Age and Moisture Effects on Thermal Expansion of Concrete Pavement Slabs

Abstract

A mechanistic-empirical pavement design guide (MEPDG) for portland cement concrete pavement (PCCP) has been developed recently and, within it, the coefficient of thermal expansion (CoTE) of concrete is considered as a crucial variable. Previous research has suggested that the concrete CoTE is affected by the availability of moisture in capillary and gel pores. The capillary pores are filled with hydration products, and their volume decreases at an early age of the concrete. However, the variation of the concrete CoTE due to hydration and moisture has not been quantified completely. The results have varied mainly due to the development of measurement techniques. The age and moisture effects on the CoTE of concrete were investigated by measuring the temperature, humidity, and strain of a cylinder specimen at both the initial and later ages. Drying shrinkage and autogenous shrinkage were considered in the calculation of the CoTE, particularly at early concrete ages. This investigation was facilitated by moving a concrete test specimen periodically from a 60°C environment to a 10°C environment over a 6-month period. Dilatometer testing and composite modeling were also conducted to verify the age and moisture effects on the concrete CoTE. Results show a close resemblance between the CoTEs determined by these different approaches. According to finite-element (FE) analysis, the behavior of the pavement slab was significantly affected by the variation of the concrete CoTE.