ABSTRACT

Earthen sites have important historical, cultural, artistic, social, and scientific values. However, they have been seriously destroyed by weathering. The methods of in situ replacement and sacrificial layer were previously presented to protect the surface of the earthen sites. This work presents the feasibility of the polyvinyl alcohol (PVA)-treated soil in a mud state as the anti-weathering material for these two methods. The desiccation cracking behaviour of soil was the main concern, and the surface peeling, hardness, and colour difference were used as the auxiliary evaluation criteria. The results showed that the PVA solution with a high degree of alcoholysis effectively inhibited soil cracking, but cannot eliminate all cracks even if the content reached 1%. The cracks of samples with the PVA mainly developed when the water content exceeded water content corresponding to air-entry value. Filamentous (or meshy) connections and cementation between particles were the main reason to inhibit the development of the cracks. The obvious advantages of the PVA in the decohesion index, hardness, colour difference, and so on cannot be also ignored. Based on these evaluation indicators, a PVA content of 0.8% may be the best choice for anti-weathering of earthen sites.

摘要

土遗址具有重要的历史、文化、艺术、社会和科学价值。然而，它们已被风化严重破坏。先前提出了原位置换和牺牲层的方法来保护土遗址的表面。这项工作提出了用聚乙烯醇 (PVA) 处理过的泥状土壤作为这两种方法的抗风化材料的可行性。主要关注土壤的干燥开裂行为，以表面剥落、硬度、色差作为辅助评价标准。结果表明，醇解度高的PVA溶液能有效抑制土壤开裂，但即使含量达到1%也不能消除所有裂缝。PVA样品的裂纹主要发生在含水量超过进气值对应的含水量时。颗粒之间的丝状（或网状）连接和胶结是抑制裂纹发展的主要原因。PVA在脱聚指数、硬度、色差等方面的明显优势也不容忽视。基于这些评价指标，0.8%的PVA含量可能是土遗址抗风化的最佳选择。