Performance of Bitumen Emulsion Mixtures utilized as Gravel Road Base incorporating Lateritic Clay Soil and Calcined Sugarcane Bagasse Ash Filler

This study investigates the usage options of Bitumen Emulsion (BE) mixtures composed entirely of Lateritic Clay Soils (LCS) using Calcined Sugarcane Bagasse Ash (CSCBA) as a filler. The LCS was chemically stabilized with 4% CSCBA to meet the plasticity index requirement of a maximum of 7% for BE stabilized materials as set out in the South African Bitumen Association (Sabita) Technical Guideline: Bitumen Stabilized Materials (TG2) and the Kenya Pavement Design Guideline for Low Volume Roads (TG1). The soil was then bound with a medium setting A4-60 anionic bitumen emulsion consisting of 60% base bitumen and 40% water. Varying proportions of BE (11%, 12%, 13%, 14%, and 15%) were mixed with LCS at a constant pre-mix water content of 12.9% to produce Marshall specimens cured for 72 hours at 40oC. The bulk density, dry density, soaked and unsoaked Indirect Tensile Strength (ITS), and Tensile Strength Ratio (TSR) were determined for the cured specimens. The optimum bitumen emulsion content was 13.82%, which gave the highest dry and wet ITS of 183.9 kPa and 132 kPa, respectively, and a TSR of 71%, meeting all specifications when compared to the TG2 and TG1 specifications. The compound also had reduced air voids, which when combined with a higher TSR, demonstrate resistance to moisture damage.