PSI - Issue 52

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

484

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3. Results and discussion 3.1. Flexural strength and toughness

This study compares the flexural strength and toughness of SIFRCCs with externally wrapped BFRP single sheet with before and after exposure to high temperature as in equation 1 for 1 hr. Mechanical properties of the SIFRCCs with the same materials properties and mixing ratio had been analysis by author Kim et al. (2020a). Table 1 shows the flexural strength from the previous study. Adding 0.5 % of polymer can reduce the failure of the SIFRCCs structure after exposed to high temperature (about 945 0 C) because water inside the element will evaporate and a part of it will flow out of the SIFRCCs. Structure can lose more strength if the internal vapor pressure cannot be release form the pore created with melting of polymer when exposed to high temperature.

Table 1. Mechanical properties of SIFRCCs, before and after exposure with high temperature (Kim et al. 2020)

Compressive strength (MPa)

Flexural strength (MPa)

Toughness (N · m)

Polymer percentage

Before exposure to high temperature

After exposure to high temperature

Before exposure to high temperature

After exposure to high temperature

Before exposure to high temperature

After exposure to high temperature

0.0 % 0.5 % 1.0 % 1.5 %

51.5 51.6 57.4 54.3

33.9 37.2 25.9 22.5

52.8 47.0 53.8 49.1

28.3 27.7 26.3 21.8

1,509 1,443 1,553 1,295

709 785 697 645

Figure 5 shows the flexural strength of variables, before and after exposure to high temperature with single layer wrapped of basalt fiber sheet. After exposure to high temperature the flexural strength of specimens with the basalt fiber sheet decreased. The average flexural strength of the different polymer percentage of specimens ranges between 37.3 MPa to 46.3 MPa before exposure to the high temperature whereas the 29.5 MPa to 32.1 MPa after exposure to high temperature with single layer of basalt sheet. At 0.5 %, 1.0 % and 1.5% of polymer, the flexural strength decrease percentage was found to be 36.28 %, 31.74 % and 13.94 % respectively with single layer of basalt fabric sheet. Adding up to 1.5 % of polymer can minimize to decrease the bending strength of structure after exposure to high temperature. From table 1 the decrease percentage of the flexure strength after exposure to temperature for 0.5 %, 1.0 % and 1.5 % was 42.34 %, 51.11 % and 55.60 % respectively. Use of basalt fiber fabric sheet and polymer can reduce the failure of structure. Moreover, the spalling on structure had been improved with use of polymer.

Figure 5. (a) Flexural strength of variables before and after exposure with high temperature.