Seasonal Load Response Behavior of a Thin Portland Cement Concrete Pavement

The mechanistic-empirical pavement design methods currently under development have demonstrated a need for seasonal material and load response behavior characterization. The seasonal dynamic load strain response of a thin [5-in. (127-mm)], low-cost, portland cement concrete pavement at the Minnesota Road Research Project was examined. Environmental and load-related factors to be considered in this type of study are described. For the truck speeds used, analysis found minimal effects on measured dynamic strain. Nonlinear temperature profiles in the slabs prompted the use of the temperature-moment concept in the analysis. For the approach side of the joint in the slabs, during periods with unfrozen base and subgrade layers, there is only a small increase in the dynamic strain response with decreasing temperature-moment. Average dynamic strain responses range from 50 to 80 microstrain, with little difference in magnitude between the 80,000-lb (355-kN) and 102,000-lb (453-kN) loadings. For the leave side of the joints in the slabs, there is a larger increase in dynamic strain response with decreasing temperature-moment. In addition, the 102,000-lb load response is nearly 60% larger than the 80,000-lb load response for large negative temperature-moments. Recommendations for improving dynamic load testing of pavements are given.