PSI - Issue 64

Shehroze Ali et al. / Procedia Structural Integrity 64 (2024) 1394–1401 Shehroze Ali et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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controlled system with a loading rate of 2 kN/s. Figure 2 shows the testing arrangements for slump, compressive strength and flexural strength tests of SFGC and GF-SFGC mixes.

Fig. 2. Testing: (a) slump test; (b) compressive strength test; and (c) flexural strength test.

3. Results and Discussion 3.1. Workability and Density

The slump values of the fresh mixes of SFGC and GF-SFGC are presented in Table 3. All the mixes were glossy and adhesive due to the presence of sodium silicate. The measured slump values for SFGC and GF-SFGC mixes were 115 mm and 88 mm, respectively. It was observed that the addition of glass fibre in the plain mix decreased the workability by approximately 23%. Similar observation was reported in Zuaiter et al. (2023). Although, an additional 25% of superplasticizer was added in GF-SFGC mix but the presence of high alkaline environment reduced the overall effectiveness of superplasticizer. Therefore, the decrease in the fluidity caused reduction in the overall efficiency of pouring and compaction in GF-SFGC mix. The average densities of SFGC and GF-SFGC mixes were 2,355 kg/m 3 and 2,350 kg/m 3 , respectively. The average densities of SFGC and GF-SFGC mix are also presented in Table 3. The test results highlighted that the addition of glass fibre in the mix slightly decreased the density of the GF-SFGC mix.

Table 3. Slump and density of SFGC and GF-SFGC mixes.

Average density (kg/m 3 )

Mix

Slump (mm)

SFGC

115

2355 2350

GF-SFGC

88

3.2. Compressive strength The average compressive strengths of plain SFGC and GF-SFGC mixes determined at 7, 28 and 56 days are presented in Table 4. Figure 3a shows the development of compressive strength with age in various mixes. It was observed that the average compressive strength of SFGC and GF-SFGC mixes increased by 54-58% at 28 days as of 7 days. This increase was due to the pozzolanic nature of the slag and fly ash used in the mixes (John et al. 2021). On the other hand, the increase in later age compressive strengths of SFGC and GF-SFGC mixes determined at 56 days was only 8-10% higher compared to their respective 28-day compressive strengths. The addition of glass fibre in the mix, caused a slight reduction in the compressive strength of slag/fly ash geopolymer concrete as shown in Figure 3a. The average compressive strength of GF-SFGC mixes was approximately 2-4% less compared to the plain SFGC mix at 7, 28 and 56 days. This could be attributed to the