A new improvement technique for expansive soils

Abstract

In this study, a Unified Soil Improvement Technique (USIT) that consists of prewetting, calcium lignosulphonate lime piles, fabric, and soil nail was applied to an expansive soil specimen to both accelerate the process and increase the effect of these techniques. 19 boreholes that had 0.45 cm diameter and 1.9 cm height were opened into an expansive soil specimen in an oedometer ring. Then, these boreholes were filled with a calcium lignosulphonate-water mixture prepared in a liquid form during the prewetting process. Thereafter, these boreholes were filled with a mixture including calcium lignosulphonate, water, and lime. Finally, a fabric was laid down over this specimen and seven pieces of soil nails were used for connecting the fabric and the lime piles. To sum up, the swelling potential of expansive soil specimens under 7 kPa decreased from 43.95 % to 1.58 % after 28 day curing period. The CBR swell of the USIT specimens, which waited in the humid room for 90 days, was measured as 1.14% under 7 kPa surcharge pressure and was measured as 0.4% under 25 kPa surcharge pressure. The significant changes in the swell potential values suggest that the Unified Soil Improvement Technique's performance is better than calcium lignosulphonate-added lime piles in the improvement of expansive clays.