High-temperature behavior of heavy-weight concretes

Heavy-weight concretes may be efficiently used to design shields for radioprotection in strategic structures, such as reactor vessels, nuclear research facilities, hospitals, etc. However, for many applications, they can undergo high-temperature exposition, or even accidental fire. In this work, the behavior of three types of concrete are analyzed, when exposed to increasing temperatures at two heating rates. The heavy-weight mixes are realized with barite (BAR) and Electric Arc Furnace (EAF) slag; additionally, a normal-weight concrete is tested too, made with natural aggregates (REF). Concretes were exposed at 150 – 300 – 450°C at low rate of heating (1°C/minute), to study their behavior under high temperature; then, they were subject to 600°C with high rate of heating (10°C/minute), to assess potential spalling occurrence. After such exposition, specimens were analyzed in terms of mass loss, density, residual compressive strength and dynamic modulus of elasticity. Results demonstrate that it is possible to design heavy-weight concrete shields with similar (or even better) performances at high temperature than normal concrete. Particularly, EAF concrete displayed less strength reduction at increasing temperatures, and at the same time, it is characterized by high gamma-ray attenuation coefficient.