Glass fiber-reinforced engineered cementitious composite (GFRECC) is being used in this study to repair short square reinforced concrete columns that are structurally weak and measure 100 mm \(\times\) 100 mm \(\times\) 1000 mm. Polypropylene fibers and E-glass rovings are combined in a cementitious matrix to create the composite. Eight columns were cast and tested: two low-strength concrete columns (E-A4), two standard control columns (E-A1), two with inadequate main reinforcement (E-A2), and two with insufficient lateral ties (E-A3). The GFRECC technology was used to repair and retrofit all specimens after they had been preloaded axially until the first obvious cracks appeared. With ANSYS 14.0, corresponding numerical models (N-A1, N-A2S, N-A3S, and N-A4S) were created and examined. To evaluate the restoration of ultimate load capacity, stiffness, energy absorption, and ductility, a parametric study was carried out. Retrofitting has enhanced the ultimate load for E-A2S and E-A3S columns. The increment was noticed as 2.36 and 2.52 times the value for the E-A1 column. A similar improvement of 2.33 and 2.48 times was noticed for N-A2S and N-A3S columns. Compared to E-A1, percentage increase in stiffness modulus for E-A2S, E-A3S, and E-A4S were 114.06%, 89.75%, and 14.19% respectively. Corresponding increment for N-A2S, N-A3S, and N-A4S were 120.5%, 100.1%, and 19.95% respectively. In the case of toughness modulus similar behavior was noticed from experimental and numerical results. Enhancement in energy ductility was 77.36%, 42.95%, and 15.7% for E-A2S, E-A3S, and E-A4S columns, compared to the control column. Corresponding increment for N-A2S, N-A3S, and N-A4S were 64.12%, 44.16%, and 23.14% respectively. Effective grouting in conjunction with extra wrapping layers improved the structural behavior of low-grade concrete columns.
