Effect of mining tailing waste on properties of cement stabilized black cotton soil

In most cases, not all available materials for road construction do meet the nominal requirements, as such; stabilization becomes necessary. This study presents the results of a laboratory experiments carried out to assess the effect of mining tailing waste (MTW) as an admixture to ordinary Portland cement (OPC) stabilized Black Cotton Soil (BCS). The MTW was obtained from a tin mining site in Bukuru, Jos South LGA of Plateau State, Nigeria, while the BCS was obtained along Kanawa-Jauro-Gotel road, in Yemaltu-Deba, Gombe, Nigeria. The specimens were prepared by admixing the four blends of OPC stabilized BCS (using 0, 4, 6, and 8% OPC) with stepped percentage of MTW(0, 5, 10, 15 and 20%) by dry weight of BCS. Atterberg’s limits, Sieve analysis, Compaction, soaked California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) test were carried out on the natural and stabilized BCS. The BCS classifies  A – 7 – 6 (40) and CH (high plasticity clay) according to the American Association of State Highway and Transport Officials (AASHTO M 145-2012) and the Unified Soil Classification System (ASTM D 2487-2011), respectively. Addition of MTW to OPC stabilized BCS affected the compaction characteristics and improved both the soaked CBR, and the UCS. The optimum blend was achieved with 20% MTW admixed to BCS stabilized with 8% OPC which gave a 4-days soaked CBR value of 35% and a 7 days cured UCS value of 1273 kN/m2. This satisfies the sub-base requirements of the Nigerian general specifications. Thus, this study recommends the use of 20% MTW with 8% OPC for BCS stabilization.