PSI - Issue 70

Shashikant Kumar et al. / Procedia Structural Integrity 70 (2025) 501–508

506

HVFA-SCC mixes prepared using ternary cementing blends of OPC, FA and SF, a more consistently dispersed viscous flow was obtained, and the results of flowability test were more consistent. These results will have due to different particle geometries of FA and SF. Fig. 3 shows excellent correlation between T-500 and V-funnel test results along with T-500 and L-box test results. 3.2. Hardened properties After 14 days, 28 days, and 56 days of fresh water curing, the compressive strength was assessed, and the split tensile strength was ascertained after 28 days. The findings of compressive and split tensile strength are displayed in Fig. 4. After a period of 56 days curing in fresh water, the maximum compressive strengths were obtained at an 8% replacement level of SF in all the HVFA-SCC mixes.

14 days 56 days

28 days

Split tensile strength

0 1 2 3 4 5 6

80

60

40

20

0

1 2 3 4 5 6 7 8 9 10111213141516 HVFA-SCC mixes

Compressive strength (MPa)

Split tensile strength (MPa)

Fig. 4. Compressive and split tensile strength of HVFA-SCC mixes Fig. 5. XRD trace of HVFA-SCC at 28 and 90 days As compared to control concrete, all of the FA incorporated concretes showed weaker strength properties at 28 days; nonetheless, they still achieved strengths between 45 and 55 MPa which is less than desired strength of 60 MPa. Even after 28 days of water curing period of HVFA-SCC, the addition of SF allowed for the higher strength of ternary HVFA-SCC mixtures. When compared to other binary mixes, the split tensile strength of HVFA-SCC including ternary blend HVFA-SCC with OPC, FA and SF was achieved to be higher. Using SEM and XRD examination, the microstructural characteristics of concrete mixes were assessed. Tests were also conducted in order to corroborate the findings of mechanical qualities and modifications brought about by the substitution of HVFA for cement in addition to SF. 3.3.1 X-ray differection (XRD) The XRD patterns of HVFA-SCC mixes containing FA replacement level of 40%, at 28 and 90 days were presented in Fig. 5. An assessment of the 28-day and 90-day XRD traces shows a noticeable reduction in the intensity of mullite and quartz peaks at 90 days. Quantitative analysis of the XRD data in Fig. 5 indicates that the mullite content reduced from 4.98% to 2.28%, while quartz content reduced from 11.44% to 6.32%. Furthermore, Fig. 5 highlights the development of calcium hydroxide (CH) and ettringite (E) peaks adjoining 30º. The dominant peaks identified in the XRD analysis of the HVFA-SCC with silica fume (SF) ternary system (Fig. 1) were those corresponding to calcium hydroxide (Ca(OH)₂), denoted as CH. All HVFA -SCC mixes exhibited CH peaks, confirming the occurrence of hydration reactions in each mix. The XRD patterns presented in Fig. 1 clearly demonstrate that the intensity of the CH peaks is lower in HVFA-SCC mixes containing SF compared to those without SF. 3.3. Microstructural properties