摘   要：针对钢板-混凝土组合索塔施工中C80高强混凝土易产生振捣浮浆，形成结构薄弱层，从而影响钢板-混凝土协同受力的问题，本文依托狮子洋大桥工程，开展C80混凝土振捣浮浆控制试验研究。从混凝土配合比参数与浇筑施工工艺两方面入手，研究了外加剂、纤维、水胶比等配合比参数及浇筑高度对振捣浮浆的影响规律，并分析了浮浆比例与混凝土工作性指标之间的相关性。结果表明：复掺10%的黏度改性材料HDC、10%的HME膨胀剂及1.0 kg/m3的PVA纤维，可有效降低混凝土黏度，并将浮浆比例控制在10.0%以内；随着水胶比、砂率和浆骨比的增加，混凝土的倒筒时间缩短，浮浆比例增大；适配工程的最优配合比为水胶比0.23、砂率41%、浆骨比0.53；浮浆比例与扩展度、倒筒时间、离析率之间均存在一定的相关性，而与含气量无明显关联，其中，倒筒时间与浮浆比例之间的相关性最高，相关性系数达0.89；随着单次浇筑高度的增加，混凝土的浮浆比例增大，综合填充密实性，建议单次浇筑高度不超过700 mm。研究成果可为钢-混组合索塔高强混凝土的浇筑匀质性控制提供技术参考。Abstract: During the construction of steel-concrete composite cable pylons, the use of C80 high-strength concrete frequently gives rise to vibration-induced laitance, which tends to form weak interfacial layers and consequently compromises the composite action between the steel and concrete. To address this practical engineering issue, this study, grounded in the Shiziyang Bridge project, conducted an experimental investigation into the control of vibration-induced laitance in C80 concrete. The effects of mix proportion parameters (including admixtures, fiber content, and water-binder ratio, etc.), as well as casting height on the vibration-induced laitance were investigated, and the correlations between laitance ratio and concrete workability indicators were analyzed. The results indicate that the combined incorporation of 10% viscosity-modifying material HDC, 10% HME expansive agent, and 1.0 kg/m3 PVA fibers effectively reduces the viscosity of the concrete, and maintains the laitance ratio below 10.0%. With the increase of water-binder ratio, sand ratio, and paste-to-aggregate ratio, the slump flow time decreases while the laitance ratio increases. The optimal mix proportion suitable for engineering application features a water-binder ratio of 0.23, sand ratio of 41% and paste-to-aggregate ratio of 0.53. The laitance ratio is moderately correlated with slump flow, slump flow time, and segregation ratio, whereas no apparent correlation exists between laitance ratio and air content. Among the evaluated parameters, slump flow time exhibits the strongest correlation with laitance ratio, with a correlation coefficient of 0.89. As the single-layer casting height increases, the laitance ratio increases. Considering the filling compactness, the single-layer casting height is recommended not to exceed 700 mm. The findings can provide a technical reference for controlling the casting homogeneity of high-strength concrete in steel-concrete composite cable pylon engineering.

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