FLEXURAL STRENGTH OF CONCRETE BLENDED WITH RECYCLED AGGREGATES, MARBLE DUST, AND BAMBOO FIBERS

Abstract

In this research article combined effect of marble dust and bamboo fiber on flexural strength of recycled aggregate concrete is presented. The recycled aggregate concrete is an effort towards achievement of sustainable development. But its lesser strength is a key issue which can be improved by using additives. Marble dust has good cementous properties, hence is used as partial replacement of cement whereas, bamboo fibers are used as fibrous material in concrete matrix. 1:2:4 mix with water cement ratio equal to 0.5 was used in preparation of the proposed concrete. Marble dust is first optimized using dosage from 2.5% to 15% with increment of 2.5%. total of six batches with three prisms (914.4mm x 152.4mm x 304.8 mm) in each batch were prepared. In all mixes recycled coarse aggregates from demolished concrete and conventional coarse aggregates were used in equal proportion. Comparison of the test result with conventional concrete prisms of same size revealed 10% marble dust as optimum as at this dosage 25% increase in the strength is recorded. In second phase of the work bamboo fibers from 0.25% to 2% with increment of 0.25% along with optimized dosage of marble dust were used in preparing of concrete prisms of same size. Total of eight mixes were prepared. In each mix three prisms were prepared and cured for 28-days. Comparison of the test results showed 1.25% of the bamboo fibers as optimum with 51.5% and 21.2% higher flexural strength than conventional concrete and concrete with marble dust. In both phases the central deflection of the proposed concrete prisms were recorded higher compared to conventional concrete but within allowable limits of ACI. This shows the positive performance of both additives.