Durability of concrete made with recycled concrete aggregates after exposure to elevated temperatures

The behaviour of concrete made with recycled concrete aggregates (RCA) at room temperature is well-studied. However, some points still need to be addressed, especially in extreme conditions such as durability and high temperature. This paper evaluates the effect of elevated temperatures on the durability of concrete made with RCA. Three concrete mixes were studied: concrete with NA (reference), 100 % direct replacement (DR) mix (RCA-100-DR) and 100 % strength-based replacement (SBR) mix (RCA-100-SBR). The latter was designed to achieve the same performance as concrete made with NA. Mixes were exposed to temperatures of 200 ^∘C , 400 ^∘C and 600 ^∘C . After cooling, durability-loss due to thermal exposure was evaluated through water porosity, capillary water absorption, permeability, chloride diffusion and accelerated carbonation tests. At room temperature, the direct addition of RCA decreased all durability parameters. The SBR mix recovered some of the durability properties. Exposure to high temperatures decreases all the properties, but it varies depending on the property. The concrete made with NA and the SBR mix showed similar performance. The durability was also evaluated using a performance-based approach, both at room and high-temperature. The proposed approaches showed potential to evaluate durability indicators, but they should be considered with precaution. Overall, concrete made with RCA reduces the durability of concrete, with or without heat damage, but this decrease can be reduced with proper mix optimization. These evaluations contribute to the post-heating durability of concrete structures made with RCA, which is fundamental to the post-fire assessment of concrete structures.