Cleavage Bonding Properties between FRP Sheet and Concrete
Masakazu MITSUI, Kimio FUKUZAWACAkira KURUMADA and Yasuyuki SUDA
Abstract:The FRP adhesion method which uses carbon or aramid fiber sheets for the strengthening of the flexural concrete members of a building or bridge has lately become a subject of special interest. The bonding properties between the FRP sheets and concrete influence the structural properties of the concrete members which are strengthened by this method. And these properties may be classified into three types according to the direction of the debonding force; the shear bonding property, the cleavage bonding property and the tensile bonding property. This paper concerns the cleavage bonding properties, which have not yet been published in any other reports. In order to obtain the properties, compact tension tests were conducted, varying the type of treatment method concerning concrete surfaces, the compressive strength of the concrete and the type of fiber sheet. The bond softening diagram and fracture energy were derived from the data as the cleavage bonding properties. The bond softening diagram was obtained by applying the poly-linear approximation method to the load-displacement curve measured from the test. Also, the fracture energy was given by integration along a softening diagram. The conclusions obtained from this study are as follows: 1) roughening of the concrete surface remarkably improves the cleavage bonding properties, if the surface treatment is carried out without loosening bond between the aggregate and the mortar matrix, 2) increase of the concrete compressive strength improves the cleavage bonding properties, and 3) the type of fiber sheet has little effect on the cleavage bonding properties. Key Words:FRP sheet, cleavage bonding property, bond softening diagram, fracture energy