Study On Modification Test And Microscopic Mechanism Of Restoration Materials For Silt Sites In Zhengzhou Area

The Zhengzhou area is the axis of Chinese civilization and one of the eight ancient capitals of China.There are many earthen sites with a long history,and most of these earthen sites are rammed with silt.At present,many existing earthen sites in Zhengzhou are seriously damaged and need to be repaired urgently.This paper takes the typical earthen ruins in Zhengzhou area-The twin giants city of the kingdom of Han dynasty as the research object,selects the surrounding soil of the earthen ruins as the main restoration materials,analyzes and screens environmentally friendly inorganic materials for single-admixture modification experiments on the surrounding soil,and selects better results according to the test results.The inorganic material natural hydraulic lime is used as the main modification material,and on this basis,the organic and inorganic mixing method is used to improve the natural hydraulic lime soil with the use of organic silicon methyl silicate waterproofing agent,and combined with Zhengzhou The main diseases,the occurrence environment and the engineering characteristics of the soil relics in the area have been carried out corresponding researches on the mechanical properties,durability and micro-mechanism of the composite modified soil.The main research results are as follows:(1)This paper and analyzes the mechanical properties,shrinkage performance,and compression performance of each inorganic material modified soil through the modification test of inorganic materials.The shrinkage performance of hard lime soil is significantly better than other materials.The compressibility of modified soil with 6%natural hydraulic lime content is the smallest and closest to the compressibility of the ruins,and it has good compatibility with the ruins and is suitable as the main restoration material.(2)This article evaluates the improvement effect of natural hydraulic lime soil mixed with sodium methyl silicate organic silicon waterproofing agent from the aspects of durability and mechanical properties,and explores the degree and law of the influence of different material ratios on the performance of composite modified soil.comparative analysis shows that when the content of natural hydraulic lime is 6%～10%and the content of sodium methyl silicate is 0.3%～0.5%,the modified soil restoration material has good water resistance,erosion resistance and resistance to dry and wet cycles.It also has good compressive strength and shear strength.Based on the test results,it is finally determined that soil + 6% natural hydraulic lime + 0.3% sodium methyl silicate is the best material ratio.(3)Scanning electron microscopy test(SEM),energy spectrum analysis test(EDS)and mercury intrusion test(MIP)on plain soil,natural hydraulic lime soil and composite modified soil,the sodium methyl silicate and natural hydraulic lime were analyzed.The modification mechanism.The analysis results show that natural hydraulic lime generates calcium carbonate through hydration and carbonization reactions.Calcium carbonate fills the pores and the interstices of the framework particles,so that the contact mode of soil particles is changed from point contact to surface contact,which makes the unit structure Dense,the strength of the soil increases,while the porosity of the soil increases,the compactness of the soil decreases,and the water absorption rate increases.The natural hydraulic lime modified soil mixed with a certain ratio of sodium methyl silicate waterproofing agent will form a waterproof membrane between the surface of the modified soil particles and the unit body,which can effectively prevent water from entering to achieve a waterproof effect.In addition,the porosity of the modified soil will decrease,the compactness will increase,and the proportion of large pores will decrease,while the proportion of hollow and small pores will increase,effectively inhibiting the rise of capillary water in the soil.Sodium methyl silicate forms a barrier between water and natural hydraulic lime,which prevents or slows down the entry of water into the soil.Thus,the carbonization reaction between water and natural hydraulic lime is slowed down,a small amount of calcium hydroxide remains on the surface of the modified soil,and the modified soil is denser.