Influence Of Calcium Source And Curing Times On The Curing Characteristics Of Granite Residual Soil

Granite residual soil is a special soil widely distributed in South China.It has the characteristics of large void ratio and easy disintegration in contact with water,which makes it easy to disintegrate when exposed to water.In the rainy season or heavy rainfall,the surface soil of the slope is easily eroded to form gullies of different depths,and local slumps will occur in serious parts,which will affect the stability of the subgrade slope surface and the later slope protection effect.Therefore,it is necessary to propose an effective granite residual soil subgrade surface protection method according to the physical properties of the granite residual soil itself.Microbial solidification technology(MICP)is a new green and environmentally friendly rock and soil treatment technology in recent years.At present,scholars have applied it to the improvement of sand,silt and clay.Therefore,in this paper,the improvement of physical and mechanical properties of granite residual soil after solidification by different calcium sources and solidification times was studied through indoor microbial solidification experiments.The specific research route is as follows:First,based on the basic physical and mechanical index determination test of granite residual soil,and then the granite residual soil sample is subjected to a microbial solidification test using the Bacillus pasteuri bacteria solution obtained by microbial expansion and the designed solidification device,and the solidification test is carried out.Three calcium sources,calcium chloride,magnesium chloride,and calcium acetate,and four curing times of 8,10,12,and 14 are orthogonal to each other.At the same time,the mineral composition and micromorphological characteristics of the samples were analyzed by scanning electron microscopy(SEM)and X-ray diffraction(XRD)tests.influence of characteristics.Based on the above experiments,the following research results are obtained:(1)Microbial solidification technology can effectively solidify granite residual soil.Under the condition of the same calcium source,the unconfined compressive strength of the solidified sample is positively correlated with the number of grouting,and the disintegration resistance of the sample has a similar law;different calcium sources The physical and mechanical properties of the samples are improved by different conditions.The three different calcium sources of calcium chloride,magnesium chloride and calcium acetate have the best effect on improving the strength and disintegration resistance of granite residual soil..(2)The solidified granite residual soil sample contains a large number of calcium carbonate crystals,but the solidification of the sample is non-uniform,and the content of different parts of the sample is different.(3)In terms of microscopic curing mechanism,through scanning electron microscope test(SEM)and X-ray diffraction test(XRD),it can be clearly known that the formed calcium carbonate precipitates are cemented on the surface of fine particles and filled in the gaps between fine particles,and the cementation-bonding effect is The fundamental reason for the solidification of granite residual soil is the internal solidification mechanism.