古代砖砌体风化性能分析及风化程度评定

自然界中气温、降水的长期作用导致古代砖砌体风化，风化损伤材料和砌体力学性能。实验采用大气环境实验舱实现自然风化作用人工模拟，根据不同饱水度和冻融次数，实验舱设定了7种非饱水冻融工况，对7种工况影响下的砖、灰浆、砌体抗压、砌体抗剪试件试件强度变化规律进行实验分析。实验表明，饱水度是反映材料冻融性能的重要指标；不同饱水度下的冻融试件强度呈现先升后降的趋势；试件在饱水度为53%的冻融作用下，砌体构件具有最佳抗力；提出古代砖砌体构件风化程度评定标准。实验对古砖砌体结构保护工作具有指导和应用价值，定期评定古塔砌体风化程度，时刻掌握古塔构件结构安全性能的变化规律，科学保护古塔。

Ancient brick masonry behavior and weathering degree evaluation

During long action of temperature and precipitation, ancient brick masonries were weathered. The experiment employed an environmental chamber to simulate natural condition. seven unsaturated freeze-thaw cases were designed to treat various specimens which are brick units, mortar cube, triple masonry and prism masonry. We carried out saturation degree measurement, compressive test and shear test to the various specimens in laboratory. The resules show that the saturation degree is one key factor to effect on material freeze-thaw resistance. The strength of specimens increaseed firstly with saturation degree and decreases after a certain saturation degree. The best compressive resistance of brick, mortar, and prism masonry was when the saturation degree is about 53%. Based on the weathering coefficient and specimen mechanical behavior, we suggested the evaluation standard of weathering degree for ancient brick masonry structures.