A method for evaluating CRCP performance based on edge-loaded FWD test

The backcalculated modulus of subgrade reaction (k-value), elastic modulus of concrete (E), and effective thickness (h_eff) given the deflection basin from the Falling Weight Deflectometer (FWD) testing has been extensively used in evaluating the response and performance of in situ concrete pavements. Traditional backcalculation assumption of an interior-loaded infinite slab can lead to large errors in backcalculated parameters for edge-loaded continuously reinforced concrete pavement (CRCP) because of the load position and closely-spaced transverse cracks. In this paper, the backcalculaion formulas for edge-loaded CRCP with various crack spacing was proposed based on 2-D finite element analysis. According to the backcalculated results, both positive and negative temperature differentials of less than 16 °F had limited impact. As expected, the larger the lateral offset of the plate, the greater the impact on backcalculated results given the minimum error in h_eff reaching 5.0% with a 4 in. lateral offset. In order to verify the proposed backcalculation method, a field CRCP test section with different base types and reinforcement ratio were evaluated. The impact of edge support provided by base layer was also shown to be significant, given the support of a 2 ft overwidth base showing the same impact of approximately 1 in. extra thick base.