Evaluation of Pavement Layer Response at the Virginia Smart Road

The heavily instrumented Virginia Smart Road project provided the opportunity to test various hypotheses on pavement nondestructive testing using falling weight deflectometer (FWD). This was achieved by analyzing the deflections obtained on top of each layer as the road was being constructed. Two loading plate sizes were used at the subgrade and aggregate subbase surfaces. Five different loadings were used in each testing. This allows an accurate backcalculation of insitu resilient modulus of each layer. Such results may be used to calibrate future FWD measurements. The study found that using the surface modulus to characterize the subgrade might sometimes be misleading. In addition, characterization of the deflection basin using deflections alone may not provide accurate results. Using the ratio between the deflection basin area centroid coordinates may provide a reasonable alternative. The distribution of pressure resulted from FWD loading was successfully measured by embedded pressure cells in the HMA base layer.