PSI - Issue 47

Noorsuhada Md Nor et al. / Procedia Structural Integrity 47 (2023) 732–743 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The finite element analysis software uses numerical algorithms to solve the equations of the model, resulting in the stresses, strains and deformations of the interlocking concrete block. This information is used to evaluate the strength and stability of the block and can help identify weaknesses or potential failures. Finite element analysis was used to optimise the design of the interlocking block by varying the state of the block - solid and hollow - to achieve the desired performance. In this paper, finite element analysis was only used to investigate the cracking of the blocks when subjected to static loading to failure.

3. Results and discussion 3.1. Compressive strength of the cubes

Fig. 7 shows the average of the compressive strength of the cubes at 7, 14 and 28 days of age. It can be seen that the average compressive strength at 7, 14 and 28 days is 16.46 MPa, 24.79 MPa and 34.54 MPa respectively, indicating that the strength at 28 days is higher than the design strength of 30 MPa. Opara et al (2016) found that the concrete containing RCA had an effect on the concrete as the compressive strength of the specimens gradually increased as the curing day progressed. However, Kim (2021) found that a 50% replacement of recycled aggregate in the concrete resulted in a compressive strength of 29.3 MPa. However, Yang and Lee (2017) found that when 50% recycled aggregate was replaced with the same volume of mortar, the concrete had about 8% higher compressive strength than the conventional concrete with recycled aggregate. This shows that the present study gives a higher compressive strength compared to other researchers, but it depends on many factors such as water-cement ratio, mixing method and others.

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Compressive strength, MPa

7 days

14 days

28 days

Age of the cubes

Fig. 7. Compressive strength of the cubes

3.2. Flexural strength of the interlocking concrete blocks Table 1 shows the results of the flexural strength and ultimate load tests for solid and one-hollow interlocking concrete block. The analysis provides valuable insight into the performance and durability of the interlocking concrete blocks under bending load at 7, 14 and 28 days of age, as shown in Fig. 8 and Fig. 9. The flexural strength of the block was determined by subjecting it to a bending load and measuring the maximum load that the block can withstand before it fails. A high flexural strength ensures that the block maintains its shape and integrity when subjected to loads, which is essential for the safety and stability of the structure. Table 1 shows that the ultimate load and flexural strength of solid and one-hollow interlocking concrete blocks at 28 days are higher than other ages. The ultimate load was 14455.23 N and 6630.21 N for solid and one- hollow interlocking concrete blocks after 28 days. The flexural strength