The ductile fracture characteristic of engineered cementitious composite (ECC) matrix can prevent debonding failure of external bonded fibre-reinforced polymer (FRP) reinforcement for strengthening reinforced concrete (RC) structures. This study investigated the flexural behaviour of corrosion-damaged RC slabs fabricated employing a combination of FRP grid and ECC. Fifteen one-way RC slabs were fabricated, consisting of three controls and 12 slabs retrofitted with a FRP grid-reinforced ECC matrix (FGREM). The experimental parameters included corrosion levels of 10% and 25% mass loss representing moderate and severe corrosion, respectively. Surface treatment techniques such as chiselling, grinding, and grooving were employed, along with the use of FRP anchors for the FGREM systems at intervals of 100 mm and 200 mm. In addition, a novel patch repair technique was introduced in this study combining it with an FGREM system with FRP anchors to strengthen the corroded RC slabs. The experimental results indicated that the corrosion-damaged RC slabs strengthened with FGREM systems exhibited an increased flexural capacity, ranging from 61.05% to 236.27% compared with the unstrengthened slabs. The utilization of an ECC matrix suppressed the flexural crack-induced intermediate debonding at the interface between the concrete substrate and the ECC. The specimens with FRP anchors exhibited the largest increase in flexural capacity compared with the unstrengthened specimens. Furthermore, the impact of the concrete surface treatment technology on the flexural performance was mild, even when employing grooving surface treatment techniques.
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