Mechanical Performance of Laterite Soil Stabilized with Cement and Grewia Bicolour Bark Juice for Road Base Construction

Abstract

This paper aims to investigate the potential of the Grewia bicolour bush as a natural stabiliser for road construction. This study evaluates the feasibility of using Grewia Bicolour Bark Juice (GBBJ) as a partial replacement for cement in the stabilization of laterite soil. The soil is mixed with Ordinary Portland Cement (OPC) at different proportions of dry soil weight, ranging from 0 to 8%, with an interval of 2%. Californian Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) tests are performed on the soil-cement mixture to determine the optimum cement content. The UCS value of 6% cement content, with a strength of 2.1 MPa after 7 days of curing, meets the standards set by the Kenya Roads Design Manual Part III. Therefore, 6% cement content is chosen as the optimum. The soil is then treated with a cement-GBBJ mixture by partially replacing the optimum 6% cement content with GBBJ at increasing steps of 1%. The results show that, regarding the standards and the targeted strength, the optimum mix proportion is 4% cement plus 2% GBBJ. The corresponding CBR and UCS values are 130.7% and 1.98 MPa, respectively. The results of the tests provide promising prospects for an economical and sustainable way of soil strengthening.