Assessment of the Flexural Strength of Binary Blended Concrete with Recycled Coarse Aggregates and Fly Ash

Abstract

This study investigated the effect of blending fly ash and recycled aggregates as replacements for cement and conventional coarse aggregates, respectively. Recycled concrete helps to reduce waste management issues and protect the environment. Fly ash was used in percentages from 0% to 10% with an increment of 2.5%, whereas demolition debris was used in a proportion of 50% with conventional aggregates. The 1:2:4 mix with a 0.5 w/c ratio was used to make six concrete mixtures, one of them made entirely of congenital aggregates. Slump tests were performed for all mixtures. A total of 30 prisms of size 500×100×100mm were made and cured for 7 and 28 days. The flexural strength of the specimens was assessed under a two-point bending test till failure. The 5% fly ash and 50% Recycled Coarse Aggregates (RCA) mixture produced better results than the other mixes, showing a decrease in flexural strength of 10.74% and 15.75% after 7 and 28 days of curing, respectively. The small reduction in flexural strength compared to preserving conventional deposits and reducing the hazardous environmental impact of cement production and debris waste makes this mix suitable for use in structural members.