This study investigated the flexural performance of 10 reinforced concrete slabs rehabilitated using thin ultra-high-performance concrete (UHPC) bonded overlay. The performance was compared to two slabs repaired using latex-modified concrete (LMC) that is widely used for bridge deck rehabilitation. Test parameters included the overlay thickness (25, 38, and 50 mm), fiber volume (2% and 3.25%), and shrinkage mitigation methods for the UHPC. The overlay slab specimens were stored outdoor for 30 months before conducting the four-point bending test. Experimental results indicated that the overlay slabs exhibited flexural failure pattern with yield of reinforcing steel, concrete crushing of the reinforced concrete substrate, and multiple cracks in the overlay. The use of UHPC thin bonded overlay enhanced cracking load by 295%–395% and flexural capacity by 35%–75% compared to the LMC overlay slabs. The maximum crack width of UHPC overlay slabs at the stage of the yield of reinforcement was less than 0.1 mm compared to 0.25–0.3 mm for the LMC overlay slabs. No slip occurred at the interface between the UHPC overlay and substrate, whereas the slip initiated following LMC overlay cracking. The increase of overlay thickness from 25 to 50 mm and fiber volume from 2% to 3.25% enhanced the flexural load capacity of the UHPC overlay slabs by 30%–40% and 10%–25%, respectively. These two strategies also reduced crack opening and propagation before the yield of reinforcing steel. The use of pre-saturated lightweight sand and CaO-based expansive agent was effective in mitigating autogenous and drying shrinkage without significantly influencing the flexural capacity of UHPC overlay slab.

本研究调查了使用薄超高性能混凝土 (UHPC) 粘合覆盖层修复的 10 块钢筋混凝土板的抗弯性能。该性能与使用广泛用于桥面修复的乳胶改性混凝土 (LMC) 修复的两块板进行了比较。测试参数包括覆盖层厚度（25、38 和 50 毫米）、纤维体积（2% 和 3.25%）以及 UHPC 的收缩缓解方法。在进行四点弯曲试验之前，覆盖板试样在室外存放 30 个月。试验结果表明，随着钢筋屈服、钢筋混凝土压碎，覆盖板呈现弯曲破坏模式。混凝土基材，以及覆盖层中的多个裂缝。使用 UHPC 薄粘合覆盖层将开裂载荷提高了 295%–395%，并且与 LMC 覆盖板相比，抗弯承载力提高了 35%–75%。UHPC 覆盖板在钢筋屈服阶段的最大裂缝宽度小于 0.1 毫米，而 LMC 覆盖板的最大裂缝宽度为 0.25-0.3 毫米。UHPC 覆盖层和基材之间的界面没有发生滑移，而滑移在 LMC 覆盖层开裂后开始。覆盖层厚度从 25 到 50 mm 和纤维体积从 2% 增加到 3.25% 分别将 UHPC 覆盖板的弯曲承载能力提高了 30%–40% 和 10%–25%。这两种策略还减少了钢筋屈服前的裂纹开口和扩展。预饱和轻质砂和 CaO 基膨胀剂的使用可有效缓解自收缩和干缩，且不会显着影响 UHPC 覆盖板的抗弯承载力。