Effect of Quarry Dust on the Geotechnical Properties of Weak Subgrade Soil

Abstract

This research focused on evaluating the effect of quarry dust on the engineering properties of weak soil subgrade. This study investigated the use of quarry dust to improve subgrade properties for highway construction. Laterite soil used for highway construction is mainly weak due to its availability and tends to pose challenges in road performance, strength, and durability. The soil sample was collected from Iyekhei Quarter, Etsako West, Edo State, at a depth of about 2.5 m below the surface, in an undisturbed condition. Laboratory tests carried out for this research were Atterberg limits, Moisture content, Sieve analysis, and compaction. The tests were conducted to assess the performance of quarry dust blends (0%, 10%, 20%, 30%, 40%, and 50%) with local soil. For a soil-quarry dust proportion of 10%, 34.25 % of the sample passed sieve No 200, for 20 % mixture, 29.7 %, for 30 % mixture, 25.5%, for 40% mixture, 24.65 %, for 50% mixture, 26.3 % and for 100% mix with quarry dust, 3.8% passed through sieve No 200. According to Unified Soil Classification System, soil is described as coarse-grained if 50 % or more of the soil particles is retained on the sieve No. 200. Therefore, the particle size analysis of natural soil is mainly silt and sand mixtures The obtained results showed a plasticity index of 22.44 %, liquid limit 43.87 % and plastic limit of 21.43 % and as such, it is not suitable for soil subgrade. The change in soil grade as a result of quarry dust addition, caused a significant reduction in clay content present to 30.65 % for liquid limit, 19.17 % for plastic limit and 11.48 % for plasticity index respectively, During the compaction, the mixture of soil and 50 % quarry dust result to the highest increase in the maximum dry unit weight with a value of 1.93 g/cm3 for BSH compaction and the optimum mix CBR value observed was 30 % S-QD with a CBR value of 30.60 % for soaked condition.