Fire resistance of steel slag aggregates concrete

Abstract

In this paper steel slag is considered as an aggregate which could improve fire resistance of concrete due to the fact that it is a material that occurs at high temperatures. For this purpose, three concrete mixtures were prepared; concrete mixture with dolomite (reference mixture) and one concrete mixture with each of slags available in Croatia. The specimens of measurements 100/100/400 mm were demoulded 24 h after the casting,- placed in a water tank for 7 days and after that placed in the chamber (temperature of about . 293±2 K (20±2 °C) and humidity level of 95±5%) and finally kept there until the age of 28 days. After 28 days, the prisms were left in the laboratory room until the age of 56 days. At the age of 56 days the specimens, with moisture content within the limits 3 - 4 %, had been exposed to high temperatures impact. The specimens were put into the test furnace, heated to target temperatures of 373, 473, 673, 873 and 1073 K (100, 200, 400, 600 and 800 °C) with the heating rate of 1 K/min and then kept at constant temperature for Ih. Upon cooling of the specimens, their residual mechanical properties (flexural strength, compressive strength and static modulus of elasticity), residual mass and residual pulse velocity were tested and compared with the same properties of reference concrete. Achieved results and microstructural analysis promote the theory that here observed slags could be used as fire resistant aggregates.