PSI - Issue 70

V. Preethi et al. / Procedia Structural Integrity 70 (2025) 271–278

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strength as cement content increases and have a less impact on aspect ratio of GF. This clearly indicates that the incorporation of GF improves concrete strength, but primarily depends on the cement content. 3.5. Effect of Cement content and Aspect ratio of GF on Flexural strength of concrete The Fig 6, illustrate the relationship between cement content, aspect ratio of fibers, and the flexural strength of concrete. The Fig 6 suggests that flexural strength increases significantly with higher cement content, particularly when the fiber aspect ratio is low to moderate. The maximum flexural strength of approximately 9.68 MPa is observed for the mix with higher cement content (600 kg/m³) and lower aspect ratios of fibers (800).

Fig. 6. Prediction results of Flexural Strength w.r.t. Cement content and Aspect ratio This indicates a synergistic interaction where the dense cement matrix enhances the bond with fibers, particularly when the fibers are shorter and less prone to alignment or entanglement issues. This trend is more noticeable in the 3D contour plot shown in figure 6, where the strength contours flatten and even drop at aspect ratios above 1960, despite increasing cement content. This might be due to dispersion challenges and fiber clustering, which hinder uniform stress transfer and may create weak zones within the composite.

3.6. Effect of Cement content and Aspect ratio of GF on Split tensile strength of concrete

Fig. 7. Prediction results of Split tensile strength w.r.t. Cement content and Aspect ratio The results reveal a positive correlation between the cement content and the split tensile strength, with strength values increasing notably as cement content increases from 318 kg/m³ to 600 kg/m³ as seen from Fig 7. This trend is primarily attributed to the enhanced matrix density and cohesive bonding due to higher cementitious material availability. Conversely, the aspect ratio of fibers shows a nonlinear influence. At lower aspect ratios (800 to 1380), the increase in tensile strength is more pronounced. This can be attributed to improved fiber distribution and more effective crack-bridging capacity. However, as the aspect ratio increases beyond 1670, the rate of strength gain becomes very low, and in some regions, a slight reduction is observed. This decline may be due to challenges in