Improvement of CL soil engineering properties by using of silica and kaolinite nanoparticles

In this study, the effect of nanosilica and nanokaolinite particles on geotechnical properties of clayey soils is investigated. The mechanical method of Planetary Ball Mill was used for nanoparticles production. In this process, initial silicate and kaolinite powders was milled in Planetary Ball Mill for 10 hours with speed of 500 Rpm. This product was in nanometer scale and FESEM images prove it. In next stage, nanoparticles were mixed with clayey soil (CL) in different weight ratio of dry soil then geotechnical properties of treated soils was determined by compaction, direct shear, cassagrande and unconfined compression tests and optimum percentage of added nanosilica and nanokaolinite obtained. As a result we understood LL and PL of soil increased while percentage of added nanoparticles increased but increasing of PL is more than LL, thus PI is decreased that is proper in geotechnical engineering for construction. Also compaction tests results was shown the density of clayey soil was increased by adding of nanoparticles with specific amount and higher than that the density would be decreased. Direct shear tests has been proved, cohesion of clayey soils increased by adding of specific amount of nanoparticles to optimum and there is no more change by increasing the nanoparticles. Results of unconfined compression tests indicated that compressive strength of amended soils could be raised up to 3 times more than unamend soil by adding nanoparticles. Results of XRD and XRF tests showed that chemical attribute of nanoparticles produced by planetary ball mill is same as initial material.