Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
143 C h a p t e r 1 6 Introduction Although PCP technology, as used today, is of recent origin, many different PCP systems have been implemented in the United States, and it is likely that refinements to the existing systems will continue to be made and new systems or system components will be developed. It is therefore necessary that highway agencies establish an independent process for evalu- ating and approving new PCP systems or components. As discussed in this chapter, new components are considered the same as new systems, because the performance of any new component needs to be demonstrated as being an integral part of any PCP system. As a minimum, the following attri- butes of a new PCP system need to be evaluated before approval of the system: 1. Constructability within the constraints of the lane closure requirements; 2. Productivity of installation; 3. Concrete quality; and 4. Structural performance a. Transverse joint load transfer provisions b. Specific base and bedding support requirements. The process for evaluating and approving any PCP system should be the same for a generic system developed by the highway agency or for proprietary systems or systems that incorporate proprietary features. Requiring PCP system ven- dors (precasters or contractors, or both) to have their systems approved before they are used at a project reduces the risks associated with implementing a new system under difficult lane closure and other site constraints, including nighttime work and limited work hours. Because the design requirements and performance require- ments are unique for intermittent repairs or continuous applications, PCP system approval should be based on the specific type of application. This chapter addresses the requirements for evaluation and approval of PCP systems. The evaluation and approval process consists of two distinct parts: (1) the submittal and review of standard drawings and proposed installation procedures and (2) the construction and evaluation of a trial installation. System Design Requirements The PCP system approval process can be based on the agency- specified standard design for system approval or based on spe- cific project needs. The design features that need to be specified by the agency for non-project-specific PCP system approval should include the following as a minimum: 1. Precast concrete panelârelated features a. Panel width; b. Panel length; c. Panel thickness; d. Concrete requirements; e. Minimum reinforcement; and f. Minimum prestressing, if applicable. 2. Trial installationârelated features a. Base support; b. Bedding requirements, if any; c. Rapid-setting materials used as grouts and for patching; d. Transverse joint LTE; e. Applied end prestress level for PPCP systems; and f. Expansion joint details for PPCP. For approval of a PCP system without reference to a spe- cific project, the standard design features given in Table 16.1 are recommended. The standard design features listed in Table 16.1 provide flexibility to the system vendor in terms of determining the panel geometry that will satisfy the PCP system approval pro- cess and that matches the vendorâs fabrication process and available formwork. System Approval and Trial Installation
144 pCp System Standard Drawings and Supplemental Information The vendor-developed drawings for the PCP system approval should be stamped by a registered professional engineer and should include, as a minimum, a cover sheet, a drawing sheet (or sheets, as needed), and a PCP system installation detail sheet (or sheets, as needed). Cover Sheet 1. General notes a. Reference to the agency specification related to PCP system approval; b. References to agency specifications and special provi- sions applicable to PCP systems; c. Reference to any proprietary components or techniques used, including patent and trademark information; d. Estimated panel placement rate per 6-hour nighttime work window after removal of existing pavement; and e. Limitations, if any, to opening the placed panel sec- tion to traffic ⢠Before effecting joint load transfer provisions and undersealing, if applicable ⢠Before posttensioning the PTSections of the PPCP system, if applicable. 2. Precast concrete plant certification-related information. 3. PCP system name and brief description. 4. Test panel dimensions a. Identification for each panel; and b. Width, length, thickness, and weight of each panel. 