Extreme Concretes Exposed to High Temperature: the Effect of Expanded Polystyrene Beads and Baritic Aggregates

The high-temperature characterization of a recently-proposed light-weight concrete (containing polystyrene beads as micro void-formers) and of one heavy concrete (containing baritic aggregate) have been lately performed in Milan in residual conditions, to gather new or fresh information on the extremes of the broad spectrum of cementitious composites. Two light-weight mixes, one baritic mix cured in two different environments and a reference mix (fc = 26-35 MPa) were subjected to thermal cycles up to 700-750°C. Roughly one hundred cylinders were tested in compression and in tension by splitting, to evaluate the compressive and tensile strengths, and the elastic modulus. Damage indexes were worked out as well, on the basis of the elastic modulus and of the ultrasonic velocity, to have information on materials deviation from linear elasticity at various temperatures. Last but not least, the thermal diffusivity was derived by instrumenting five cylinders. At any temperature both concrete types behave similarly to ordinary concrete, but baritic concrete tends to retain its linear behavior longer than both EPS and ordinary concretes, and EPS concrete is weakened by the macroporosity due to EPS beads, thus requiring much higher cement contents.