Propriedades do estado fresco e de longa duração de concretos de resistência normal e alto desempenho contendo agregados de resíduo de concreto de diferentes origens

Abstract

The main difference between recycled and natural aggregates is the higher porosity and, consequently, water absorption of recycled aggregates which it requires an increase in the mixing water in the mix-design of concretes, to assurance suitable workability. Many studies have been developed to investigate the influence of the use of recycled aggregates on the mechanical properties of concrete, but the knowledge about the effects of recycled concrete aggregates (RCAs) on the main concrete deformations is still very limited. In this context, this study aims to evaluate how the physical properties of RCAs of different sources influence the fresh state (rheology and hydration process) and long-term properties (creep and shrinkage) of normal and high performance recycled concrete and compare these results with prediction models of the literature. The recycled aggregates of different sources were processed on an industrial scale and the mixtures were composed according to the scientific mix-design concepts for the optimization of the granular mixture, through the Compressible Packing Model (CPM). The results showed that the use of CPM was essential to avoid significant changes in concrete properties due to source and the size fraction of the recycled concrete aggregates. In addition, the attached mortar content and, consequently, the total mortar volume of the mixtures were key-parameters for the definition of different properties of the recycled aggregate concrete.