Authors : Noor Al- Hassnawi, Rasha Jasim and Mohammed Qasim
Abstract: Expansive soil cover most areas in the middle of Iraq and create major problems for the construction of buldings. The low bearing capacity and high compressibility of the expansive soil, preclude the support of structures on them. This study presents laboratory test for expansive soil mixing with additives, identified as by-paass which is usually brought from cement industry which is called (by-pass) to improve the expansive soil properties for possible use as a foundation bearing soil. An experminatal research including liquid limit, plastic limit, plasticity index, specific gravity and soil classification was carried out to determine the physical properties of clayey soil samples without additives. The research also included conducting unconfined compression test on soil samples without additives and samples contained several ratios of by-pass (6, 12, 18 and 24%) while keeping the misture content at 20%. Moreover, the chemical compostitions of the baypass material were obtaited through a chemical laboratory experiment. The result have shown that with the increase of the by-pass ratio the soil became more ductile and unconfined compression strength increases whereas the strain decrease. The undrained shear strength increased from 0.25 kg/cm2 for a soil without additives to 1.6 kg/cm2 for a soil contained 24% by-pass. The ingrediants of the by-pass were found to be as same as for those of ordinary cement.
Noor Al- Hassnawi, Rasha Jasim and Mohammed Qasim, 2018. Using Bypass Addition to Improve Expansive Soil Strength. Journal of Engineering and Applied Sciences, 13: 9739-9743.