Strength Characteristics And Modification Theory Of Loess Modified By Nano Silica Sol

Nano silica sol is a colloidal solution of colloidal silica particles in nanoscale, which has advantages such as big specific surface area, large dispersion and high adsorbability. It is widely used for fiber, textile, rubber, coating and ceramics industries. However, researches on nano silica sol as curing agent in soil are less. As soil stabilizer, the new nano material overcome the disadvantages such as low permeability and harm to environment as other chemical soil stabilizers do. In this paper, the ratio and mechanism of nano silica sol solution solidified loess is studied,and three kinds of nano silica sol with different particle sizes are utilized to solidify loess. In order to research Consistency characteristic, phase characteristics of mechanical properties, chemical composition and the changes of microstructure of solidified loess and to analyse the solidification theory, water content test, liquid and plastic limit test, unconfined compressive strength test, SEM,X-ray diffraction test, physical adsorption test and Fourier infrared spectrum test are carried out.(1)Unconfined compressive strength of loess solidified by three different consistences nano silica sol all increases significantly, and the more the amount of admixture, the larger the amplification of strength. Early strength of solidified samples is comparatively high and length of curing period under same circumstance has little influence. Under the same dosage, the smaller the particle size of nano silica sol is, the greater the unconfined compressive strength and solidification effect of solidified samples will be.(2)With the increasing of nano silica content,the liquid-plastic limit of loess solidified by nano silica in size 10 nm and 29 nm were increased,but the liquid-plastic limit of loess solidified by nano silica in size 100 nm was decreased. The X-RD patterns of loess solidified by nano silica and loess compacted were basically matched,there were appeared serried and low amorphous phase material peaks without new crystalline material. The main of nano silica solidified loess were granular overhead and inlaid contact structures,but it’s particle surface was adsorbed and parceled by gel films,the particle margin became rough and unclear,the contact area increase.When the content of nano silica were same,with the partical size of the nano silica particle decreased, the specific surface area and the size of nano level hole were increase;when the partical size of nano silica were same,with the content of nano silica increase,the specific surface area and the size of nano level hole were increase,which loess solidified by nano silica in particle size10.7nm and 29 nm formed a lot mesoporous hole.(3)The effect of nano silica sol solidified loess were reunion filling effect and gel cementation effect evocableed by high surface energy,the solidified process improved solidified soil structural strength and issue of the hole,the number of big hole decreased,the sample’s specific surface area and dielectric distributed capacitance increased. Smaller of the nano silica,the little particle reunion filling effect more clear,especially less than 5μm.