Published Paper Details:

High strength and high performance concretes are being widely used nowadays all over the world. In developed countries, use of high strength concrete in structures today has resulted in both technical and economical advantages. In high strength concrete, it is necessary to reduce the water-cement ratio and which in general increases the cement content. To overcome low workability problem, different kinds of pozzolanic mineral admixtures and super plasticizer are used to achieve the required workability. At the same time, scarcity of concrete constituents and their cost are increasing day by day demanding the promotion of utilization of suitable waste materials as alternatives. Particularly, substitute to conventional sand in concrete are given prime importance due to many social, environmental, economical and budget oriented problems. The present work deals with the development of quarry dust concrete with total replacement of conventional sand with quarry dust and the study is made with systematic approach with sequential steps. A conventional M30 grade concrete mix design was made using ACI, BS and IS methods and based on the 7 day strength an optimum mix was recommended for experimental studies. In the designed mix sand ii replacement by weight of 0%, 20%, 40%, 60%, 80% and 100% with quarry dust was considered. Concrete with these six different mix ratios were prepared and for the sake of exclusive reality, no plasticizer was used. Workability tests were conducted; relevant specimens were cast, cured and tested for strength and water absorption characteristics. Irrespective of the percentage replacement of sand with quarry dust, as the variations in the strength results were found negligible, a total 100% sand replacement with quarry dust was considered for further research. However as the water consumption is slightly more compared to sand concrete, it was decided to use minimum dosage of plasticizer and same recommended for the next phase of study after conformation. To study the feasibility and adoptability of using quarry dust for concrete instead of conventional sand, quarry dust concrete was further considered for thorough investigation. M30 grade quarry dust concrete was designed with the properties of quarry dust as fine aggregate and workability and strength characteristics were determined. The results are compared with that of sand concrete also. Similar trials were made for higher grades that include M40, M50 and M60 grades exclusively with quarry dust as fine aggregate. M30 and M40 grades iii concrete were designed using IS method and M50 and M60 grades by ACI method. To modify, based on the observations on concrete, additives to concrete namely fly ash and silica fume were also considered. Cement replacement by 10%, 20% and 30% of flyash and silica fume by 5% and 10% replacement were considered. For comparison, sand concrete of the above four grades were also considered then and there. Including sand concrete and quarry dust concrete with additives like flyash and silica fume, totally twenty six different mix proportions were considered for experimentation. For these different grades of concrete the workability, strength in various nature and durability characteristics were obtained. Compressive strength at 90 days of curing was also obtained in addition to 7, 28 and 60 days of curing. Based on the observation from the test results, workability of fresh concrete was gradually improved with super plasticizer and for higher grades of concrete including silica fume, when compared to control concrete. The strength and durability characteristics of quarry dust concrete was increased up to 15% by adding silica fume with QDC when compared to control concrete. The overall test results revealed that quarry dust as fine iv aggregate with silica fume as a partial replacement of cement up to 10% is an excellent substitute to yield higher strength of concrete. ANN model has been proposed to predict the compressive strength of concrete for different grades. A reasonably close agreement has been obtained between the experimental and the predicted values. The qualitative and quantitative conclusions are presented. It is concluded finally that, development of quarry dust concrete by totally replacing conventional river sand is possible, viable and feasible with all positive and negative strategies similar to conventional river sand concrete promoting cost effective technologies at same time promoting the environmental protection against sand mining.