article/us-kenya-environment-recycling/ kenyan-recycles-plastic-waste-into-bricks-stronger-than-concrete-idUSKBN2A211N Juan, R., Domínguez, C., Robledo, N., Paredes, B., and García-Muñoz, R. A. 2020. Incorpora- tion of recycled high-density polyethylene to polyethylene pipe grade resins to increase close-loop recycling and underpin the circular economy. Journal of Cleaner Production 276:124081. https://doi.org/10.1016/j.jclepro.2020.124081 Kamdem, D. P., Jiang, H., Cui, W., Freed, J., and Matuana, L. M. 2004. Properties of wood plastic composites made of recycled HDPE and wood flour from CCA-treated wood removed from service. Composites Part A: Applied Science and Manufacturing 35(3):347-355. Khalid, F. S., Irwan, J. M., Ibrahim, M. H. W., Othman, N., and Shahidan, S. 2018. Perfor- mance of plastic wastes in fiber-reinforced concrete beams. Construction and Building Materials 183:451-464. https://doi.org/10.1016/j.conbuildmat.2018.06.122 Koerner, R. M. 2012. Designing with Geosynthetics, Vols. 1 and 2. XLibris Publishers.

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 171 Kou, S. C., Lee, G., Poon, C. S., and Lai, W. L. 2009. Properties of lightweight aggregate con- crete prepared with PVC granules derived from scraped PVC pipes. Waste Management 29(2):621-628. https://doi.org/10.1016/j.wasman.2008.06.014 Krishnaswamy, P., and Francini, R. 1998. Long-Term Durability of Recycled Plastic Lumber in Structural Applications. Engineering Mechanics Corporation of Columbus, Ohio. https://d3pcsg2wjq9izr.cloudfront.net/files/0/articles/2183/2183.pdf Kumi-Larbi, A., Yunana, D., Kamsouloum, P., Webster, M., Wilson, D. C., and Cheeseman, C. 2018. Recycling waste plastics in developing countries: Use of low-density polyethyl- ene water sachets to form plastic bonded sand blocks. Waste Management 80:112-118. https://doi.org/10.1016/j.wasman.2018.09.003 Lampo, R., Nosker, T., Barno, D., Busel, J., Maher, A., Dutta, P. and Odello, R. 1998. Con- struction Productivity Advancement Research (CPAR) Program. https://apps.dtic.mil/sti/ pdfs/ADA355970.pdf Lampo, R., Nosker, T., and Sullivan, H. 2003a. Development, Testing and Appli- cations of Recycled Plastic Composite Cross Ties. U.S. Army Engineer R&D Center. https://www.researchgate.net/profile/Thomas-Nosker/publication/265011359_ Development_Testing_and_Applications_of_Recycled_Plastic_Composite_Cross_Ties/ links/5446768d0cf2d62c304dc066/Development-Testing-and-Applications-of-Recycled- Plastic-Composite-Cross-Ties.pdf Lampo, R., Nosker, T., and McLaren, M. 2003b. Demonstration Installations of Recycled- Plastic Lumber for Bridges, Marine Pilings, and Railroad Ties. https://d3pcsg2wjq9izr. cloudfront.net/files/0/articles/2222/demonstration.pdf Lei, Y., Wu, Q., Yao, F., and Xu, Y. 2007. Preparation and properties of recycled HDPE/ natural fiber composites. Composites Part A: Applied Science and Manufacturing 38(7):1664-1674. Levie, B. 1993. Evaluation of Recycled Plastic Lumber for Marine Applications. Risk Reduc- tion Engineering Laboratory, Office of Research and Development, U.S. Environmental Protection Agency. Los Angeles Harbor Department. 2012. Berths 302 to 306 [APL] Container Terminal Proj- ect, p. 1-46. https://www.waterboards.ca.gov/losangeles/board_decisions/tentative_ orders/individual/non-npdes/Berths_302-306_Terminals/POLA_Berths%20302-306%20 Final_EIS_EIR_May%202012.pdf Love, L., Post, B., Tekinalp, H., Wang, P., Atkins, C., Roschli, A., Zhao, X., and Rencheck, M. 2021. Assessment of Commercial Composite Power Pole Performance. ORNL/TM- 2021/2068. Oak Ridge National Laboratory. https://doi.org/10.2172/1818691 Machalaba, D. 2004. New recyclables market emerges: Plastic railroad ties. The Wall Street Journal, October 19. https://www.wsj.com/articles/SB109812734542348276 McHenry, M., Baillargeon, J., and Gao, J. 2018. Implementing Improved Composite Tie De- sign and Testing Guidelines into the AREMA Manual for Railway Engineering. AREMA. https://railtec.illinois.edu/wp/wp-content/uploads/Implementing-Improved-Composite- Tie-Design-and-Testing-Guidelines.pdf Morrell, J. J. 2016. Estimated service life of wood poles. North American Wood Pole Council Technical Bulletin. https://woodpoles.org/portals/2/documents/TB_ServiceLife.pdf Mustafa, M. A., Hanafi, I., Mahmoud, R., and Tayeh, B. A. 2019. Effect of partial replacement of sand by plastic waste on impact resistance of concrete: Experiment and simulation. Structures 20:519-526. https://doi.org/10.1016/j.istruc.2019.06.008 Najafi, S. K. 2013. Use of recycled plastics in wood plastic composites—A review. Waste Management 33(9):1898-1905. https://doi.org/10.1016/j.wasman.2013.05.017 Najafi, S. K., Hamidinia, E., and Tajvidi, M. 2006. Mechanical properties of composites from sawdust and recycled plastics. Journal of Applied Polymer Science 100(5):3641-3645.