5. Concrete requirements a. Reference to agencyâs paving concrete requirements; b. Form stripping strength, typically a minimum of 2,500 lbf/in.2 (17.2 MPa); c. Design strength and age, typically a minimum of 4,000 lbf/in.2 (27.6 MPa) at 28 days; d. Shipping strength, typically same as the design strength; and e. Curing requirements, including steam-curing require- ments, if applicable. 6. Reinforcement details a. Reinforcement type, typically epoxy coated; b. Reinforcement layout: number of mats (single or top and bottom); Table 16.1. Standard Design Features for System Approval Design Feature Value Panel width (ft) 12 Panel thickness (in.) 8 to 12 Panel length, jointed systems (ft) 6 to 15 (repair) 12 to 15 (continuous) Panel length, PPCP systems (ft) 8 to 40 Base support type Granular Modulus of subgrade reaction over base (pci) 200 to 400 Minimum LTE, jointed systems 90 Minimum LTE, PPCP systems with expansion joint width of 2 in. 80 Minimum concrete compressive strength at 28 days (lbf/in.2) 650 Concrete and concrete aggregates Meet requirements for agencyâs paving-class concrete Minimum panel reinforcement in each direction (% of cross- sectional area) 0.18 Strength of rapid-setting dowel slot grout and patching materials at 4 hours (lbf/in.2) 2,500 Strength of rapid-setting undersealing grout material at 4 hours, if applicable (lbf/in.2) 500 Reinforcement type Epoxy-coated deformed bars, Grade 420, or other approved reinforcement Minimum applied panel prestress for pretensioning (lbf/in.2) 200 Minimum PTSection end prestress for PPCP systems (lbf/in.2) 200
145 c. Reinforcement amount: bar size and spacing; and d. Reinforcement clear cover. 7. Panel lifting and handling details a. Lifting insert, swivel lift plate, and lifting bolt details; b. Lifting assembly (rigging) details (to ensure equal loading at each insert); c. Insert locations on the panel; and d. Lifting and insertârelated safety information. 8. Panel fabrication tolerances. 9. Bedding material information, as applicable a. Fine-grained granular material; b. Rapid-setting flowable material; and c. Polyurethane foam. 10. Rapid-setting dowel slot grout and patching material information. 11. Rapid-setting undersealing grout information, if applicable. 12. PPCP system: prestressing system details a. Tendon type and diameter; b. Tendon duct grout; c. Tendon connectivity at intermediate joints; d. Intermediate joint keyway epoxy; and e. Intermediate joint grout and patching material infor- mation, as applicable. 13. Prestressed panels: prestressing system details a. Tendon type and diameter; and b. Tendon detensioning details. 14. On-site equipment requirements a. For panel lifting and placing (crane rating); b. For bedding material application, if applicable; c. For undersealing material application; and d. For stressing tendons (loading jacks). 15. Panel shipping-related cautions. Drawing Sheet(s) 1. Panel geometry details for each panel type submitted for approval a. Plan details; b. Cross-section details (transverse and longitudinal); and c. Panel tolerances. 2. Reinforcement layout a. Bar details; b. Bar spacing; and c. Clear cover. 3. Load transfer provision details, as applicable (Note: Dowel bars used as an example; for other load transfer devices, provide similar relevant details.) a. Dowel bar properties (diameter, length, and spacing); b. Layout of dowel bar slots; and c. Layout of embedded dowel bars. 4. Lift insert details a. Layout; and b. Lift insert embedment details. 5. Panel lifting stress calculations (PCI 2004). 6. Layout of grout ports, as applicable. 7. Jointing details, as applicable a. Transverse joints; and b. Longitudinal joints. 8. For PPCP systems a. Tendon duct layout; b. Tendon details (type and diameter); c. Tendon anchorage details; d. Location of tendon duct grout ports; e. Tendon stressingârelated details, as applicable ⢠Stressing pockets ⢠Anchorage pockets; f. Intermediate joint connectivity, as applicable ⢠Conventional keyway ⢠Double keyway; and g. Expansion joint details, as applicable ⢠Joint sealing ⢠Load transfer provision ⢠Expansion joint panel details ⢠Gap panel details. 9. For prestressed panels a. Tendon type and diameter; and b. Tendon spacing. 10. Any other detail deemed necessary for the specific system under review. PCP System Installation Detail Sheet(s) All necessary information and requirements related to the PCP system installation should be detailed on these sheets. This information should include the following as a minimum: 1. Base requirements a. Type; and b. Grading. 2. Bedding requirements a. Type; b. Thickness; and c. Placement method. 3. For repair applications a. Repair area dimensional tolerances; b. Load transfer provisions in the existing concrete pave- ments, as applicable ⢠Provisions for dowel bar slots ⢠Provisions for drilled and grouted dowel bars; c. Panel placement method ⢠Placed directly on prepared base or bedding ⢠Placed using strongback beams
