DOI QR코드

DOI QR Code

An Experimental Study on the Degradations of Material Properties of Vinylester/FRP Reinforcing Bars under Accelerated Alkaline Condition

급속 알칼리 환경하에서의 비닐에스터/FRP 보강근의 재료성능 저하 특성에 관한 실험적 연구

Oh, Hongseob;Kim, Younghwan;Jang, Naksup
오홍섭;김영환;장낙섭

  • Received : 2018.10.26
  • Accepted : 2019.01.15
  • Published : 2019.03.01

Abstract

There is increasingly more research focusing on the application of FRP reinforcing bars as an alternative material for steel reinforcing bars, but most such research look at short term behavior of FRP reinforced structures. In this study, the microscopic analysis and tensile behavior of Basalt and Glass FRP bars under freezing-thawing and alkaline conditions were experimentally evaluated. After 100 cycles of the freezing and thawing, the tensile strength and elastic modulus of FRP bars decreased by about 5%. In the case of microstructure of FRP bars during the initial 20 days, no significant damages of FRP bar sections were found under $20^{\circ}C$ alkaline solution; however, the specimens immersed in $60^{\circ}C$ alkaline solution were found to experience resin dissolution, fiber damage and the separation of the resin-fiber interface. In the alkaline environment, the strength decrease of about 10% occurred in the environment at $20^{\circ}C$ for 100 days, but the tensile strength of FRPs exposed for 500 days decreased by 50%. At temperature of $40^{\circ}C$ and $60^{\circ}C$, an abrupt decrease in the strength was observed at 50 and 100 days. Especially, the tensile strength decrease of Basalt fiber Reinforced Polymer bars showed more severe degradation due to the damage caused by dissolution of resin matrix and fiber swelling in alkaline solution. Therefore, in order to improve the long-term performance of the surface braided FRPr reinforcing bars, surface treatment is required to ensure alkali resistance.

Keywords

Alkaline conditions;Fiber Reinforced Polymer (FRP);Freezing-thawing;Long-term performance;Tensile strength

Acknowledgement

Supported by : 연구재단