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2Quality assurance specifications that specify end-product quality have often been used by trans- portation agencies to ensure the construction quality of highway pavements. However, agencies are increasingly incorporating performance-related specifications (PRS) in construction contracts to specify quality in terms of parameters related to desired long-term performance. These PRS also provide a means to account for the value lost or gained by the variances of these parameters from the specified target values. Although such PRS have been used in the construction of new pavements, their use for pavement preservation treatments has been limited. If adopted, PRS will enable agencies to ensure quality pavement preservation treatments are delivered while creating a fair bid environment for contractors. There are no widely accepted guidelines for PRS for pavement preservation treatments that correlate key engineering properties to treatment quality and long-term performance. Therefore, research was needed to develop guidelines to facilitate developing PRS for pavement preserva- tion treatments that directly relate key material and construction characteristics to performance. NCHRP Project 10-82A was initiated to address this need. These guidelines will help highway agencies develop and incorporate PRS in preservation treatment contracts. The PRS will enable agencies to specify an optimum level of quality that represents the best balance of costs and per- formance and to establish quality-related pay adjustment factors, if desired. 1.1 Objective The objective of this research was to develop guidelines for use in preparing PRS for pavement preservation treatments for both flexible and rigid pavements. 1.2 Research Approach In this report, preservation treatments are defined as actions applied to preserve an existing roadway, slow future deterioration, and maintain and improve roadway functional condition (without substantially increasing structural capacity). Preventive maintenance treatments com- monly applied to hot-mix asphalt (HMA) pavements include crack sealing and crack filling, slurry seals, chip seals, microsurfacing, cape seal, fog seals, hot in-place recycling (HIR), cold in-place recycling (CIR), and thin HMA overlays. Treatments applied to portland cement concrete (PCC) pavements include joint resealing, crack sealing, joint and spall partial-depth repair, load-transfer restoration, diamond grinding, and under-sealing. The typical PRS quality assurance specifications describe the desired levels of key materials and construction quality characteristics that have been found to correlate with fundamental engineering properties that predict performance. These characteristics (e.g., air voids in asphalt Introduction C h a p t e r 1
Introduction 3 concrete and compressive strength of PCC) are amenable to acceptance testing at the time of construction (Perera et al. 1998; Epps et al. 2002; Hughes 2005; National Academies of Sci- ences, Engineering, and Medicine 2001; Fugro Consultants, Inc., and Arizona State University 2011; Burati et al. 2003; Hughes 1996; Smith 1998). However, PRS not only describe the desired levels of these quality characteristics, but also use the quantified relationships containing the characteristics to predict as-constructed pavement performance. As a result, PRS provide the basis for rational acceptance/pay adjustment decisions. This research was performed to develop guidelines to help develop such PRS. This objective was accomplished by performing the following tasks: â¢ Documenting relevant issues â¢ Identifying common preservation treatments â¢ Identifying a process for developing guidelines â¢ Addressing data needs and availability and identifying relevant related issues â¢ Developing the PRS guidelines and presenting examples to illustrate their use This report documents the work performed in these tasks. 1.3 Report Organization The report has seven chapters. Chapter 1 documents the background and the need for devel- oping PRS guidelines for pavement preservation treatments. Chapter 2 presents the overall pro- cess used for developing the guidelines. Chapter 3 summarizes the relevant issues in pavement preservation and reviews current pavement preservation practices, acceptance quality charac- teristics, and performance measures for preservation treatments. Chapter 4 provides details for establishing a sampling method and associated uncertainties and ways to minimize asso- ciated risks. Chapter 5 presents the guidelines. Chapter 6 presents two examples, using field data, which illustrate the application of the guidelines to common preservation treatments for flexible and rigid pavements. Chapter 7 summarizes the findings and suggests future research. Appendix A pre sents examples (using simulated data because field data were not available) for other treatments.