Table 1 Effect of recycled aggregate on concrete properties.

Durability

Durability of Recycled Aggregate (RA) can be influenced by coarse aggregate replacement ratio, concrete age, w/c ratio, and moisture content; generally, a lower w/c ratio generates a more durable concrete mix. RA concrete is less durable due to high porosity of recycled aggregate. However, lower resistance to ingress of certain agents might be compensated by the combination of recycled aggregate with CO₂ and chlorides which reduces their penetration rates. SCM are used to improve strength and durability of RA concrete

Thomas et al. (2013), Fathifazl and Razaqpur (2013), Kou and Poon (2012), Chen and Ying (2011), Corinaldesi and Moriconi (2009), Gonclaves et al. (2004)

Compressive strength

50 to 100 % replacement of virgin aggregates with recycled aggregate decreases the compressive strength by 5 to 25 %. However, it was found that up to 30 % virgin aggregate can be substituted with RCA without any effects on concrete strength. Strength gain for RCA concrete is lower than normal aggregate concrete (NAC) for the first 7 days. On the other hand, fine RA has a more detrimental effect on compressive strength than coarse RA

Malešev et al. (2010), Rahal (2007), Yehia et al. (2008), Limbachiya et al. (2004), Xiao et al. (2012b), Corinaldesi (2010), Rahal (2007), Garg et al. (2013), Sim and Park (2011)

Fresh concrete Properties:

Workability

Moisture Content

More water is needed to achieve similar workability to that of NAC due to higher absorption capacity of recycled aggregate which can be attributed to the presence of impurities and attached cement hydrates. As the RA content increase in the mix, the workability reduces especially at lower w/c ratio in their study found that the entrapped air content was similar when compared to normal concrete mix having a range of 2.4 ± 0.2 %. In fact, there is no significant effect regarding the air content up to 25 % replacements

Xiao et al. (2012b), Sagoe-Crentsil et al. (2001), Tabsh and Abdelfatah (2009), Medina et al. (2014), Qasrawi and Marie (2013), Sagoe-Crentsil et al. (2001)

Flexural strength

Recycled aggregate has marginal influence on flexural strength, some studies showed that flexural strength reduction is limited to 10 % in RA concrete. Others indicated that RA concrete has very similar flexural behavior with virgin aggregate concrete

Malešev et al. (2010), Xiao et al. (2012b), Chen et al. (2010), Limbachiya et al. (2004)

Modulus of elasticity

Modulus of elasticity is greatly reduced by the use of recycled aggregate; it can reach 45 % of the modulus of elasticity of corresponding conventional concrete. This percentage reduction varies based on the percentage substitution. The 45 % reduction was found at 100 % substitution, while up to 15 % reduction was observed at 30 % substitution

Vyas and Bhatt (2013), Xiao et al. (2012b), Corinaldesi (2010)

Split tensile strength

A reduction of up to 10 % in split tensile strength was observed when virgin aggregate was substituted with recycled aggregate. Studies suggest that split tensile strength is more dependent on the binder quality rather than the aggregate type

Malešev et al. (2010), Thomas et al. (2013), Sagoe-Crentsil et al. (2001)

Specific gravity and bulk density

Padmini et al. (2009) found that the specific gravity and bulk density are relatively low for recycled aggregates when compared to fresh granite aggregate (FGA). This is mainly due to the high water absorption of the RA, as mortar has higher porosity than aggregates; hence RA absorbs more water than FGA

Padmini et al. (2009).

Aggregate size

Padmini et al. (2009) found that as the maximum size of the RA increases, the achieved strength increases

Padmini et al. (2009).

Shrinkage and creep

Shrinkage and creep deformation of RA concrete are higher than those of conventional concrete, 25 and 35 % higher, respectively. Percentage of substitution, size and source of parent aggregate, mixing procedure, curing, SCM and chemical admixture affect shrinkage and creep of the RA concrete. Recent studies showed improved behavior could be achieved by mix proportioning, low w/c ratio and curing

Silva et al. (2015), Fathifazl and Razaqpur (2013), Fathifazl et al. (2011), Henschen et al. (2012), Domingo-Cabo et al. (2009), Xiao et al. (2014).