Re-evaluate Current Potential Vertical Rise (PVR) Design Procedures

Project Description

The principal problem with pavements on expansive soils is that they swell and shrink during climatic wet and dry cycles, causing the pavement to become rougher. Field observations and measurements of subgrade moisture and pavement profiles were made at all representative moisture climatic zones across Texas to monitor how the test sections became rougher with time and traffic. The current project was performed to determine whether the current potential vertical rise (PVR) pavement design procedures could be updated to reflect results of the monitoring. In this project researchers developed a new pavement design procedure based on results of the many years of monitoring and analysis. To make sure that the new procedure worked well in practical applications, three case studies were performed. To support the new design procedure, researchers developed two computer programs, laboratory test protocols in standard Texas Department of Transportation specification format, and instructional CDs. One of the programs calculates the changes of moisture and movement of an entire cross section over an extended period of years in response to the local weather patterns, drainage, vegetation, and moisture control measures that the designer wishes to consider. The other program is a design program that makes use of the subgrade movement-versus-roughness relationships that were developed during pavement monitoring. Comparative studies showed that the existing PVR method usually overpredicts swelling movement while neglecting shrinkage movements, which in some cases can be equally severe. The new procedure can provide realistic simulations of both soil swelling and shrinkage.

Project Publications

Design Procedure for Pavements on Expansive Soils: Volume 1 0-4518-1 (V1)

Re-evaluation of Potential Vertical Rise Design Procedures 0-4518-S

Design Procedure for Pavements on Expansive Soils: Volume 2 0-4518-1 (V2)

Design Procedure for Pavements on Expansive Soils: Volume 3 0-4518-1 (V3)

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