Structural Performance of Recycled Concrete Aggregate with Steel Fibre Reinforcement
1Awolowo, O. E., and 2Dahunsi, B. I. O.
1Department of Civil Engineering, University of Ibadan, Ibadan, Nigeria.
2 Department of Civil Engineering, University of Ibadan, Ibadan, Nigeria
DOI: 10.36108/laujoces/6202.71.0172
Abstract
The increasing demand for sustainable construction materials has stimulated the utilization of recycled concrete aggregate (RCA) in concrete production; however, its application is often constrained by inferior mechanical properties compared to conventional granite-based concrete. This study investigates the structural performance of RCA concrete reinforced with varying steel fibre contents, considering fibre volume fractions of 0%, 0.25%, 0.5%, and 1.0%. Fresh and hardened properties were evaluated through slump, compressive strength, and flexural strength tests. Slump values were first determined to assess workability, followed by strength tests conducted at 7, 14, and 28 days. The results indicate that the control granite concrete mix (gc) exhibited a slump of 83 mm, while the fibre-free recycled aggregate mix (rc) recorded 80 mm. The inclusion of steel fibres resulted in a progressive reduction in workability, with slump values of 72, 60, and 50 mm for mixes r2, r3, and r4, respectively. Compressive strength ranged from 15.90–19.20 MPa at 7 days, 17.12–21.06 MPa at 14 days, and 20.33–26.54 MPa at 28 days, showing improvement with fibre addition. Similarly, flexural strength increased from 4.0–4.6 MPa, 4.7–5.9 MPa, and 5.1–6.4 MPa at 7, 14, and 28 days, respectively. The findings demonstrate that steel fibre reinforcement enhances the mechanical performance of RCA concrete, thereby improving its suitability for structural applications.
Keywords: Recycled Concrete Aggregate, Steel Fibres, Compressive Strength, Flexural Strength, Workability.