国家自然科学基金 (51968035)；云南省教育厅科学研究基金 (2019J0043)；云南省重点研发计划项目(202003AC100001)；云南省交通厅科技基金 (2017A-04)；昆明理工大学分析测试基金(2018M20182210048).
1.Faculty of Civil Engineering and Mechanics,Kunming University of Science and Technology,Kunming;2.Yunnan Green High Performance Concrete Co,Ltd,Kunming
Engineering cementitious composites (ECC) have excellent toughness and crack control ability, which can be used in underground and hydraulic engineering solving the problems of concrete cracking and leakage. ECC with high water-cement ratio (1.03) has excellent fluidity, but its impermeability is poor. Meanwhile, the high-water cement ratio also induces large slump and poor cohesiveness, leading poor sprayable abilities. In order to solve the above problems, Silica fume (SF) was then introduced into ECC (1.03) with different SF/cement mass ratios to improve its workability, impermeability, microstructure, and mechanical behaviour. The results indicate that when SF/cement ratio was 15%, the workability of ECC (1.03) was greatly improved, which could be pumped and sprayed. At the same time, the impermeability of ECC (1.03) is improved to above P8; The SEM and energy dispersive spectrometer (EDS) observations confirmed that adding SF made ECC microstructures denser, but also could reduce the alkaline substances to inhibit alkali-aggregate reaction and improve durability. In the scope of this research, a comprehensive research on toughness, impermeability and pumpable and sprayable performance at the same time was carried out for ECC, and finally ECC with good toughness, impermeability and workability was obtained, which can be used for promotion and application in practical engineering.