Recycled Aggregates Effect on Concrete Mechanical Performance Subjected to High Temperatures

This study presents the results of an experimental campaign aimed at investigating the influence of recycled aggregates, derived from concrete debris (i.e., recycled concrete aggregates, RCAs), on the mechanical performance of the resulting concrete (i.e., Recycled Aggregate Concrete, RAC) after the exposure at elevated temperatures. As a matter of principle, RCAs are, generally, more porous in comparison with natural aggregates, due to the presence of the Attached Mortar (AM) and, this, may affects the physical properties of the aggregates as well as the RAC performance produced with RCAs. For this reason, in order to promote the possible use of RCAs for structural concrete production there is a strong need of understanding the influence of RCAs on the concrete performance, especially when these mixtures are subjected under “extreme conditions”. In this aim, the present experimental campaign investigates the “residual” mechanical performance of both ordinary and high strength concrete class (i.e., C25 and C65) produced with coarse RCAs (up to 100 %) and subjected at elevated temperatures (up to 650°C). The results unveil the role of the AM on affecting the compressive and tensile strengths as well as the elastic modulus of RACs exposed to elevated temperatures.