THE EFFECT OF THE PARTIAL REPLACEMENT OF ORDINARY PORTLAND CEMENT WITH COW BONE ASH

This research investigates the suitability of cow bone ash (CBA) as a partial replacement for ordinary Portland cement (OPC) in concrete production, with the aim of reducing cement consumption, lowering environmental impact, and promoting sustainable waste management practices in Nigeria. Cow bones, which constitute a major agricultural waste product, were processed into ash through controlled calcination and evaluated for their potential pozzolanic contribution in concrete. The study focused on assessing the effects of varying percentages of CBA on the fresh and hardened properties of concrete, particularly particle size distribution, workability, strength development, and durability. To achieve the objectives of the study, concrete mixes were prepared using a nominal mix ratio of 1:2:4 and a constant water–cement ratio of 0.50. Cow bone ash was used to partially replace cement at replacement levels of 0%, 5%, 10%, 15%, 20%, and 25% by weight. Laboratory tests were conducted in accordance with relevant British and ASTM standards. These tests included sieve analysis to determine particle size distribution, slump test to assess workability, compressive and flexural strength tests at curing ages of 7, 14, and 28 days, and water absorption tests to evaluate durability characteristics. The results showed that concrete containing 5–10% cow bone ash exhibited improved performance compared to the control mix. At these replacement levels, improved particle packing and additional calcium silicate hydrate (C–S–H) formation led to enhanced strength and reduced water absorption. However, workability decreased with increasing CBA content due to higher water demand, and replacement levels above 15% resulted in reduced strength and increased water absorption caused by higher porosity and unreacted ash particles. In conclusion, cow bone ash can be effectively used as a supplementary cementitious material at replacement levels of up to 10–15%, offering an environmentally friendly and cost-effective alternative to conventional cement in concrete production.