Internal curing of recycled aggregates concrete

Curing is essential to achieve durable concrete. Internal curing is defined as water provision inside concrete to achieve curing internally instead or in addition to the commonly used external water spraying. Generally, internal curing results in reducing water consumption, improving concrete homogeneity and reducing surface cracking. In this work, recycled concrete aggregates is utilized as the medium for water supplements to provide internal curing, due to its high water absorption compared to virgin aggregates. Different percentages of locally available recycled coarse and fine aggregates were utilized in designing different concrete mixes with water/cement ratios of 0.4 and 0.6. Resulting, concrete mixes were tested for their workability, unit weight, air content, compressive strength, flexural strength of beams and slabs, shrinkage and freeze and thaw resistance. It was found that the use of recycled aggregates in general slightly reduce mechanical properties due to its inferior properties. Its use, however, for internal curing improve properties such as delay of cracking, freeze-thaw resistance, and dynamic modulus of elasticity. It was recommended, therefore, to use 50% recycled aggregates for internal curing as this will improve properties in addition to the well-known sustainability benefits of both internal curing and utilization of recycled materials that are also discussed in the paper. (C) 2020 Elsevier Ltd. All rights reserved.