Chemically foamed geopolymers for 3D printing applications

abstract

Using chemically foamed geopolymers in 3D-printed building applications offers multifunctionality to the construction sector and enhances environmental sustainability; however, this topic remains virtually unexplored. To this end, the first part of this paper focuses on the fundamental stabilisation mechanism of chemically foamed geopolymers. In the second part, the most promising compositions were selected for applications in two potential areas: i) integration as an infilling material in 3D-printed sandwich envelopes, and ii) direct 3D printing of foam geopolymers. The findings indicated that to prevent instability mechanisms, various mix-design practices are necessary, including the use of an appropriate surfactant to inhibit coalescence, and the regulation of rheological properties to control drainage and coarsening. Implementing stabilised foam as infill in 3D-printed walls significantly enhances thermal performance due to its low thermal conductivity. Additionally, by adjusting Al dosage (up to 0.3 %) and using SDS as a stabilising surfactant, the foams were successfully printed with densities and compressive strengths ranging from 0.58 to 1.1 g/cm3 and 1.2-13.5 MPa, respectively. Moreover, 3D-printed foams demonstrated a thermal conductivity of 0.097 W/m & sdot;K and an impressive sound absorption coefficient (0.84 at 630 Hz) for the mix containing 0.3 % Al. The results underscore the viability of 3D-printed chemically foamed geopolymers in future construction projects.

keywords

CONCRETE; POROSITY; STRENGTH; SURFACTANTS; IMPACT; WATER

subject category

Construction & Building Technology; Materials Science

authors

Lori, AR; Novais, RM; Ascensao, G; Fernandes, F; Ranjbar, N; Spangenberg, J

Groups

G4 - Renewable Materials and Circular Economy

Projects

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

acknowledgements

This work was developed and financially supported by the Technical University of Denmark (DTU) at the Department of Civil and Mechanical Engineering. N. R. would like to acknowledge the research grant (VIL42098) from VILLUM FONDEN. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020) , UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020) , financed by national funds through the FCT/MCTES (PIDDAC) . G.A. work was supported by FCT-Fundacao para a Ciencia e Tecnologia, I.P. by project reference UIDB/04450/2020 and DOI identifier < https://doi.org/10.54499/UIDB/04450/2020 >. This work was supported by Fundacao para a Ciencia e a Tecnologia, I.P. with the following projects UIDB/00481/2020 (DOI 10.54499/UIDB/00481/2020) and UIDP/00481/2020 (DOI 10.54499/UIDP/00481/2020) . The authors would also like to thank Prof. Astri Bj & oslash; rnetun Haugen and Dr. Kyriakos Didilis of DTU Energy for their assistance with surface tension measurements, and Dr. Luciana Rocha of the University of Aveiro for her help in micro-CT measurements.