Mechanical and Durability Properties of Self Compacting Concrete Containing Fly Ash and Steel Fibers

Abstract

Self compacting concrete (SCC) is relatively a recent development in the construction world. SCC is defined basically by two properties: Deformability and segregation resistance. It flows under its own weight while remaining homogeneous in composition. This research is aimed at examining the feasibility of using steel fibers and fly ash as supplementary cementitious material. In this research, the main variables are the proportion of steel fibers by volume (0%, 0.5%, 1.0%, and 1.5%). Parameters kept constant are the amount of cement, fly ash, fine aggregates, coarse aggregates, water, SP content, w/b ratio. The primary aim of this study is to explore the feasibility of using steel fibers in SCC by examining its fresh properties, mechanical properties (compressive strength, splitting tensile strength and flexural tensile strength) and durability properties (porosity, rapid chloride permeability and ultra sonic pulse velocity). The test results revealed that the fresh properties were significantly influenced by steel fiber content. All the results were in range as per code specified. Mix SCC4 showed minimum workability. The increase of compressive strength of about 12% was observed from control mix (SCC1) to SCC3.The increase of about 44% tensile strength at 7 days, 39% tensile strength at 28 days was observed with increase of steel fiber content from control mix (SCC1) to SCC4. The increase of flexural tensile strength of about 24% at 7 days, 33% at 28 days was observed with increase of steel fiber content from control mix (SCC1) to SCC4. Maximum splitting and flexural tensile strength was also obtained by the mix SCC4. Greatest increase in mechanical properties was observed for the mix containing 1.5% steel fibers i.e. SCC4. The inclusion of fly ash as replacement of cement and steel fibers improved strength properties for all the SCC mixes. The inclusion of 10% fly ash as replacement of cement and steel fibers (0.5%, 1.0% and 1.5%) does not affect the durability properties negatively as they showed low chloride penetration range for all mixes and maximum increase in porosity is 6% for SCC4 mix. The decrease in ultra sonic pulse velocity was about 17% from control mix (SCC1) to SCC4.