A study on drying shrinkage and creep of recycled concrete aggregate

Abstract

Although it is not a new material, in the last years the recycled aggregates of concrete RCA have had a great progress and are highly valued because of being friendly with the environment, multiple studies find feasible their use in structural concrete but when it is intended to be used in singular structures or prefabricated pieces that require high performance levels an exhaustive evaluation of its properties dealing with deformation and durability are needed. The paper presents an experimental study on drying shrinkage and creep of recycled concrete at constant standard ambient conditions, 8 concrete mixtures with 2 water/cement ratio (0,5 and 0,65) and 4 substitution levels of natural coarse aggregates by recycled concrete aggregates (0%, 20%, 50% and 100%) were used and the influence on this two important time-dependent deformations of recycled concrete were examined in conformity the ASTM C 512 for creep and UNE 83-318-94 for shrinkage. The effects of recycled concrete aggregates on the mechanical properties were analyzed and coefficients and recommendations to fit design are provided. The experimental results showed that the recycled aggregate have a significant effect on the overall elastic properties of concrete, the creep and drying shrinkage increases considerably, as the substitution level increases, without a lineal relation with the elasticity modulus variation when high performance concrete is used.