Development of lightweight engineered cementitious composite for durability enhancement of tall concrete wind towers

Recently, concrete (especially high strength concrete) is considered the most suitable material for building tall wind turbine towers. However, concrete is prone to cracking and the durability of tall concrete towers can be compromised when large cracks (> 300 mu m) occur on their exterior surfaces. In this study, a lightweight engineered cementitious composite (ECC), reinforced by high tenacity polypropylene fiber, was developed based on performance driven design approach to serve as protective coatings on the tall concrete towers. By using fly ash cenospheres as lightweight filler material, a lightweight ECC with a density of 1810 kg/m(3) can be achieved. Guided by micromechanics-based design theory, this newly developed ECC can achieve a tensile strength above 2 MPa, tensile ductility above 2%, and maximum crack width of 100 mu m in both direct tension and flexural fatigue tests. The high ductility and excellent crack control of ECC coating can improve the cracking resistance of the hybrid tall ECC/concrete towers, therefore enhancing their durability and extending their service life.