PSI - Issue 70

Ragupathi V. et al. / Procedia Structural Integrity 70 (2025) 548–555

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4.3 Durability Studies The water absorption (WB) test evaluates the permeability and absorbency of concrete, which directly affects its durability. The use of bagasse ash, foundry sand, and steel fibres significantly reduces water absorption in concrete as depicted in Figure 5. The control concrete (CC) had the highest water absorption at 3.25%, while the optimal mix BWFRC3 had the lowest absorption at 2.64%, indicating an 18.77% reduction relative to CC. This improvement is attributed to the compact microstructure generated by the pozzolanic action of bagasse ash and the filler effect of foundry sand.

Fig. 5. Water absorption test results

The test outcomes for the sulphate attack after the specified interval are presented in Table 4. The deterioration in weight and strength resulting from sulphate attack intensified over time for all concrete mixtures. The mix CC exhibited the most significant deterioration, with a weight loss of 2.76% and a strength reduction of 11.4% at 90 days, signifying a diminished resistance to sulphate attack. The incorporation of bagasse ash and foundry sand (BF mix) marginally enhanced resistance, diminishing weight and strength degradation relative to CC. The optimal performance was recorded in BWFRC3 (1.0% steel fibre), demonstrating the minimal weight loss (1.62%) and strength reduction (7.8%) at 90 days. This enhancement results from the densification of the concrete matrix and the crack-bridging effect of steel fibres, which mitigated sulphate-induced deterioration. The findings indicate that fibre-reinforced concrete (BWFRC mixes) markedly improved durability characteristics, rendering it a more appropriate material for sulphate-exposed environments. Table.4. Summary of test outcomes from the sulphate attack assessment Mix ID Mass loss (%) Loss in strength (%) 28 th (day) 56 th (day) 90 th (day) 28 th (day) 56 th (day) 90 th (day) CC 0.92 1.85 2.76 3.5 7.2 11.4 BF 0.78 1.60 2.35 3.0 6.5 10.1 BWFRC1 0.65 1.42 2.10 2.8 6.1 9.5 BWFRC2 0.53 1.25 1.85 2.5 5.6 8.9 BWFRC3 0.40 1.10 1.62 2.1 4.8 7.8 BWFRC4 0.48 1.18 1.75 2.3 5.2 8.3 5.Conclusion This study explores the partial substitute of cement with bagasse ash and river sand with waste foundry sand in M25 concrete, along with the incorporation of steel fibres to enhance mechanical and durability characteristics. The