THE SUITABILITY OF USING COAL ASH ADMIXED WITH CEMENT FOR THE STABILIZATION OF BAMA RIDGE SOIL

ABSTRACT Bama Ridge soils, found in certain areas of Borno and Yobe States, exhibit considerable strength when dry and typically do not pose significant problems for structures. However, when wet, these soils are prone to rapid collapse and can experience volume reductions of up to 10-15%. This collapse can lead to substantial surface displacement, often several feet or more. Similar behaviors are commonly observed in old landfills and poorly placed earth fills. The collapse phenomenon is primarily attributed to the open structure of these soils, and various classifications based on parameters such as moisture content, dry density, Atterberg limits, and clay content have been proposed as indicators of collapse potential. Direct measurement of collapse magnitude through laboratory and field tests is critical when a soil shows signs of collapse potential. This study provides a comprehensive review of collapsible soils, covering their types, collapse mechanisms, identification and classification methods, and laboratory treatment techniques. The primary objective of this project is to evaluate the effectiveness of stabilization in improving the strength properties of collapsible soils. Specifically, the project focuses on cement-coal ash stabilization. Soil samples will undergo preliminary tests, including determination of natural moisture content, sieve analysis, specific gravity, free swell test, and compaction tests to determine their Optimum Moisture Content (OMC) and maximum dry density. The compacted samples will be cured for specified periods and subsequently tested for the Coefficient of Permeability, for soaked sample. The results will be analyzed to assess the improvement indices, with recommendations for the application of stabilized soils in civil engineering projects, such as road construction and other infrastructure works.