PSI - Issue 70

C. Manoj Prabhu et al. / Procedia Structural Integrity 70 (2025) 207–214

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1510 Coulombs for 10M-25 and 1480 Coulombs for 12M-25. This decrease occurred due to RHA's enhancement of the pore morphology and the advancement of geopolymerization (Kim et al, 2014). The 12M mixtures exhibited lower RCPT values compared to the 10M mixtures, thus affirming that increased NaOH molarity enhances the density and durability of the concrete. Consequently, the incorporation of RHA and an increased molarity enhances chloride resistance, thereby augmenting the durability of GPC. Test findings the RCPT are illustrated in Fig.4.

Fig.4 Test values on RCPT

4.4. Sulphate Attack Test Sulphate resistance is critical for the durability of concrete in aggressive environments. Figure 4 depicts the variation in weight and strength loss due to the sulphate attack. At 30 days and 90 days, the control mix exhibited the greatest weight loss, with a maximum of 1.25% and 1.90%, respectively. The strength decrease was 6.5% at 30 days and 10.25% at 90 days. All geopolymer concrete sample demonstrated higher sulphate resistance than the control mix. Weight and strength loss decreased with an increase in the percentage of RHA. The mix with 25% RHA replacement lost the least weight, 0.98% at 30 days and 1.35% at 90 days. The reduction in strength loss was 2.85% after 30 days and 5.96% after 90 days. 12M mixtures exhibited reduced weight and strength loss compared to 10M mixtures. This enhancement occurred because RHA improved the geopolymer matrix, lowering porosity and increasing the concrete's resistance to sulphate attack. Fig 5 illustrates the strength and weight reduction of GPC specimens exposed to sulphate attack after 30 and 90 days. .

Fig.5. Strength and weight loss during sulphate attack