Enhancemant of strength and corrosion resistance in quarry dust concrete using mineral admixtures and inhibitors

Abstract

Concrete is the most widely used building material in the world due to its versatility, low cost and durability. The most commonly used fine aggregate is natural river sand. The demand for natural sand in the construction industry has consequently increased due to the extensive use of concrete resulting in the reduction of sand sources and increase in price. The Government has already banned sand mining due to environmental problems in some identified areas of major rivers. Thus, an investigation is needed to identify a suitable substitute that is eco- friendly and inexpensive and in this connection the use of quarry dust as fine aggregate has occupied a promising factor in the preparation of concrete. Quarry dust can be defined as residue, tailing material after the extraction and processing of rocks to form fine particles less than 4.75mm. Quarry dust being, by and large, a waste product, will also reduce environmental impact, if consumed by construction industry in large quantities. Hence, the use of quarry dust as fine aggregate in concrete will reduce not only the demand for natural sand but also reduces the environmental problems. Moreover, the replacement of sand by quarry dust will offset the production cost of concrete, and hence the successful utilization of quarry dust as fine aggregate will turn this waste material into valuable resource. Corrosion of steel in concrete is one of the major causes of premature deterioration of reinforced concrete structures, leading to structural failure. A number of remedies such as use of mineral admixtures, addition of inhibitors and rebar coating have been suggested to prevent corrosion of steel iv in concrete structures. Mineral admixtures are finely divided siliceous materials which are added to concrete in relatively large amounts, generally in the range of 20 to 50% by weight of Portland cement.