Strength and Durability of Recycled Concrete Strengthened with Steel Fibers and Styrene Butadiene Rubber Latex

Demolition of any structure is costly, and simultaneously there is non-accessibility of land or disposal sites in nearby areas. Recycling such demolished concrete material and converting it into an appropriate size of aggregates can be further used for the following construction cycle. Prior exploration showed utilization of Steel Fibers (SF) and Styrene Butadiene Rubber (SBR) latex in Recycled Concrete (RC) independently for various strength and durability improvements. This experimental work cast RC as M25 & M40 grade to satisfy reinforced concrete and rigid concrete pavement concrete demand. Total 132 cubes, 198 cylinders, and 198 beams of Normal Concrete (NC), RC, and RC reinforced by SF with SBR latex cast and termed as Polymer Modified Steel Fiber Reinforced Recycled Concrete (PMSFRRC). The objective was to evaluate the properties due to SF and SBR latex blending and obtaining the optimum dosages of SF and SBR latex. A strength and durability study was carried out to find out cube compressive strength, indirect tensile strength, flexural strength, chloride attack, and sulfate attack. The concrete was modified with the SBR latex dosage range of 2.5% –7.5% by cement weight. SF was added as 0.5% – 1.5% by concrete mix volume at the average length of 25 mm and 0.5 mm in diameter. Experimental findings of PMSFRRC for grade M25 with SF 1% volume fraction of concrete and SBR latex 5% of cement weight improve NC in indirect tensile strength by 9.93% and 8.58%, flexural strength by 10.01% and 8.99% at 28 and 91 days, respectively. Similarly, there was an enhancement in indirect tensile strength by 13.18 % and 11.11 % and flexural strength by 12.88 % and 10.78 % at 28 and 91 days, respectively, for PMSFRRC of grade M40 compared to NC. Durability analysis shows that a combined dosage of SF 1.5% volume of concrete mix and SBR latex 7.5% of cement weight seemed to be excellent concrete additives for good resistance to acid and sulfate attack for both mixtures. The results exhibited improved hardened properties of modified concrete due to the combined addition of SF and SBR latex, improved cracking resistance, flexure resistance, and reduced acid and sulfate attack rate into the specimens. The study also demonstrated an effective way of preparing sustainable concrete with SF and SBR latex to improve strength and durability.