Study On Microscopic Characteristics Of Solidified Sulphate Saline Soil

The microstructure characteristic is one of the main parameters to evaluate the curing effect of saline soil.Different curing materials will cause the internal microstructure of saline soil to be changed in different ways,thus producing different curing effects.This paper selects three kinds of schemes to cure saline soil,respectively lime fly ash,water glass,lime and fly ash +water glass.Through unconfined compressive strength test to study the strength characteristics and compressive strength of saline soil solidified with different solidified materials.In this paper,the pore characteristics of saline soil with different solidified materials and the pore characteristics change of saline soil with the content of solidified material were studied by NMR test,SEM and MIP test,and discussed the influence of micro-characteristic changes on curing effect of cured saline soil.(1)Nuclear magnetic resonance(NMR)test shows that: there were significant differences in the total pore changes between different curing schemes.Lime-fly ash mainly leads to the decrease of larger pores in cured saline soil;The total pore volume of lime fly ash + water glass cured saline soil decreases,but at the same time,there is a large pore formation.While the water glass causes the porosity of solidified saline soil to increase,but the pore volume decreases with the concentration of water glass.(2)Scanning electron microscope(SEM)test shows that: By hydration and condensation,the gel is produced in lime fly ash or water glass solidified saline soil,and the aggregates are formed.The contact mode of particles is developed from point contact to surface contact,and pore structure is gradually developed from intergranular pores to aerial pores to form a more compact structure.In lime fly ash + water glass solidified saline soil,a large number of gel substances,wrapped in the surface of soil particles,and formation a dense spatial network structure,the soil structure becomes more compact.(3)The pressure Mercury Test(MIP)test shows that: the pore volume of lime-fly ash cured saline soil was reduced in the large aperture area,and the pores in the small aperture area increased.The low concentration water glass(20°Bé and 30°Bé)and the high concentration water glass(40°Bé)cured saline soil shows different pore characteristics,and the total pore size of glass-cured saline soil increased,the pore range enlarged and the pore volume increased..The large and small pores of lime-fly ash + water-glass cured saline soil are obviously reduced.With the increase of solidified materials,the porosity and pore volume of lime-fly ash + water-glass solidified soil decreased.