Mechanical performance of carbon fibre reinforced vinyl ester composite plate bonded concrete exposed to tropical climate
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Date
2007
Authors
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Publisher
Universiti Teknologi Malaysia
Abstract
Most of the past and recent short-term and long-term experimental studies on Fibre Reinforced Polymer (FRP) plate or laminate system bonded to reinforced concrete members have shown an improvement in terms of mechanical performances but the findings on the bond durability characteristics are still in doubt. This study programme focused on the mechanical performances of Carbon Fibre Reinforced Polymer (i.e. CFRP with vinyl ester matrix) composite plate bonded to concrete exposed to tropical climate conditions. In this programme the test samples were divided into three groups, namely; CFRP plate, epoxy adhesive and CFRP plate bonded to concrete (stressed and unstressed). The specimens were experimented to designated exposure conditions for six months, namely; laboratory (LB), outdoor (OD), plain water (PW-wet/dry cycles) and salt water (SW wet/dry cycles). After exposure, the groups of CFRP plate and epoxy adhesive were loaded in tensile and shear while the group of CFRP plate bonded to concrete was loaded to failure under tension-compression loads. The performance of the exposed specimens was then compared with that of similar control specimens in terms of strength and modulus for CFRP plate and epoxy, respectively. In addition, the load carrying capacity, bond slips, local force and bond stress distribution for CFRP plate bonded to concrete were studied. The results of the study had indicated that exposure to tropical climate had reduced the strength properties of CFRP plate by nearly 10% for those exposed to plain and salt water, while in contrast to that, those specimens exposed to outdoor showed an increment of strength of up to 5% compared to the control group. Meanwhile, the elasticity of CFRP plate was significantly affected by exposure to salt water, i.e. 15% reduction compared to the control ones. It was also found that all the exposure conditions had reduced the epoxy shear strength by nearly 32%, with the exposure to plain water being the most aggressive. On the other hand, the exposure conditions had also affected the epoxy shear modulus by up to 25%, where the most reduction was shown by specimens exposed to plain water. Finally, it can be said that the tropical climate conditions had significantly influenced the mechanical bond performances of the bonded specimens. This could be seen for those specimens that had been exposed to outdoor condition which experienced debonding at load level about 30% of the ultimate load compared to about 50 to 60% load level for those exposed to the other three exposure conditions. It was also found, that all exposure conditions produced non-linear bond slips at specimens’ most stressed end which could be related to the influences of moisture ingression on bond interfaces that weaken the bond performances
Description
Thesis (Ph.D (Mechanical Engineering))
Keywords
Carbon fibers, Reinforced plastics