Experimental Investigation on the Properties of Gap Graded Aggregate Medium Strength Concrete

Abstract

Concrete is a mixture of cementations material, aggregate, and water. Aggregate is commonly considered inert filler, which accounts for 60 to 80 percent of the volume and 70 to 85 percent of the weight of concrete. Thus concrete properties are highly affected by physical properties of its aggregate. The particle size distribution of coarse and fine aggregate (grading of aggregate) may have an effect on concrete behaviour. However, due to the inherent difficulties related to the characterization of fine sized particles, little research has been made to evaluate the effect of grading. In the present investigation, packing density of combined aggregate is considered as the criteria for aggregate gradation thus selecting four combinations of gap graded aggregate for making medium strength (M40) concrete mixes. The workability, density and strength results from these concrete mixes are finally compared with conventional concrete to propose a suitable aggregate gradation. Within the premises of this study, it is concluded that gap graded concrete, though of a relatively stiffer and drier mix, can be placed and finished without undue effort for the non-structural, massive construction works demand less workability wherein continuously graded concrete has been customarily used heretofore. A considerable saving in cement content, sand and notable improvements in mechanical properties are the realistically achievable advantages through the use of gap graded concrete. Good control and, above all, care in handling, so as to avoid segregation, are essential.