Early shrinkage experiment of concrete and the development law of its temperature and humidity field in natural environment

Abstract

Concrete shrinkage is one of the main causes of structural deterioration, and clear understanding of the development law of temperature and humidity field is a key to accurately predict concrete shrinkage. To study the effect of temperature and humidity (T&H) difference of concrete caused by curing conditions on its shrinkage, this study designs a concrete shrinkage experiment with three different maintenance conditions of moisture-thermal exchange, moisture retention, and moisture-thermal retention. Subsequently, a data correlation algorithm combining maximum information coefficient (MIC) and random walk (RW) is proposed. The correlations between the environment T&H and the concrete T&H, concrete temperature and its humidity, as well as the concrete T&H and its shrinkage are quantitatively investigated. The experimental results indicate that the curing conditions of moisture retention and moisture-heat retention respectively reduce the concrete shrinkage strain by 30.7% and 11.3% compared with the moisture-heat exchange condition at the age of 125 days. The coupling effect between the change rate of temperature and the change rate of humidity needs to be considered in the analysis of the moisture and heat field of concrete, while the influence of the second derivative of temperature with respect to space on the humidity change rate (that is, the Soret effect) can be ignored. The conclusions obtained in this study can provide a basis for the selection of coupling terms in the moisture and heat transfer analysis of concrete and the establishment of shrinkage prediction models.