Influence of different curing regimes on the microstructure and macro performance of UHPFRCC

This study investigates the influence of different curing regimes on the microstructure and macro properties of ultra-high performance fiber reinforced cementitious composite （UHPFRCC）, and aims to discover whether it is possible to produce qualified UHPFRCC using different curing regimes. A control mix of UHPFRCC is prepared. The mechanical performance and the short-term durability of the UHPFRCC matrix under three curing regimes are studied. In addition, the microstructures of the UHPFRCC matrix with different curing conditions are analyzed by combining scanning electron microscopy （SEM） and mercury intrusion porosimetry （MIP）. The results explore how different UHPFRCC curing regimes affect its microstructure and how the microstructure affects its macro behavior. Heat and steam curing for 3 d is succeeded to produce the UHPFRCC with nearly the same mechanical properties and durability as those of the 90 d standard curing. However, the heat cured UHPFRCC does not show great resistance to chloride-ion penetration.

超高性能纤维增强水泥基复合材料的抗冲磨性能研究

水工泄洪建筑物的冲磨破坏现象较为普遍,给国家带来巨大的经济损失,而当前的技术手段并不能有效解决问题,迫切需要新材料和新技术的产生和应用.本文主要采用圆环法和水下钢球法研究了超高性能纤维增强水泥基复合材料(UHPFRCC)的抗冲磨性能.结果表明:UHPFRCC可实现高流动度(扩展度可达690 mm)、超高强度(28 d抗压强度可达190 MPa)、超高抗冲磨强度(28 d抗冲磨强度可达C50混凝土的5.5倍).

纤维混杂对超高性能纤维增强水泥基复合材料力学性能的影响

采用最紧密堆积理论对UHPFRC进行配合比设计,并通过应用Excel Solver Tool进行编程求解,实现了UHPFRCC符合体系的理论设计,利用石灰石粉改善流动性的作用得到最终配合比。基于基准配合比,研究了钢纤维与合成纤维混杂对UHPFRCC的力学性能的影响。试验结果表明:基于Dinger-Funk模型可实现自密实UHPFRCC的配合比设计;混杂纤维可增强UHPFRCC的抗压强度,但抗折强度有所降低;相比于单掺2%钢纤维的UHPFRCC,合成纤维的取代掺入均降低了UHPFRCC的抗压强度和抗折强度。

超高性能纤维增强水泥基复合材料单根钢纤维拔出行为研究

基于Funk-Dinger模型求解计算,实现超高性能纤维增强水泥基复合材料(UHPFRCC)基体配合比的确定,并在此基础上分别研究了纤维埋入深度、基体中纤维掺量以及纤维埋入角度对单根钢纤维在UHPFRCC中拔出行为的影响。试验结果表明,纤维埋入深度、基体性能和纤维埋入角度均对UHPFRCC中单根钢纤维拔出行为影响显著,粘结强度和拔出功均随着埋入深度和基体强度的增加而大幅度提高。