Effect of Bagasse Ash on the Properties of Cement Stabilized Black Cotton Soil

摘要

When proximate and locally available materials to be used for road pavement construction are deficient to meet the nominal requirements of the intended flexible pavement layer; then stabilization becomes necessary. Therefore, this paper presents the results of laboratory experiments undertaken to assess the effect of sugarcane Bagasse Ash (BA) as an admixture to cement stabilized Black Cotton Soil (BCS). The Bagasse was obtained from a dump-site at Kasuwan Shanu market Bauchi and was incinerated at a controlled temperature range between 600℃ and 700℃ to get the BA, 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 cement stabilized BCS (using 0, 4, 6, and 8% cement) with stepped percentage of BA (0, 1, 2, 3 4, 5, and 6%) by dry weight of the BCS. The experiments carried out on both the natural and treated BCS include; Atterberg's limits, Sieve/hydrometer analysis, Free swell, Compaction, soaked California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS) at 7, 14, and 28 days curing periods. The BCS was classified as A - 7 - 6 (68), and CH (high plasticity clay) using the American Association of State Highway and Transportation Officials (AASHTO) and Unified Soil Classification System (USCS) respectively. In addition, the soil was also categorized as High swell potential BCS under Nigerian Building and Road Research Institute (NBRRI) classification. It was found that; addition of BA to cement stabilized BCS affected their compaction characteristics, and improved both the soaked CBR, and the UCS. On the other hand, the addition of BA alone does not improve the strength properties of the natural BCS. The optimum blend was achieved with 5% BA as admixture to BCS stabilized with 8% cement, this blend gave a 7-days soaked CBR of 73% and a UCS value of 851 kN/m~2 after curing for 7 days therefore, satisfied the sub-base requirements of the Nigerian Federal Ministry of Works. This study finally recommends the use of 5% BA with 8% cement for BCS stabilization for use as sub-base in flexible pavement construction.