As the fibre reinforced polymer (FRP) sheets/textiles strengthening the inorganic cementitious materials technique was presented by some researchers, a few of potential shortcomings, such as penetrating difficultly of cementitious materials to and much brittle of FRP sheets, have been found in recent years. Therefore, a new strengthening system, which was FRP grid strengthening ECC system, in combination with the Engineered Cementitious Composites (ECC) and FRP grid was proposed by the present authors. By applying this system to reinforce the reinforced concrete (RC) beams, the dual strengthening effects can be provided and the intermediate crack-induced debonding failure can also be suppressed by externally bonded the FRP gird reinforced ECC composite layer to the tensile surface of the original RC beams. To investigate the tensile mechanical behaviour of FRP gird reinforced ECC composite layer, six non-strengthened ECC specimens and eighteen basalt fibre reinforced polymer grid (BFRP) strengthening ECC composite specimens (FRP-ECC specimens) subjected to the unidirectional axial tensile loading were conducted in this paper. Three kinds of different thickness BFRP grid were applied to investigate their reinforcement effects. The test results showed that there was no slip at the interface of BFRP grid and ECC substrate significantly. The failure modes were the internal PVA fibers ruptured or pulled out from ECC substrate for the non-strengthened ECC specimens and the rupture of BFRP reinforcements of grid for the strengthened FRP-ECC specimens. The axial stiffness of FRPECC specimens and the ultimate tensile stress and strain were obviously increased after the ECC substrate cracked, which indicated the contribution of the internal BFRP grid reinforcements. Moreover, an analytical model was also presented to predict the stress-strain relationship and the tensile strength of the FRP-ECC specimens and validated through comparison with the rest results.
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