WRSC

Home Laboratory facilities Research Projects Training and Outreach Lab Safety Links Reach Us		WESTERN REGIONAL SUPERPAVE CENTER
		PAVEMENT DESIGN AND REHABILITATION Development of Overlay Design Procedure This project was sponsored by the Nevada DOT and was completed in 1993. The overall design procedure allows for three design applications: a) design without non-destructive testing data, b) design with non-destructive testing data, and c) design with non-destructive data and unit delineation. The design without NDT data allows the engineer to use experience or laboratory testing data. The design with NDT uses the results of the falling weight deflectometer to evaluate the in-situ properties of the pavement structure. The design process accounts for seasonal variations in materials properties using seasonal coefficients developed through a five-year long NDT testing program. The overlay design procedure includes a menu-driven window-based computer software which conducts the analysis as a function of pavement life. The final outcome is a relationship between overlay thickness and number of years which allows the design engineer to assess the impact of various overlay thicknesses. Available Information: Overlay Design Software can be obtained by contacting WRSC. Final Report can be obtained by contacting WRSC. Development of Performance Models for Pavement Maintenance and Rehabilitation Techniques This project was sponsored by the Nevada DOT and was completed in 1998. The project investigated the various factors that impact the long term performance of the various maintenance and rehabilitation techniques for flexible pavements. The maintenance techniques included: Chip seals and sand seals. The rehabilitation techniques included: overlay, mill and overlay, and roadbed modification. Using the identified factors along with the pavement performance data in NDOT’s pavement management system, the project developed performance models which predicts the long term behavior of flexible pavements. Statistical analyses were used to develop regression models relating the long term performance of pavement rehabilitation and maintenance techniques to materials, structure, environment, and traffic factors. The research also provided techniques for conducting life cycle cost analyses and network optimization. Available Information: Network Optimization Software can be obtained by contacting WRSC. Final Report can be obtained by contacting WRSC. Evaluation of Cold In Place Recycling of HMA Pavements This project was sponsored by the Nevada DOT and is still on-going. In 1997, NDOT started using cold in place recycling (CIR) as a rehabilitation alternative on roads with medium-low traffic volumes. The objective of CIR is to transform the cracked, old, and brittle hot mixed asphalt layer into a flexible layer thereby reducing the potential for reflective cracking through the new HMA overlay. The first three projects were constructed on US95 (Nye), US50 (Eureka), and SR396 (Pershing). The main concern with CIR was the potential of the in-place materials of becoming brittle with time. Therefore, its was decided to sample the projects over a period of time and evaluate their resilient modulus properties. Core samples were obtained from the three projects during the past five years and have been evaluated in the laboratory to evaluate the long term performance of the CIR mixtures. Available Information: Download Final Report. Rehabilitation of Rigid Pavements. This project was sponsored by the Nevada DOT and was completed in 1999. the objective of the research was to identify an effective method for rehabilitating the aging rigid pavements in Nevada. The research constructed crack/seat and rubblization test sections on Interstate 80 near Elko, Nevada. The sections were both overlaid with HMA layers between 3.5 - 5" thick. The location of the sections subjected them to heavy traffic and severe environmental conditions (very cold winters and very hot summers). The design of the sections was optimized through the use leveling course and polymer-modified HMA mixtures which provided the greatest flexibility and resistance to reflective cracking. The sections have been continuously monitored for the past five years and indicate excellent performance. Available Information: Final Report can be obtained by contacting WRSC.