Stabilization of Laterite for Base Course Construction

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Addis Ababa University


The demand for different kinds of naturally occurring construction materials is increasing in areas like the road construction industry. Unfortunately, not all the natural materials along the vicinity of road projects are suitable for the proposed construction because these materials fail to fulfill the standard quality requirements. One of these materials are lateritic materials which often do not fulfill the plasticity index (PI); California Bearing Ratio (CBR) and gradation requirements of many agencies for road base material. Hence, this research was initiated with the motivation of upgrading and utilizing the laterite material, which is one of the abundantly available substandard materials in the Western part of Ethiopia. In this research, the laterites, found along the Assosa – Kurmuk road, were sampled and stabilized so that they can be used for the construction of the base layer of all standard roads. The stabilization was done using lime and cement as two alternative stabilizers. Moreover, cost comparison were also carried out to assess the cost benefit of using stabilized laterite road base in lieu of the crushed stone road base in such areas where laterites are available in surplus quantity. Accordingly, it was found that both lime and cement stabilized laterites can be used for road base construction. In both the lime and cement stabilization cases, the optimum binder content to meet the Joint US Army and Air Force (1994) strength and durability requirements is 10% by weight of the host material. However, the optimum binder contents to satisfy the requirements of ERA Standard Technical Specification (2013) are 4% and 6% for both lime and cement stabilized laterites, both percent by weight of the host material. The cost comparison, on the other hand, indicated that based on the current market price during the study period, only the cement stabilized laterite has cost benefit against using the crushed aggregates for the road base construction. Key words: laterite, cement-stabilization, lime-stabilization, base course, marginal quality materials



laterite; cement-stabilization; lime-stabilization; base course; marginal quality materials