Avaliação da trabalhabilidade de concretos contendo agregado reciclado de argamassa

Abstract

To use of recycled aggregates in concrete is essential to improve the study of its characteristics and behavior. Usually the recycled concrete, made from construction and demolition waste aggregates, has different fresh and hardened properties. This work evaluated the influence of replacement of fine and coarse natural aggregates by recycled mortar aggregates (0, 50 and 100%) and the influence of the rate of compensation of the absorption rate of these recycled aggregates on the workability and compressive strength of concrete. The workability was evaluated by three tests: slump test, flow table and VeBe time. The compressive strength was evaluated at 28 days. The results show that the rough and irregular surface texture of the recycled aggregates reduce the workability of concrete compared to conventional concrete, which can be minimized with the increase in compensation rate of water absorption rate of aggregate. The comparison between different methods of evaluation of workability demonstrates that tests using dynamic energy are more suitable for use with recycled concrete. Despite the reduction in compressive strength with increasing addition of recycled aggregate and increased free water in the mix, it is possible to design recycled concrete as strong as the matrix and with adequate workability.