Flexural performance of concrete reinforced with ultra-high ductility magnesium phosphate cement-based composites and CFRP

With the aim to develop and assess an effective reinforcement technique for concrete beams, the approach of the combination of ultra-high ductility magnesium phosphate cement-based composites (UHDMC) and carbon fiber reinforced polymer (CFRP) was analyzed and established based on the measured parameters, including failure mode, load-deflection curve and feature points. The results showed that, for specimens reinforced by UHDMC alone or the combination of UHDMC and CFRP, several cracks in the concrete layer and multi-cracks in the UHDMC layer were both shown, presenting a ductile failure and three distinct stages in the load-deflection curve. Moreover, compared with the specimens reinforced by CFRP alone and UHDMC alone, the ultimate load and ultimate deflection both were improved in the specimens reinforced by UHDMC and CFRP. Furthermore, the strain distribution of CFRP was symmetrical along both sides of the test specimen, presenting a general law of large in the middle and small in the two ends, and its more and more obvious phenomenon with the increase of the number of CFRP layer. To some extent, the inclination trend of the overall strain of CFRP can be used to determine the location of the weak surface. •An effective method to strength the flexural performance of concrete was developed.•Multi-cracks characteristic and thus ductile failure in the UHDMC layer was shown.•Ultimate load and ultimate deflection both were improved by the combination of UHDMC and CFRP.•The inclination trend of the overall strain of CFRP predicted the location of the weak surface.