Study on reinforcement mechanism and microscopic morphology of steel-basalt mixed fiber HPCC

• Published in: Construction & building materials 2020-09, Vol.256, p.119480, Article 119480
• Main Authors: Xu, Junpeng, Wang, Jing, Zheng, Chuanfeng
• Format: Article
• Language: English
• Subjects: Bridge and tunnel engineering; Grey correlation; Macroscopic mechanical properties; Microscopic analysis; Mixed fiber HPCC; Reinforced mechanism
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2020.119480

•Steel-basalt mixed fiber has higher tensile strength than steel fiber alone.•Steel fiber affects material strength by changing the microstructure of the matrix.•Basalt fiber affects material strength by its own strength and interfacial adhesion. To further improve the working performance of steel fiber cement-based composites, reduce the construction difficulty and explore the mechanism of mixed fibers in cement-based composites. Based on the single blending of steel fiber, the substitution rates of seven different basalt fibers are studied by the equal volume replacement method. And the microstructures of mixed fiber cement-based composites are studied by the method of environmental scanning electron microscopy (ESEM) and by using Image-Pro Plus (IPP). Results show that when the fiber replacement rate reaches 20%, the positive hybrid effect of the two fibers are the best for the cement-based composites. The splitting tensile strength of the mixed fiber cement-based composites also reaches the maximum value of 20.07 MPa, which is 110% of the corresponding strength of the single-doped steel fiber, and the working performance is also greatly improved. In microscopic view, a reasonable mixing of fibers can effectively improve the internal structure of the matrix and enable the pores to be smaller and more uniform than before. At the same time, the fiber-reinforced crack resistance effect can greatly improve the deformation resistance of the matrix, so that the matrix can still maintain a good integrity in the final destruction. The main factors affecting the macroscopic mechanical properties of the mixed fiber cement-based composite are found by grey correlation, which essentially reveals the influence of the changes in fiber content on the macro-performance of the matrix. The results provide a foundation for the research and application of mixed fiber cement-based composites.