Disease Analysis And Chemical Reinforcement Of Banpo Site In

Xi’an Banpo site is promulgated the first batch of national key cultural relics protection units by the state council in 1997. The Institute of Archaeology CASS conducted 5 times excavations from September 1954 to the summer of 1957. It is the first museum of prehistoric sites and the only well-preserved ruins of primitive society at present. It has important artistic value and academic value in the study of human society and the process of civilization. Yet as time passed, the Banpo site produced many diseases, such as cracks, crisp powder, dust pollution and so on, during to itself and external environmental factors. In one hand the diseases greatly affects the appearance of the Banpo ruins, in the other hand diseases also poses a serious of threats to the safety of the Banpo ruins. In view of the banpo site problems, this paper carrys out the following several aspects:Section one:I carefully research the main disease type of Banpo site and counter the disease distribution. It turns out to be that the main diseases are alkali and crisp powder, dust and fabric pollution, crack instability and shell off. What is more the disease of crisp powder and dust pollution are the large rones in area, more serious in degree.Section two:I analyze the reasons of the diseases from the nature and environment, The result shows that the Banpo site disease is generated by the internal and external interaction. The mineral compositions of Banpo site pronee to weathering and the soluble salt content is higher in the surface layer. With the change of temperature and humidity of the external environment, soluble salt migrates to site surface resulting in enrichment and recrystallization which lead to the structure damage and Crisp powder. The dust and fabric on site surface are mainly suspended solids and textile fiber producted by the surrounding textile factory, which got into the Preservation Hall with the atmospHeric flow. Duing to poor air flow within the hall, the dust and fabric appear deposition and enrichment. The reason why the hard shell fall off is large differences in strength, water resistance and soluble salt content between the hard shell and soil mass inside. When the outside temperature and humidity change, there exists a difference in volume change between them resulting in a strain in the interface, what is more, Recrystallization of soluble salts in the interface make the cementation force descend, under the multiple factors, the bad result appears.Section three:Based on the results of the banpo site disease analysis, I carry out a experiment to explore the effect of external environment on specimens containing Na2SO4 and NaCl, The experimental results show that freeze-thaw cycle and alternation of wetting and drying can have influence on the structure of specimens, what is more, the destructive degree of soluble salt is different and Na2SO4 is more destructive,the reason of which is the large difference in volume change during the recrystallization process.Section four:Ⅰ choose some common reinforcing agent to reinforce Banpo site in laboratory and evaluate their performance through the color change, weight lifting, the quality of air permeability, reinforcement strength level, water resistance and the result of freeze-thaw test, The experimental results show that the CB reagent and CB-TEOS mixed have a relatively balanced performance in the series of tests, which is suitable for the Banpo site reinforcement.Section five:The permeability and reinforcement strength of CB reagent were measured in the simulation pit to evaluate strengthening performance of CB reagent in real environment. The experiment results show that the penetration depth of CB reagent in the natural soil can reach 8-10 cm and can form a concentration gradient in soil, which largely avoids the reinforced and unreinforced area generating layered shedding, resulting from a obvious difference in the properties which is caused by a sag of reinforcement agent concentration. At the same time, CB reagent can competent a heavy processing role to sites which had reinforced by water glass, meanwhile, CB reagent can through the reinforced layer and improve the stability of surface soil.Section six:Ⅰ evaluate the effect of the partial reinforcement using CB reagent earlier. The experiment results show that the degree of crisp powder and shell off considerably of reinforced parts is lighter than the unreinforced parts. CB reagent showes a good performance of reinforcement.