PSI - Issue 70

C. Raghu Rami Reddy et al. / Procedia Structural Integrity 70 (2025) 223–230

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Split tensile strength (MPa)

Flexural strength (MPa)

Compressive strength (MPa)

Fig 2. Mechanical strength development of candidate mixes (M1 – M4) at various curing ages.

5. Conclusions

This study evaluated the mechanical and microstructural performance of foamed concrete at a density target of 1200 kg/m³. contained 0.8% polypropylene (PP) fibers and 10% mineral admixtures (fly-ash, metakaolin, and silica fume). The following deductions are made in light of the experimental findings and SEM analysis: • The incorporation of mineral admixtures and PP fibers significantly improved the compressive, flexural, and split tensile strengths compared to the reference mix. • The silica fume-based mix (M4) exhibited the highest mechanical performance across all curing ages due to its ultrafine particle size, high pozzolanic reactivity, and formation of a dense, homogeneous C – S – H matrix with refined pores. • The metakaolin-based mix (M2) outperformed the fly ash-based mix (M3), showing higher strength and a more refined pore structure due to faster pozzolanic activity and improved matrix densification. • The fly ash mix (M3) recorded the lowest strength among the fiber-reinforced mixes, attributed to slower pozzolanic reactivity, larger particle size, weaker fiber-matrix bonding, and incomplete reaction leading to less homogeneous matrix formation. • Polypropylene fibers enhanced flexural and split tensile strengths in all modified mixes by bridging microcracks, with the highest effectiveness observed in M4 due to a well-developed interfacial transition zone. • SEM analysis confirmed superior matrix densification, fiber integration, and pore refinement in M4, followed by M2, whereas M3 exhibited improved workability but limited structural enhancement.