Effect of Size of Aggregate on High Strength Self Compacting Concrete

Concrete is a versatile widely used construction material. Researchers are always trying to improve its quality and enhance its performance, ever since concrete has been accepted as a material for construction. Recent changes in construction industry demand improved durability of structures. From a strength based concept to a performance based design, there is a methodological shift in the design of concrete. At present scenario on performance aspect of concrete there is a large emphasis. The development of Self Compacting Concrete (SCC) is one of the idea of such researches. It is considered as the most revolutionary development in concrete construction. SCC is a new kind of High Performance Concrete (HPC) with excellent deformability and segregation resistance. It can flow through and fill the gaps of reinforcement and corners of moulds without any need for vibration and compaction during the placing process the guiding principle behind self-compaction is that the sedimentation velocity of a particle is inversely proportional to the viscosity of the floating medium in which the particle exists. The other features of mix proportion of SCC include low water to cementations material ratio, high volume of powder, high paste to aggregate ratio and less amount of coarse aggregate. One of the popularly employed techniques to produce Self Compacting Concrete is to use fine materials like Fly Ash, GGBFS etc in concrete, besides cement, the idea being to increase powder content or fines in concrete. The present investigation is aimed at developing high strength Self Compacting Concrete of M70 Grade. The parameters of study include grade of concrete and effect of size of aggregate. The existing Nan Su [2001] method of mix design was based on packing factor for a particular grade of concrete, obtained on the basis of experimental investigation. SCC characteristics such as flow ability, passing ability and segregation resistance have been verified using slump flow, L box and V funnel tests.