Mechanical and Chemical Stabilization of Laterite Gravel with Crushed Stone Aggregate and Lime for Use as Flexible Pavement Material

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Addis Ababa University


Laterite gravels are marginal materials, which are locally available in southern and western part of Ethiopia, but not usually meet the specification to be used as pavement material for heavy traffic due to their gab grading and having higher plasticity. The focus of this study is to use laterite gravels as flexible pavement materials through mechanical and chemical stabilization by Crushed Stone Aggregate and lime, respectively on the samples collected from western part of Ethiopia. Three sources were taken from two different routes and two of them have been subjected to Geo-chemical tests. In the first phase of investigation, mechanical stabilization was carried out at different proportion of Crushed Stone Aggregate blended with laterite gravel in order to determine the optimum Crushed Stone Aggregate with respect to strength. The second phase of investigation was focused on examining the possibility using of lime treated laterite gravel as lime stabilized pavement material with the addition of 4-16% of lime. In the last phase of investigation, mechanical as well as lime stabilization were carried out simultaneously in which 20-60% of Crushed Stone Aggregate and 4-16% of lime were blended with laterite gravel. Based on the laboratory test results, the geo-chemical characteristics indicate that the blended laterite is pure laterite. It is shown that the laterite gravel fulfilled the CBR, LAA and TFV requirement when blended it with 40% and 60% Crushed Stone Aggregate for base course and 20% Crushed Stone Aggregate for subbase, regardless of having out values beyond the specification. The laterite stabilized with 12% lime fulfilled all of the requirements set for sub base materials. It was found out that the natural laterite gravel can be used for base course construction by stabilized it with a combination of 40% Crushed Stone Aggregate+8% lime and 60% Crushed Stone Aggregate+8% lime for CB2 and CB1, respectively. Key words: Laterite gravel, laterite-CSA, laterite-lime, laterite-CSA-lime, stabilization, subbase , base course.



Laterite gravel; laterite-CSA; laterite-lime; laterite-CSA-lime; stabilization; subbase ; base course