Study Of Inorganic Gelling Materials For The Conervation Of Immovable Relics

There are numerous immovable cultural relics in China. Most of these relics are huge and are situated in open air. Because of natural weathering, air pollution, human factors as well as inadequate protection, these precious historical relics have suffered damage in varying degrees. If this situation goes as it is, many of these cultural relics will disappear gradually in the near future. However, existing materials can not give enough conservation for these kinds of relics. Therefore, it is vital and urgent to develop high-performance materials for the protection of the open-air sites.This paper summarizes the common diseases, failure mechanism, conservation materials and methods of the immovable relics including earthen sites, ancient buildings and historic stones. The progress of the conservation materials has been discussed. Based on the development of protection materials for cultural heritages and the precious work of our laboratory, the application of inorganic gelling material for the conservation of immovable relics has been studied in this thesis. The followings are the main points:The liquid hydraulic material for the in situ consolidation of earthen sites was studied. Based on the mechanism of the lime or cement stabilized soil, a kind of liquid and hydraulic material was developed. The calcium source adopted was the alcohol dispersion of calcium hydroxide and the silicon source adopted was the solution of potassium silicate. The strategy was like below:first, the alcohol dispersion of calcium hydroxide was applied on the surface of the earth samples by spraying. Then the solution of potassium silicate was applied on the surface of the earth samples by the same method. SEM, XRD, EDX, compressive strength test and water resistance test were employed to evaluate the efficiency of the conservation. The results indicate that the introduced calcium and silicon source reacts and produce a kind of net-shape structure. This net-shape structure composed of Si, Ca and K can joint the loose soil particles together. The concept of liquid hydraulic materials is proposed for the first time, which provides a new perspective for the conservation of earthen sites.The mechanism of sticky rice lime mortar and its application in the conservation of ancient buildings were studied. The development and the role sticky rice lime mortar played were reviewed. The sticky rice lime mortar technology appeared about in the North-south Dynasty. It was widely used in many of the important buildings in the past. As a kind of inorganic-organic material, sticky rice lime mortar was an important technology innovation in that time. Mortar samples from ancient constructions were analyzed by FT-IR, XRD, TG-DSC, iodine-starch test. The results indicate that the siticky rice lime mortar was used in the construction of Xi'an city wall of Ming Dynasty and the Nanjing city wall of Ming Dynasty. Modeling sticky rice-lime mortar was fabricated and analyzed, and the role sticky rice amylopectin played in the sticky rice-lime mortar was explored. It was found that amylopectin in the mortar acted as an inhibitor-the growth of the calcium carbonate crystal was controlled and a compact micro-structure was produced, which should be the cause of the good performance of this kind of organic-inorganic mortar. For the conservation of ancient constructions, sticky rice lime mortar was fabricated and tested. The test results of the modeling mortars show that the sticky rice-lime mortar has more stable physicochemical properties, greater mechanical strength and better compatibility than pure lime mortar, which make it a suitable restoration mortar for ancient masonry building. Sticky rice-lime mortar has been used in the restoration of some ancient masonry constructions like Shouchang Bridge built in Song Dynasty and Fantianshi stone censers buit in the Five Dynasties. The study of sticky rice lime mortar is important for the reuse of tradition technology, especially for the conservation and restoring of ancient buildings.Conservation of the weathered historic calcareous stones by apatite was studied. By mimicking the growth of bone, calcium and phosphorus were introduced into the weathered stone and then mineralized at room temperature. The conservation efficiency was investigated by SEM, EDX, XRD, "Scotch Tape Test" (STT), compressive strength test, capillary water uptake test, water vapor permeability test and weather resistance test. The results of SEM, EDX and XRD show that the produced bone-like hydroxyapatite can bind the introduced calcium carbonate and the weathered stone blocks together. The test results also indicate that this conservation method can improve the surface strength, compressive strength and weather resistance of the treated samples significantly. Besides, due to the porous nature of the bone-like apatite, the water vapor permeability of treated stone is not affected and its "breathe function" is retained. Therefore, the proposed method will be a good candidate for the in situ conservation of historic calcareous stones. This study gives a good solution for the problem of adhesion between the existing inorganic consolidants and the weathered historic stones.In conclusion, for the conservation of earthen sites, ancient constructions and historic stones, liquid hydraulic material, traditional sticky rice lime mortar and biomimic apatite were studied, respectively. These exploring works presented here provide new insights for the conservation of immovable cultural relics.