Abstract
The use of fluid catalytic cracking (FCC) by-products as aluminosilicate precursors in geopolymer binders has attracted significant interest from researchers in recent years owing to their high alumina and silica contents. Introduced in this study is the use of geopolymer concrete comprising FCC residue combined with fly ash as the requisite source of aluminosilicate. Fly ash was replaced with various FCC residue contents ranging from 0–100% by mass of binder. Results from standard testing methods showed that geopolymer concrete rheological properties such as yield stress and plastic viscosity as well as mechanical properties including compressive strength, flexural strength, and elastic modulus were affected significantly by the FCC residue content. With alkali liquid to geopolymer solid ratios (AL:GS) of 0.4 and 0.5, a reduction in compressive and flexural strength was observed in the case of geopolymer concrete with increasing FCC residue content. On the contrary, geopolymer concrete with increasing FCC residue content exhibited improved strength with an AL:GS ratio of 0.65. Relationships enabling estimation of geopolymer elastic modulus based on compressive strength were investigated. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns revealed that the final product from the geopolymerization process consisting of FCC residue was similar to fly ash-based geopolymer concrete. These observations highlight the potential of FCC residue as an aluminosilicate source for geopolymer products.
Highlights
With low rheological properties such as yield stress and plastic viscosity, fly ash-based geopolymer concrete showed better workability compared to specimens comprising
For the incorporation of fluid catalytic cracking (FCC) residue into geopolymer concrete, there was a need for extra alkali liquid to maintain similar workability to fly ash-based geopolymer concrete
The 7-day compressive strength, elastic modulus, and flexural strength of geopolymer concrete investigated in this study varied within 10–26 MPa, 12.3–21.3 GPa, and
Summary
The term geopolymer, introduced for the first time by Davidovits in 1979 [1], typically implies binders with zero or low levels of cement that negate environmental issues associated with conventional. Portland cement production, such as high embodied carbon. The carbon footprint of geopolymer material manufacture has been reported to be 43% of that for conventional 4.0/). The supply of fly ash (one of the most commonly used and cost-effective binder materials for geopolymers) has decreased due to a reduction in coal-fired power plants related to increasing uses of renewable energy sources such as wind and solar [11]. The fly ash shortage in the U.K. is anticipated to be approximately 2 million tons in 2030 due to the planned closure of all coal-fired power plants by 2025 [12,13]
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