Synergistic Effects of Alkali Activator Dosage on Carbonation Resistance and Microstructural Evolution of Recycled Concrete: Insights from Fractal Analysis and Optimal Threshold Identification
The synergistic mechanism between alkali activation and carbonation in fly ash recycled aggregate concrete (FRAC) remains a critical challenge for enhancing durability and promoting solid waste utilization. This study systematically investigates the effects of CaO-based alkali activator dosages (0%,...
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2025-05-01
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| author | Yier Huang Aimin Gong Zhuo Jin Yulin Peng Shanqing Shao Kang Yong |
| author_facet | Yier Huang Aimin Gong Zhuo Jin Yulin Peng Shanqing Shao Kang Yong |
| author_sort | Yier Huang |
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| description | The synergistic mechanism between alkali activation and carbonation in fly ash recycled aggregate concrete (FRAC) remains a critical challenge for enhancing durability and promoting solid waste utilization. This study systematically investigates the effects of CaO-based alkali activator dosages (0%, 4%, 8%, 12%) on carbonation resistance, compressive strength, and pore structure evolution. The results demonstrated 8% CaO maximized compressive strength (48.6 MPa, 10.76% higher than the control group) and minimized porosity (22.87% vs. 39.33% in untreated samples), with enhanced carbonation resistance (35% depth reduction after 28 days). Fractal dimension (FD) analysis revealed that 8% dosage optimized pore complexity (FD > 1.9), forming a dense C–S–H/AFt network that suppressed CO<sub>2</sub> diffusion. CaO addition introduces embodied carbon (9.84 kg CO<sub>2</sub>/m<sup>3</sup>), and the synergy between fly ash’s cement replacement (120 kg CO<sub>2</sub>/m<sup>3</sup> reduction) and extended service life (theoretically, 15–20 years) ensures a net carbon benefit. These findings establish 8% as a critical threshold for optimizing alkali activation efficiency and durability in low-carbon concrete design. These findings offer theoretical and technical foundations for low-carbon concrete design and sustainable solid waste recycling in construction. |
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| spelling | doaj-art-cc11bc9a0e26432cab5a3dfc2b2a27da2025-08-20T03:47:52ZengMDPI AGBuildings2075-53092025-05-011510174210.3390/buildings15101742Synergistic Effects of Alkali Activator Dosage on Carbonation Resistance and Microstructural Evolution of Recycled Concrete: Insights from Fractal Analysis and Optimal Threshold IdentificationYier Huang0Aimin Gong1Zhuo Jin2Yulin Peng3Shanqing Shao4Kang Yong5College of Hydraulic Engineering, Yunnan Agricultural University, Kunming 650201, ChinaCollege of Hydraulic Engineering, Yunnan Agricultural University, Kunming 650201, ChinaCollege of Hydraulic Engineering, Yunnan Agricultural University, Kunming 650201, ChinaAcademic Affairs Office, Yunnan Agricultural University, Kunming 650201, ChinaCollege of Hydraulic Engineering, Yunnan Agricultural University, Kunming 650201, ChinaCollege of Hydraulic Engineering, Yunnan Agricultural University, Kunming 650201, ChinaThe synergistic mechanism between alkali activation and carbonation in fly ash recycled aggregate concrete (FRAC) remains a critical challenge for enhancing durability and promoting solid waste utilization. This study systematically investigates the effects of CaO-based alkali activator dosages (0%, 4%, 8%, 12%) on carbonation resistance, compressive strength, and pore structure evolution. The results demonstrated 8% CaO maximized compressive strength (48.6 MPa, 10.76% higher than the control group) and minimized porosity (22.87% vs. 39.33% in untreated samples), with enhanced carbonation resistance (35% depth reduction after 28 days). Fractal dimension (FD) analysis revealed that 8% dosage optimized pore complexity (FD > 1.9), forming a dense C–S–H/AFt network that suppressed CO<sub>2</sub> diffusion. CaO addition introduces embodied carbon (9.84 kg CO<sub>2</sub>/m<sup>3</sup>), and the synergy between fly ash’s cement replacement (120 kg CO<sub>2</sub>/m<sup>3</sup> reduction) and extended service life (theoretically, 15–20 years) ensures a net carbon benefit. These findings establish 8% as a critical threshold for optimizing alkali activation efficiency and durability in low-carbon concrete design. These findings offer theoretical and technical foundations for low-carbon concrete design and sustainable solid waste recycling in construction.https://www.mdpi.com/2075-5309/15/10/1742recycled aggregatealkali activationcarbonation resistancemicrostructure evolutionfractal dimension of pore structuresolid waste utilization |
| spellingShingle | Yier Huang Aimin Gong Zhuo Jin Yulin Peng Shanqing Shao Kang Yong Synergistic Effects of Alkali Activator Dosage on Carbonation Resistance and Microstructural Evolution of Recycled Concrete: Insights from Fractal Analysis and Optimal Threshold Identification Buildings recycled aggregate alkali activation carbonation resistance microstructure evolution fractal dimension of pore structure solid waste utilization |
| title | Synergistic Effects of Alkali Activator Dosage on Carbonation Resistance and Microstructural Evolution of Recycled Concrete: Insights from Fractal Analysis and Optimal Threshold Identification |
| title_full | Synergistic Effects of Alkali Activator Dosage on Carbonation Resistance and Microstructural Evolution of Recycled Concrete: Insights from Fractal Analysis and Optimal Threshold Identification |
| title_fullStr | Synergistic Effects of Alkali Activator Dosage on Carbonation Resistance and Microstructural Evolution of Recycled Concrete: Insights from Fractal Analysis and Optimal Threshold Identification |
| title_full_unstemmed | Synergistic Effects of Alkali Activator Dosage on Carbonation Resistance and Microstructural Evolution of Recycled Concrete: Insights from Fractal Analysis and Optimal Threshold Identification |
| title_short | Synergistic Effects of Alkali Activator Dosage on Carbonation Resistance and Microstructural Evolution of Recycled Concrete: Insights from Fractal Analysis and Optimal Threshold Identification |
| title_sort | synergistic effects of alkali activator dosage on carbonation resistance and microstructural evolution of recycled concrete insights from fractal analysis and optimal threshold identification |
| topic | recycled aggregate alkali activation carbonation resistance microstructure evolution fractal dimension of pore structure solid waste utilization |
| url | https://www.mdpi.com/2075-5309/15/10/1742 |
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