Influence of air cooled and granulated blast furnace slag on the thermal resistance of cyclic high‐temperature concrete

Concrete is the most widely used building material. Particularly in industrial floors or air ducts in steel and foundry industries, it is often exposed to high continuous or cyclical temperatures. In these applications, high temperature resistance of the concrete is essential to ensure high bearing capacity and durability. In addition to the temperature level, the composition of the concrete is also important regarding long‐term stability of the exposed concrete members.

This study investigates the effect of slag cements as well as granulated and air‐cooled blast furnace slag as industrial aggregates on the hot and residual strength of concretes exposed to temperatures up to 700 °C. In addition, the material parameters determined were transferred to the component level to calculate the bearing capacity of model walls. It was shown that the hot and residual strength, as well as the bearing capacity at the component level, are high when concretes are made from these materials. The characteristics are comparable to those of concrete made with thermally stable but relatively expensive basalt and even significantly better when quartzitic aggregates were used. The results allow suggestions to be made for additions to current fire resistance design codes.