High-temperature behavior of reduced-mass concrete containing Expanded-Polystyrene Syntherized (EPS) particles

The renewed interest for cementitious composites containing Expanded-Polystyrene Syntherized particles – EPS is mainly due to the needs of materials recycling for sustainable constructions, as EPS particles generally come from ground polystyrene waste. By partly replacing traditional aggregates with EPS particles, concrete mass is reduced as well, to the detriment – it is fair to say - of concrete mechanical performance in ordinary environmental conditions. Other properties, however, may be of some interest, like the enhanced insulation properties and the larger macro-porosity, that may improve the mechanical properties at high temperature, something that has never been investigated so far. For such reasons, research projects are in progress in Milan and Benevento on two mixes containing EPS particles and on one reference mix (fc = 25-30 MPa). In Milan the main objective is to investigate the residual mechanical properties at the reference temperatures of 20, 150, 300, 500 and 700°C, as well as the thermal diffusivity up to 700°C. On the whole, the normalized mechanical decay of EPS concretes is slightly higher but still close to that of ordinary concrete, while the thermal diffusivity is definitely lower, to the advantage of the insulating capability. The still open problem, however, is to understand whether the game (polystyrene recycling and mass reduction) is worth the candle (more cement to counterbalance the somewhat lower mechanical properties).