Modified beam test for assessment of bond strength between Basalt textile reinforced mortar and concrete

Textile Reinforced Mortar (TRM) systems are increasingly recognized as viable alternatives to Fiber Reinforced Polymer (FRP) systems for structural strengthening. Traditional bond strength tests often rely on single-lap or double-lap shear specimens, which present challenges in accurately replicating real bond behavior. To address these limitations, this study investigates the bond between Basalt TRM (BTRM) and concrete using a modified beam bond test setup with optimized dimensions. The beam specimens have a square cross-section of 150 mm, with two parts, each measuring 260 mm in length. Key parameters such as concrete compressive strength, substrate surface preparation, bonded length, and mesh size were analyzed in this study. Three compressive strengths were considered: C20, C30, and C40. Two surface preparation conditions were evaluated: roughened and non-roughened. Two bonded lengths, 50 mm and 75 mm, were tested. Additionally, three mesh sizes, M5, M10, and M34, were examined. The results demonstrated that the beam bond test yields significantly higher bond strength compared to conventional shear bond tests. Increasing the compressive strength from C20 to C40 enhanced bond strength by up to 68 %. Surface roughening increased bond stress by 50 % and shifted failure modes from BTRM debonding to textile rupture. Increasing the bonded length from 50 mm to 75 mm raised bond strength by 127 %, while altering the mesh size from M5 to M10 improved bond strength by 39 %. However, further increasing the mesh size to M34 reduced bond strength by 65 % due to slippage. The proposed equation aligns well with experimental data, providing a reliable method for predicting bond behavior, though further validation is recommended. This study highlights the effectiveness of the modified beam bond test in accurately determining bond strength and effective bond length, offering a practical alternative for evaluating TRM systems in structural applications.