| Popis: |
Experiments were conducted to determine the suitability of iron ore tailings and quarry dust as fine aggregates replacement of river sand for concrete production, and thereby to utilize the enormous quantities of wastes from Itakpe mines and the numerous granite quarries in Nigeria to address concerns of environmental pollution. Eight concrete mixes were produced with different levels of sand replacement by either iron ore tailings or quarry dust, while the ninth mix of 100 % river sand served as the control. The highest 28-day compressive strength of 29.2 N/mm2 was obtained by blending 75 % sand and 25 % quarry dust with cement, which was 7 % higher than the 28-day compressive strength of 27.4 N/mm2 of the control. The strength exceeded the designed characteristic strength of 21 ± 4 N/mm2 recommended by British Research Establishment and Nigerian Code of concrete practice. A sieve analysis indicated that the iron ore tailings were of poor grading quality and produced con-crete of relatively low strength. The strength for the tested mixes was adequate for normal concrete work, but to ensure grading appropriate for high performance concrete, the aggregates should be sieved in single sizes and later combined in appropriate proportions. |
