Cassava Peel Ash Stabilized Lateritc Soil as Highway Pavement Material

Cassava peel ash (CPA) was used to stabilize lateritic soil (LS) as highway material. The treated soil was subjected to British Standard heavy (modified Proctor) compactive effort and tested in order to determine the index properties, compaction characteristics (maximum dry density, MDD and optimum moisture content, OMC) and strength characteristics (unconfined compressive strength, UCS and California bearing ratio, CBR) of the treated soil. Test results show that the properties of lateritic soil improved when treated with CPA. The particle size grading for 100% LS show a composition of predominantly 99.6% coarse aggregates and 0.4% fines. This composition, however, improved with the addition of cassava peel ash to contain 94.3 - 99.6 % coarse aggregates and 0.4 - 5.7 % fines for the various lateritic soils - cassava peel ash mixes. The optimum mix of 70% LS + 30% CPA which gives the maximum unconfined compressive strength values of 630.59 kN/m2 (1st day-unsoaked), 577.67 kN/m2 (7th day-unsoaked) and 1009.40 kN/m2 (7th day-soaked) and California bearing ratio values of 55 % (soaked for 24 h) and 35 % (unsoaked) can be used as subbase and subgrade materials in road construction. Further works may be assessed in terms of the resilience modulus of the material.