Geopolymer bricks prepared by MSWI fly ash and other solid wastes: Moulding pressure and curing method optimisation

Yanying Bai; Weichao Guo; Jianwei Wang; Zehua Xu; Shuai Wang; Qingxin Zhao; Jinman Zhou

doi:10.1016/j.chemosphere.2022.135987

Geopolymer bricks prepared by MSWI fly ash and other solid wastes: Moulding pressure and curing method optimisation

Chemosphere. 2022 Nov;307(Pt 3):135987. doi: 10.1016/j.chemosphere.2022.135987. Epub 2022 Aug 13.

Authors

Yanying Bai¹, Weichao Guo², Jianwei Wang³, Zehua Xu⁴, Shuai Wang⁴, Qingxin Zhao⁵, Jinman Zhou⁶

Affiliations

¹ State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, 066000, China; Hebei Province Engineering Research Center for Harmless Synergistic Treatment and Recycling of Municipal Solid Waste, Yanshan University, Qinhuangdao, 066000, China; Key Laboratory of Green Construction and Intelligent Maintenance for Civil Engineering of Hebei Province, Yanshan University, Qinhuangdao, 066000, China.
² State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, 066000, China; Hebei Province Engineering Research Center for Harmless Synergistic Treatment and Recycling of Municipal Solid Waste, Yanshan University, Qinhuangdao, 066000, China; Key Laboratory of Green Construction and Intelligent Maintenance for Civil Engineering of Hebei Province, Yanshan University, Qinhuangdao, 066000, China. Electronic address: guoweichao@ysu.edu.cn.
³ Hangzhou Jianfeng Commodity Concrete Co.,Ltd, Hangzhou, 310000, China.
⁴ State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, 066000, China; Key Laboratory of Green Construction and Intelligent Maintenance for Civil Engineering of Hebei Province, Yanshan University, Qinhuangdao, 066000, China.
⁵ State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, 066000, China; Hebei Province Engineering Research Center for Harmless Synergistic Treatment and Recycling of Municipal Solid Waste, Yanshan University, Qinhuangdao, 066000, China; Heibei Province Low-carbon and Clean Building Heating Technology Innovation Center, Yanshan University, Qinhuangdao, 066000, China.
⁶ China University of Geosciences, Beijing, 100000, China.

PMID: 35970219
DOI: 10.1016/j.chemosphere.2022.135987

Abstract

The preparation of geopolymer from alkaline solid waste instead of strong alkali presents the disadvantage of low early strength. However, improving the early mechanical properties of the geopolymer to meet the engineering requirements is challenging. In this paper, the effects of different moulding pressures and curing methods on the properties of red mud-ground granulated blast furnace slag activated by municipal solid waste incineration fly ash (MSWIFA)-carbide slag (CRMG) were studied and evaluated in terms of compressive strength and XRD, FTIR, SEM, and MIP techniques analysis. The results showed that the moulding pressure of 30 MPa could increase the compressive strength at 3 d by 182% and decrease the porosity from 30.28% to 27.38%. These results are attributable to the fact that the moulding pressure causes the particles to be tightly bound and promotes the geopolymerisation reaction. High-temperature (HT) curing could accelerate the hydration reaction and increase the compressive strength at 3 d by 133.7% and 141.6% compared with those obtained by water curing (WC) and room-temperature (RT) curing, respectively. Microscopic analyses showed that HT curing can promote the generation of C-(A)-S-H gel, geopolymer gel and hydrate calcium chloroaluminate (HCC), fill the pores, and increase the structure's compactness. Finally, the proposed method was verified by synthesising geopolymer pavement bricks (GPB), and the compressive strength at 3 d was found to reach 54 MPa under an optimal curing method (moulding pressure of 30 MPa, 90 °C for 12 h). Compared with concrete pavement bricks, GPB presents broad application prospects for saving economic costs and protecting the environment. The results provide a theoretical basis and technical support for the application of CRMG in rapid demoulding projects such as unfired bricks.

Keywords: Curing method; Geopolymer; Moulding pressure; Municipal solid waste incineration fly ash; Waste material.