The use of the pull-off test to evaluate the interfacial bond strength between substrate concrete and bonded materials can result in failure of the concrete substrate without clear indication of the interfacial bond strength. Proper knowledge of the interfacial bond strength between a repair material and concrete substrate is critical for the selection of repair materials and for the modeling of the performance of the composite section. This includes ultra-high performance concrete (UHPC) used for thin bonded overlays of concrete bridge decks. The bond strength of UHPC to concrete substrate sections was evaluated in this study using the pull-off test, a modified version of the pull-off test, and the modified splitting tensile strength test. The results identified some challenges with respect to the characterization of interfacial bond and associated variability of test results. A new test method proposed to determine the interfacial bond strength showed that bond strength can range between 2.3 and 3.5 MPa and low coefficient of variation of 1.4% and 3.4%, respectively.

中文翻译：

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评估 UHPC 与混凝土基材之间粘结强度的脱粘试验方法

使用拉拔试验来评估基材混凝土和粘合材料之间的界面粘合强度会导致混凝土基材失效，而没有明确的界面粘合强度指示。正确了解修复材料和混凝土基材之间的界面结合强度对于修复材料的选择和复合材料截面的性能建模至关重要。这包括用于混凝土桥面板薄粘合覆盖层的超高性能混凝土 (UHPC)。在本研究中，UHPC 与混凝土基材部分的粘合强度使用拉脱试验、拉脱试验的改进版本和改进的劈裂拉伸强度试验进行评估。结果确定了在界面键的表征和测试结果的相关可变性方面的一些挑战。为确定界面结合强度而提出的一种新测试方法表明，结合强度可以介于 2.3 和 3.5 MPa 之间，变异系数分别为 1.4% 和 3.4%。