Effect of different fine recycled aggregates and superplasticizer on microconcretes’ performance

This present work aimed to evaluate the behavior of microconcretes with different types of construction waste (ceramic block, mixed mortar and structural concrete), partial replacers of the fine natural aggregate (FNA), for a condition of constant consistency acquired with aid of a superplasticizer. It was performed not only analysis in macro scale (mechanical performance and durability), but also in the microstructure of this composites, studying the interfacial transition zone (ITZ) of them through scanning electron microscopy (SEM). Physical characteristics of the studied fine recycled aggregates (FRAs) were diverse. However, the use of the combination of particle-size distribution curves (generating a continuous distribution), together with the reduction of the effective w/c ratio (due to the greater water absorption of the FRAs) and the use of superplasticizer, generated microconcretes with greater compressive strength, maintenance of the dynamic modulus of elasticity and less water absorption capacity. Consequently, the electrical resistivity increased and the carbonation depth decreased in the microconcretes. SEM analysis helped to confirm the behavior of the microconcretes, mainly related to the porosity of the matrixes, and improvements of ITZ could be detected in the microconcretes with FRA. FRAs’ characteristics are essential for the mix design of the microconcretes and can maximize the use of recycled aggregates (RAs) in civil construction if carefully evaluated. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.