Assessing Structural Capacity and Performance of Two – Way Concrete Slabs Reinforced with Reused GFRP Bars for Sustainable Construction

The mechanical properties of reused Glass Fibre Reinforced Polymer (GFRP) bars retrieved from previously collapsed slabs were first measured before they were used to reinforce two-way concrete slabs. A total of six two-way reinforced concrete slabs measuring 100 mm x 1200 mm x 1200 mm were cast. Three were reinforced with 8mm diameter reused GFRP bars, and the other three were reinforced with 12 mm reused GFRP bars. The mechanical test results revealed that the re-used bars exhibited a complete linear stress-strain relationship without yielding, but with reduced elongation and failure strain that were identical to the original GFRP bars. The Young’s modulus of elasticity was 50.02 N/mm2 and 41.34 N/mm2 for the 8mm and 12mm, respectively. Similarly, the ultimate tensile strength of the 8mm and 12mm reused bars averaged approximately 1079N/mm2 and 800N/mm2, respectively, which confirms the dependence of mechanical properties on bar size as observed in previous studies and in consonance with ACI 440.IR-15 code. Reused GFRP reinforced concrete slabs were tested under monotonic loading. The load-carrying capacity of these slabs maintained approximately similar load levels of 82kN for the 8mm and 76.67kN for the 12mm as the concrete slabs reinforced with the virgin GFRP bars for similar concrete grades. Overall, the experimental results indicate that using reused GFRP bars as reinforcement for two-way concrete slabs, sourced from demolished structures, is feasible and reliable, as they achieved nearly similar outcomes. Furthermore, there was good agreement between the experimental results and the theoretically predicted model.