Deepening the effect of selectively crushed wind-turbine blade on the dimensional stability and high-temperature resistance of concrete

Abstract

Selectively Crushed Wind-Turbine Blade (SCWTB) is obtained through knife crushing of panels from wind-turbine blades. Two thirds of SCWTB weight consist of GFRP-composite fibers, which may improve both dimensional stability and high-temperature resistance of concrete. In this investigation, the evaluation of such aspects in concrete containing 1.5 %, 3.0 %, 4.5 % and 6.0 % SCWTB by volume is addressed. For this purpose, plastic shrinkage, drying shrinkage, total shrinkage, and thermal expansion were evaluated regarding dimensional stability, while resistance to high temperatures was assessed through accelerated-aging and thermal-shock tests. The results revealed that 6.0 % SCWTB reduced by half concrete plastic shrinkage, and total shrinkage by 40–50 % at 7 days and by 10–20 % at 91 days. Furthermore, the initial thermal strain was decreased from SCWTB contents of 3.0 %, which in turn reduced the linear thermal expansion coefficient, which had a value of 1.49·10−5 °C−1 in concrete with 6.0 % SCWTB. Finally, concrete with SCWTB maintained adequate compressive strength after accelerated aging and air-heating thermal shock, reaching values above 40 MPa, and halved the loss of flexural strength when added in a content of 6.0 %. Scanning electron microscopy revealed that high temperatures caused micro-cracks that started in weak zones and propagated along the glass fibers of GFRP, but the bond between the cementitious matrix and the GFRP-composite fibers was ideal, so the matrix fractured instead of the fibers slipping when loading. The improvements induced by SCWTB were statistically significant, so this waste can be considered a value-added material in terms of the concrete behavior analyzed.