Experimental study on bamboo grid reinforced copper slag overlying soft subgrade

Abstract

Design and construction of pavements and structural foundations on soft ground are risky and costly projects for civil engineers because of the low bearing capacity of soil and the massive amount of granular fill required for replacing it. Improvement of the soft ground using natural materials is a sustainable, efficient, and cost-effective technique for providing a stable and supportive base for various civil engineering structures. This paper focuses on the use of bamboo grids to effectively improve the performance of soft subgrade underlying copper slag. Two types of bamboo grids in different aperture shapes were used to compare their effectiveness. The performance of the bamboo grids was evaluated on the basis of placement depths and their sizes. Model tests were carried out to analyse the effect of thickness of copper slag layer on footing pressure and settlement response of the base-subgrade system. A substantial improvement in footing pressure and footing settlement was observed at different levels of settlement. The tridirectional bamboo grid (hexagonal aperture) reinforced foundation base exhibited better performance than the bidirectional bamboo grid (square aperture). The footing pressure improvement ratio in the foundation bed using the tridirectional and bidirectional bamboo grid was found to be 2.28 and 1.89, respectively, while footing settlement reductions were obtained as 87% and 78%, respectively, for the same size of reinforcement. From the present study, it has been suggested that the bamboo grid and copper slag can be used for improving the soft subgrade, especially considering their availability and cost.