172 RECYCLED PLASTICS IN INFRASTRUCTURE Najafi, S. K., Tajvidi, M., and Hamidina, E. 2007a. Effect of temperature, plastic type and virginity on the water uptake of sawdust/plastic composites. Holz Als Roh- und Werk- stoff 65(5):377-382. Najafi, S. K., Kiaefar, A., Hamidina, E., and Tajvidi, M. 2007b. Water absorption behavior of composites from sawdust and recycled plastics. Journal of Reinforced Plastics and Composites 26(3):341-348. Najafi, S. K., Kiaeifar, A., Tajvidi, M., and Hamidina, E. 2008. Hygroscopic thickness swelling rate of composites from sawdust and recycled plastics. Wood Science and Technology 42(2):161-168. Najafi, S. K., Mostafazadeh-Marznaki, M., Chaharmahali, M., and Tajvidi, M. 2009. Effect of thermomechanical degradation of polypropylene on mechanical properties of wood- polypropylene composites. Journal of Composite Materials 43(22):2543-2554. https:// doi.org/10.1177/0021998309345349 National Academies of Sciences, Engineering, and Medicine (NASEM). 2018. NCHRP Re- search Report 870: Field Performance of Corrugated Pipe Manufactured with Recycled Polyethylene Content. Washington, DC: The National Academies Press. https://www.trb. org/NCHRP/Blurbs/176741.aspx Ness, K.E., Nosker, T.L., Renfree, R.W., and Killion, J.R. 2001. Long-term creep of commercially produced plastic lumber. Rutgers University, New Jersey. https://amipp.rutgers.edu/sites/ default/files/uploads/Publications/LongTermCreepComProducedPlasticLumber_1998 Nodehi, M., and Taghvaee, V. M. 2022. Applying circular economy to construction indus- try through use of waste materials: A review of supplementary cementitious materials, plastics, and ceramics.  Circular Economy and Sustainability  2:987-1020. https://doi. org/10.1007/s43615-022-00149-x Northeast Recycling Council (NERC) and Association of Plastic Recyclers (APR). 2022. Plas- tic Drainage Pipes with Post-Consumer Recycled Content—Now You Can! https://nerc. org/documents/Why%20use%20PCR%20Drainage%20HDPE%20Pipes.pdf Nosker, T. 1989. Improvements in the properties of commingled waste by the selective mixing of plastics waste. Proceedings, SPE Recycling RETEC, Charlotte, NC. Nosker, T. et al. n.d. The development of polyolefin based oriented glass fiber building materi- als. Accepted for publication, Proceedings, SPE ANTEC. Nunez, J. 2016. NYCT installs composite ties as part of Staten Island project. Railway Track and Structures. https://www.rtands.com/passenger/commuter-regional/nyct-installs-composite- ties-as-part-of-staten-island-project Occupational Safety and Health Administration (OSHA). 2023. Coal Tar Pitch Volatiles. https://www.osha.gov/coal-tar-pitch-volatiles Office of Environment and Planning Noise and Air Quality Branch. 1995. Highway Traffic Noise Analysis and Abatement Policy and Guidance. Part 772—Procedures for Abate- ment of Highway Traffic Noise and Construction Noise. Code of Federal Regulations. https://www.ecfr.gov/current/title-23/chapter-I/subchapter-H/part-772 Petchwattana, N., Covavisaruch, S., and Sanetuntikul, J. 2012. Recycling of wood–plastic composites prepared from poly (vinyl chloride) and wood flour. Construction and Build- ing Materials 28(1):557-560. PlasticRoad. 2022. PlasticRoad as Bike Path in Zwolle. https://plasticroad.com/en/projects/ plasticroad-as-a-bike-path-in-zwolle Plastics Industry Pipe Association of Australia (PIPA). 2022. The Use of Recycled Material in Plastic Pipes. https://pipa.com.au/wp-content/uploads/2022/06/PIPA-Disucssion-Paper- The-use-of-recycled-materials-in-plastic-pipes-June-2022.pdf Railway Tie Association (RTA). 2022. Frequently Asked Questions. https://www.rta.org/faq

