Precast Concrete Panel Systems for Full-Depth Pavement Repairs: Field Trials
Chapter 1 Introduction
The traditional practice of rehabilitating concrete pavements is an excellent way to extend the remaining service life of the overall pavement network. In most instances, this method of paving has satisfied the requirements of the specifying agency. However, the luxury of prolonged lane closures is an option whose time is long gone. Increasing traffic volumes and sensitivity to user delays and costs have required pavement construction and rehabilitation to be put on a "fast track" as much as possible. The objective of fast-track paving is to minimize the time a roadway is out of service (Federal Highway Administration [FHWA] 1994). The resulting pavement can be opened to traffic (both construction and public) after adequate strength has been achieved. Fast-tracking has resulted in the use of chloride accelerators in combination with increased cement content to accommodate the short traffic opening times. These modified mixtures are susceptible to durability problems.
Precast structural elements have long been used successfully in the building and bridge industry. The authors of this study investigated the feasibility of doweled precast panels as an alternative full-depth repair strategy. The use of doweled precast panels provides an attractive alternative that can potentially address construction time, short-term and long-term concrete durability, and performance issues. The precast panels can be fabricated by using conventional concrete paving mixture designs (without the need for setting- or strength-accelerating admixtures) and cured under controlled conditions if necessary at a precast plant. Such "factory made" concrete is less susceptible to construction and material variability.
The objectives of this study were as follows:
- Review the literature and document the known practices.
- Conceptualize various construction alternatives as they relate to precast concrete patches.
- Identify potential preventative maintenance projects along in-service concrete pavements in Colorado and Michigan, and install precast concrete patches. For the purposes of comparison control, cast-in-place full-depth patches were also installed.
- Investigate the effectiveness and efficiency of precast patches through the development of maintenance performance guidelines.
- Recommend strategies for monitoring the "newly" installed precast patches.
- Produce step-by-step guidelines for the construction of precast concrete patches.
The completion of these objectives is to assist in evaluating the feasibility of precast panels as an alternative to conventional full-depth repair of jointed concrete pavements.
Organization of the Report
This final report, which consists of four chapters, summarizes the findings of the 3-year study. Chapter 2 provides a summary of the literature concerning precast concrete pavements, and Chapters 3 and 4 summarize the Michigan and Colorado field studies, respectively. A sample distress documentation report is presented in Appendix A, a presentation of construction guidelines is presented in Appendix B, and a sample special provision specification developed as part of the study is presented in Appendix C.