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CPTP Status Report - Task 65 Engineering ETG Review Copy
Chapter 2 - CPTP Focus Areas
CPTP Focus Area 4: Rapid Repair and Rehabilitation
Pavement rehabilitation is a major activity for all highway agencies and has several consequences on agency resources and traffic disruptions because of extensive and extended lane closures. The traffic volumes on the primary highway system, especially in urban areas, have seen tremendous increases over the last 20 years, leading in many instances to an earlier-than-expected need to rehabilitate highway pavements. Efforts continue to develop techniques and procedures that will result in cost-effective and longer-lasting concrete pavement rehabilitation to serve the nation's highway system well into the 21st century. In addition, many agencies continue to wrestle with the age-old problem: longer delays now and longer service life versus shorter delays now and shorter service life.
Projects in this area are looking at ways to improve or advance concrete pavement rehabilitation technologies that will allow for faster and more durable repair and rehabilitation/reconstruction of concrete pavements. This effort includes the use of high early strength concrete materials and the use of precast pavement technology. Highlighted projects within this focus area are described below.
In Eastern Washington, three major HMA intersections were reconstructed with PCCP in August 2000. The entire reconstruction of each intersection, including demolition of the existing HMA pavement and its replacement with PCCP, took place over a period of 3 days (starting on Thursday evening and opening the intersection to the traffic on Monday morning). Under CPTP Task 7C, the researchers documented this effort along a section of SR 395 in order to provide practitioners additional options for rapid reconstruction of urban facilities. The final report for Task 7C included an analysis of the cost benefit ratio; documentation of the construction process, including innovative construction practices and production rates; and documentation of traffic management strategies. Additionally, video documentation was produced for use in technology transfer. The study documentation and video are being used to educate pavement construction professionals and university students on how urban highway facilities can be reconstructed on a fast track basis, with minimal user disruption, using innovative construction techniques and traffic management optimization principles. This study was performed in collaboration with the Washington State Department of Transportation.
Under CPTP Task 1, weekend reconstruction of another urban highway facility was also documented. This project involved reconstruction of a 1.8-mile section of I-10 near Pomona, California over one weekend period (55 hours). The documentation prepared under Task 1 provide guidelines for considering factors that improve construction productivity under tight reconstruction schedules and identifies factors that may constrain overall productivity. This study was performed in collaboration with the California Department of Transportation.
One of the most promising rehabilitation techniques undergoing field trials is the precast concrete pavement technique. This technique, dating back several decades, is being applied to rapid repair of localized failures in concrete pavements (full-depth repairs) and to rehabilitate long lengths of existing poorly performing asphalt and concrete pavements. The precast paving technology has matured and is ready for widespread use. Use of this technology will result in more durable repairs and rehabilitation, help shorten lane closures, and increasing user satisfaction.
Under CPTP Task 7E, the use of precast paving for full-depth repairs of jointed concrete pavements has been demonstrated in Michigan and Colorado. Using this process, full-depth repair patches can be opened to traffic within 6 to 8 hours of lane closure. In the demonstration projects, factory cast 6 by 12 ft panels were used to repair deteriorated joints along sections of the interstate highway system. The repairs involved removal of deteriorated joint concrete, preparation of the base support, placement of a fast-setting bedding material, installation of precast panels, and installation of retrofitted dowel bars at the transverse joints. These projects are under evaluation to determine long-term performance.
Under Task 58, several studies have been funded to determine the feasibility and cost-effectiveness of using precast pavement to rapidly rehabilitate or reconstruct existing concrete or asphalt pavements. In the initial study, the researchers developed a concept for precast concrete pavement and recommended testing the concept through pilot projects. In March 2002, Texas DOT successfully completed the first pilot project on a frontage road near Georgetown, Texas. At this pilot project, the following design and construction features were incorporated:
A successfully developed precast pavement rehabilitation technique will provide many benefits, including the following:
Additional precast pavement repair and rehabilitation demonstration projects are planned for the Year 2004.
The history of the UTW pavements is still short; however, early evaluations have shown promising performance. Corner cracking and delaminations appear to be the most predominant distress types. With the use of UTW pavements increasing, naturally, the next question is how to repair the system when distresses do occur. The construction of the UTW test sections at the Federal Highway Administration's (FHWA) Turner-Fairbank Highway Research Center (TFHRC) (CPTP Tasks 5 and 55, see Focus Area 1 discussion), subjected to accelerated loading tests, provided an excellent opportunity for evaluating potential UTW pavement repair methods. Under CPTP Task 7B, UTW repair techniques were demonstrated by using some of the distressed slab panels at the FHWA's UTW test section. The repair panels were subjected to accelerated load testing. The study demonstrated that distressed UTW can be quickly and effectively replaced. A final report and a video documenting the repair process are available.
Under CPTP Task 54, efforts are underway to develop systematic, user-friendly guidelines for the repair and rehabilitation of distressed concrete pavements. As part of this effort, a set of guidelines has been developed for evaluating the condition of existing concrete pavements and for determining the most effective strategy for repair and/or rehabilitation of the pavement, considering future traffic, condition of the existing pavement, cost, and desired service life of the repaired/rehabilitated pavement. A user-friendly software has also been developed to assist pavement engineers identify the most effective rehabilitation alternative for a given set of conditions.
CPTP Task 52 is the continuation of FHWA's SP-205 field demonstration program. The SP-205 is developing field-tested guidance on concrete pavement rehabilitation and repair techniques as well as strategies that emphasizes the do's and don't's, and why and when for concrete pavement restoration (CPR) and preventive maintenance of concrete pavements.
SP-205 is evaluating pavement repair/rehabilitation sites and techniques studied by FHWA in the mid 1980s and testing and evaluating new and innovative CPR techniques and strategies through new test and evaluation projects. The rehabilitation and maintenance strategies considered are full-depth patching, partial-depth patching, sub-sealing, joint resealing, retrofitted load transfer, and grinding and grooving. Periodic evaluation of the field test sites is being carried out under CPTP. About 40 sites are under evaluation. Based on the analysis of the field data, proper timing for repair and preventive maintenance will be defined. A series of updated Technical Bulletins will be published for each technique included in this project.