APPLICATIONS OF RECYCLED PLASTICS IN OTHER INFRASTRUCTURE 173 Rigby, N. 2008. Prestudy of Utility Poles in Fiber Composite. M.S. thesis, Svenka Kraftnät. https://www.svk.se/siteassets/5.jobba-har/dokument-exjobb/2008_krafledningsststolpar_ i_fiberkomposit.pdf Roads & Infrastructure. 2021. Geofabrics Recycled Geotextile Wins Global Sustainabil- ity Award. https://roadsonline.com.au/geofabrics-recycled-geotextile-wins-global- sustainability-award Roschke, P. N., and Esche, S. T. 1999. Construction of a full-scale noise barrier with recycled plastic. Transportation Research Record 1656(1):94-101. https://doi.org/10.3141/1656-13 Saadeghvaziri, M. A., and MacBain, K. 1998. Sound barrier applications of recycled plastics. Transportation Research Record 1626(1):85-92. Selke, S. E., and Wichman, I. 2004. Wood fiber/polyolefin composites. Composites Part A: Applied Science and Manufacturing 35(3):321-326. Shahi, P., Behravesh, A. H., Daryabari, S. Y., and Lotfi, M. 2012. Experimental investiga- tion on reprocessing of extruded wood flour/HDPE composites. Polymer Composites 33:753-763. Siddique, R., Khatib, J., and Kaur, I. 2008. Use of recycled plastic in concrete: A review. Waste Management 28(10):1835-1852. https://doi.org/10.1016/j.wasman.2007.09.011 Smith, S. T. 2022. Railroads Specify Creosote for Good Reasons. Creosote Council. https:// creosotecouncil.org/railroads Smith, W. B., and Kyanka, G. H. 1994. Strength and performance characteristics of sustainable building materials. Proceedings of the First International Conference of Cib Tg. Tampa, FL. Center for Construction and Environment M.E. Rinker Sr. School of Building Con- struction College of Architecture University of Florida. Stewart, J., Cisko, A., Beasley, J., and Howard, I. L. 2023. Plastics crisis: Responsible recy- cling within military railroad infrastructure. Transportation Research Record. https://doi. org/10.1177/03611981231157389 Tayeh, B. A., Almeshal, I., Magbool, H. M., Alabduljabbar, H., and Alyousef, R. 2021. Per- formance of sustainable concrete containing different types of recycled plastic. Journal of Cleaner Production 328:129517. https://doi.org/10.1016/j.jclepro.2021.129517 Transportation Research Board (TRB). 2011. Performance of Corrugated Pipe Manufactured with Recycled Polyethylene Content. Washington, DC: The National Academies Press. https://doi.org/10.17226/14570 U.S. Department of Transportation (USDOT). 2015. Pipeline & Hazardous Materials Safety Administration. Fact Sheet: Pipeline Materials. https://primis.phmsa.dot.gov/comm/ FactSheets/FSPipelineMaterials.htm –––. 2022. PHMSA. Pipeline Miles and Facilities 2010+. https://portal.phmsa.dot.gov/ analytics/saw.dll?Portalpages&PortalPath=%2Fshared%2FPDM%20Public%20 Website%2F_portal%2FPublic%20Reports&Page=Infrastructure U.S. Environmental Protection Agency (USEPA). 1993. Evaluation of Recycled Plastic Lum- ber for Marine Applications. Washington, DC: U.S. Environmental Protection Agency. https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NRMRL&dirEntryId=342136 –––. 2022a. Creosote. https://www.epa.gov/ingredients-used-pesticide-products/creosote –––. 2022b. Pentachlorophenol. https://www.epa.gov/ingredients-used-pesticide-products/ pentachlorophenol –––. 2023. Waste & Debris Fact Sheets. https://iwaste.epa.gov/guidance/natural-disaster/ fact-sheets/types-of-waste?id=cca-treated-wood Victoria’s Big Build. 2022a. ecologiQ. https://bigbuild.vic.gov.au/about/ecologiq –––. 2022b. Technical Specification [V676] Plastic Noise Walls. https://bigbuild.vic.gov.au/__ data/assets/pdf_file/0016/704221/Technical-specification-draft-Plastic-Noise-Walls.pdf Vollin, T. 2021. Life of a Wooden Crosstie. Mississippi State University. https://www.cfr. msstate.edu/news/news_article.asp?guid=738

