关键词: 混凝土, 持续压荷载, 干湿循环, 毛细吸水, 吸水率, 回归分析

Abstract: Both loading and wet-dry cycle have a key influence on the internal material transport and service life of concrete structures. In order to study the capillary water absorption properties of concrete under the coupled effect of loading and wet-dry cycle, continuous compressive loading at 0%, 10%, 20% and 35% load levels were applied to the concrete specimens, and the changes in the water level in the tube were observed during the 1st, 3rd and 7th wet-dry cycle of water absorption at different load levels, and the cumulative water absorption curves for the first 300 min of the water absorption process were obtained by processing. The results show that the cumulative water absorption of concrete and the water absorption rate at each stage are negatively correlated with the times of wet-dry cycle. When the times of wet-dry cycle are the same, there is a threshold value for the change of the initial water absorption rate S₁ of concrete with higher stress level, and the threshold value decreases with more times of wet-dry cycles. The difference between the initial water absorption rate S₁ of concrete and the later water absorption rate S₂ decreases with more times of wet-dry cycles. The establishment of correlating regression model can well describe the variation trend of concrete capillary water absorption properties under the coupling effect of loading coupled with dry-wet cycle.

Key words: concrete, continuous compressive loading, wet-dry cycle, capillary absorption, water absorption rate, regression analysis