Use of Crystalline Silica Waste for Enhancement of Engineering Properties of Black Cotton Soil

Abstract

Construction of pavement layers on subgrade soil with excellent properties reduces the thickness of pavements and consequently reduces the initial cost of construction. However, construction of pavement on poor soil subgrade like black cotton soil is unavoidable due to several constraints. In such a situation, the enhancement of subgrade properties can be attained by the addition of foreign materials. The worldwide growing usage of cement has led to a larger collection of crystalline silica from the cement manufacturing plants. The disposal of the crystalline silica is extremely challenging and also causes an environmental impact. Hence this waste material can be used for enhancement of the strength of the weak soils. Chemical analysis has revealed that crystalline silica is rich in oxides such as silicon oxide, aluminium oxide and calcium oxide. In this study, the black cotton soil is blended with 8%, 12%, 16%, 18% and 20% crystalline silica by the weight of the dry soil. Laboratory tests, namely, standard proctor compaction test, California Bearing Ratio (CBR) test and Unconfined Compressive Strength (UCC) test were carried out to examine the performance of crystalline silica mixture in black cotton soil. The outcome suggests that a potential increase in crystalline silica content enhances the maximum dry density (MDD). The results also indicate there is a huge potential to use crystalline silica as an admixture to strengthen the black cotton soil. Moreover, the employment of crystalline silica might also benefit the environment and construction cost.

Keywords

• black cotton soil, crystalline silica, maximum dry density, pavements