Comparative Analysis of CO<sub>2</sub> Resistance on NaOH-Activated and Na<sub>2</sub>C<sub>2</sub>O<sub>4</sub> + Ca(OH)<sub>2</sub>-Activated Geopolymers
The combination of Na<sub>2</sub>C<sub>2</sub>O<sub>4</sub> and Ca(OH)<sub>2</sub> acts as an eco-friendly alkaline activator characterized by low alkalinity, reduced carbon footprint, and controllable thickening behavior. Calcium oxalate, a byproduct of the Na<sub>2</sub>C<sub>2</sub>O<sub>4</sub> and Ca(OH)<sub>2</sub> reaction, may enhance the CO<sub>2</sub> resistance of geopolymers. In this study, we compared the CO<sub>2</sub>-resistant performance of geopolymers activated by Na<sub>2</sub>C<sub>2</sub>O<sub>4</sub> + Ca(OH)<sub>2</sub> and NaOH under high-temperature conditions (110 °C, 5 MPa CO<sub>2</sub>). Fly ash sinking beads and slag were used as precursors. Trends in alkalinity and strength variations were recorded, and changes in microscopic composition were analyzed via XRD, FTIR, and DTG. The results demonstrated that after 21 days of CO<sub>2</sub> exposure, the compressive strength of geopolymers activated by either NaOH or Na<sub>2</sub>C<sub>2</sub>O<sub>4</sub> + Ca(OH)<sub>2</sub> increased by 7.14-22.58%. Notably, both activators exhibited no significant difference in the CO<sub>2</sub> resistance. Extending the pre-exposure curing time more effectively enhanced the geopolymers' CO<sub>2</sub> resistance, with samples cured for 7 days exhibiting 28.9-34.2% higher compressive strength than those cured for 1 day. Fourier-deconvolution spectroscopy analysis revealed that N-A-S-H gels displayed superior CO<sub>2</sub> resistance compared to C-A-S-H gels.
Authors
- Shenglai Guo
- Jiajun Tang (ORCID: https://orcid.org/0000-0002-0254-9764)
- Jie Ren (ORCID: https://orcid.org/0000-0003-2806-7226)
- Yuanhai Zhang (ORCID: https://orcid.org/0009-0004-5387-9503)
- Danzhu Zheng (ORCID: https://orcid.org/0000-0003-4965-5385)
- Rong Wang (ORCID: https://orcid.org/0000-0002-0094-6256)
- Ye Zhang (ORCID: https://orcid.org/0000-0003-1827-2752)
- Ruihua Zhang (ORCID: https://orcid.org/0000-0001-9521-9694)
Institutions
- University of Colorado Boulder (US)
- University of Colorado System (US)
- China University of Petroleum, East China (CN)
- University of Tulsa (US)
- China National Petroleum Corporation (China) (CN)
Publication Details
- Journal
- ACS Omega
- Published
- 2025-04-24
- DOI
- https://doi.org/10.1021/acsomega.4c11082
- Citations
- 2
- Primary Topic
- Concrete and Cement Materials Research
- Type
- article
- Field-Weighted Citation Impact
- 1.91
Funders
- National Natural Science Foundation of China
- Natural Science Foundation of Shandong Province