Feasibility of Polyvinyl Alcohol-Treated Soil in a Mud State as the Anti-Weathering Material for Earthen Sites.

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. [ABSTRACT FROM AUTHOR]