Tensile strength is a crucial mechanical property of rock. Various mass ratios kCE curing agent to eco-friendly epoxy resin are used to repair fractured rock masses by considering kSCA(mass concentrations of SCA) for rock surface treatment. To address the issue of asymmetry in bi-material samples, a novel stress-balanced sample (SRSBD) is proposed for conducting Brazilian splitting tests to evaluate the tensile behavior of repaired granite. The initiation and propagation characteristics of cracks in intact and repaired samples with different repair material thicknesses are investigated using AE and digital DIC techniques. At the minimum bonding thickness, the tensile strength (at 28 d and 42 d) is approximately 11.45 MPa with a strength recovery rate of 83.58%; however, the energy absorption is 1.28 times that of the intact rock, indicating improved ductility characteristics. For UPC, the repair effect is only 4.25 MPa at 42 d. As the epoxy thickness increases, the tensile strain proportionally increases. The tensile strength initially rises and then declines, reaching a maximum of 12.78 MPa with a 1 mm-repair. Moreover, DIC indicates that the tensile strain of the epoxy-repaired sample surpasses that of the intact specimen; while AE displays a postponed ringing onset and a reduction in early-stage frequency. Changes in kCE and the kSCA have minimal impact on the tensile repair effect, with damage primarily originating from the rock side rather than the repair material. This finding demonstrates that the eco-friendly epoxy-repaired material has a clear advantage over UPC, providing a favorable repair effect for establishing sufficient bond strength and ensuring stability in underground engineering projects.