Repurposing carbonate-based waste for producing an innovative binder: optimization and characterization

Elshimy, Ahmed S., Abadel, Aref A., Alghamdi, Hussam, Tuladhar, Rabin, El-Sokkary, Tarek M., Abdel-Gawwad, Hamdy A., and Seliem, Moaaz K. (2023) Repurposing carbonate-based waste for producing an innovative binder: optimization and characterization. Environmental Science and Pollution Research, 30. pp. 89430-89441.

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Abstract

This study reports the full recycling of dolomite waste (DW) in the fabrication of a novel cementitious material through a facile and eco-efficient method. The proposed technique includes mixing different alkali-activators (i.e., NaOH and Na2SiO3) with DW powder, followed by curing at room temperature. Based on the alkali-activator type, sodium oxide concentration, and curing time, the formulated mixtures yield a wide range of compressive strengths. When DW powder is mixed with different contents of NaOH (2.5, 5, and 7.5 wt.% Na2O), the resulting hardened materials exhibited modest compressive strengths (less than 11 MPa) due to the formation of the gaylussite Na2CO3·CaCO3·5H2O phase. Concerning the other chemical activator (Na2SiO3), a significant improvement in the compressive strengths of the resulted hardened materials was detected. This was ascribed to the formation of calcium silicate hydrate, with a high binding capacity, through the exchange reaction between Na2SiO3 and CaCO3 inside DW. The sample activated with Na2SiO3 (silica modulus of 1.5) equivalent to Na2O of 7.5 wt.% offered the highest 90-day compressive strength (34 MPa). At silica modulus lower or higher than 1.5, a noticeable decrease in the performance of the hardened materials was observed, which could be attributed to the alter in binding phase composition. Overall, the present work presented a new approach in utilizing the available and low cost carbonate-based wastes as main precursors in the family of promising alkali-activated materials.

Item ID: 79524
Item Type: Article (Research - C1)
ISSN: 1614-7499
Keywords: Alkali-activation, Calcium silicate hydrate, Compressive strength, Dolomite waste, Sodium silicate
Copyright Information: © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023
Date Deposited: 08 Aug 2023 02:49
FoR Codes: 40 ENGINEERING > 4005 Civil engineering > 400505 Construction materials @ 80%
40 ENGINEERING > 4005 Civil engineering > 400510 Structural engineering @ 20%
SEO Codes: 12 CONSTRUCTION > 1203 Construction materials performance and processes > 120301 Cement and concrete materials @ 100%
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