This study investigates the performance of concrete containing desert sand (desert sand concrete and desert sand self-compacting concrete) as overlay concrete to bond with normal-strength concrete substrate, with different bonding interfaces being considered. The impermeability of the bonding interface is determined by the electrical resistance test. Static bonding strength is tested by conventional mechanical tests. The dynamic properties of bonded specimens are also studied by dynamic response tests. Non-linear parameters, low-frequency energy parameters and ultrasonic velocity are included in the bonding interface ultrasound detection. The microstructural and chemical compositional of the overlay transition zone (OTZ) are analysed to reveal the mechanisms of bonding behaviour. The results indicate that the interface electrical resistance is positively related to bonding strength. Using concrete containing desert sand as the overlay concrete improves bonding interface adhesion for 30 % at most. Bonding performance can be affected by the interface pattern and volume density in both static and dynamic conditions. The bonding strength and damping ratio with properly treated interfaces can be increased by over 300 % and 38 % than those of untreated groups, respectively. The dynamic response of the bonded specimens can effectively reflect the bonding performance. The non-linear ultrasound method and the ultrasound energy method are more accurate and sensitive than traditional way (ultrasonic velocities) in detecting the bonding interface. The incorporation of desert sand in the concrete or lowering W/B considerably contributes to a series of benefits to the microstructure of the bonding interface. The bonding gap width is reduced by 17 % and 72 % for DS incorporation and lower W/B, respectively. Characterized by Ca/Si, the OTZ width is reduced by 10 % and 31 % for DS incorporation and lower W/B, respectively. Characterized by micro-hardness, the OTZ width is reduced by 21 % and 24 % for DS incorporation and lower W/B, respectively, which provides an important reference for the engineering application of desert sand self-compacting concrete.

中文翻译：

---

沙漠砂自密实混凝土加铺层与普通强度混凝土基材的粘结性能：宏观、微观和超声波测试


本研究研究了含有沙漠砂的混凝土（沙漠砂混凝土和沙漠砂自密实混凝土）作为罩面混凝土与普通强度混凝土基材的粘结性能，并考虑了不同的粘结界面。粘接界面的抗渗性通过电阻测试来确定。静态结合强度通过常规机械测试来测试。还通过动态响应测试研究了粘合样本的动态特性。键合界面超声检测包括非线性参数、低频能量参数和超声速度。分析覆盖过渡区 (OTZ) 的微观结构和化学成分，以揭示粘合行为的机制。结果表明，界面电阻与结合强度呈正相关。使用含有沙漠沙的混凝土作为覆盖混凝土，最多可提高粘结界面附着力30%。在静态和动态条件下，粘合性能会受到界面图案和体积密度的影响。经过适当处理的界面，其粘合强度和阻尼比比未经处理的组分别提高了 300% 和 38% 以上。粘接试件的动态响应可以有效地反映粘接性能。非线性超声法和超声能量法在检测键合界面时比传统方法（超声速度）更准确、更灵敏。在混凝土中掺入沙漠砂或降低 W/B 可以为粘结界面的微观结构带来一系列好处。 DS 掺入和较低的 W/B 使粘合间隙宽度分别减少 17% 和 72%。以 Ca/Si 为特征，由于 DS 的掺入和较低的 W/B，OTZ 宽度分别减少了 10% 和 31%。以微硬度为特征，掺入DS后OTZ宽度分别减小21%和24%，降低W/B，为沙漠砂自密实混凝土的工程应用提供重要参考。