PSI - Issue 52

Cheolwoo Park et al. / Procedia Structural Integrity 52 (2024) 480–486 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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sheet is a recently introduced material for fiber-reinforced polymers and structural composites. In contrast to carbon fiber, it boasts a broader range of operating temperatures, withstanding temperatures as low as -452 °F and as high as 1200 °F. It also possesses high strength and durability, making it suitable for use in demanding applications. Additionally, it has excellent resistance to high temperatures and corrosive environments, while remaining lightweight in comparison to other materials. 2.2. Fabrication of the specimens To obtain the filling performance of the prepared slurry, the water binder ratio was fixed to 0.35. First steel fibers were filled in mold (100 mm x 100 mm x 300 mm) with steel volume fraction of 5%. Steel fibers were randomly sprinkled in the mold should not overfill the mold's depth and levelled up as much as possible. Slurry, as prepared after mixing the materials, was poured until no more bubbles were seen to ensure infiltration of the slurry into the fibers because the void has a negative effect on the strength of the concrete. The amount of polymer powder added during slurry mixing was 0%, 0.5%, 1.0%, and 1.5%. The silica fume was added at 15% of the cement weight. The fiber volume fraction variables were set to 5%. The cement and aggregate ratio was 1:0.5, and percent of Shrinkage Reducing Agent (SRA) was 0.05% of the binder. Mix proportion ratio of the mixture for this study is shown can be found in reference Kim et al. (2020). Figure shows the order of mixing process of materials and preparation of the specimens. First the slurry was prepared as shown is figure and then it was poured to the prepared mold. The specimens were kept in a laboratory for 28 days under a laboratory temperature of 23°C and specimens were taken out than wrapped with a single layer of basalt fabric sheet.

Figure 1. (a) Mixing of cement; (b) Silica Fume; (c) Adding powder polymer; (d) Adding water; (e) Adding cement; (f) pouring slurry in the prepared model with steel fiber.

2.3. Experimental method Specimens having a dimension of 100 mm x 100 mm x 300 mm were prepared. After curing for 28 days, specimens were externally wrapped with a basalt sheet. Single-layer basalt sheet wrapped externally on the specimens. All side of the specimens were covered by fire resistance fiber cerawool expect top face of the specimens as shown in figure 2 in furnace. The specimens were heated for one hour in a high temperature (about 945 °C) furnace according to the KS F 2257 (ISO 834) standardized material temperature curve shown in figure 3. The ISO 834 curve is a standard fire test that is used to evaluate the fire resistance of materials. The average temperature inside the high-temperature furnace was maintain according to equation 1. T = 345 log 10 (8t + 1) + 20 (1) Here, T is the average temperature on degree Celsius inside the furnace and t represent time in minutes.