Performance enhancement of recycled coarse aggregate concrete by incorporating with macro fibers processed from waste GFRP

Reprocessing into coarse aggregates of concrete is a sustainable solution for the disposal of construction and demolition (C&D) waste. The use of recycled coarse aggregates however leads to a degradation in the mechanical properties of the resulting concrete, which then limits the use of recycled aggregates concrete (RAC) in structural elements. The incorporation of discrete fibers shows to be effective in eliminating the mechanical degradation problem of RAC, and this paper has therefore proposed to use macro fibers recycled from waste glass fiber reinforced polymer (GFRP) to reinforce RAC, thus improving the robustness of using RAC in structural elements. The effect of incorporating macro fibers on the mechanical properties of RAC has been first examined through a series of compression and bending tests. The tensile constitutive law of concrete was then derived based on the load-deflection response of the beam specimens using an inverse analysis. The results revealed that the mechanical properties (e.g., compressive toughness, flexural strength, flexural toughness) of RAC can be significantly enhanced by adding macro fibers. For concrete with 50% recycled aggregate (RA), the increase of macro fibers (from 0% to 0.5%, 1%, and 1.5%) leads to the enhancement of flexural strength from 3.13 MPa to 3.54, 4.69, and 5.97 MPa, and the toughness (T150) from 1.4 J to 35.5, 59.2 and 77.6 J, respectively. Such enhancements in the mechanical properties of RAC demonstrate the feasibility of the proposed method.