PSI - Issue 64

Rawan Ramadan et al. / Procedia Structural Integrity 64 (2024) 1927–1934 Author name / Structural Integrity Procedia 00 (2019) 000–000

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3.3. Expansion (EXP) Figure 5 shows the development of expansion in cement paste for a total period of 7 days. Similar to the trends observed in shrinkage parameters (DR-SH and AUTO-SH), the EXP trend diminishes with the incorporation of PA fibers as shown in Fig. 5. The addition of 2% PA fibers results in a reduction of approximately 16.35% compared to the control mix. This decline is attributed to the structural constraints imposed by PA fibers, which restrict expansion as curing time increases. The fiber structure hinders the hydration mechanisms within the matrix, thereby reducing its expansion (Zhang et al. 2020). Additionally, in elevated ambient temperatures, PA fibers may absorb this heat and prolong the hydration process over time, gradually releasing it into the matrix (Khatib et al. 2021; Ramadan et al. 2024).

Fig. 5. Exp of cement paste with different percentages of PA fibers at 45°C.

3.4. Correlations Figure 6 displays the correlation between shrinkage parameters (DR-SH and AUT-SH) as well as EXP for varying percentages of PA fibers (0%, 0.5%, 1%, and 2%). Across all these figures, a consistent trend is observed, suggesting a uniform fiber mechanism. As the percentage of PA fibers increases, the gap between both shrinkage parameters and expansion decreases. For example, in the control mix, the ratio between DR-SH and EXP is 0.6. This ratio decreases with the inclusion of 0.5%, 1%, and 2% PA fibers (0.56, 0.49, and 0.52, respectively). A similar trend is evident between AUT-SH and EXP, where the ratio for the control mix is 0.57, decreasing to 0.55, 0.47, and 0.54 for 0.5%, 1%, and 2% PA fibers, respectively. These findings indicate that PA fibers play a crucial role in reducing both expansion and shrinkages (Khatib et al. 2022; Ramadan et al. 2023a).