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Sustainable Lightweight Thermal Insulating Geopolymer Mortars from End-of-Life Materials for 3D Printing. (2026-03)

10.1016/j.conbuildmat.2026.145977

Ekinci Mehmet, Belendir Utku,  Demiral Nazim,  Şahin Oğuzhan,  İlcan Hüseyin,  Şahmaran Mustafa,  Lachemi Mohamed
Journal Article - Construction and Building Materials, Vol. 520, No. 145977

Abstract

The aim of this study is to develop lightweight, thermal insulating geopolymer materials from construction and demolition waste (CDW) for 3D printing applications. Various CDWs, including hollow bricks, red clay bricks, roof tiles, concrete, and glass, were used as precursors. Sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)₂) served as alkali activators, while recycled concrete aggregate (RCA) and expanded perlite aggregate (EPA) were utilized as aggregates. Rheological properties of mortar mixtures were assessed through flow table and buildability tests, and their mechanical properties were evaluated via flexural and compressive strength tests. Additionally, high-temperature resistance and thermal conductivity were analyzed. Results indicated that replacing RCA with EPA reduced the water-to-binder ratio for similar flowability but negatively impacted buildability. Mortar with only RCA exhibited the highest dry density (2.13 g/cm³), whereas mortar with only EPA had the lowest (1.42 g/cm³). Mechanical strength decreased consistently with EPA addition. However, incorporating EPA above 50% significantly enhanced temperature resistance. Thermal conductivity ranged from 0.3482 W/m·K (RCA only) to 0.2336 W/m·K (EPA only), strongly correlating with density. The 3D-printed samples demonstrated higher density and thermal conductivity than casted samples. Visual inspection revealed that higher EPA content improved the surface quality of printed filaments. These comprehensive experiments showed that, by considering the effects of pumping and extrusion in 3D printing, thermally insulating, load-bearing wall systems can be successfully developed, demonstrating potential for energy-efficient masonry structures.

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0 Citations

BibTeX 
@article{ekin_bele_demi_sahi.2026.SLTIGMfEoLMf3P,
  author            = "Mehmet Özkan Ekinci and Utku Belendir and Nazim Çağatay Demiral and Oğuzhan Şahin and Hüseyin İlcan and Mustafa Şahmaran and Mohamed Lachemi",
  title             = "Sustainable Lightweight Thermal Insulating Geopolymer Mortars from End-of-Life Materials for 3D Printing.",
  doi               = "10.1016/j.conbuildmat.2026.145977",
  year              = "2026",
  journal           = "Construction and Building Materials",
  volume            = "520",
  pages             = "145977",
}
Formatted Citation

M. Ö. Ekinci, “Sustainable Lightweight Thermal Insulating Geopolymer Mortars from End-of-Life Materials for 3D Printing.”, Construction and Building Materials, vol. 520, p. 145977, 2026, doi: 10.1016/j.conbuildmat.2026.145977.

Ekinci, Mehmet Özkan, Utku Belendir, Nazim Çağatay Demiral, Oğuzhan Şahin, Hüseyin İlcan, Mustafa Şahmaran, and Mohamed Lachemi. “Sustainable Lightweight Thermal Insulating Geopolymer Mortars from End-of-Life Materials for 3D Printing.”. Construction and Building Materials 520 (2026): 145977. https://doi.org/10.1016/j.conbuildmat.2026.145977.