Exploratory Research On The Anti-weathering Sacrificial Layer Of Beiting Ancient City

The exterior force is the most important factor, which cause the weathering of earthen architecture. At present, PS is an excellent anti-weathering consolidation material for earthen architecture site protection in the aird regions of Northwest China. Unfortunately, it is frequently used but not universal, particularly for the type with thicker weathered layer or located in concentrated rainfall regions. In this paper, according to conservation situations and occurrence characteristics of Beiting site, a famous historical relic, we proposed “sacrificial layer” anti-weathering technology to protect it by being covered with protective coating on the surface of the earthen architecture. Study results are as follows:(1) By summarizing the research progress on the anti-weathering of earthen architecture, the “sacrificial layer” technology is put forward, and then the technical route which includes the material ratio and construction process is determined.(2) Physical properties added with different materials, such as volume shrinkage, heat sensitive, chrominance, breathability and permeability, are conducted respectively. The experiment results indicate: By adding plant fiber or sand into soil block, dehydration shrinkage of block could be obviously reduced, and the effect is positively correlated to the content of supplements. And by mixing fiber with sand, the best results could be got. Temperature sensitive will increase by adding sand, and the soil block volume could be decreased by adding hemp fiber, which caused by temperature variation; The chromaticity caused by adding plant fiber and sand is little; hemp fiber could not only improve the strength, but also increase the ductility. However, adding the chaff could reduce the strength of the soil;Hemp fiber, chaff and sand could improve the gas permeability, the effect of hemp fiber is more apparent, for gas permeability effect: hemp fiber>chaff> original soil, after aging, chaff soil is better in gas permeability;For water permeability ability: sand> Hemp fiber>chaff.(3) By assessing the performance of weather-resistant test for “sacrificial layer”, wetting-drying test, freezing-melting circulation test and rain erosion test are conducted respectively. The results indicate that the influence of wet-dry cycling on sacrificial layer mainly concentrates on fracture development, wheat bran or hemp can narrow the surface fracture, the former make it short and narrow, the latter can disperse stress distribution, both supplements contributed to restrain fracture forming; The influence of freezing-melting circulation on sacrificial layer mainly focus on it’s surface weathering, hemp fiber soil’s anti-weathering effect is better than chaff soil; Adding plant fiber can significantly improve its anti-rain erosion property, and the effects: Hemp fiber>chaff>sand.(4) After preliminary exploratory experiments, we determine the technical route which includes the material ratio and construction process, and then enlarges the measuring range and the finally results is perfect. Between sacrifice layer and sites interface, there is no clear separation of ontology, and it has reversibility...