146 ⢠Placed using setting bolts ⢠Placed using polyurethane grout; d. Panel alignment requirements ⢠Panel alignment within repair area ⢠Vertical alignment with respect to existing concrete pavement; e. Load transfer provisions after panel placement ⢠Grouting or patching of dowel bar slots; f. Longitudinal jointârelated provisions; g. Undersealing requirements; and h. Opening to traffic ⢠At the end of lane closure before dowel bar slot grout- ing or patching and before undersealing ⢠At the end of next lane closure after dowel bar slot grouting or patching and before undersealing ⢠Cautionary notes related to opening to traffic. 4. For continuous jointed system applications a. Panel placement method ⢠Placed directly on prepared base or bedding ⢠Placed using setting bolts ⢠Panel placement sequence; b. Panel alignment requirements ⢠Panel alignment with respect to existing adjacent lanes and adjacent precast panels ⢠Vertical alignment along transverse and longitudinal joints; c. Load transfer provisions after panel placement ⢠Grouting or patching of dowel bar slots; d. Longitudinal jointârelated provisions; e. Undersealing requirements; and f. Opening to traffic ⢠At the end of lane closure before dowel bar slot grout- ing or patching and before undersealing ⢠At the end of next lane closure after dowel bar slot grouting or patching and before undersealing ⢠Cautionary notes related to opening to traffic. 5. For PPCP applications a. Panel placement method ⢠Placed directly on prepared base or bedding; b. Panel alignment requirements ⢠Panel alignment with respect to existing adjacent lanes and adjacent precast panels ⢠Vertical alignment along transverse and longitudinal joints; c. Connecting of adjacent panels ⢠Treatment of keyways ⢠Duct connection details ⢠Temporary posttensioning details; d. Longitudinal jointârelated details; e. Posttensioning details ⢠Tendon load application ⢠Tendon elongation monitoring; f. Expansion jointârelated activities ⢠Setting expansion joint width ⢠Use of gap panel, as applicable ⢠Provisions for load transfer; g. Longitudinal jointârelated provisions; h. Undersealing requirements; i. PTSection anchoring details; and j. Opening to traffic ⢠At the end of lane closure before dowel bar slot grout- ing or patching and before undersealing ⢠At the end of next lane closure after dowel bar slot grouting or patching and before undersealing ⢠Cautionary notes related to opening to traffic. 6. Post-installation activities, as applicable ⢠Joint sealing; and ⢠Surface grinding. The removal of existing pavement is not incorporated in the PCP system approval process because such pavement removal is typically project-specific and contractor-specific and is independent of any PCP system that may be used. The PCP system approval process should be based on a standard granular base type. In addition to the standard drawings submittal, the PCP vendor should provide supplemental information related to the materials and systems used. This supplemental informa- tion may include the following: 1. Cementitious materials mill reports per agency requirements; 2. Concrete aggregate test data per agency requirements; 3. Concrete test data per agency requirements; 4. Concrete admixture technical data sheets; 5. Lifting insert technical data sheets; 6. Proprietary grout and patching material technical data sheets; 7. Prestressing hardware technical data sheets; 8. Copies of plant certification; 9. Copies of plant personnel certification; and 10. Crane technical data sheet. The standard drawings and supplemental information should be submitted to the highway agency at least 30 days before the trial installation of the system. trial Installation The trial installation of a PCP system is an important part of the PCP system approval process. The trial section is the demonstration by the PCP system vendor that the proposed PCP system can be installed, within an imposed time con- straint, using the panels as fabricated and using the prescribed materials, techniques, and equipment.