174 RECYCLED PLASTICS IN INFRASTRUCTURE Waita, E. 2021. Kenyan recycles plastic waste into bricks stronger than concrete. Reu- ters. https://www.reuters.com/article/us-kenya-environment-recycling/kenyan-recycles- plastic-waste-into-bricks-stronger-than-concrete-idUSKBN2A211N Youngquist, J. A., Myers, G. E., Muehl, J. H., Krzysik, A. M., and Clemons, C. M. 1995. Composites from recycled wood and plastics. USDA Forest Service, Forest Product Labo- ratory, Madison, WI. https://www.osti.gov/biblio/6613464 Zabel, R. A., and Morrell, J. J. 2020. Decay problems associated with some major uses of wood products. In Wood Microbiology (Second Edition), edited by R. A. Zabel and J. J. Mor- rell. Academic Press, pp. 385–410. https://doi.org/10.1016/B978-0-12-819465-2.00015-2 Zyka, K., and Mohajerani, A. 2016. Composite piles: A review. Construction and Building Materials 107:394-410. https://doi.org/10.1016/j.conbuildmat.2016.01.013

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In the U.S., most plastics waste is disposed in landfills, but a significant amount also ends up as litter on land, rivers, and oceans. Today, less than 10 percent of plastics waste is recycled in the U.S. annually. The use of recycled plastics in infrastructure applications has potential to help expand the market and demand for plastics recycling.

These are among the findings in TRB Special Report 347: Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities from the Transportation Research Board of the National Academy of Sciences, Engineering, and Medicine.

The report emphasizes that pursuing the recycling of plastics in infrastructure depends on goals, policy, and economics. To that end, life cycle economic and environmental assessments should be conducted to inform policies on plastics waste reuse.

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