Abstract

The objective of this research was to apply a previously recommended laboratory testing protocol to specific aggregate base materials that are also the subject of ongoing full-scale field testing. The scope of this research involved three aggregate base materials selected from three sites where full-scale field testing programs have been established. The first and second field sites included five different geogrid types, categorized as either biaxial or triaxial, in a singlelayer configuration, while the third site included only the triaxial geogrid type in either a singleor double-layer configuration. Geogrid-stabilized and unstabilized control specimens were evaluated using the American Association of State Highway and Transportation Officials T 307 quick shear testing protocol. Measurements of load and axial displacement were recorded and used to develop a stress-strain plot for each specimen tested. The peak axial stress, the modulus to the peak axial stress, the modulus of the elastic portion of the curve, and the modulus at 2 percent strain were then calculated. Statistical analyses were performed to investigate differences between geogridstabilized specimens and unstabilized control specimens and to investigate differences between individual geogrid products or geogrid configurations. Depending on the method of data analysis, the quick shear test results indicate that geogrid stabilization, with the effect of geogrid stabilization averaged across all of the geogrid products evaluated in this study, may or may not improve the structural quality of the aggregate base materials evaluated in this study. The results also indicate that, regardless of the method of analysis, one geogrid product or configuration may be more effective than another at improving the structural quality of a given aggregate base material as measured using the quick shear test. All results from this research are limited in their application to the aggregate base material types, geogrid products, and geogrid configurations associated with this study. Additional research is needed to compare the results of the laboratory quick shear testing obtained for this study with the structural capacity of the geogrid-stabilized and unstabilized control sections that have been constructed at corresponding full-scale field testing sites. Specifically, further research is needed to determine which method of laboratory data analysis yields the best comparisons with field test results. Finally, correlations between the results of quick shear testing and resilient modulus need to be investigated in order to incorporate the findings of the quick shear test on geogrid-stabilized base materials into mechanistic-empirical pavement design.

Degree

College and Department

Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering

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