PSI - Issue 70

Muhibur Rahman S. et al. / Procedia Structural Integrity 70 (2025) 627–634

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Fig.3. Split tensile strength of various mixes

4.3 Flexural Strength (fflex) of CC with CCA and BACA

The f flex of the concrete mixes, both with CCA and BACA, was evaluated at different curing intervals, as shown in Table 5. In the M 20 grade concrete, the f flex increased from 3.25 MPa to 4.49 MPa between 7 and 28 days, as depicted in Fig.4. The concrete mix with BACA (M 20 BACA) showed a slightly higher strength progression, rising from 3.36 MPa to 4.53 MPa between 7 and 28 days, resulting in a percentage increase of 35.0%. This reflects a marginally greater enhancement in flexural strength (ff lex ) for the BACA mix compared to the CCA mix. For M 25 grade concrete, the f flex improved from 3.61 MPa at 7 days to 4.86 MPa at 28 days, indicating a 34.7% increase. Similarly, the M 25 concrete incorporating BACA (M 25 BACA) showed a rise in f flex from 3.66 MPa to 4.94 MPa over the same period, representing a 34.9% increase. These findings indicate that both M 20 and M 25 concrete mixes with BACA experienced comparable gains in flexural strength over time. Overall, the BACA mixes consistently achieved superior flexural performance, with M20 and M25 grades showing slightly improved results compared to their CCA-based equivalents.

Table 5. f c , f sts and f flex results of CC with CCA and BACA f c (MPa)

f sts (MPa)

f flex (MPa)

7 Days

14 Days

21 Days

28 Days

14 Days

21 Days

28 Days 3.15

14 Days 3.59

21 Days 4.15

28 Days 4.49

7 Days

7 Days

M 20

14.73 20.52 21.20 22.76 2.74

2.86 3.05

3.25

M 20 (BACA)

14.80 20.69 21.59 23.11 2.85

2.96 3.14

3.37

3.36

3.67

4.19

4.53

19.21 25.80 26.73 30.3

2.96

3.13 3.39

3.55

3.61

3.98

4.34

4.86

M 25

M 25 (BACA)

19.36 26.52 27.14 31.8

3.04

3.20 3.46

3.68

3.66

4.05

4.39

4.94

5. Conclusion 1. The study concludes that the physical properties of BACA differed significantly from CCA. The specific gravity of BACA ranged from 2.11 to 2.15, reflecting a 20.44% reduction compared to 2.76 for CCA. BACA exhibited higher water absorption, ranging from 8.41% to 8.77%, marking an increase of approximately 1025% compared to the 0.78% of CCA. Additionally, the bulk density of BACA, between 1027 kg/m³ and 1039 kg/m³, was 33.04% lower than the 1551 kg/m³ recorded for CCA. 2. Mechanical properties also highlighted notable differences. The impact value of BACA ranged from 11.35 to 20.54, representing a reduction of up to 41% compared to CCA. The crushing value of BACA varied between 27.06 and 38.32, an increase of up to 129% relative to 16.70 for CCA. Furthermore, the abrasion