Mechanical performance of CFRP-confined sustainable geopolymeric recycled concrete under axial compression

Sustainable geopolymeric recycled aggregate concrete (RAC) by utilizing environmentally-friendly binder-geopolymer and constructional solid waste-recycled aggregate (RA) will facilitate the sustainability in concrete industry. This study investigated the compressive behavior of sustainable geopolymeric RAC confined by carbon fiber-reinforced polymer (CFRP) jackets. A total of 72 cylindrical fly ash/slag-based geopolymeric concrete specimens, including 48 CFRP-confined specimens and 24 unconfined specimens were fabricated and tested. The testing variables included: coarse aggregate type (i.e., natural aggregate and RA), thickness of CFRP jackets (i.e., 1, 2, and 3 layers) and (iii) slag content (i.e., 0, 10%, 20% and 30% of the total binder by mass). The results indicate that the CFRP confinement remarkably enhances the compressive strength and ultimate strain of geopolymeric concrete, and the enhancement is more pronounced with the increase of CFRP jacket thickness. Moreover, the RA replacement and the inclusion of slag have minor influences on the CFRP confinement performance for the compressive strength, but have obvious effects on the CFRP confinement performance for the ultimate axial strain. Based on the test results, empirical stress and strain models were proposed to predict the ultimate condition of the CFRP-confined geopolymeric concrete.