GFRP筋与自密实混凝土黏结性能的试验研究

为了研究玻璃纤维增强树脂复合材料(GFRP)筋与自密实混凝土(SCC)的黏结性能，制作了66个GFRP/SCC试件进行中心拉拔试验，研究SCC混凝土保护层厚度、GFRP筋直径和黏结长度以及SCC中添加纤维种类等因素对两者黏结性能的影响，并对试件的破坏形式进行分析。结果表明:试件主要出现了三种破坏形式，即劈裂破坏、拔出破坏、拔出带缝破坏；通过电镜扫描发现SCC浇筑方向对GFRP筋与SCC黏结界面的结构有一定影响，GFRP筋上部界面与SCC黏结更紧密。当SCC保护层厚度由4D增大至7D时，黏结强度提高了约44.05%；当GFRP筋黏结长度由5D增大至15D时，黏结强度降低了约65.43%；当GFRP筋直径由12 mm增大至16 mm时，黏结强度降低了约22.57%；SCC中添加聚丙烯纤维、钢纤维、聚丙烯纤维+钢纤维的试件黏结强度比不添加纤维的试件黏结强度分别提高12.80%、15.16%、15.09%。可以通过适当增加SCC保护层厚度、在SCC中添加纤维等措施来提高GFRP/SCC试件的黏结强度。 

Experimental study on bond properties between GFRP bars and self compacting concrete

In order to study the bond behavior between glass fiber reinforced polymer (GFRP) bars and self compacting concrete (SCC), pull-out tests on sixty-six GFRP/SCC specimens were deployed and carried out. The effects of SCC cover thickness, bond length and diameter of GFRP bars as well as the fiber types added to SCC on bond properties were investigated. In addition, the failure modes of specimens were analyzed. The results show that there are mainly three failure modes, namely splitting failure, pull-out failure and pull-out failure with cracks. It is found by scanning electron microscopy (SEM) that the infilling direction of SCC has a certain influence on the structure of the bar-SCC interface. The upper interface of GFRP bars is bonded more closely to SCC compared with the lower one. When the SCC cover thickness increases from 4D to 7D, the bond strength is increased by about 44.05%. When the bond length of GFRP bars increases from 5D to 15D, the bond strength decreases by about 65.43%. When the diameter of GFRP bars increases from 12 mm to 16 mm, the bond strength decreases by about 22.57%. Meanwhile, the bond strengths of the specimens mixed with polypropylene fiber, steel fiber, hybrid fiber (polypropylene fiber and steel fiber) in SCC are about 12.80%, 15.16%, 15.09% higher than that of the specimens without any fibers respectively. Hence, the bond strength of GFRP/SCC specimens can be improved by increasing the SCC cover thickness, or adding fibers to SCC etc.