Coefficient of Thermal Expansion of Concrete Materials

Abstract

The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires the coefficient of thermal expansion (CTE) of concrete materials as a direct input to determine critical pavement distresses. The CTE can be determined using AASHTO TP 60. For this study, a CTE measuring device in compliance with AASHTO TP 60 was acquired. Three replicate specimens were prepared for each of 24 concrete and cement paste mixtures and tested at 7 and 28 days. The range of CTE determined in this study was in agreement with the range of values reported by other studies, and the variability of test results was favorably comparable. Analysis of variance and sensitivity analyses were performed to evaluate the influence of mixture properties on the CTE and the effect on pavement performance predictions of using Level 1- and 3-CTE inputs. It was concluded that the type of coarse aggregate used in portland cement concrete (PCC) mixtures significantly influenced the CTE and pavement performance predictions. The proportion of coarse aggregates in the PCC mixture could significantly affect the CTE depending on the types of aggregates used in the mixture. In addition, recommendations for Level-3 CTE input can be used for PCC mixtures with limestones and sandstones. However, CTE recommendations for PCC mixtures with gravels were not available for comparisons. It is recommended that a future CTE testing program for supporting implementation of the MEPDG include primary local aggregate types and that CTE recommendations for Level-3 CTE input in the design software be updated to include more aggregate types, especially gravels.