Issue 67

B. O. Mawlood et alii, Frattura ed Integrità Strutturale, 67 (2024) 80-93; DOI: 10.3221/IGF-ESIS.67.06

surrounding concrete may have caused the decrease in concrete strength resulting from adding more disc to the mix. However, the average strength is higher than the minimum compressive strength (i.e., 17 MPa) specified in the ACI 318-19 code [1] for structural concrete. The results of the experiment revealed the disc waste could improve the tensile strength of concrete in the splitting tensile and flexural test results at a lower percentage of sand replacement. The increments were considerably less than those observed in compressive strength and complied with the results obtained by [37,38] . The average tensile strengths of the modified concrete determined by the splitting tensile strength test method improved by 12.5% and 3.1% when the percentage of disc content was increased from 0% to 4% and 8%, respectively, but reduced by 9.4% as the percentage of disc content was increased to 12%. The situation had the opposite influence on the specimens’ flexural strength; as the disc contents increased, the effect flipped. In other words, at 4% disc content, the flexural strength improved by 26.9%; at 8% disc content, it decreased by 4.4%; and at 12% disc content, it increased by 6.7%. However, the conclusions derived from the experimental data tests are not reasonable.

b d (mm)

d l (mm)

P (kN) U (MPa)

Mix No.

Specimen No.

Disc Content (%)

Failure Shape

D0-1 D0-2 D0-3 D0-4 D0-5 D0-6 D0-7 D0-8 D0-9

50

10.69 33.65 41.2 18.34 28.15 65.73 10.1 32.77 64.55 13.15 41.59 40.81 21.09 32.37 62.2 12.36 39.04 76.91 9.42 32.96 41.45 10.99 49.15 53.42 19.57 41.01 76.13 11.77 39.24 42.43 5.79 32.72 48.07 22.17 24.13 83.97

7.02 11.04 ----- 10.27 7.88 ----- 4.07 6.60 8.67 8.63 ----- ----- 11.81 9.06 ----- 4.98 7.87 10.33 6.18 10.82 ----- 6.15 13.76 ----- 7.89 8.26 10.22 7.72 12.88 ----- 3.24 9.16 8.97 8.93 4.86 11.28

Splitting-2 pieces Splitting-2 pieces Yield and Fracture Splitting-2 pieces Splitting-2 pieces Yield and Fracture Splitting-2 pieces Splitting-2 pieces Splitting-2 pieces Splitting-3 pieces Yield and Fracture Yield and Fracture Splitting-3 pieces Splitting-3 pieces Yield and Fracture Splitting-3 pieces Splitting-2 pieces Splitting-3 pieces Splitting-3 pieces Splitting-2 pieces Yield and Fracture Splitting-2 pieces Splitting-2 pieces Yield and Fracture Splitting-3 pieces Splitting-3 pieces Splitting-3 pieces Splitting-2 pieces Splitting-2 pieces Yield and Fracture Splitting-3 pieces Splitting-2 pieces Splitting-2 pieces Splitting-2 pieces Splitting-4 pieces Slip

10

100 150 100 150 100 150 100 150 100 150 100 150 100 150 100 150 100 150 100 150 100 150 100 150 50 50 50 50 50 50 50 50 50 50 50

M1

0

12

16

D4-10 D4-11 D4-12 D4-13 D4-14 D4-15 D4-16 D4-17 D4-18 D8-19 D8-20 D8-21 D8-22 D8-23 D8-24 D8-25 D8-26 D8-27 D12-28 D12-29 D12-30 D12-31 D12-32 D12-33 D12-34 D12-35 D12-36

10

12

M2

4

16

10

12

M3

8

16

10

12

M4

12

16

Table 4: Pull-out test results.

Bond Strengths The norm for the construction of a secure or reliable reinforced concrete structure is the strength of the bond developed between the constituent concrete particles and the steel bar through which it is extended. When exposed to an external

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