Effect of mineral additives and two-stage mixing on the performance of recycled aggregate concrete

There is an increasing tendency to use recycled aggregate to produce concrete due to diminishing sources of natural aggregate. The properties of recycled aggregate concrete (RAC) are inferior to that of normal aggregate concrete. Several strategies including the use of supplementary cementitious materials (SCMs) are adopted to improve the properties of RAC. The two-stage mixing approach (TSMA) is also used as an improvement strategy. The present study was aimed to examine the individual and combined effects of using SCMs and TSMA on the fresh and hardened properties of RAC. Three SCMs, namely, fly ash, ground granulated blast furnace slag, and silica fume were used with and without TSMA. The experimental data indicated the beneficial effect of SCMs and TSMA on workability, strength, shrinkage, and durability of RAC. Further, the cost per unit strength of the RAC with SCMs and TSMA was less than that of RAC without any treatment. The use of developed RAC will lead to technical, economic, and environmental benefits.