PSI - Issue 42

Jamal A. Abdalla et al. / Procedia Structural Integrity 42 (2022) 1231–1238 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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is attributed to the slight difference in the compressive strength of concrete between the two mixes. In general, both sets of beams were closely predicted by the ACI provisions. Hence, it can be concluded that the shear design provisions of the ACI 318-19 (2019) and ACI440.2R-17 (2017) could be safely implemented to predict the capacity of NAC and RAC beams.

Table 4. Analytical predictions

Specimen

V n(exp) (kN)

V n(pred) (kN)

V n(exp) / V n(pred)

NC RC NU RU

30.0 27.2 40.8 43.4

24.9 24.5 57.9 57.0

1.20 1.11 0.70 0.76

4. Conclusions In this study, an experimental research was performed to investigate shear strengthening of normal aggregate concrete beams and recycled aggregate concrete beams using CFRP U-wraps. Four-point bending tests were performed on the RC beam specimens and the following conclusions were drawn: • The unstrengthened specimens failed by the critical shear crack, while the CFRP U-wrapped specimens failed by debonding of the CFRP laminates. • Strengthening NAC and RAC beams with CFRP U-wraps significantly enhanced the shear capacity by 36 and 60%, respectively. • The recycled aggregate beams provided similar shear capacity to that with normal aggregate beams, with maximum percentage difference of 5%. • The use of recycled concrete aims at reducing the carbon footprint and hence contributes to a positive impact on the environment without compromising the beam’s shear strength. • Design provisions of the ACI318-19 could be effectively used to predict the shear capacity of NAC and RAC beams. Acknowledgements The support for the research presented in this paper had been provided, partially, by Riad Sadek Endowed Chair in Civil Engineering at the American University of Sharjah. Additionally, the authors would like to acknowledge MAPEI for providing the carbon fibers and epoxy. Additionally, the authors acknowledge Chemcrete for casting the beams and Emirates Recycling LLC for providing and testing the recycled aggregates. The support is highly appreciated. The views and conclusions expressed or implied, in this study, are those of the authors and should not be interpreted as those of the donors or the institution. References Abdalla, J. A., Mohammed, A., and Hawileh, R. A. 2020. Flexural Strengthening of Reinforced Conference Concrete on Fracture Beams with Externally Bonded Hybrid Systems Flexural Strengthening of Reinforced Concrete Beams with Externally Bonded. Procedia Structural Integrity, 28(2019), 2312 – 2319. Abdalla, J. A., Thomas, B. S., Hawileh, R. A., Yang, J., Jindal, B. B., and Ariyachandra, E. 2022. Influence of nano-TiO2, nano-Fe2O3, nanoclay and nano-CaCO3 on the properties of cement/geopolymer concrete. Cleaner Materials, 4, 100061. Abhilash, P. P., Kumar, D., Sangoju, B., and Kumar, R. 2021. Effect of nano- silica in concrete ; a review. Construction and Building Materials, 278, 122347. Abuodeh, O. R., Abdalla, J. A., and Hawileh, R. A. 2020. Prediction of shear strength and behavior of RC beams strengthened with externally bonded FRP sheets using machine learning techniques. Composite Structures, 234, 111698. ACI 318-19. 2019. Building Code Requirements for Structural Concrete. Farmington Hills, Michigan: American Concrete Institute . ACI440.2R-17. 2017. Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures. American Concrete Institute, Farmington Hills, U.S.A.