Thermal parameters of UHPC in case of fire: an approach to the Brazilian standard ABNT NBR 15200

Abstract

Abstract Ultra-high-performance concrete (UHPC) has exceptional mechanical properties at room temperature. However, there are no standardized thermal procedures proposed by ABNT NBR 15200 to characterize UHPC at high temperatures, such as in the case of fire. This is due to the lack of research on the subject, leaving gaps for experimental and numerical investigations. Based on experimental analyzes on standardized, small-scale specimens, this research collects a set of parametric data for UHPC at high temperatures. Thermal diffusivity, thermal conductivity, thermal expansion and specific heat as thermal parameters were defined for different temperature ranges. The results were compared with other structural concretes proposed in the literature (NSC, HSC and UHSC). The UHPC exhibited a particular fire behavior. Compared to NSC, HSC and UHSC, the thermal expansion and mechanical parameters of UHPC are less affected at high temperatures, but its thermal conductivity and mass loss are higher. UHPC also has the highest specific heat compared to other concretes. The thermal field of UHPC tends to be higher compared to the other concretes.