冻融循环作用下再生混凝土砖砌体通缝受剪试验研究

本文报导了对冻融循环作用下96个再生混凝土砖砌体抗剪试件进行的沿通缝抗剪试验。研究涉及冻融循环对再生混凝土砖砌体抗剪力学性能的影响,对比分析不同胶结材料试件的破坏形态及其抗剪强度,揭示冻融损伤对再生混凝土砖砌体抗剪强度的影响规律,并从微观角度探讨砂浆孔隙变化对砖砌体抗剪承载力的影响,建立再生混凝土砖砌体抗剪强度冻融损伤衰减模型。结果表明:砖砌体抗剪强度受冻融环境影响非常明显,其抗剪强度随冻融循环次数的增加而降低,降低的速度呈现出先慢后快的趋势;粉煤灰的加入有助于改善冻融环境下砖砌体的抗剪能力;对于石灰砂浆抗剪试件,初期的抗剪能力及冻融后的抗剪能力均下降;建立了考虑冻融损伤影响的砖砌体抗剪强度衰减模型,试验数据与计算结果吻合较好。

Experimental Study of Seam Shear Strength of Recycle Concrete Brick Setting Subjected to Freeze-Thaw Cycle Action

A seam shear-resistance experiment for 96 recycled concrete brick (RCB) setting specimens subjected to freeze-thaw cycle action was carried out. The aim of study is first to understand the effect of freeze-thaw cycle on the shear-resistance of recycled concrete brick setting, second, to comparatively analyze the failure mode and shear strength of specimens made of different cementing material, third, to reveal the regularity of recycled concrete brick setting shear strength change due to freeze-thaw damage, then to investigate from microscopic point of view the effect of mortar porosity on the shear capacity of brick setting, and finally to establish shear strength degradation model for recycled concrete brick setting. Results indicate that the effect of freeze-thaw environment on the shear strength is very obvious; shear strength reduces with the increase of number of freeze-thaw cycle, its dropping is slow at the beginning, and becomes faster later. The addition of fly ash helps to improve the shear capacity of brick setting in freeze-thaw environment. For lime mortar shear test specimens, the shear capacity on initial stage and after freeze-thaw cycle is always decreased. Based on freeze-thaw damage coefficient of shear strength, shear strength degradation model of recycled concrete brick setting is established, results of which are in good agreement with experimental data.