Hydration and pore structure characteristics of concrete incorporating internal curing materials in a dry and large-temperature-difference environment

Abstract

Abstract The climate in the Central Asian area is extreme dry, with a large temperature difference between day and night, and the concrete is easy to crack during the construction period under the conditions of traditional external curing. Therefore, this study concerns understanding the application of internal curing materials in a dry and large-temperature-difference environment. The effects of three internal curing materials, namely, Super Absorbent Polymer (SAP), Light Weight Aggregate (LWA) and Perforated Cenospheres (PCs), on hydration and pore structure characteristics of concrete were investigated. Scanning electron microscope (SEM) and x-ray diffractometer (XRD)were used to observe the microscopic morphology and physical phase composition of concrete, and the evolution of pore characteristics was analyzed using mercury intrusion porosimeter (MIP) to explore the mechanism of pore structure refinement. Results show that the pores formed by the release of water provide space for the accumulation of hydration products, thereby accelerating the formation of ettringite crystals. Results indicate that the continuous release of internal curing materials allows the interior of the concrete to continue to be hydrated, which greatly promotes the overall hydration of the cement. The effect of supplementary cementitious materials (GGBS, FA) and implications of large-temperature-difference environment on concrete durability are discussed.