A coupled hygro-thermal model of early-age concrete based on micro-pore structure evolution

In order to analyze the hygro-thermal coupling effect in early-age concrete, this research establishes a coupling hygro-thermal model based on hybrid mixture theory (HMT) considering the characteristic of the microstructure evolution of early-age concrete. The adsorption curve of early-age concrete is acquired based on the microstructure evolution through establishing the relationship between saturation and several factors, such as hydration degree, temperature, capillary pressure and so on. An innovative coefficient for counting the influence of humidity on hydration rate is proposed, which takes the influence of humidity on hydration rate under self-desiccation as a reference based on the existing test. The research results indicate that the coupled hygro-thermal model constructed based on the micro-pore structure evolution can accurately predict the time-dependent development of temperature and humidity field inside the early-age concrete. The research can theoretically support the investigation on the deformation and cracking of the early-age concrete.