Determining the Compactive Effort Required to Model Pavement Voids Using the Corps of Engineers Gyratory Testing Machine

About the report:

Various agencies have used the Corps of Engineers gyratory testing machine (GTM) to design and test asphalt mixes. Materials properties such as shear strength and strain are measured during the compaction process. However, a compaction process duplicating void levels in the pavement after traffic has not been clearly defined when using the oil-filled roller. The intent of this project was to determine the laboratory compactive effort for the GTM that duplicates the voids in pavement after being exposed to traffic. Samples of asphalt mix were obtained during construction often field projects and tested in the laboratory with six different compactive efforts using various angles of gyration and vertical pressures. Voids were also measured in pavement immediately after construction and after several years of exposure to traffic. Regressions were then developed to allow the prediction of pavement voids from the voids obtained by the laboratory compaction procedures. A high correlation between voids obtained in the laboratory and pavement voids after several years of traffic was obtained with the gyratory testing machine at two combinations of gyratory angle and vertical pressure; however, the degree of correlation was mostly dependent on the inclusion of the post-construction voids.

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