Experimental and theoretical analysis on coupled effect of hydration, temperature and humidity in early-age cement-based materials

Abstract

Cement-based materials are widely used as building materials in practice. However, the deformations caused by changes in temperature and humidity are large and can easily result in cracking at an early age. Early-age cracking significantly affects the durability of concrete. In this paper, experiments on temperature and relative humidity (RH) were conducted, and a coupled model of temperature and RH was proposed. The test results showed that the coupled phenomenon of temperature and RH could be clearly observed and divided into three stages. The RH rapidly decreases with a large temperature increase and rate of temperature increase in the first stage and sharply increases with a large temperature decrease and rate of temperature decrease in the second stage. Finally, the RH decreases again throughout the remainder of the test. Based on a comparison of the predicted values and experimental data, the coupled model proposed can accurately predict the temperature and humidity field in early-age cement-based materials. Additionally, the coupled model demonstrates that excepting for the self-desiccation and moisture diffusion, the early change in RH is significantly affected by the large temperature change and rate of temperature change in the early age.