Fusion of phosphate by-products and glass waste for preparation of alkali-activated binders
Moukannaa, Samira; Aboulayt, Abdelilah; Hakkou, Rachid; Benzaazoua, Mostafa; Ohenoja, Katja; Palomo, Angel; Fernández-Jimenez, Ana (2022-06-13)
Moukannaa, S., Aboulayt, A., Hakkou, R., Benzaazoua, M., Ohenoja, K., Palomo, A., & Fernández-Jimenez, A. (2022). Fusion of phosphate by-products and glass waste for preparation of alkali-activated binders. Composites Part B: Engineering, 242, 110044. https://doi.org/10.1016/j.compositesb.2022.110044
© 2022 The Authors. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
https://creativecommons.org/licenses/by/4.0/
https://urn.fi/URN:NBN:fi-fe2022112366659
Tiivistelmä
Abstract
Landfilling of mine and industrial waste streams leads to environmental and economic issues. Sustainable management methods through valorization in manufacturing green construction materials are a current research interest. Here, a promising process for recycling mine tailings, such as phosphate sludge, is proposed. A mixture of phosphate sludge, kaolin clay (Al source), and glass waste (Si source) was prepared. Three fluxing agents were tested at 1000 °C (NaOH, Na2CO3, Na2SO4). Na2CO3 was selected as the most cost-effective. The precursors were alkaline activated with NaOH solution (2, 6, and 8 M). At 28 days of curing (20 h room temperature + 6 h 85 °C + room temperature), the best compressive strength (of more than 45 MPa) was obtained with 8 M NaOH. The reaction products, characterized by XRD, FTIR, SEM, and MAS NMR, show that the main reaction products is a gel N–A–S–H/(N,C)–A–S–H together with some unreacted crystalline phases formed during the fusion.
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