Enhancing performance of concrete with glass fiber-reinforced polymer short rebars as coarse aggregates by confinement

Abstract

Cutting glass fiber-reinforced polymer (GFRP) waste into aggregate-size reinforcing bars (short rebars) as coarse aggregates in concrete shows to be an effective approach for recycling waste GFRP composites. The resulting concrete with such short rebars however exhibits a reduction in the compressive strength comparing to the corresponding normal concrete, making it unable to be directly used for structural elements. The concept of using the confining jacket is therefore employed for such concrete to improve its compressive strength and toughness and to be used in structural elements. A total of 48 cylindrical specimens were prepared and tested under axial compression with the replacement ratio of coarse aggregates by the GFRP short rebars and the stiffness of the confining jacket as the two test parameters. The test results indicate that incorporating short GFRP rebars results in a reduction in compressive performance by up to 57.2%, and the use of CFRP jacketing significantly enhances the performance of the concrete with or without GFRP short rebars. Such enhancement tends to be more significant when the stiffness of the confining jackets or the replacement ratio increases. The reduction in the compressive strength due to the incorporation of 25% recycled GFRP short rebars is from 57.2% to 30.7%, when the number of layers of the confining CFRP jacket increases from 0 to 3 piles. Comparisons were made between the test results and the predictions from two widely-used stress-strain models for confined concrete, showing that both models overestimate the ultimate axial strain and Teng et al.'s model generally produces the compressive strength slightly higher than the corresponding test results as well as the predictions from Jiang and Teng's model.