2025/07/21 by Awoke Mesfin, Nigus Getu, Worku Yifru +3
#Brewery spent grain ash · Gypsum · Expansive soil · Stabilization
paper · doi:10.20372/nadre:10689
Abstract The problem of expansive soil is a major one, since it causes damage to civil engineering projects and has an impact on Ethiopia’s road development expansion. Brewery spent grain (BSG) is an agro-industrial solid waste product of the beer manufacturing process. Determine the pozzolanic property and elemental composition of BSG ash after it has been converted to ash. Gypsum (G) is also employed as a stabilizer, but because of its scarcity and expensive cost, it is not suitable. To adjust the strength of expansive subgrade soil, the blending effect is preferred over the individual components. After the completion of the required laboratory analysis for gypsum 5–20% with a 5% interval and BSG ash 5–20% with a 5% interval individually, the subgrade was stabilized. To adjust the strength of expansive subgrade soil, the blending effect is preferred over the individual components. After the completion of the required laboratory analysis for gypsum 5–20% with a 5% interval and BSG ash 5–20% with a 5% interval individually, the subgrade was stabilized. The maximum effect for gypsum stabilization occurs at 20%, which was the high strength of subgrade. For this percent, the plastic index (PI), linear shrinkage (LS), optimum moisture content (OMC), maximum dry density (MDD), California bearing ratio (CBR), and CBR swell values were 24.93%, 11.43%, 30%, 1.475 g/cm3, 5.51%, and 3.87%, respectively. The best effect of BSG ash stabilized for subgrade strength occurs at 5%, with laboratory results of 36.3%, 15%, 29%, 1.472 g/cm3, 4.97%, and 4.08% for PI, LS, OMC, MDD, CBR, and CBR swell, respectively. The percent of gypsum 20% which have the maximum effect on the strength of subgrade was taken as the total amount for different (G: BSG ash) ratios of 1:1, 1:2, 1:3, and 1:4 in the blending stabilization. The optimum blending effect on the strength of stabilized subgrade occurs at a 1:2 ratio containing 6.7% gypsum and 13.3% BSG ash, with laboratory results of 29.84%, 14.29%, 33%, 1.32 g/cm3, 5.53%, and 3.65%, respectively, for PI, LS, OMC, MDD, CBR, and CBR swell. As a result, at a 1:2 ratio, 13.3% gypsum was substituted with BSG ash, which had a similar effect on subgrade strength due to the optimal percent of gypsum stabilized.