Investigation of the Supplementary Cementitious Potentials of Oyster Shell Powder for Eco-Friendly and Low-cost Concrete

This experimental study was carried out to investigate the recycling potentials of oyster shell powder (OSP) as supplementary cementitious material (SCM) in concrete, which is a waste arising from fishing in coastal areas, like the Niger Delta region of Nigeria was geared towards mitigating/reducing the menace of pollution, global warming and health hazards arising from the production of cement. Ordinary Portland cement was partially replaced at the rate of 0%, 5%, 10%, 15%, 20% and 25% in concrete. A total of 72 cubes of concrete were cast in a metal mould and cured for 3, 7, 14 and 28 days. The properties of fresh and hardened concrete were quantitatively investigated. The results reveal that the increase of osp delays both the initial, 45mins (0%); 70mins (25%) and final, 105mins (0%); 155mins (25%) setting times of cement paste, which offers advantage of concreting in hot weather. The improved workability, 80mm slump for 0% and 99mm slump for 25% that goes with increased dosage of osp results in easier placement and compaction of osp-cement concrete; hence, improved ldurability. In addition, the compressive strength, 39.85N/mm(2) for 0% and 23.78N/mm(2) for 25%, though slightly decreased, produces concrete of high compressive strength for general concrete works. Hence, oyster shell powder, which has resemblance with limestone powder used in the production of cement can be used effectively to partially replace cement in concrete without compromise to the concrete properties, while offering the advantages of environmental management, pollution, and cost reduction.