09-11-2012, 04:04 PM
STRENGTH AND DURABILITY PROPERTIES OF CONCRETE CONTAINING QUARRY ROCK DUST AS FINE AGGREGATE
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ABSTRACT
Common river sand is expensive due to excessive cost of transportation from natural sources. Also large-scale depletion of these sources creates environmental problems. As environmental transportation and other constraints make the availability and use of river sand less attractive, a substitute or replacement product for concrete industry needs to be found. River sand is most commonly used fine aggregate in the production of concrete poses the problem of acute shortage in many areas. Whose continued use has started posing serious problems with respect to its availability, cost and environmental impact.
In such a situation the Quarry rock dust can be an economic alternative to the river sand. Quarry Rock Dust can be defined as residue, tailing or other non-voluble waste material after the extraction and processing of rocks to form fine particles less than 4.75mm. Usually, Quarry Rock Dust is used in large scale in the highways as a surface finishing material and also used for manufacturing of hollow blocks and lightweight concrete prefabricated Elements. Use of Quarry rock dust as a fine aggregate in concrete draws serious attention of researchers and investigators.
This paper presents the feasibility of the usage of Quarry Rock Dust as hundred percent substitutes for Natural Sand in concrete. Mix design has been developed for three grades using design an approach IS, ACI, USBR, RN.No.4 and BRITISH for both conventional concrete and quarry dust concrete. Tests were conducted on cubes and beams to study the strength of concrete made of Quarry Rock Dust and the results were compared with the Natural Sand Concrete. An attempt has also been made to durability studies on Quarry Rock Dust when compared with the Natural Sand concrete. It is found that the compressive, flexural strength and Durability Studies of concrete made of Quarry Rock Dust are nearly 10% more than the conventional concrete.
INTRODUCTION
Currently India has taken a major initiative on developing the infrastructures such as express highways, power projects and industrial structures etc., to meet the requirements of globalization, in the construction of buildings and other structures concrete plays the rightful role and a large quantum of concrete is being utilized. River sand, which is one of the constituents used in the production of conventional concrete, has become highly expensive and also scarce. In the backdrop of such a bleak atmosphere, there is large demand for alternative materials from industrial waste.
The consumption of cement content, workability, compressive strength and cost of concrete made with Quarry Rock Dust were studied by researchers Babu K.K. et al. [1], Nagaraj T.S. et al. [11] and Narasimahan et al. [13]. The mix design proposed by Nagaraj et al. [12] shows the possibilities of ensuring the workability by wise combination of rock dust and sand, use of super plasticizer and optimum water content using generalized lyse Rule. Sahu A.K. et al. [17] reported significant increase in compressive strength, modulus of rupture and split tensile strength when 40 percent of sand is replaced by Quarry Rock Dust in concrete. Ilangovan and Nagamani [18,19] reported that Natural Sand with Quarry Dust as full replacement in concrete as possible with proper treatment of Quarry Dust before utilization.
TEST SPECIMENS AND TEST PROCEDURE
The 150 mm size concrete cubes, concrete beams of size 100 mm x 100 mm x 500 mm were used as test specimens to determine the compressive strength and flexural strength respectively. The specimens were cast for M20, M30 and M40 grade and for coarse aggregates of size 20 mm was used. The workability of fresh concrete was measured in terms of slump values, V-B time and compaction factor. To obtain the required slump value, V-B time and equivalent compacting factor superplasticiser (0.7 to 2.4 % of weight of cement) were added. The properties of fresh concrete were measured according to IS: 1199-1959 [6]. The ingredients of concrete were thoroughly mixed in mixer machine till uniform consistency was achieved.
DURABILITY STUDIES
For Durability Studies the Indian Standard mix Proportion (by weight) use in the mixes of Conventional Concrete and Quarry Rock Dust concrete were fixed as 1:0.99:1.56 and 1:0.91:1.56 after several trials. The water/cement ratio for both two mixes was 0.35 and 0.38 by weight. Water reducing admixture was used to improve the workability and its dose was fixed as 275 m1/50kg of cement. The objective of this durability study was to investigate the drying and shrinkage studies, deterioration, and water absorption studies for both Conventional Concrete and Quarry Rock Dust concrete as per codel provisions.
CONCLUSIONS
Based on the above discussions, following conclusions are drawn: