Strength development in fine-grained paddy field soil by lime addition

Abstract

Due to high population density, the people of Bangladesh are building houses and the government is establishing infrastructure (such as roads, flyovers, bridges) on agricultural land that pose significant settlement issues. Consequently, such development works require prior improvement of the soft soil or improvement during construction to restrict post-construction failures. Soil stabilization, a conventionally used ground improvement method, is often utilized to alter engineering properties of fine-grained soil such as strength, stability, permeability, weathering resistance, etc. to maintain the required construction criteria. Moreover, the addition of lime in the soil is demonstrated to markedly reduce the hydraulic conductivity, which will prevent the vertical movement of pore water. With this in mind, in the current study an attempt has been undertaken to increase the strength of fine-grained soil of agricultural land by adding commercially available hydrated lime, which may in the future be used as foundation material. For this purpose, lime was added at various percentages (0–12%) by weight to soil collected from a paddy field. The study noted the collected soils as being inorganic silts of high plasticity or organic clays of medium to high plasticity. Unconfined compression tests were conducted on cylindrical mold prepared specimens with clayey soil in the presence of lime, and all specimens were cured for 3–90 days for strength development. The study revealed 7% added lime as the optimum content, with the corresponding unconfined compressive strength (UCS) observed to be 344 kPa and 356 kPa at the end of 28 days and 90 days, respectively. The evolution of unconfined compressive strength was higher in hotter and more alkaline environments.