Study On The Physical And Chemical Mechanism Of Glutinous Rice Mortar Modified By Sodium Methyl Silicate And Sisal Fiber

As one of the important components of Chinese civilization,ancient masonry buildings have important humanistic,historical,and academic values.Most ancient masonry buildings are exposed to the natural environment and are prone to various damages caused by environmental factors.Therefore,we must adopt the principle of "protection first,rescue first,rational use,and strengthened management".The protection measures follow the current concepts of "repairing the old as the old" and the "four original principles" for the restoration of cultural relics,and the selection of restoration materials is as close to the original building materials as possible.Glutinous rice mortar is an organic-inorganic composite mortar made of lime as the base material and glutinous rice as organic additives.It is a commonly used cementing material in ancient Chinese architecture.Traditional glutinous rice mortar has the characteristics of large early shrinkage,low strength,and poor water resistance,so it needs to be modified.This paper takes traditional glutinous rice mortar as the research object,uses sodium methyl silicate solution and sisal fiber as additives to study the physical properties and chemical mechanism of modified glutinous rice mortar,and provides relevant experimental basis for improving the performance of traditional glutinous rice mortar.The research and analysis of the modified glutinous rice mortar combined with quantification and single variable control,mainly draw the following conclusions:(1)The material ratio of traditional glutinous rice mortar is lime:loess:sand=1:2:2(mass ratio);through the control of the consistency of glutinous rice mortar,the water ash of modified glutinous rice mortar with different types and different proportions of additives is determined In comparison,the experimental mortar is divided into two types:ordinary glutinous rice mortar and modified glutinous rice mortar.(2)Related experimental researches on the physical properties of glutinous rice mortar,such as workability,shrinkage,water absorption,and surface hardness,were carried out.The experimental results show that the water retention of traditional glutinous rice mortar and modified glutinous rice mortar are both greater than 91%,which meets the design requirements of masonry mortar.Among them,modified glutinous rice mortar with sisal fiber content of 0.7%and sodium methyl silicate solution concentration of 0.5%has the best water retention,reaching 95.54%;modified sisal fiber content of 0.7%and sodium methyl silicate solution concentration of 0.5%The water absorption rate of the glutinous rice mortar is the lowest at 23.74%,which is 2.28%lower than the 26.02%of the traditional glutinous rice mortar test block;the addition of sisal fiber and sodium methyl silicate can significantly increase the surface hardness of the modified glutinous rice mortar with the highest increase It can reach 30.9%.(3)Research the compressive strength,shear wave velocity and microscopic mechanism of traditional glutinous rice mortar and modified glutinous rice mortar.The experimental results show that the compressive strength and shear wave velocity of the modified glutinous rice mortar block first increase and then decrease with the increase of sisal fiber content.When the sisal fiber content reaches 0.7%,the compressive strength of the mortar block The highest value is 0.507MPa,which is an increase of 81.7%compared to the blank glutinous rice mortar test block 0.203MPa.The content of sisal fiber continues to increase,and its compressive strength gradually decreases.This is due to the critical volume rate of fiber blending;the addition of sodium methyl silicate solution does not have a significant impact on the compressive strength of traditional glutinous rice mortar.As the concentration of the sodium methyl silicate solution increases,it first increases and then decreases.When the concentration of the sodium methyl silicate solution is 0.5%,the compressive strength is the largest at 0.482MPa,which is 72.8%higher than the blank glutinous rice mortar;The shear failure strength of modified glutinous rice mortar first increases and then decreases with the increase of sisal fiber content.When the sisal fiber content is 0.7%,the shear strength of modified glutinous rice mortar test block is the largest,and the failure load can reach 711.46KN.The blank test block increased by 113.41%.(4)Both sisal fiber and sodium methyl silicate increase the density of the internal structure of glutinous rice mortar to a certain extent.The sisal fiber is uniformly and non-directionally distributed inside the mortar,which acts as reinforcement and can absorb external loads.,Control the development of cracks in the mortar;the silanol groups in the sodium methyl silicate solution and the silanol groups in the mortar are dehydrated and cross-linked to form a micro-expansive polymer compound,which improves the compactness of the modified mortar and improves the density of the mortar particles.A hydrophobic film is formed on the surface,which improves the waterproof durability of the modified glutinous rice mortar.