PSI - Issue 70

Suresh Kumar Verma et al. / Procedia Structural Integrity 70 (2025) 327–334

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Table 3. Compressive Strength (MPa)

Mix ID

3 Days

7 Days

28 Days

C (Control)

22 24

32.5

43 52

NS1 NS3 NS5 NA1 NA3 NA5

35

26.5

39.5 37.5 34.5

56.5 53.5 47.5 49.5

25 26 29

37 36

27.5

47 45

NCC1 NCC3 NCC5

23 25

33.5

36 35

46.5

24.5

45

The study confirms that nano-silica (NS), nano-alumina (NA), and nano-calcium carbonate (NCC) significantly influence the compressive strength of cementitious composites. Among them, NS3 exhibited the highest 28-day strength, highlighting its superior pozzolanic reactivity and microstructural refinement capability. NA3 demonstrated the best early-age strength due to its strong nucleation effect and hydration acceleration. NCC3 provided moderate improvements through its filler effect and enhancement of matrix density. Across all nanomaterials, 3% replacement emerged as the optimal level for maximizing performance. Higher dosages (5%) led to agglomeration and reduced strength. NS was most effective for long-term strength gain, while NA was beneficial for early-age applications. NCC served as a functional filler with added benefits for workability. 3.3. Water Absorption Water Absorption (% by mass) is a critical durability parameter that reflects the material's porosity and its ability to resist moisture ingress. Reduced water absorption generally indicates a denser microstructure, which translates to higher durability and resistance against aggressive environmental agents like chlorides, sulfates, and carbon dioxide. The results are shown in Table 4.

Table 4. Water Absorption Results

Mix ID

Water Absorption (%)

C

5.2 3.4 3.9 4.2

NS3 NA3

NCC3

The control mix (C) had the highest water absorption at 5.2%, indicating higher porosity and poor resistance to moisture ingress. NS3 achieved the lowest absorption (3.4%), showing a 35% improvement due to its pozzolanic activity and effective microstructural densification. NA3 recorded 3.9% absorption, with nano-alumina enhancing early hydration and reducing permeability through its nucleation effect. NCC3 showed moderate improvement with 4.2% absorption, acting mainly as a filler to refine pore structure. All nano-modified mixes significantly reduced water absorption compared to the control. Among them, NS3 was the most effective, followed by NA3 and NCC3. The enhanced performance is attributed to better packing, reduced porosity, and improved hydration mechanisms. NS contributed both chemically and physically, while NA mainly accelerated early hydration. NCC, although less reactive, provided a physical barrier through improved matrix density. These outcomes confirm the role of nanoparticles in improving durability against moisture ingress.