The effect of long term immersion in seawater at different temperatures on the properties of pultruded glass fibre reinforced polymer (GFRP) composite rebar was investigated. Samples were conditioned in seawater and in dry at 23, 55 and 75 °C for 0, 8, 20, 30 and 36 months to analyse the changes in shear properties such as transverse shear strength (TSS) and short beam shear strength (SBSS). Both TSS and SBSS increased after conditioning in dry at 55 and 75 °C; on the other hand, TSS decreased gradually due to conditioning in seawater at 23, 55 and 75 °C, whereas SBSS decreased due to conditioning in seawater only at 75 °C. Microscopic analysis specified that the shear strength decreased due to fibre/matrix interfacial failure as a result of de-bonding and fibre pull-out. Compared to the short beam shear test, the transverse shear test was found to be a sensitive technique to measure the durability of pultruded GFRP rebar. FT-IR analysis indicated superficial hydrolysis reaction of polymer matrix occurred when the sample was conditioned at 75 °C. A reversible change in glass transition temperature (T_g) and in viscoelastic property of the polymer matrix was observed due to conditioning in seawater at 23 and 55 °C.

研究了在不同温度下长期浸泡在海水中对拉挤玻璃纤维增​​强聚合物（GFRP）复合材料钢筋性能的影响。将样品置于海水中并在23、55和75°C的干燥温度下分别处理0、8、20、30和36个月，以分析剪切性能的变化，例如横向剪切强度（TSS）和短梁剪切强度（SBSS） 。在55和75°C下干燥后，TSS和SBSS均增加；另一方面，由于在23、55和75°C的海水中调节，TSS逐渐下降，而仅在75°C的海水中SBSS下降。显微分析表明，由于脱粘和拉出纤维，导致纤维/基体界面破坏，使剪切强度降低。与短梁剪切试验相比，发现横向剪切试验是测量拉挤GFRP钢筋耐久性的灵敏技术。FT-IR分析表明当样品在75℃条件下发生时聚合物基体发生表面水解反应。玻璃化转变温度（T）的可逆变化_g）和由于在23和55℃的海水中调节而观察到的聚合物基质的粘弹性。