Experimental Study on the Stabilization of Expansive Soil with Blended Fine Cinder Gravel and Waste Marble Dust: A Case Study of Jimma Town

Abstract

Expansive soils refer to a particular type of soil characterized by volume change due to variation in moisture content. To avoid this risk from the expansive soil, a technique of soil stabilization should be made for this type of soil to enhance some of its properties. In this study, experimental investigations have been made into the suitability of Waste Marble dust (MD) and Cinder gravel (CG) to improve the properties of expansive soil. The important parameters to determine the Engineering properties such as Moisture Content, Atterberg Limits, Particle Size Distribution, Free Swell Index, Specific gravity, and California Bearing ratio (CBR) values. To realize the desired objective, a purposive sampling technique which is non–a probability method was adopted to collect disturbed soil samples at a depth of 2.m and waste Marble dust (WMD) from the Gulele marble industry and Cinder gravel (CG) from woliso quarry local available material then the sample ware Air dried for the preparation of different laboratory tests. According to the laboratory test result the expansive soil is classified as A-7-6(0) soil in the AASHTO classification system and as CH soil in the USCS soil classification system. Such type of soil needs modification to be a subgrade material. while the chemical composition of expansive soil and cinder gravel shows main oxides (SiO2 + Al2O3 + Fe2O3) were 90.76% and 74.75%, respectively, which is above the minimum of (70%) specified by ASTM (C618). The waste marble dust is mainly composed of calcium (CaO) content of 51.18% and all materials satisfy the minimum requirement of Natural Pozzolanic materials. The experimental laboratory test result analysis shows the improved engineering property of the soil with the optimum result that was achieved, Pi decreased from 34.09% to 10.28%, and the swell index decreased from 14.6 % to 1.96. OMC decreased from 24.02% to 14.00%, the free Swell Index decreased from 81.8 % to 36.4%. MDD increased from1.45% to 1.65%, the CBR increased from 1.00% to 22.69%, and UCS increased from 112.9kN/m2 to 311.7kN/m2 . According to this study, the results compared to the ERA manual, at the addition of 8%, 12%, and 16% of stabilizers improved the subgrade class of the Sample from S3, S4, and S5. respectively, But with the addition of 24% all results slightly changed to the reverse and the subgrade class of the Sample declined to S2, Finally The optimal result achieved at (16% WMD +16% CG) replacement showed significant improvement in the soil's engineering properties. Notably, Pi, Swell Index, OMC, Free Swell Index, MDD, CBR, and UCS exhibited favorable changes. The results were compared with the ERA manual, indicating the best performance at the 16% replacement, making it suitable as a sub-grade material for road construction.