Abstract
This paper presents the results of pull-out tests conducted to investigate the interfacial bond behavior between a carbon-fiber-reinforced polymer (CFRP) grid–polymer cement mortar (PCM) reinforcing layer and existing concrete, and proposes a simplified mechanical model to further study the interface bond mechanism. Four specimens composed of a CFRP grid, PCM, and concrete were tested. The influence of the type of CFRP grid and the grid interval on the interface bond behavior was discussed. The failure patterns, maximum tensile loads, and CFRP grid strains were obtained. The change process of interface bond stress was investigated based on the grid strain analysis. In addition, the simplified mechanical model and finite element model (FEM) were emphatically established, and the adaptability of the simplified mechanical model was validated through the comparative analysis between the FEM results and the test results. The research results indicate that a CFRP grid with a larger cross-sectional area and smaller grid interval could effectively improve the interface bond behavior. The tensile stress was gradually transferred from the loaded edge to the free edge in the CFRP grid. The interface bond behavior was mainly dependent on the anchorage action of the CFRP grid in the PCM, and the bond action between the PCM and the concrete. The FEM results were consistent with the test results, and the simplified mechanical model with nonlinear springs could well describe the interface bond mechanism between the CFRP grid–PCM reinforcing layer and concrete.
Highlights
Considering that the interface between the Carbon-fiber-reinforced polymer (CFRP) grid–polymer cement mortar (PCM) reinforcing layer and concrete consists of three materials, and the PCM–concrete interface is divided into a checkerboard pattern by CFRP grid, resulting in a complicated stress state of the interface, experiments alone are not enough to reveal the bond mechanisms between CFRP grid, PCM, and concrete in detail, and further investigations based on mechanical analysis and numerical simulation are needed—similar to the research of N.K
This could attributable to the fact that epoxy primer was used on the surface between the CFRP grid–PCM reinforcing layer and the concrete, resulting in the improvement of interface bond action
The critical deflection dt and maximum deflection dmax of the nonlinear spring were determined by the concrete material test, and the maximum resistant action Rmax was determined by the interface shear strength between the PCM and concrete, along with the tensile strength of the PCM
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. A new strengthening technique for concrete structures using CFRP grids and sprayed. FRP sheets/plates sheets/plates and in wet wet environments For this this strength and existing existing concrete concrete in new strengthening method, the drawbacks can be effectively avoided by riveting the new strengthening strengthening method, method, the the drawbacks drawbacks can can be be effectively effectively avoided avoided by by riveting riveting the the new CFRPgrid gridto tothe theconcrete concretesurface. PCM is sprayed on the outside surface of the CFRP grid and concrete. By means of this construction technique, the grid–PCM reinforcing layer and the existing concrete constructiontechnique, technique,the.
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