Influence of curing on the mechanical performance of FRP laminates

Carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) laminates are used in different structural elements of buildings such as beams, columns, floor slabs, hand railings and for the strengthening of structures. Strength and stiffness of CFRP and GFRP laminates are highly dependent on curing temperature and time. Therefore, it is important to study the influence of temperature and duration of curing on the strength and stiffness of laminates. This study deals with the influence of curing duration and temperature of CFRP and GFRP laminates on the tensile, compressive and flexural characteristics. Laminates were cured at temperatures of 80 °C, 120 °C and 160 °C for different time periods such as 1, 2 and 3 h in a hot air oven and another laminate cured at room temperature for 15 days as a reference. It is observed that the mechanical properties of the CFRP and GFRP specimens have better performance when cured under oven heating than being fabricated at room temperature. Conclusions have been drawn that longitudinal tensile strength of CFRP and GFRP laminates is better at 80 °C temperature curing for three hours and the maximum Young's modulus of CFRP and GFRP laminates was achieved at 80 °C and 120 °C temperature for 3-h curing, respectively. Similarly, peak longitudinal compressive strength for CFRP specimens was obtained at 80 °C temperature cured for three hours and GFRP specimens cured at 80 °C temperature for 1-h. The flexural strength of CFRP and GFRP specimens was highest at 160 °C temperature cured for 1-h. However, the flexural stiffness of CFRP and GFRP specimens was dominant at a temperature of 120 °C cured for 1-h and 3-h, respectively.