Experimental Study On Improvement Of ExpansiveSoil With Basalt Fiber And Two Ash

In recent years, with the dramatic development of China’s infrastructures, it has more and more strict demands for the skills of geotechnical engineering, and the improvement technique of swelling soil is one point. At current, the most common way to improve swelling soil is lime and coal ash. In addition, the method, fiber reinforced material, also gains more attention.The study on this paper is expansive soil from a highway in Nanyang, Henan. First,the paper introduces basic engineering properties and demerits of expansive soil and concludes its ways to differ a wide range of expansive soils. Then, it studies its basic indicators in the indoor on moisture content, water ratio limit, particle analysis as well as free swelling rate and acquires their basic index parameter. Last, it gets the best ratio of lime-ash of expansive soil by these experiments and adds different dose basalt fiber,0%, 0.1%,0.3% and 0.5%, into these expansive soil. Different curing period as a viable, the paper analyses the swelling soil’s the rules of its swell-shrink, compressive strength, ductility, sensitivity, dynamic sensitivity and shearing strength through experiments of free load swelling ratio, load swelling ratio, no-side limitation compressive strength and direct shear. The results shows under the condition of best ratio of lime-ash:(1) Basalt fiber and curing period can curb the swell of expansive soil and adding0.3% basalt and 28 days curing period are the best to inhibit expansive soil.(2) Basalt fiber and curing period can curb the shrink of expansive soil and adding0.3% basalt and 28 days curing period are the best to inhibit expansive soil.(3) When adding some basalt fiber, both the compressive strength and ductility of expansive soil improve. However, adding 0.3% is the best because at the moment the strength of expansive soil climbs its most and ductility is the best, and then after some days’ curing the strength of expansive soil also intense and its no-side limitation compressive strength reaches the crest.(4) Sensitivity first will decrease slowly, then increase with adding more and more basalt fiber. Adding 0.3% sensitivity is the lowest. Sensitivity first will decrease, then increase with more days’ curing. At the 14 th day sensitivity is the lowest.(5) Dynamic sensitivity generally will increase, then decrease with adding basalt fiber and can reach its zenith. Sensitivity first will decrease, then be stable with more days’ curing. The later curing exerts little influence on sensitivity.(6) Basalt fiber can obviously improve the resisting shear strength of lime-ash expansive soil, and adding 0.3% is the best. The resisting shear generally improve linearly with more days’ curing and at 28 th day its resisting shear strength reaches its peak.