Built-in temperature's regional characteristics of cement concrete pavement and its effect on slab curling

Based on the climate parameters of five Chinese regions, the distributional characteristics of built-in temperatures of cement concrete pavements in different regions with different altitudes and latitudes were studied by using the computational program of early-age temperature field of cement concrete pavement. The superposition effect of built-in temperature and ambient temperature was considered, the influence characteristics of built-in temperatures in different regions on the curling and uplifting of pavement were analyzed by using the 3 Dfinite element program. Research result shows that slab curling is affected by the built-in average temperature and built-in temperature difference between slab's top and bottom. Annual built-intemperature differences of cement concrete pavements in different regions present the bimodal distribution characteristics with low-wide and high-cuspidal peaks that respectively denote the distributions of negative and positive differences. Negative built-in temperature difference normally forms in the daytime, and has a large variability, which causes slab corner's upward curling. While positive built-in temperature difference basically forms in the nighttime, and has a numerical concentration, which causes slab corner's downward curling. The built-in temperatures of the pavements in different regions were compared, negative built-in temperature difference in the plateau area is the largest, and the high-frequency difference can reach-17.2℃in Lhasa. The second one is in the north area where the high-frequency difference can reach-13.2 ℃ in Harbin. Built-in average temperature is generally negative, and its distribution is the single-peak type. The annual range of air temperature in the high latitude region is larger, which directly results in the larger variation range of built-in average temperature. High-frequency built-in average temperature in Harbin is approximately-30.4℃, and approximately-18.4℃in Lhasa. Negative built-in average temperature also causes the downward curling of slab corner, and the effect of built-in average temperature on the curling is approximately 30%-50% effect of built-in temperature difference under the same condition. Different built-in temperatures combined with local climate have difference effects on the curling and uplifting of service pavement. When the negative built-in temperature difference of-20℃is added to local climate, the curling of slab increases by approximately 1.5-2.0 mm. It is suggested that pavement structure with quadrangular constraints is used in significant curling area to improve the engineering performance of the pavement.