Improvement of black cotton soil with cattle bone powder

Abstract

Laboratory tests were conducted on black cotton soil (BCS) treated with cattle bone powder (CBP) in incremental order of 2 % up to 10 % of dry weight of soil sample, to ascertain its suitability for use as flexible pavement material. Classification, free swell, compaction, California bearing ratio (CBR) and unconfined compressive strength (UCS) tests, were conducted on BCS samples treated with CBP. Results of the tests showed that, BCS is an A – 7 – 6 and CL respectively using the American Association of State Highway and Transport Officials (AASHTO) and unified soil classification system (USCS) respectively. The plasticity index (PI) and free swell of BCS reduced from 29.3 % and 48 % to 17.8 % and 36 % respectively. The maximum dry density reduced from 1.59 Mg/m 3 to 1.40 Mg/m 3 at 10 % CBP. The reduction in the values of PI and free swell are indication of improvement in the swelling property of BCS. At 10 % CBP content, maximum unconfined compressive strength (UCS) results values of 367 kN/m 2 , 670 kN/m 2 and 1031 kN/m 2 were obtained at 7, 14 and 28 days respectively. The improvements in some of the geotechnical properties of BCS observed were not adequate enough for its use in road work. However, CBP can be used as a modifier, in the stabilization of BCS with cement or other additives.