关键词: 建筑垃圾复合粉体材料, 抗冻性能, 预测模型, 损伤机理, 孔结构

Abstract: The pile-up of significant amount of construction waste and the deterioration of the durability of cement concrete under freezing-thawing cycling are two major challenges in civil engineering. In order to improve the reuse rate of the construction waste and to have better understanding of the deterioration mechanism of concrete mixed with construction waste (brick powder) composite powder materials (CWCPM) under freezing-thawing condition, laboratory experiment and theoretical analysis were carried out. The effect of different factors on the macroscopic performance deterioration of concrete was investigated and the freezing-thawing damage evolution model of concrete mixed with CWCPM was established by multifactor analysis. The microscopic structure and appearance and pore structure of the concrete were also analyzed, and the deterioration mechanism was revealed. The results show that the degree of freezing-thawing damage increased with the increase of water cement ratio, the number of freezingthawing cycles and the concentration of the salt solution. The anti-frost performance of the concrete was improved by the CWCPM. Compared with the control specimen, the amount of stripping per unit area and the compressive strength of the concrete specimen with 30% CWCPM decreased by 27． 1% and increased by 6． 2% respectively, after 50 cycles of freezing-thawing. The freezing-thawing damage evolution model based on macroscopic test results can predict the frost resistance of concrete accurately. In essence, the deterioration of the concrete under freezingthawing condition is a physical process during which its microscopic structure gradually become loose and its pore structure become worse.

Key words: construction waste composite powder materials, anti-frost performance, prediction model, deterioration mechanism, pore structure