Evaluation of the behaviour of structural concrete bearing waste wind-turbine blade under tensile stresses

Abstract

It is generally acknowledged that it is an urgent task of the concrete industry to find new ways of introducing waste materials in their mixtures in order to increase its sustainability. Wind power industry can play an important role in this challenge, while solving the problem of the recycling of the old wind turbine structures that are reaching the end of their lifecycle, which is currently imperative. Hence, the need for the disposal of Waste Wind-Turbine Blade (WWTB) sets an opportunity to introduce it after crushing as a raw material in concrete, being able to reduce its content of natural aggregates and cement. This research aims to conduct an exhaustive material characterization and analyse the feasibility of adding WWTB in concrete for structural purposes. For this study, five different concrete mixes were produced with variable WWTB volume contents (0.0%, 1.5%, 3.0%, 4.5% and 6.0%). The amount of siliceous aggregate used in all five mixtures remained invariable, as well as the cement content. All the resulting mixtures were characterised in terms of the slump, fresh- and hardened-density tests. Besides, splitting tensile strength and flexural strength allowed evaluating the performance of the concrete mixes under tensile stresses. The results demonstrate that a rise in the WWTB content up to 1.5% can result in a slight increase of the splitting tensile strength, whereas high contents of this waste (6.0%) allow maintaining constant the flexural strength. The values of both properties remain approximately stable when adding WWTB, thus preserving the basic mechanical properties of structural concrete. According to this study, it is feasible to evaluate the addition of WWTB as a method of obtaining structural concrete without compromising any of its tensile-related mechanical properties, simultaneously transform an industry hitherto considered polluting into a more sustainable one.