THE EFFECT OF ACTIVATED MALINA AND LOCUST BEANS SAW DUST ASH ON THE STRENGTH CHARACTERISTIC OF LATERITIC SOIL USE AS SUB BASE MATERIAL FOR ROAD CONSTRUCTION

Abstract

This study employed the used of saw dust ash obtained from Malina (SDAM) and Locust beans (SDALB) trees activated with NaOH to stabilized soil obtained from Bauchi LGA, Bauchi state. The soil was classify as A-6 and CL according to American Association (AASHTOH) and unified classification system (UCS) .The chemical analysis of the soil revealed the soil to be Laterite due to the Silica-sesquioxide (S-S) ratio of 1.25, the SDAM and SDALB revealed SiO2 of 20.389% and 8.251%, Al2O3 of 3.442% and 2.597% and Fe2O3 of 2.124% and 1.379%, CaO of 33.054% and 55.766% respectively as the main chemical composition. Unconfined compressive strength (UCS) shows improvement in the characteristic of the stabilized soil with a maximum value of 592 kN/m2 for SDAM and 575 kN/m2 for SDALB in comparison to that of the natural soil with value of 215kN/m2, these UCS values does not meet the Nigerian general specification values of 750 – 1500 kN/m2. The unsoaked California bearing ratio (CBR) shows increased with maximum value of 75 % for SDAM and decreased with maximum values of 11 % for SDALB as compared to that of the natural soil which is 39%. While for soaked CBR, showed increased with a maximum value of 43% for SDAM and decreased with a maximum value of 11% for SDALB, as compared to that of the natural soil which 28 %, the unsoaked and soaked CBR values met the Nigerian general specification while that of SDALB does not meet the standard. Based on the findings, SDA from malina and locust beans are not pozzolanic materials but possess high CaO which could be responsible for the strength gain recorded.