PSI - Issue 70

R. Karthikeyan et al. / Procedia Structural Integrity 70 (2025) 89–96

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by the steel fibres led to the observed increases in structural capacity, confirming the effectiveness of this composite approach in enhancing the performance of rubberized concrete beams

Fig.5 Response of Sand Coated rubber aggregate and Steel Fibre Reinforcement on Ultimate Load

Beam deflection is primarily influenced by factors such as the nature of loading, span length, the moment of inertia of the cross- section, and the Young’s modulus of the concrete. In the case of rubberized concrete beams, the incorporation of steel fibre leads to a noticeable increase in stiffness, which significantly affects their deflection behavior across the pre-cracking, cracking, and post-cracking stages. This enhancement in stiffness, brought about by micro-reinforcement, contributes to improved load distribution and crack control. Specifically, the test beams SR11 and SR12 exhibited an increase in deflection at ultimate load by 20% and 30%, respectively, when compared to SC. These results, as presented in Table 3 and illustrated in Fig. 6, clearly indicate that the combined use of sand-coated rubber coarse aggregates and steel fibre had a measurable and positive impact on the deflection characteristics of the beams at peak loading.

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Fig.6 Response of Sand Coated rubber aggregate and Steel Fibre on Deflection at Ultimate Load

Table 4. Test Results of Rubberized Concrete Beam (SR21&SR22) SI.No Identification of beams First crack (k N) Deflection at FCL (mm)

Yield Load (k N)

Def @YL

Ultimate Load (k N)

Deflection at Ultimate

1.

SR21

23.00

3.20

38.25

6.90

66.50

16.80

2. 18.60 Table 4 presents the ultimate load of the sand-coated rubberized concrete beams designated as SR21 and SR22. These beams demonstrated even more pronounced improvements in load-bearing performance compared to the control specimen SR11, SR12 and SC. Specifically, SR21, which contained a combination of 5% rubber content and 0.5% steel fibre, achieved a 10.83% increase in ultimate load, while SR22, with 5% rubber and 1.0% steel fibre, exhibited an even higher increase of 14.16%. The test results, as shown in Fig. 7. Moreover, the inclusion of steel fibres played a critical role in enhancing the tensile performance and post-cracking behaviour of the beams. The fibres effectively bridged micro cracks, delayed crack propagation, and distributed stresses more evenly throughout the structure. When SR22 25.00 3.26 41.00 7.45 68.50