Effect of spatial distribution of polymer fibers on preventing spalling of UHPC at high temperatures
Polypropylene (PP) fibers are commonly used for the prevention of thermal spalling of ultra-high performance concrete (UHPC). In this work, the effect of fiber distribution on permeability and spalling resistance is investigated and an analytical model for permeability at 150 °C is proposed. This mo...
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| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/152258 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | Polypropylene (PP) fibers are commonly used for the prevention of thermal spalling of ultra-high performance concrete (UHPC). In this work, the effect of fiber distribution on permeability and spalling resistance is investigated and an analytical model for permeability at 150 °C is proposed. This model, considering the parameters like fiber dimensions, dosage, and percolation, is based on Kozeny-Carman equation. It was found that the percolation of the interconnecting fiber network resulted in a significant increase in permeability of UHPC. X-ray tomography data on the three-dimensional spatial distribution of fibers reiterated that fiber aspect ratio and dosage (and fiber number density) were critical in increasing the fiber connectivity (percolation). It was also found that a vapor permeability of larger than 0.6 × 10⁻¹⁶ m² at 150 °C could eliminate spalling. Further, based on a semi-empirical approach, aspect ratio between 300 and 600 was recommended for spalling prevention with a fiber dosage of 0.3–0.4 vol%. |
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