Quantifying Effective Built-in Temperature Difference for Decades- Old Jointed Plain Concrete Pavements in Eastern Washington State

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Fifteen Portland cement concrete (PCC) slabs from four Jointed Plain Concrete Pavement (JPCP) sections in the Long-Term Pavement Program (LTPP) located in eastern Washington State were studied in this paper. Dipstick-measured transverse deflection profile along with temperature measurements across slabs’ depths collected during falling weight deflectometer (FWD) testing were used in the study. The youngest section in the study was 24 years old at the time of testing. The objective was to characterize the total effective linear temperature difference (TELTD) and the effective built-in temperature difference (EBITD) in the slabs. EBITD is a temperature differential representing the combined effects of construction built-in, as well as long-term drying shrinkage, and creep equivalent temperature differences. Using ISLAB2000, several iterations were run for each slab to identify the TELTDs that would produce slab curvatures close to those measured in the field. For validation purposes, the found TELTDs were used in Westergaard’s closed-form solution for deflections in the transverse direction. Transverse profiles predicted by ISLAB2000 and Westergaard equations matched well. EBITD, was then obtained by simply subtracting the in-field measured temperature differential from TELTD. Variations of EBITDs were found among the four sections, ranging from +31 to -120 °C (55 to -215 °F). Multiple factors, such as structural features, material properties, construction conditions, and climatic conditions, were identified as influential for the predicted EBITDs.