Mechanical properties and volumetric deformation of early-age concrete containing CaO-MgO blended expansive agent and temperature rising inhibitor

Abstract

The early-age cracking occurred frequently because of the large autogenous shrinkage and the substantial and rapid temperature drop in high-strength and high-performance concrete structure, which seriously prejudices the durability and even the safety of the structure. This paper aimed at utilizing the combination of CaO-MgO blended expansive agent (CMEA) and Temperature rising inhibitor (TRI) to compensate for the concrete contraction. The results showed that the addition of TRI and/or CMEA weakened the strength and dynamic elastic modulus (DEM) as well as increasing the curing temperature. The CMEA addition could improve the relative humidity (RH) in specimens with or without TRI. When TRI content increased, the RH of specimens with TRI only decreased apparently but the RH decline in specimens containing CMEA and TRI was negligible. The CMEA could compensate for the concrete shrinkage not merely at the early stage but the later stage. The combination of CMEA and TRI increased the expansion peak and reduced autogenous shrinkage compared to single CMEA addition. With the increasing TRI content, the autogenous shrinkage of concrete increased visibly but the autogenous shrinkage of specimens containing TRI and CMEA decreased first and then increased. Additionally, the autogenous shrinkage and shrinkage rate of specimens with TRI and CMEA decreased markedly with curing temperature due to CMEA better expansion effect at high curing temperature.