Effect of Molasses and Water–Cement Ratio on Properties of Recycled Aggregate Concrete

摘要

Despite recycled aggregate concrete (RAC) presenting economic and environmental benefits, it has inferior fresh and hardenedstate properties. Recycled coarse aggregates (RCA) obtained from demolished concrete demand more water to satisfytheir absorption capacity than natural aggregates; therefore, concrete incorporating the higher volume of RCA leads toinferior properties. Using a suitable plasticizer, water demand of RAC can be reduced as noted by many researchers; hence,properties of RAC are improved. Moreover, sugarcane molasses is a by-product of sugar mills and has water-reducing properties;therefore, it can be used as a cheap substitute of conventional plasticizers. In this study, the influence of four differentconcentrations of molasses (0%, 0.25%, 0.50% and 1% by weight of cement) on the properties of RAC is investigated usingthree different water–cement (W/C) ratios (0.45, 0.50 and 0.55). Workability, fresh density, compressive strength, waterabsorption, sorptivity coefficient and chloride penetrations are investigated. The results encouraged the use of 0.25–0.50%molasses in RAC for maximum strength and durability. Blank and molasses-added mixes showed maximum strength anddurability at 0.55 and 0.50 W/C ratios, respectively.