Multiple effects of nano-SiO2 and hybrid fibers on properties of high toughness fiber reinforced cementitious composites with high-volume fly ash |
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| Affiliation: | 1. Department of the Built Environment, Eindhoven University of Technology, Eindhoven, The Netherlands;2. ENCI HeidelbergCement Benelux, Rotterdam, The Netherlands;1. College of Civil Engineering, Tongji University, Shanghai 200092, China;2. School of Transportation, Southeast University, Nanjing 210096, China;1. School of Environment and Technology, University of Brighton, UK;2. Dept. of Civil Engineering, University of Babylon, Babylon, Iraq;3. School of Ocean and Earth Science, University of Southampton, UK;4. School of Engineering, Nazarbayev University, Astana, Kazakhstan;5. School of Pharmacy and Biomolecular Sciences, University of Brighton, UK;1. College of Civil Engineering at Tongji University, Shanghai 200092, China;2. School of Civil Engineering at Southeast University, Nanjing 210096, China;3. State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Research Institute of Building Science Co., Ltd., Nanjing 210008, China |
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| Abstract: | This article explores multiple effects of nano-SiO2 and hybrid fibers on the flowability, microstructure and flexural properties of high toughness fiber reinforced cementitious composites. Only a little negative influences of nano-SiO2 and hybrid fibers on the flowability are observed. SEM and MIP analysis reveal that nano-SiO2 results in much smaller pore size in the composites. However, the porosity increases gradually with nano-SiO2 addition. Three-point bending test results show that nano-SiO2 increases the flexural strength of the composites with nearly equivalent deformability, but higher strength of the matrix leads to wider cracks. Due to larger volume fraction and higher modulus, hybrid fibers effectively mitigate this adverse influence on crack width and further enhance the flexural strength. The composites reinforced with 1.4% steel fiber and 2.5% polyvinyl alcohol (PVA) fiber exhibit the best flexural properties in the test. Finally, a simplified model is proposed to illustrate the reinforced mechanism of steel-PVA fibers. |
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| Keywords: | Hybrid fibers Microstructure Flexural properties Crack width Pull-out curve |
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