基于环境变迁影响的古砖孔结构及饱和系数

Ancient Brick Pore Structure and Saturation Coefficient Based on Environmental Variation

摘要:

通过不同水平下的淡水冻融、盐水冻融，人工模拟山西某地区环境变迁特征，采用蒸煮法和压汞法实验，建立古砖不同孔径孔隙体积和饱和系数的对应关系，评估分析环境变迁对古砖孔结构及饱和系数的影响.针对同一区域的某古建筑群不同年代的实体砖进行实验验证.研究结果表明，环境变迁导致古砖的孔隙率和孔径分布变化；其中，淡水冻融导致砖孔隙率呈现规律性变化，孔隙率缓慢增长；盐水冻融导致砖孔隙率呈现间歇性变化；小于1 μm孔径孔隙体积占总孔隙体积百分数逐渐减少，1~5 μm孔径孔隙体积占总孔隙体积百分数逐渐增大；孔径孔隙体积变化性能和饱和系数具有很好的相关性，有利于解决文物建筑实验样品数量不足的问题，用其替代饱和系数评定古建筑砖抗风化性能具有可行性.

Abstract:

Salt solution and temperature fluctuation are predominant factors influencing the weathering performance of ancient bricks. This paper conducted laboratory test to explore weathering performance of ancient bricks in the Yellow River region. The experiment simulated brick freeze thaw cycle in fresh water and salt water, and used mercury intrusion porosimetry and five hours boiling in water to obtain pore structure characteristics and saturation coefficient. The experiment results show that the volume fraction of pore diameter of less than 1 μm decreases while that of 1 to 5 μm increases, and the saturation coefficient index is closely related to pore structure index. Pore structure index can replace saturation coefficient in evaluating the weathering performance.