Paper Number
PO57 

Session
Poster Session

Title
Early-age rheological properties of sustainable geopolymer binders: Applications in additive manufacturing

Presentation Date and Time
October 12, 2022 (Wednesday) 6:30

Track / Room
Poster Session / Riverwalk A

Authors (Click on name to view author profile)

1. Egnaczyk, Ted M. (University of Delaware, Chemical and Biomolecular Engineering)
2. Wagner, Norman J. (University of Delaware, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Ted M. Egnaczyk and Norman J. Wagner
Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716

Speaker / Presenter 
Egnaczyk, Ted M.

Keywords
experimental methods; additive manufacturing; construction materials

Text of Abstract
Cement production is one of the leading contributors to global CO₂ emissions. Geopolymers are ceramic-like binders that provide a sustainable alternative to cement with the potential to reduce up to 80% of CO₂ emissions [Duxson et al., Cement and Concrete Research 2007, 12 (37), 1590-1597.] and enable in situ resource utilization (ISRU). Additive manufacturing (AM) is an exciting application of geopolymer technology with benefits including the design of complex structures and the potential to manufacture in harsh and extraterrestrial environments. The main challenge hindering wide adoption of geopolymers in AM is the complexity of controlling property development from initial chemistry. The chemical composition of geopolymer binders is known to impact macroscopic properties including workability and strength. Therefore, research connecting geopolymer chemistry and early-age rheological properties is required to design materials for successful AM applications.

This work creates early-age rheology profiles from geopolymers of varied chemistry and determines trends in key properties for AM applications. Geopolymers are synthesized by the alkaline activation of metakaolin as an aluminosilicate source and described by their nominal elemental silicon/aluminum/sodium (Si/Al/Na) composition. Temporal rheology profiles are created via small-amplitude oscillatory shear (SAOS) measurements with a vane geometry. Properties including yield stress, viscoelastic moduli, and storage modulus recovery are connected to the potential geopolymer printability. Preliminary results show that decreasing the nominal Si/Al and Si/Na ratio leads to a higher yield stress and storage modulus value, resulting in a more printable composition. Compositions are adjusted to meet printability criteria [Chan et al., Journal of the American Ceramic Society 2020, 10 (103), 5554-5566.], which demonstrates the feasibility of formulating for optimal AM performance given an ISRU aluminosilicate composition.