The Laboratory Test Study Of Baotou Urban District Silt Polluted By Hydrochloric Acid Solution

In recent years, with the sustainable development of social economy, in theproduction practice of civil engineering,it was found that as a result of contaminated soilengineering,construction problems has increased.While It is till insufficient at presentpolluted soil research of nature and causes, especially the study on silt polluted by acidsolution is vacant in our country.In view of this situation,based on the typical silt inbaotou city, to pick out the0%(water),1%,4%,8%,12%concentration of hydrochloricacid solution soak simulation test,by the soil test,the chemical composition analysis,and scanning electron microscope to research the physical and engineering properties ofcontaminated soil, material composition, microstructure,it explains properties changecharacteristics and reasons of silt polluted by acid solution partly, the mainconclusion was as follows:⑴The clay mineral in secondary mineralsn of soil,water soluble salt of undissolvedsalt and organic will matter hydrochloric acid with chemical dissolution, precipitation,the hydrogen ion combine with carboxylic acid root,generate new mineralcomposition.The clay minerals(magnesium oxide), the undissolved salt(calciumcarbonate) and the organic matter content, along with the increase of the concentrationof hydrochloric acid solution had reduced.⑵Analysis the electronic microscope photos of the silt polluted by hydrochloricacid,it can be found that the microstructure of soil also changes with the increase ofconcentration of hydrochloric acid to present as follows: the soil particle surfacesmoothing, large particle size decreased and the decrease in the number of smallparticles and pore had greaten and deepen, contact between soil particles change, newsubstance had formed.⑶The physical properties of silt had changed as well. With the increase ofconcentration of hydrochloric acid, the appearance of the color of soil wasdeepen,developed corrosive odor. Quality, dry density, specific gravity, moisture contentand void ratio were increased.Due to the high density of undissolved salt, organic colloid were reacted, the liquid limit of soil was reduced, the plastic limit was increased.The plastic index decrease, it was influenced by the thickness of diffusion layer inbound water,sthe minerals of silt and organic matter composition.⑷The basic mechanical properties of silt had changed as well.The compressioncoefficient was increased, the compression modulus was decreased,the soil compressionindex, the index of volume compressibility and resilience were increased.At the sametime,the cohesive force was increased,the internal friction angle was decreased.