高强混凝土在超高程泵送过程中的流动行为

Due to the strengthened load-bearing capacity, light-weight of elements and low consumption of materials, there has been increasing interest in the use of high strength concrete (HSC) for great constructions like high-rise buildings and long-span bridges. However, some severe problems, such as drop of workability, high requirement of pumping pressure, and lack of scientific and accurate evaluation system revealing the pumping performance, are faced frequently for pumping of HSC. To resolving the above problem, the present project will firstly be deal with flow state of HSC in pumping pipes, based on an invented tiny pressurized concrete pumping circuit. Then rheological properties of HSC under pressure should be clarified and formation mechanism of lubrication layer should be investigated. After that, two theoretical and computational models will be presented for establishing pumpability of HSC coupled with its rheological properties and lubrication layer characteristics. With the guide of above models, the pumpability of HSC could be evaluated accurately. Also, design frame and regulation direction, with respect to pumpability of HSC, could be set up. Finally, the expected results could not only provide technical support to solve the problem of HSC in pumping process encountered, but also support a theoretical basis for the preparation of HSC and the selection of pump with preferred parameters.

高强混凝土具有提高承载力、减少结构自重和节约材料等诸多性能优势，已开始在超高层建筑、大跨径桥梁超高索塔等工程中应用。然而，高强混凝土超高程泵送施工过程中却存在泵送压力大、流动性损失和泵送性能评价方法缺失等一系列问题。本项目围绕高强混凝土在泵送管道中的流动行为，从研制混凝土泵送性能实验室评价系统出发，探讨高强混凝土在泵送管道中的流动状态，明晰压力作用下高强混凝土的流变性能，揭示泵送管道中润滑层的形成机制，建立基于润滑层特性和混凝土流变性能的高强混凝土泵送阻力预测模型以及计算机数值模拟方法，实现高强混凝土泵送性能的精确评价，并形成高强混凝土泵送性能设计和调控方法。研究成果不仅可为解决工程中遇到的高强混凝土泵送问题提供技术支撑，还可为制备高强泵送混凝土、优选泵送参数等提供理论指导依据。

高强混凝土具有提高承载力、减少结构自重和节约材料等诸多性能优势，已开始在超高层建筑、大跨径桥梁超高索塔等工程中应用。然而，高强混凝土高远程、超高远程泵送施工过程中却存在泵送压力大、流动性损失和泵送性能评价方法缺失等一系列问题。项目围绕高强混凝土拌合物在泵送管道中的流动行为，开展了高强混凝土流变行为、泵送性能评价方法、润滑层形成机制、泵送阻力预测、泵送性能设计与调控等方面的研究，取得如下主要进展：（1）基于同轴圆筒流变测试仪，设计了光圆转子剪切模拟混凝土泵送过程的润滑层形成过程，建立了高强混凝土泵送性能实验室快速评价试验装置和测试方法；（2）基于嵌入式压力传感器以及多普勒超声流速仪，成功跟踪测试了混凝土泵送全过程的压力和速率，建立了高强混凝土泵送性能现场监测方法；（3）建立混凝土在管道中泵送阻力—泵送速率关系模型，准确预测了高强泵送阻力，并经泵送模拟试验验证；（4）表征了高强混凝土泵送过程中颗粒迁移机制和润滑层特性，明确了间隙液特性和水膜层厚度对高强混凝土粘度的影响机理，揭示了泵送压力作用下高强混凝土性能变化的根源，提出了降粘型减水剂和微纳米材料协同降阻技术，形成了配合比优化、气泡调控以及施工工艺参数优化等相结合的高强混凝土泵送性能调控成套技术。. 项目成果经现场模拟超高层泵送试验的验证，成功实现了C120混凝土1800米水平盘管（相当于垂直高度620米）的超远程泵送；成果还成功指导工程实践，应用于北京中国尊、南京金鹰天地、重庆俊豪国际商业金融中心、重庆来福士广场等超高层建筑的高强混凝土施工，解决了高强混凝土粘度大和超高程泵送阻力大的施工技术难题，有力推动了我国高强混凝土超高层泵送施工技术的进步。