Bending performance of concrete with coarse recycled aggregate and raw-crushed wind-turbine blade at an early age

Abstract

The bonded mortar in the Coarse Recycled Aggregate (CRA) reduces both the adhesion in the interfacial transition zones and the stiffness of concrete, which worsens concrete bending behavior. These aspects are more remarkable at early ages due to the lower strength and stiffness developed by the concrete matrix. The stitching effect of the 66.8% by weight of Glass Fiber-Reinforced Polymer (GFRP) fibers contained in Raw-Crushed Wind-Turbine Blade (RCWTB) can counteract these phenomena. This research analyzes the bending behavior of concrete made with up to 100% CRA in combination with 6% RCWTB as aggregate replacement. Early ages (1, 3, and 7 days) and both moist and ambient curing are considered to cover all possible put-into-service situations of concrete elements. Compared to concrete with the same composition but without RCWTB, this waste increased the pre-failure compliance by up to 26.9%, the failure deflection by up to 12.8%, and the failure stress by up to 37.5% when combined with as much as 50% CRA. An earlier concrete age and ambient curing made such effects more notable due to the weaker cementitious matrix. Furthermore, RCWTB provided post-failure load-bearing capacity to concrete, the incorporation of 6% RCWTB to concrete with 50% CRA increasing the absorbed energy under bending loading by 135%. RCWTB also allowed the energy absorbed by concrete to be almost unaffected when adding any CRA amount. All these effects were statistically significant and demonstrate that RCWTB improves the bending deformability of concrete produced with CRA, mainly because of the deflection improvement it caused.