Study On Sacrificial Layer Protection Material Of Anti-weathering Of Earthen Wall In Xinzhou

There are a large number of earthen sites in China.The earthen sites exposed to outdoor environment have been damaged by rain and wind erosion for a long time.The indoor earthen sites suffer water evaporation,body drying,salt crystallization and other weathering factors.The earthen sites are slowly dying out,and their protection is imminent.The common methods of seepage reinforcement and protection generated irreversible effects on earthen sites.According to the preservation status and conditions of earthen wall in Shanxi Xinzhou,a sacrificial layer covering method was put forward to protect the earthen sites.The sacrificial layer was prepared with soil as the main material and polyacrylate emulsion and hydrated lime as additives.The sacrificial layer was applied on the surface of the earthen sites by means of pasting.The mechanical properties of sacrificial layer should be similar to that of the earthen sites.(1)The diseases of Xinzhou earth site mainly include undercutting,sheet peeling,runoff gully,animal and plant damage,among which undercutting is the main threat to the earthen site.(2)The effects of polyacrylate emulsion,silicone acrylic emulsion and hydrated lime on the properties of sacrificial layer were studied.The bonding strength,flexural strength,compressive strength,shrinkage,thermal expansion,permeability and durability of the sacrificial layer were evaluated.The results showed that,for the compound modified sacrificial layer by polyacrylate emulsion and hydrated lime,the volume shrinkage rate decreased and compressive strength,salt resistance and freeze-thaw resistance increased as the amount of hydrated lime increased.However,water vapor permeability,flexural strength and bonding strength decreased as the amount of hydrated lime increased.When the amount of emulsion increased,the mechanical strength and durability of the sacrificial layer increased significantly,but the heat shrinkage rate increased and the water vapor permeability decreased.According to the protection principle of earthen sites,the properties of sacrificial layer should be similar to that of the protected soil matrix.The comprehensive analysis showed that the optimum dosage of calcium hydroxide is 50?100 g,and the best dosage of polyacrylate emulsion is between 72?96 g.Compared to polyacrylate emulsion,the sacrificial layer modified by silicone acrylic emulsion has low adhesive strength,low permeability and high volume shrinkage.So,the properties of the former are better in this study.(3)The sacrificial layer was used to cover the dry earthen site and the wet earthen site respectively.After tracking and observation,the interface between the sacrificial layer and the soil site was well bonded,and there was no cracking,stripping and animal and plant diseases on the surface.