Fig. 5 shows the modulus of elasticity of concretes that were investigated at 28, 60, and 90 days. The results showed that the modulus of elasticity of all concretes increased with the increase of compressive strength. However, the elastic modulus of recycled aggregate concrete with and without GBA was lower than that of CON concrete by approximately 19% when the compressive strengths of both concretes were the same. Some researchers reported
that the recycled aggregate concrete has the modulus of elasticity lower than that of the conventional concrete by approximately 25–26% [9,29]. The modulus of elasticity of concrete not only depends on the compressive strength of concrete but also on the bonding between aggregates and cement pastes also has significant influenced on the modulus of elasticity of concrete, especially at the early age of concrete [30]. Therefore, the results indicated that the use of GBA could not improve the modulus of elasticity of recycled aggregate concrete.