147 The trial installation of the PCP system provides an oppor- tunity for the agency to identify potential problem areas and to require adjustments to be made before system approval or use of the system on a production project. The trial installation should be closely observed by representatives of the agency and the PCP system vendor. A full suite of the required acceptance tests should be conducted to verify compliance with specifica- tion requirements or test installation requirements. The trial installation should meet all acceptance testing requirements without any corrective work needed for the as-placed test section panels. If the trial installation cannot be constructed without corrective work, it is unlikely that the contractor will be able to construct a quality PCP sys- tem in accordance with any project-specific specification. For the highway agency, the most successful outcome for the trial installation is full compliance with the specifica- tion. Therefore, it is important that the PCP system vendor demonstrate during the trial installation that a quality PCP system can be constructed in accordance with the agency specification. The PCP system vendor is responsible for arranging the trial installation, at no cost to the highway agency, at a facility agreeable to the agency. The trial section should incorporate the following: 1. Work area a. For repair application: Work area bounded by an existing pavement or a simulated existing pavement. Work area dimensions must allow a 0.5-in. (13-mm)-perimeter gap around the panel to be used. b. For continuous application: Work area bounded by an existing pavement or a simulated existing pavement along the longitudinal joints. Work area dimensions must allow a 0.5-in. (13-mm) gap along the two longi- tudinal joints of the panels to be used. 2. Granular base: compacted and graded. 3. Number of panels a. For repair applications: two panels; b. For continuous jointed system: three panels placed contiguously; and c. For PPCP systems: a PTSection incorporating at least two end panels for a minimum length of 50 ft (15.2 m) and an expansion joint panel or a gap panel. As a minimum, the following items should be evaluated: 1. The sequencing and duration of each installation activity; 2. Base compaction using an LWD; 3. Granular bedding compaction using an LWD; 4. Damage to panel(s) during placement; 5. Assessing the PCP system installation process with respect to the documented system installation process; 6. Understanding of the installation process by the installa- tion crew; 7. Panel alignment with respect to specified alignment tolerances; 8. Vertical panel alignment with respect to adjacent panels or existing pavement or simulated existing pavement; 9. Effectiveness of tendon grouting for PPCP systems, includ- ing observations of grout leakage; 10. Observation of temporary posttensioning of adjacent panels for PPCP systems, including the treatment at the intermediate joints; 11. Observation of the posttensioning process for PPCP sys- tems, including monitoring of tendon elongation; 12. LTE at transverse joints for repair applications and for jointed continuous systems; 13. LTE at transverse expansion joint(s) for PPCP systems; and 14. Observation of safety protocols by the work crew. The following materials-related tests, as applicable, should be performed: 1. Grout sampling and testing; 2. Patching material sampling and testing; and 3. Polyurethane material sampling and testing. The following tests should be performed on the installed PCP system: 1. Joint deflection testing a. LTE at transverse joints for repair applications and for jointed continuous systems; and b. LTE at transverse expansion joint(s) for PPCP systems. 2. Coring a. Cores over the dowel slots to examine grout and patch- ing material coverage and to examine panel concrete quality; and b. Cores at several locations to evaluate the condition of the bedding material, if used. Deflection Testing Requirements Deflection testing should be performed using an FWD. The load applied for the LTE testing should be about 9,000 lb (4,082 kg). Tests should be performed about 2 ft (0.6 m) away from the lane edge (wheelpath location) and at the approach and leave sides of each tested joint. Deflection testing at the joint is conducted to verify the ability of the load transfer system to transfer the wheel load across a joint. The testing also provides an indication of the overall response of the PCP system to the applied loading.
