Creep Behavior of Reinforced and Unreinforced Recycled Lump/Aggregate Concrete

Compressive creep tests on thirty-seven recycled lump/aggregate concrete (RLAC) specimens were carried out to reveal the creep behavior of RLAC by taking the replacement ratio of demolished concrete lumps (DCLs), replacement ratio of recycled coarse aggregates (RCAs), replacement ratio of recycled sand rooted from alluvialproluvial (A-P) soil, stress level and reinforcement ratio as parameters. The results show that the specific creep of reinforced/unreinforced RLAC is greater than that of reinforced/unreinforced recycled aggregate concrete (RAC). The increase rate of RLAC is 10.1% when unreinforced and the increase rate is 13.4% and 11.5% when the reinforcement ratio is 1.16% and 1.57%, respectively. As the replacement ratio of RCAs in new concrete increases from30% to 50%, the specific creep of reinforced/unreinforced RLAC increases by 7.4% and 11.4% respectively; when the fine aggregate (i. e., river sand) of new concrete is completely replaced by the recycled sand from A-P soil, the creep behavior of reinforced/unreinforced RLAC shows almost no change, but both of the shrinkage deformation decrease. As the reinforcement ratio increases from 1.16% to 1.57%, the specific creep of RLAC and RAC decrease by 5.0% and 6.6%, respectively. Reinforcement reduces the shrinkage deformation of RAC and RLAC, and the reduction grows with the increase of reinforcement ratio. As the replacement ratio of RCAs in new concrete increases from 30% to 50%, the elastic modulus of RLAC have little change and it is also almost free from the impact of replacing the fine aggregate (i. e., river sand) of new concrete with the recycled sand from A-P soil; and when the stress level is less than 0.4, the specific creep of RLAC is nearly deemed as irrelevant to the stress level.