In this study, direct shear behavior after exposure to high temperatures of epoxy-coated carbon textile-reinforced mortar (TRM) modified with different types of microfibers was investigated. Three primary test parameters were examined: elevated temperature levels (200°, 250°, and 300 °C); different microfiber types (polyvinyl alcohol (PVA) fibers, steel fibers, amorphous metallic (AM) fibers, and hybrid fibers made up of steel and PVA fibers); and heating time periods (2 and 4 h). In total, 88 direct shear test specimens were manufactured and tested. The direct shear tests were performed based on the FIP standard by employing test specimens with a pre-formed notch around the vertical middle plane. From the test results, it was observed that elevated temperatures significantly affected bond performance between the textile reinforcement and the mortar matrix, leading to degradation in shear mechanical properties of the test specimens. Under ambient temperature, the addition of microfibers to the mortar matrix was beneficial to most shear mechanical properties of TRM specimens, compared with TRM specimens without microfibers. However, the benefits of PVA fibers were significantly diminished at elevated temperatures of 200–300 °C, while AM or steel fibers adequately maintained benefits at the same temperatures. Heating periods investigated in this study did not significantly affect the shear behavior of the TRM specimens. In addition, an analytical model to predict the ultimate shear stress of TRM specimens with and without microfibers (steel or AM fibers) was proposed, and the prediction results agree with the experimental results.

在这项研究中，研究了用不同类型的微纤维改性的环氧涂层碳纤维织物增强砂浆 (TRM) 在暴露于高温后的直接剪切行为。检查了三个主要测试参数：高温水平（200°、250° 和 300°C）；不同的超细纤维类型（聚乙烯醇 (PVA) 纤维、钢纤维、无定形金属 (AM) 纤维以及由钢和 PVA 纤维组成的混合纤维）；和加热时间段（2 和 4 小时）。总共制造和测试了 88 个直剪试样。直剪试验是基于 FIP 标准进行的，采用在垂直中间平面周围具有预先形成的缺口的试样。从测试结果来看，据观察，升高的温度会显着影响织物增强材料和砂浆基质之间的粘合性能，导致试样的剪切机械性能下降。在环境温度下，与没有微纤维的 TRM 试样相比，在砂浆基质中添加微纤维有利于 TRM 试样的大多数剪切力学性能。然而，PVA 纤维的优势在 200-300 °C 的高温下显着减弱，而 AM 或钢纤维在相同温度下充分保持优势。本研究中调查的加热时间对 TRM 试样的剪切行为没有显着影响。此外，