PROPERTIES OF HIGH-PERFORMANCE FIBER-REINFORCED CONCRETE AFTER THERMAL TREATMENT AT HIGH TEMPERATURES

A complex analysis of the effect of a high-temperature load on the parameters of a high-performance fiber-reinforced concrete (HPFRC) is presented. The HPFRC containing steel fibers was exposed to temperatures of up to 1000 degrees C. In order to reveal the effect of the elevated temperatures on the concrete performance, its basic physical, mechanical, hygric and thermal properties were determined after the thermal treatment. To observe physical and chemical processes in the HPFRC as a function of temperature, a simultaneous thermal analysis (STA) and a thermodilatometry analysis (TDA) were used. The high-temperature exposure led to an increase in the porosity and pore size and to a significant decrease in the mechanical strength. The values of hygric and thermal properties correspond to the changes in the material structure after the thermal treatment. STA and TDA data showed structural changes of the studied material and allowed identification of critical temperatures for its damage.