Nano-Modified Fly-Ash-Based Geopolymer Concrete Filled Carbon Fiber-Reinforced Polymer Tube Composite: Mechanical Model and Life Cycle Assessment

Abstract

Geopolymer concrete holds immense potential as a viable alternative to ordinary Portland cement (OPC) concrete; however, its application for structures has been hindered by its low compressive strength relative to conventional OPC concrete. This study investigates the utilization of carbon-fiber-reinforced polymer (CFRP) tubes to confine fly-ash-based geopolymer (FAGPR) concrete and its graphene oxide (GO)-modified counterpart (GFAGPR), with the aim of enhancing compressive strength. Experimental investigation reveals significant improvements in mechanical strength. Furthermore, we conducted a life cycle assessment (LCA) to compare the environmental impacts and economic costs of OPC, FAGPR, and GFAGPR-concrete-filled CFRP tube composites, and their concrete-only counterparts, over a 100-year service life. The LCA results indicate that the (G)FAGPR composites exhibit significantly lower CO₂ emissions than their OPC-tube counterpart. However, the OPC composite is currently the most economic among all candidates. Additionally, the admixed GO not only mitigates the environmental impacts but also reduces the cost of FAGPR-tube composite, likely because of the GO-enhanced strength of core FAGPR concrete reducing the usage of CFRP tube that features higher cost and higher GWP coefficient.