148 However, the overall response of the PCP system depends on the support system (subgrade, subbase, base, and bedding if used), and the support system is not an item of evaluation in the PCP system approval process. The adequacy and cover- age of the bedding material, if used, should be determined by coring. With respect to the ability of a load transfer system to transfer the applied load across a joint, the following two assessment approaches have been used: 1. LTE: The deflection at the joint of the unloaded side (du) is compared with the deflection at the joint of the loaded side (dl). For new construction, an LTE of at least 90% is expected. 2. Relative deflection across the joint: The relative deflection across the joint (drel) is determined. This is simply the deflection at the joint of the loaded side minus the deflec- tion at the joint of the unloaded side. The relationship between LTE and drel is shown in Table 16.2 for a range of support conditions and an FWD load of 9,000 lb. As Table 16.2 shows, no global relationship exists between LTE and drel because the LTE for a given drel is greatly influ- enced by the support condition and panel thickness. The stiffer the support and thicker the panel, the lower the LTE will be. Field testing of the PCP projects indicates that the joint deflection for repair applications and jointed PCP sys- tems typically ranges from about 5 to 10 mils under FWD testing using a 9,000-lb (4,082-kg) load, indicating medium- stiff to stiff support for these projects. It is unlikely that any PCP trial section will be constructed over softer support conditions that result in joint deflections at the loaded side of 15 mils or greater under an FWD load of 9,000 lb (4,082 kg). It is therefore recommended that for the purpose of a PCP system approval that incorporates the approval of a specific joint load transfer system, that the joint deflection criteria be based on the drel value, not to exceed 1.5 mils. This restriction will allow the LTE values to range from about 70% for a stiffer support condition to about 90% for a softer support condi- tion. The proposed criterion is for system approval process only and is for assessment of the load transfer device itself and not for the evaluation of the entire PCP system. The pro- posed criterion is independent of slab (panel) curling and time of testing. Although other deflection-based criteria may be used for a test section of a specific repair or rehabilitation project and for acceptance testing during the installation of the PCP sys- tem, it is recommended that the drel â¤1.5 mils criterion be used for these purposes, as well. Using this criterion will allow acceptance of LTE <80% for a stiffer support condition; how- ever, for stiffer support conditions the overall deflection is relatively small, and the joint deflection and the correspond- ing LTE value are less critical for long-term pavement performance. For PPCP systems, the large joint width has a significant influence on the measured LTE and drel values. With that con- sideration, for the purpose of PCP system approval that incorporates the approval of a specific joint load transfer sys- tem, the joint deflection criteria for PPCP systems can be based on a drel value not to exceed 2.5 mils. Table 16.2. LTE and Relative Deflection LTE (%) for Support Condition dl (mil) drel = 0.5 mil drel = 1 mil drel = 1.5 mil drel = 2 mil drel = 5 mil Stiff 4 88 75 63 50 NA Stiff 5 90 80 70 60 0 Stiff 6 92 83 75 67 17 Stiff 8 94 88 81 75 38 Medium stiff 10 95 90 85 80 50 Medium stiff 12 96 92 88 83 58 Medium stiff 14 96 93 89 86 64 Softer 16 97 94 91 88 69 Softer 18 97 94 92 89 72 Softer 20 98 95 93 90 75 Note: NA = not available.
149 Approval of a PCP System by Comity A highway agency may approve a PCP system without requir- ing a trial installation if the system has been approved for use by another agency within the past 12 months and the approval is based on the system described by the submitted standard drawings. Summary PCP technology is of recent origin, and it is likely that refine- ments to the existing systems will continue to be made and new systems or system components will be developed. It is therefore necessary that highway agencies establish an independent pro- cess for evaluating and approving new PCP systems or com- ponents. Guidelines for evaluating and approving new PCP systems or components were presented in this chapter. As a minimum, the following attributes of a new PCP system need to be evaluated before approval of the system: 1. Constructability within the constraints of the lane closure requirements; 2. Productivity of installation; 3. Concrete quality; and 4. Structural performance a. Transverse joint load transfer provisions b. Specific base and bedding support requirements. Requiring PCP system vendors (precasters and contrac- tors) to have their systems approved before use at a project reduces the risks associated with implementing a new system under difficult lane closures and other site constraints, including nighttime work and limited work hours.
