Durability of recycled aggregate concrete modified with sugarcane molasses

Abstract

Utilization of plasticizer (or water-reducing admixture) in recycled aggregate concrete (RAC) reduces the water demand, mitigates its poor workability, consequently, improves the mechanical strength and durability. Moreover, sugarcane molasses is a by-product of sugar mills which can be used as a cheap substitute of the conventional plasticizer to reduce the water demand. In this research, the influence of various dosages of molasses (0%, 0.01%, 0.05%, 0.1%, 0.5%, and 1% by weight of cement) is investigated on the properties of both RAC and natural aggregate concrete (NAC). Mechanical properties such as compressive strength and split tensile strength are studied. To evaluate the durability of each mix, several parameters such as water absorption, sorptivity coefficient, chloride penetration, and acid attack resistance are investigated. Results of the testing revealed that molasses can be used to mitigate the poor mechanical and durability performance of RAC. Molasses improved the workability of both RAC and NAC by reducing the water demand to maintain standard consistency. RAC modified with 0.5% molasses exhibited improvement in the compressive strength up to 10–12% and split tensile strength 11–19%. Maximum reduction in water absorption, sorptivity, chloride penetration, and mass loss due to acid attack of RAC was observed at 0.1–0.5% molasses. Behaviour of RAC and NAC is similar with varying dosage of molasses.