The Mechanism And Applied Evaluation Of Typical Cementing Material Used In The Protection Of Immovable Cultural Relics

During the long history, there are numerous unmovable cultural heritages in China. These cultural heritages usually lie in the open air. Due to natural weathering, environmental pollution with the development of modern industry, human factors and lack of effective protection technology, these precious historical heritages are suffering a great destruction. Some even have died out. Thus, we should take action to protect these cultural relics as soon as possible.Cementing material is regarded one impartant material in the protection of unmovable cultural heritages. It could bond the pellet and bulk together. Based on the development tendency of protection materials for cultural heritage and the previous work of our laborotary, the mechanism of tradional lime-based mortar, the design and service life of cement-based grouting materials have been studied in this work.The following are the main points:The mechanism and performance of traditional blood lime mortar were studied. In the protection of historic building, air-hardening lime has good compatibility. But its'defects like bad mechanical property, long curing time and high water absorbent also restrict its application. In this work, we choose blood to modify the aerial lime-based mortar following an ancient Oriental technology.The results showed that the mortar prepared by blood with lime had better binding strength, waterproof property, weather resistance and curing speed than common lime mortar. Through the conductivity, FT-IR, XRD, SEM, TG and curing speed test it was found that the excellent performance of blood lime mortar was caused by the hydrophobic enhancement of blood proteins under alkaline condition.On the surface, these modified proteins controlled the crystal growth and formed a compact skin layer which changed the surface property of the hardening render. In the middle floor, they played as air entraining substance and promoted weather resistance. In the interface of mortar and supports, their water retention enhanced bonding strength.The performances and mechanisms of traditional Tung-oil lime mortar were discussed. Tung-oil-lime mortar is a special organic-inorganic binding material invented by the ancient Chinese people. It was widely used in wooden ship and special moisture-proof structures of ancient buildings due to its good sealing and waterproof performances. In this paper, the formula, performances and mechanism of tung-oil-lime mortar are discussed. The results show that the mortar prepared by tung-oil with calcium hydroxide has better mechanical properties, water-resistivity and weather resistance than common lime mortar. The effective compositions of tung-oil-lime mortar were carboxylic acid calcium, curing tung-oil and calcium hydroxide. And these good performances of tung-oil-lime mortar come from the compact structure which is established through coordination reaction of Ca2+from the Ca(OH)2 and the oxidation aggregation reaction of C=C double bonds in unsaturated fatty acid.The brown sugar and egg-white are wildly used as lime mortar additives in southeast of China and other regions. In this work, the mechanical properties testing and the composition and structure after curing were used to discuss the impact of these two additives on the performance of lime mortar and their mechanism. The results indicate sugar could reduce the water-lime ratio of lime mortar due to sugar reacts with lime and forms sugar calcium.. However, the excessive sugar content would affect the compressive strength and water resistance of mortar. The addition of egg-white could make the mortar become much more compact and slow down the carbonation progress of lime mortar. This result improves the self-recovery ability of lime mortar.The application and service life of cement-based grouting material under acid rain attack were researched. Cement-based grouting material is widely applied to reinforce the unsafe rock of stone inscription although many researchers regard this kind material is inappropriate in protection of ancient sites. However, there are little literature discuss and trace the pros and cons of applying cement mortars in this field. In this work, first, both laboratory research and field investigation are applied to evaluate these mortars. The results demonstrated that the type of cement had important influence on the properties of mortar. Introducing some additives could improve the performances of hardened mortar, while had little influence on the properties of fresh mortar. Moreover, using metakaolin to replace some part of cement could improve the workability of mortar. Second, a universal formula based on the dissolved amount of calcium ion to predict the deterioration rate of cement-based grouting material caused by acid deposition in the laboratory was proposed. The experimental results showed that the dissolved amount of calcium ion had a linear relationship with InT and the pH value, with better accuracy when the pH value was greater than 3.0. This work provided a facile and quantitative method to help us predict the service life of cement-based grouting material under acid rain attack outdoors.