Study On The Relationship Between Physical And Mechanical Properties Of Lime Materials And Their Raw Material Components In Cultural Relics Protection

As one of the four ancient civilizations,China has quite a lot of historical relics,and immovable cultural relics are an important part of it.In the northwestern part of China,there are various forms of immovable cultural relics that need to be protected.Geotechnical relics are important types,such as Dunhuang Mogao Grottoes,Shanhaiguan Great Wall dominated,and Huashan Mountain in Guangxi.The rock carvings of the cliffs and so on.A considerable part of these types of cultural relics are important raw materials for the construction of lime-based materials.Because of the age,after undergoing various changes in the natural environment,there are different degrees of damage,and their protection is urgent.In the construction process of the cultural relics protection project,the selection of materials similar to the cultural relics body for repair has an important impact on the protection effect after construction.The cultural relics repair materials represented by modified ginger nut and modified aga soil have been widely used in cultural relic protection projects,such as the Jiayuguan Great Wall Maintenance Project and the Chengde Mountain Resort Protection and Maintenance Project.The main component of the raw materials for the production of such repair materials is calcium carbonate,and the secondary component is silica.After calcination and aging,a material of gas-hard calcium hydroxide and hydraulic calcium silicate and calcium aluminosilicate is produced.Since the material itself has both gas-hardness and hydraulic properties,it has a good work in construction.Performance,such as high early strength（higher than lime）,low shrinkage,high mechanical strength,strong weatherability,and low final strength（far lower than cement）,thus stand out among many materials.These kinds of repair materials have a good record of use,but they still have some differences in mechanical properties,although their main components are lime after modification,the reason behind their different performance performance is worth Explore further.The chemical composition of the material determines its reaction characteristics,which in turn determine the physical and mechanical properties of the material,and further reflect the performance during actual construction and use.In order to study the reasons behind the differences in the work performance of these materials,this paper takes their chemical composition as the starting point,and uses XRD,XRF,SEM as chemical analysis methods,combined with physical and mechanical experiments under the same conditions,to explore them.The relationship between composition and performance.Since the selected main components of the selected materials are all of the hard-wound calcium hydroxycalcite,which is limited to the percentage of carbon dioxide in the air（0.03%）,the combination of calcium hydroxycalcite and carbon dioxide hardens into calcite.The hardening process is very slow and has little effect on the early strength growth of the material.From this point,these lime-like materials with different silica contents are similar;however,since these lime-lime materials are themselves oxidized The difference in silicon content results in different levels of hydraulic components produced after calcination modification,while the performance of hydraulic components is characterized by a fast reaction rate and a hydraulic reaction with water to form high-strength hydrated calcium silicate.And the hydrated aluminum silicate,this significant difference will lead to different performance of the early work performance of the material.In order to clarify the relationship between the mechanical properties of the modified material and the silica content of the raw material itself,an experiment was designed:After screening a wide range of lime-based raw materials containing different silicas by chemical analysis,three lime-like materials with different silica contents(aga soil（wSiO₂10%）（Material No.A）,Qinan were selected.Ginger nut（wSiO₂20%）（Material No.LQ）,Chengxian ginger nut（wSiO₂30%）（Material No.LC）,modified under the same conditions（1000°C,2 h）,under the same conditions（room temperature 25°C,humidity 60%）After aging,test blocks were prepared,and physical and mechanical experiments were carried out on them to test the mechanical properties and weatherability.At the same time,the microscopic characterization of several materials was carried out,and the physical and mechanical properties were explored by means of XRD and SEM.Relationship with the internal mechanism of action of the material.The study found that:（1）After testing the physical and mechanical properties of the test piece made by modifying the three materials,it was found that the mechanical properties of several materials increased,and the lime content of the silica content was 20%.The post-physical properties are the strongest（28-day compressive strength is 5.704 MPa）;followed by the silica content of 30%（28-day compressive strength is 5.14 MPa）,the physical and mechanical properties are stronger,the lowest strength is two A sample having a silica content of 10%（28-day compressive strength of 2.485 MPa）.（2）After modification of the three materials,according to XRD diffraction analysis,the main components are all of the hard-witted calcium hydroxycalcium,and the secondary components are hydraulic calcium silicate and calcium aluminosilicate.During the different ages of 3d,7d,14d and 28d,the conversion rate of calcium sulphate to calcite produced by three materials was slower.Among the raw materials of several materials,the content of hydroxycalcite changed less..The largest change in content is the calcium silicate and calcium aluminosilicate formed after the modification.They form hard hydrated calcium silicate and calcium hydrated calcium silicate after hydration.Through SEM microscopic analysis,it was found that the material with high hydraulic composition content gradually shrinks as the age increases,the material becomes denser and the structure becomes stronger.The presence of hydraulic components contributes to a rapid increase in the strength of the material.（3）The weather resistance test shows that all three materials have good weather resistance,stability,alkali resistance,freeze-thaw resistance,temperature and humidity resistance are strong,have good environmental adaptability,and can meet cultural relics.Protection engineering needs for materials.（4）The work performance of different physical and mechanical properties and chemical composition characteristics of the three materials provides a reliable basis for the selection and use of protective materials in different cultural relic protection projects.（5）Among the raw material components of the lime-based material,the content of silica increases,which contributes to an increase in the content of the hydraulic component in the modified material.However,there is not a linear relationship between the content of silica in the raw material and the physical and mechanical properties of the modified material.Excessive silica content in the lime raw material also leads to a decrease in physical and mechanical properties.