Synthesis of metakaolin-based geopolymer foamed materials using municipal solid waste incineration fly ash as a foaming agent

Xiang Tian; Kuizhou Liu; Xuetong Yang; Tianyong Jiang; Bohao Chen; Zhongchu Tian; Jie Wu; Ling Xia; Dunwen Huang; Hui Peng

doi:10.1016/j.wasman.2023.07.003

Synthesis of metakaolin-based geopolymer foamed materials using municipal solid waste incineration fly ash as a foaming agent

Waste Manag. 2023 Sep 1:169:101-111. doi: 10.1016/j.wasman.2023.07.003. Epub 2023 Jul 6.

Authors

Xiang Tian¹, Kuizhou Liu¹, Xuetong Yang², Tianyong Jiang¹, Bohao Chen¹, Zhongchu Tian¹, Jie Wu³, Ling Xia⁴, Dunwen Huang¹, Hui Peng¹

Affiliations

¹ School of Civil Engineering, Changsha University of Science and Technology, Changsha 410114, China.
² Research Group LIWET, Department of Green Chemistry and Technology, Ghent University, Campus Kortrijk, Sint-Martens-Latemlaan 2B 5, B-8500 Kortrijk, Belgium. Electronic address: Xuetong.Yang@UGent.be.
³ Doctorado Institucional de Ingeniería y Ciencia de Materiales, Universidad Autonoma de San Luis Potosi, Av. Sierra Leona 530, San Luis Potosi 78210, Mexico.
⁴ School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China.

PMID: 37421822
DOI: 10.1016/j.wasman.2023.07.003

Abstract

The existence of metallic aluminum in municipal solid waste incineration fly ash (MSWIFA) makes it challenging to recycle MSWIFA into cement materials because expansion occurs in the resultant matrices. Geopolymer-foamed materials (GFMs) are gaining attention in the field of porous materials due to their high-temperature stability, low thermal conductivity and low CO₂ emission. This work aimed to utilize MSWIFA as a foaming agent to synthesize GFMs. The physical properties, pore structure, compressive strength and thermal conductivity were analyzed to assess different GFMs which were synthesized with various MSWIFA and stabilizing agent dosages. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis were conducted to characterize the phase transformation of the GFMs. Results showed that when MSWIFA content was increased from 20 to 50%, the porosity of GFMs increased from 63.5 to 73.7%, and bulk density decreased from 890 to 690 kg/m³. The addition of stabilizing agent could trap the foam, refine the cell size, and homogenize the cell size range. With the stabilizing agent increase from 0 to 4%, the porosity increased from 69.9 to 76.8%, and the bulk density decreased from 800 to 620 kg/m³. The thermal conductivity decreased with increasing MSWIFA from 20 to 50%, and stabilizing agent dosage from 0 to 4%. Compared with the collected data from references, a higher compressive strength can be obtained at the same level of thermal conductivity for GFMs synthesized with MSWIFA as a foaming agent. Additionally, the foaming effect of MSWIFA results from the H₂ release. The addition of MSWIFA changed both the crystal phase and gel composition, whereas the stabilizing agent dosage had little impact on the phase composition.

Keywords: Compressive strength; Expansion; Geopolymer foamed materials; Metallic aluminum; Municipal solid waste incineration fly ash; Thermal conductivity.

MeSH terms

Coal Ash / chemistry
Compressive Strength
Excipients
Incineration* / methods
Solid Waste*

Substances

Solid Waste
Coal Ash
Excipients