Effect of heating–cooling regimes on the compressive strength of Alfa fiber Concrete

In the first part of this research, concretes with different dosage on Alfa fibers were formulated. At ambient temperature, the results show that the incorporation of 1% per volume of concrete of untreated Alfa fiber represents the highest mechanical values among the Alfa fiber concretes. Further, the addition of Alfa fibers induces an increase in ductility, compared to no fiber concrete. In the second part, specimens of ordinary concrete, concrete with polypropylene fibers, with treated and untreated Alfa fibers are heated to various temperature plateaus up to 800°C, with an average heating rate 7- 8°C/min, in steps of 100°C, maintained for 3 h. At the end of these heating parts, two cooling regimes are applied: air and water cooling regimes. The impact of these heating-cooling regimes has been valued through the study of the residual compressive strength. For both regimes and for all types of fiber concretes, compressive strength drastically reduces, up to 800°C with linear tendencies. More damage is noticed in the case of fiber concrete quenched in the water. Furthermore, for both cooling regimes, the use of Alfa fibers allowed an improvement in the residual compressive strength of ordinary concrete and more particularly in the temperature range [500-800°C].