Desempenho mecânico, estrutural e durabilidade de concretos de resistência normal e alta resistência produzidos com agregados reciclados de diferentes origens

Abstract

In literature, there is still no agreement on the consequences of the presence of recycled concrete aggregates (RCA) in the connection between steel and recycled aggregate concrete (RAC), especially under real conditions of use of the structures. The experimental investigation was carried out to evaluate the influence of RCAs on the mechanical, structural and durability behavior of concrete of normal strength (35 MPa) and high strength (60 MPa) before and after degradation processes (freezing-thawing cycles and wetting-drying cycles). In a pilot scale case study, RCAs were generated in the fractions coarse 0 (9.5 mm) and coarse 1 (19 mm) from approximately 20 tons of concrete waste from three different sources: laboratory, construction and demolition. Structural investigation was carried out through tension stiffening tests, which provide a comprehensive analysis regarding the steel-matrix interaction and the cracking mechanisms. It was identified that the main properties of RCAs are directly related to the Attached Mortar (AM) content, which can be defined as a fundamental parameter of quality control for classification of RCAs. It is evident that the total mortar volume of the mixture governs one of the main particularities of the recycled concrete, the total water absorption. In addition, this parameter was identified as the key characteristic for understanding the effects of degradation processes on the mechanical and structural performance of concrete.