Experimental investigation on the compressive strength of PFGP-covered concretes exposed to high temperature

Purpose - This study aims to investigate the effect of high temperature (600 degrees C) on the compressive strength of concrete covered with a mixture of polypropylene fiber and gypsum plaster (PFGP). Design/methodology/approach - To study the compressive strength of concrete specimens exposed to temperature, 16 cubic specimens (size: 150 mm x 150 mm x 150 mm) were made. After 28 days of processing and gaining the required strength of specimens, first, polypropylene fiber was mixed with gypsum plaster (CaSO4.2H2O) and then the concrete specimens were covered with this mixture. To cover the concrete specimens with the PFGP, the used PFGP thickness was 15 mm or 25 mm. The polypropylene rates mixed with the gypsum plaster were 1, 3 and 5 per cent. A total of 14 specimens, 12 of which were covered with PFGP, were exposed to high temperature in two target times of 90 and 180 min. Findings - The results show that the PFGP as covering materials can improve the compressive strength lost because of the heating of the concrete specimens. The results also show that the presence of polypropylene fiber in gypsum plaster has the effect on the compressive strength lost because of the heating of the PFGP-covered concrete. The cover of PFGP having 3 per cent polypropylene fiber had the best effect on remained strength of the specimens. Originality/value - The cover of PFGP having 3 per cent polypropylene fiber has the best effect on remained strength of the PFGP covered specimens exposed to temperature.