高湿度环境下钢桥面结露控制与防水层施工关键技术研究

Research on Condensation Control and Key Construction Technologies for Waterproof Layers of Steel Bridge Decks in High-Humidity Environments

摘要: 为解决高湿度环境下钢桥面防水层粘结失效的技术难题，本文以上海北横通道新建一期工程为背景，通过理论分析与工程实践，开展高湿度天气下钢桥面防水层施工技术研究。考虑钢桥面因热传导系数为混凝土桥面的25倍、比热容仅0.5倍，易低于露点温度(26℃、85%湿度时露点23.4℃)产生结露，导致防水层粘结强度下降(常温设计强度 ≥ 1.0 MPa)、空鼓失效。为此，提出综合技术解决方案：开发“大功率吹扫 + 辅助加热”主动干燥工艺，使钢桥面含水量控制在2 g/m²以下；优化“干燥–喷涂”连续作业模式，衔接距离 ≤ 10 m、时间间隔 ≤ 5 min；建立物联网环境监测系统，实时监测温湿度、露点温度等参数，优选夜间至清晨桥面板温度高于露点温度的安全施工窗口。工程应用结果显示：施工期间环境最高湿度93%，防水层常温粘结强度达1.28 MPa，50℃高温粘结强度0.62 MPa，厚度合格率98.2%，平整度合格率99.1%。经5年长期跟踪监测，无因防水层失效导致的铺装层病害。研究表明，该综合技术可有效抑制钢桥面结露影响，显著提升防水层的施工质量与耐久性，为长三角、珠三角等高湿度区域类似工程提供技术参考。

Abstract: To address the technical challenge of adhesive failure in waterproof layers on steel bridge decks in high-humidity environments, this study, based on the Phase I project of the Shanghai North Crossing, explores construction techniques for waterproof layers on steel bridge decks under high-humidity conditions through theoretical analysis and engineering practice. Considering that steel bridge decks, with a thermal conductivity 25 times that of concrete bridge decks and a specific heat capacity only 0.5 times that of concrete, are prone to condensation below the dew point temperature (26˚C, with a dew point of 23.4˚C at 85% humidity), leading to a decrease in the adhesive strength of the waterproof layer (design strength at room temperature ≥ 1.0 MPa) and failure due to hollowing, a comprehensive technical solution is proposed: developing an active drying process of “high-power purging + auxiliary heating” to control the moisture content of the steel bridge deck below 2 g/m², optimizing the continuous operation mode of “drying-spraying” with a connection distance of ≤10 m and a time interval of ≤5 min, and establishing an IoT environmental monitoring system to real-time monitor parameters such as temperature, humidity, and dew point temperature, preferably during the safe construction windows from night to early morning when the steel deck temperature is higher than the dew point. The engineering application results show that during the construction period, the maximum environmental humidity reached 93%, the adhesive strength of the waterproof layer at room temperature reached 1.28 MPa, the adhesive strength at 50˚C was 0.62 MPa, the thickness pass rate was 98.2%, and the flatness pass rate was 99.1%. After five years of long-term tracking monitoring, there were no pavement defects caused by failure of the waterproof layer. The research indicates that this comprehensive technology can effectively mitigate the impact of condensation on steel bridge decks, significantly improving the construction quality and durability of the waterproof layer, providing technical reference for similar projects in high-humidity regions such as the Yangtze River Delta and the Pearl River Delta.