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Advances in Nano Research Volume 15, Number 5, November 2023 , pages 467-484 DOI: https://doi.org/10.12989/anr.2023.15.5.467 |
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Multiple effects of nano-silica on the pseudo-strain-hardening behavior of fiber-reinforced cementitious composites |
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Hossein Karimpour and Moosa Mazloom
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| Abstract | ||
| Despite the significant features of fiber-reinforced cementitious composites (FRCCs), including better mechanical, fractural, and durability performance, their high content of cement has restricted their use in the construction industry. Although ground granulated blast furnace slag (GGBFS) is considered the main supplementary cementitious material, its slow pozzolanic reaction stands against its application. The addition of nano-sized mineral modifiers, including nano-silica (NS), is an alternative to address the drawbacks of using GGBFS. The main object of this empirical and numerical research is to examine the effect of NS on the strain-hardening behavior of cementitious composites; ten mixes were designed, and five levels of NS were considered. This study proposes a new method, using a four-point bending test to assess the use of nano-silica (NS) on the flexural behavior, first cracking strength, fracture energy, and micromechanical parameters including interfacial friction bond strength and maximum bridging stress. Digital image correlation (DIC) was used for monitoring the initiation and propagation of the cracks. In addition, to attain a deep comprehension of fiber/matrix interaction, scanning electron microscope (SEM) analysis was used. It was discovered that using nano-silica (NS) in cementitious materials results in an enhancement in the matrix toughness, which prevents multiple cracking and, therefore, strain-hardening. In addition, adding NS enhanced the interfacial transition zone between matrix and fiber, leading to a higher interfacial friction bond strength, which helps multiple cracking in the composite due to the hydrophobic nature of polypropylene (PP) fibers. The findings of this research provide insight into finding the optimum percent of NS in which both ductility and high tensile strength of the composites would be satisfied. As a concluding remark, a new criterion is proposed, showing that the optimum value of nano-silica is 2%. The findings and proposed method of this study can facilitate the design and utilization of green cementitious composites in structures. | ||
| Key Words | ||
| cementitious composites; digital image correlation (DIC); fracture behavior; greenness; ground granulated blast furnace slag (GGBFS); micromechanics; nano-silica; strain hardening | ||
| Address | ||
| Hossein Karimpour and Moosa Mazloom:Department of Structural and Earthquake Engineering, Faculty of Civil Engineering, Shahid Rajaee Teacher Training University, I. R. Iran | ||