EFFECT OF CURING TIME ON STRENGHT DEVELOPMENT OF BLACK COTTON SOIL TABILIZED WITH QUARRY FINES AND CEMENT KILN DUST

Abstract

ABSTRACT Black Cotton Soils (BCS). create problems for structures built.on.them due to high swelling and shrinkage charac eristics. I~ generally has 10',1/ shear strength and hence low bearing capacity..Preliminary tests 0; the Black Cotton Soil, collected from Damsa, Adamawa State, show that it belongs to .4.-7-6 in the AASHfO Soil Classification system and has index properties that indicate an inadequacy for most practical engineering use. Cement Kiln Dust (CKD) in step concentrations ofO, 4,8,12 and 16% each by dry weight of soil with Quarry Fines (QF) blend of 10%, was used to treat the soil. Soil samples were subjected to general classification test. Compaction was carried out using British Standard Light (BSL) energy and the criterion for the evaluation of strength (UCS) was considered. Results showed that Liquid Limit (LL), Plastic Limit (PL) and Plasticity Index (PI) reduced with increase in CKD contents. The MDD increased while the OMC reduced with increase in CKD contents. The UCS values recorded from 96.11, 136.71, 194.81, 219.29 and 257.17kN/m2, for the unstabilized soil, to 222.20, 315.87, 417.94, 530.26 and 755.65kN/m2 for the stabilized soil, when cured for 0, 7, 14, 21 and 28 days respectively. The strength development of UCS increased with curing ages, thus indicating that the blend has potential for time-dependent increase in strength. The study found that the use of CKD was potentially promising in stabilizing soils for engineering applications .