The Characteristic Analysis Of Surface Deterioration And Mechanism Study On West Yellow Temple StoneHeritage

West Yellow Temple Located on the northbound of An Ding Men Wai Avenue in Beijing .It was built in Qianlong 46th year (AD 1781) and completed in 47 years of Qing Dynasty (AD 1782),It is built for the Qing Qianlong Emperor Praising the master of the Sixth Panchen passed away . Many of these beautiful stone are in outdoor, in the destruction of natural factors and human factors, many stone surface spalling, corrosion, and scaling . Severely affects the appearance and integrity of the stone, and many diseases are still in the developmental stages, coupled with environmental degradation in recent years, increased greatly accelerate the corrosion rate of stone artifacts.In this paper, for the two kinds of rock materials,grey mediun-grained clay feldspathic sandstone and microlite dolomitic marble,by means of Schmidt hammer test,X-ray diffraction,scanning electron microscope and other testing methods, Studying the affect of the damage on the surface of common phenomenon - peeling, corrosion, scaling to the physical properties of the stone, mechanical properties, physical properties of water, mineral and chemical composition, draw all kinds of mechanism of degradation formation, the results show that:(1) The mechanism of sandstone surface spalling: rainfall makes sandstone surface erode, providing the condition for water going into the sandstone interior. Interior of the sandstone could be greatly influenced by water. The parts which contain more expansive clay minerals and gypsum rapidly expend when contacted with water. As a result, a greater expansion pressure generates. Because of the existence of expansive clay minerals and gypsum, the rock's connection strength is lower and the rock occurs spalling or hollowing due to the expansion pressure. The expansive clay minerals and gypsum forming as sheet parallel to peeling surface, therefore the surface of the spalling or hollowing is generally parallel to the outer surface of the rock. In addition, unloading, processing damage, stress concentration and temperature change also increase peeling of the rock surface. The mechanism of the marble granular peeling: Since there are less cement particles, the rock's Cementation Strength is lower. The cement particles are damaged because of unloading, processing damage, stress concentration and temperature change. As a result, the surface of the rock is easily peeled of.(2) Sandstone dissolution is mainly because the calcite occur erosion under the action of water. In addition, the dolomite in the sandstone also occur a small amount of water erosion. The marble corrosion mechanism is because the dolomite in the rock occur dissolution.(3) The mechanism of white Coagulation on the foundation of tower: the mortar of the joint occur erosion under the action of water. The erosion flow precipitates and recrystallizels on the rock, forming the white Coagulation.