Flexural Strength and Modulus of Elasticity of Concrete Beam Cast with Binary Blending of Recycled Concrete Aggregate and Marble Dust

Abstract

This research paper presents the combined effect of recycled coarse aggregates and marble dust on the flexural strength and modulus of elasticity of concrete. Use of the waste materials in concrete leads to sustainable development; and is the need of the day. Recycled aggregates were processed from demolishing waste and ensured by sieve analysis for well-graded concrete. Marble dust was used as cement replacement from 2.5% to 10% in increments of 2.5%. Recycled aggregates were used in equal dosage with conventional aggregates. A total of five batches of beams and cubes were cast using normal mix concrete. The curing of the specimens was done for 28 days. Ultrasonic pulse velocity testing was done to evaluate the modulus of elasticity. The same was also evaluated using an empirical equation of ACI and from the literature. A comparison of the results shows that both UPV testing and numerical equation by ACI can comfortably be used for evaluation of the modulus of elasticity of recycled aggregate concrete. Beams were tested under central point load for flexure. Comparison of flexural strength and deflection with control concrete shows that a 5% dosage of marble dust as cement replacement along with 50% replacement of conventional coarse aggregates with coarse aggregates from demolishing waste is optimum as with this replacement level residual flexural strength is 88% and the deflection is only 5% more than control concrete and less compared to the maximum approximate deflection allowed by ACI-31.