Experimental investigation of stress transfer and failure mechanism between existing concrete and CFRP grid-sprayed PCM

Abstract

Abstract Carbon fiber reinforced polymer (CFRP) grid and sprayed polymer cement mortar (PCM) has been widely applied to retrofit and strengthen concrete structures. This paper focused on the stress transfer and failure mechanism between the concrete and CFRP grid with sprayed PCM. Pull-out tests of the single grid point in CFRP grid and plate-type specimens consisting of concrete, PCM and CFRP grid were carried out. Types of CFRP grids, grid interval and whether or not to use primer were selected as analysis parameters. The maximum tensile loads, failure modes and strains in the CFRP grid were obtained. The stress transfer process was investigated through analysis of the changing process for the resistant action of horizontal grid and the bond action of vertical grid. The stress transfer mode and its influence parameters were investigated based on the strain share ratios of grid points. In addition, the failure mechanisms of specimens were discussed through mechanical analysis. The research results indicated that the tensile strength of grid point was no more than 50% of the tensile strength of CFRP grid. The stress transfer mode was not constant, and it would gradually change with the increase of tensile load. The failure mechanism of the specimen could be evaluated based on the difference among the ultimate tensile action of CFRP grid, bond capacity between concrete and PCM with CFRP grid and the anchorage capacity of CFRP grid in the PCM. In order to make full use of the tensile strength of CFRP grid, the bond capacity between concrete and PCM with CFRP grid and the anchorage capacity of CFRP grid in the PCM should be larger than the ultimate tensile action of CFRP grid.