Studies About The Weathering Mechanism And Protecting Materials Of Rock Paintings In Hetankou

The rock arts located in Helan mountains belong to immobile stone relics outdoor, which have been serious weathering with the key patterns of crack propagation and exfoliation because of long-term effects of environmental conditions. In this present paper, rock arts in Helankou were taken as the research object. At first, on the basis of the investigation on current status, the RMT-150C rock mechanics test system was used to study mechanics strength of splitting test, uniaxial compression experiment, triaxial compression experiment and direct shear test of the rock near the rock paintings in Helankou. Then, the data of humidity, wind and temperature have been analyzed statistically. In addition, the weathering mechanism was studied through using XRD, SEM and EDS analyses methods and combining with freeze-thaw test and wind tunnel test in laboratory for rock arts. At last, the SiO2protective film was prepared on rock surface by using bio-mimetic synthesis technology. The results show that the rock in Helankou is poor in ductility, strong in brittleness, so it is easy to break upon external force. So a larger temperature difference, moderate humidity and frequent sandstorms all the year round in Helankou made rock paintings weathering. And the microstructure is porous with little cementing material and fissure development is multidirectional. The changing of temperature causes rock crack that make the rock mechanical strength decrease obviously. Sandstorm erosion makes rock quality reduced obviously, and the wind erosion modulus present increasing trend with the increase of sand flow speed. At the same time, the black attachments on the surface where there has microbial growth present clumps and block colloids. And, the hydration caused rock volume increased sharply. At last, the membranes were characterized and tested which were preparation of ethyl silicate and sodium fluosilicate as silicon respectively. The picture of SEM for two plans showed that there covered with a layer of compact spherical particles on the sample surface, but the film microstructure was more homogeneous and dense that prepared by silicon source of ethyl silicate. The tests results show that pollution resistance has increased, on the other hand, water absorption and hydrophilicity have reduced. These studies would provided a comprehensive, scientific understanding of the weathering mechanism of rock paintings and a theoretical support for their subsequent protection work.