Confinement effectiveness of CFRP strengthened concrete cylinders subjected to high temperatures

The current study investigated experimentally the effectiveness of Carbon Fiber Reinforced Polymer (CFRP) in confining concrete cylinders after being subjected to high temperature. Parameters examined were: (a) the exposing temperatures (20, 100, 200, 400 600and 700oC) and (b) the number of CFRP layers (1 and 3 layers). A uniaxial compressive testing was carried out on 36 concrete cylinders with dimensions of 150 mmx300 mm. The results obtained show that the compressive strength reduced with the increased of temperature compared to that measured at 20oC. In particular, the reduction in the compressive strength was more observed when the temperature exceeded 400oC. Further, the concrete cylinders confined with one and three layers of CFRP significantly increased the compressive strength compared to the counterpart unconfined specimen tested at the same temperature. Also, the average percentages of the increase in the compressive strength were approximately 112% and 158% when applying 1 and 3 layers of CFRP, respectively, compared to the counterpart unstrengthened specimen tested at the same temperature.