Design of Fly Ash-Based Geopolymer Concrete-Filled FRP Tube Composite for Highly Durable and Environmentally Friendly Infrastructure
Dr. Xianming Shi
Although fly ash-based geopolymer (FAGPR) binders have been increasingly explored for the last decade, there is still an urgent demand for high-performance FAGPR binder to meet the requirement of more durable and environmentally friendly infrastructure. It is also necessary to identify viable strategies to compensate for the lower early-age strength, short setting time, and less-than-ideal flowability of FAGPR, which are considered as the main drawbacks that hinder its widespread application. To this end, this proposed project will build on the team’s patented FAGPR technology and develop a novel tube/concrete composite, which features promising load-bearing capacity, durability performance, and damping properties. The final design of this composite consists of a fiber-reinforced polymer (FRP) tube filled with well-designed concrete of expansive FAGPR. At the first stage of this work, the laboratory study aims to:
1) Design a FAGPR concrete that features promising strengths, expansion characteristics, and damping coefficient, and
2) Design a FAGPR concrete-filled FRP tube composite that features outstanding load-bearing capacity, durability performance, and damping behavior.
Specifically, a novel nanomaterial (graphene oxide) and silica fume will be introduced into the alkali-sulfate-activated FAGPR to improve the mechanical strengths of the cementitious material. The volume expansion of the FAGPR concrete will be adjusted by sodium sulfate and lime, which are known to also benefit the development of strength properties. Surface-modified crumb rubber (powder) will be introduced into the mix design to improve the damping coefficient of the geopolymer concrete. Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), Thermogravimetry analysis (TG), Differential Scanning Calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), Electron probe microanalysis (EPMA), and X-ray diffraction analysis (XRD) will be employed to investigate the hydration mechanisms of the nanomodified FAGPR paste and to shed light on how the constituent materials affect the strength, expansion, and damping properties of the concrete.