Recycled aggregate produced from crushed waste concrete is suitable for use in structural concrete. It reduces the demand for non-renewable resources and also for energy in general. However, RA is more porous than most natural aggregates. The porosity of the concrete cover defines the corrosion resistance of reinforced concrete, and it is therefore disputed how the use of recycled aggregate may affect the durability of reinforced concrete. This paper describes the corrosion-related performance of reinforced concrete with recycled aggregates in the initiation stage (determined by the carbonation and chloride ingress) and propagation stage (determined by the electrical resistivity and cracking) of corrosion. The aspects of interest are not only the porosity of RA but also its effects on the chloride binding, carbonation, electrochemical properties and corrosion cracking development.

Recycled aggregate concrete (RAC) includes recycled concrete aggregates (coarse and/or fine) as substitutes for natural aggregates as an approach to achieving a circular economy. Some concerns remain about its performance, including the carbonation resistance. The higher porosity of recycled concrete aggregates is logically a disadvantage, but the analysis must address many other factors. This paper provides an in-depth examination of recent advances in the carbonation performance of RAC. The emphasis is on factors that influence CO₂ diffusion and the carbonation rate, e.g., the replacement ratio, source concrete quality, interfacial transition zone features, residual portlandite content, and porosity. The influences of previous treatments, combined action with supplementary cementitious materials, and loading conditions are also discussed. The replacement ratio has a significant impact on the carbonation performance of concrete, but it is also dependent on other factors. During carbonation, the physical effects of the porosity of the aggregate and the physical–chemical effects of the portlandite content in the adhered mortar are particularly important. The residual portlandite is especially significant because it is the primary hydration product responsible for the alkaline reserve for carbonation and the potential pozzolanic reaction, which are per se competing factors that determine the carbonation rate.

En este trabajo se evaluó el comportamiento del concreto con escoria de horno de cubilote (EHC), triturada en porcentajes de sustitución de arena del 0, 10, 15 y 20 %, sometido a ataques químicos acelerados de carbonatación, sulfatación y reacción álcali-agregado (RAA). Se determinaron las características de absorción del sonido del material a través del coeficiente de absorción acústica (α) y el índice de reducción de ruido (NRC). La carbonatación se evaluó por medio de una cámara cerrada con 70 % de concentración de dióxido de carbono y condiciones de humedad relativa entre 50 y 70 %. Los resultados mostraron que la profundidad de penetración de CO₂ es menor mientras mayor es el porcentaje de sustitución. Para acelerar el ataque por sulfatos, se sumergieron probetas en solución acuosa de sulfato de sodio anhidro (Na₂SO₄) 1N con ciclos de humedecimiento y secado. Se determinó que el deterioro presentado en la pasta de concreto es directamente proporcional al porcentaje de sustitución. La aceleración de la RAA en el concreto se realizó sumergiendo probetas en una solución acuosa de hidróxido de sodio (NaOH) durante dieciséis días. Se concluyó que la inclusión de EHC no es favorable por RAA. La medición del coeficiente de absorción acústica se realizó a través del método de tubo de impedancia, relacionando valores máximos y mínimos de amplitud de onda estacionaria. Los resultados mostraron que concretos de EHC con mayores sustituciones de arena por escoria son favorables para la absorción de ruidos en las edificaciones.