Flexural behavior of a box ferrocement beams consisting of self-compacted mortar reinforced by fiber glass mesh and GFRP bars after exposure to high temperatures

Abstract

The subject of the study deals with the investigation into the bending response of box-ferrocement beams with cement mortar that is self-compacted after being exposed to elevated temperatures. Beams were reinforced by GFRP, consisting of rebars and mesh of fiber glass, and compared with beams reinforced by conventional steel rebars and steel wire mesh. The experimental program consisted of twelve beams have sizes (225 × 150 × 1000) mm, with a 50 mm thickness as well as hollow of (125 × 50) mm. Six beams were reinforced by GFRP, and the other six beams were reinforced with steel. The beams were subjected to different temperatures: ambient temperature, 200 °C, 300 °C, and 400 °C. The bending performance of all beams was tested under a two-point load after extracting them from the furnace and after they had cooled. The study showed that the beams with steel or GFRP, they lose their properties when exposed to high temperatures. At 400 °C, an ultimate load, ductility, and toughness of GFRP-hollow beams were reduced by 86.34%, 36.82%, and 92.25%, respectively compared with the same beam at ambient temperature. The reduction in steel-hollow beams was less than GFRP-hollow beams. At 400 °C, the ultimate load, ductility, and toughness steel-hollow beams were decreased by 24.78%, 17.6%, and 63.86%, respectively compared with the same beam at ambient temperature. These beams still have not completely lost their strength, so they are able to withstand temperatures of more than 400 °C. The results proved that ferrocement beams reinforced by conventional steel have good properties in regard to higher ductility, higher first crack load, lower deflection, better controlling crack width, and are better than beams reinforced by GFRP after exposed to heat, where the ferrocement beams reinforced by GFRP were inefficient for heat resistance. Although these beams were given a higher ultimate load at ambient temperature than steel-reinforced beams.