The Effect Of Teff Straw Fiber And Lime On Strength And Compressibility Of Soil: The Case Of Black Cotton Soil Of Sendafa Town, Ethiopia

Abstract

In developing countries like Ethiopia, there is high development of the construction industry. However, some soils at the site of construction might not be appropriate for supporting heavy structures. Many stabilization methods and materials exist for improving the strength and compressibility characteristics of the soil. Investigation of waste materials as geo material over the ordinary and market-oriented stabilizers has both economic and environmental significance. In this work, the effect of teff straw fiber, which is one of the waste products, on strength and compressibility characteristics of black cotton soil was investigated. The combined effect of fiber reinforcement and lime treatment was also investigated. To achieve the objective of this research, the sample of black cotton soil was collected from Sendafa town and different laboratory tests were conducted as per the ASTM manual to classify soil. Samples of soil reinforced with various contents (0%, 0.5%, 0.75%, and 1% by weight) and lengths (20mm, 40mm, and 60mm) of teff straw fibers and mixed with various percentages of lime (2%, 4%, and 6%) were prepared to conduct compaction test, UCS test, and consolidation test. The result showed that MDD decreased and OMC increased with increasing both fiber and lime percent, while unconfined compressive strength increased for both uncured and cured conditions until 0.75% for teff straw fiber with each length and 4% (optimum %) of lime. The strength increased by more than double when the soil is reinforced with optimum percentage (0.75%) of fiber content and lime (4%) treated as compared to when the soil is stabilized by lime (4%) only. Similarly, fiber reinforcement and lime stabilization significantly reduced the compressibility and swelling potential of soil. The finding of the work suggests that a combination of fiber reinforcement and lime stabilization is more effective for ground improvement than lime stabilization alone.