Analysis of the Strength Development, CO<sub>2</sub> Emissions, and Optimized Low-Carbon Design of Fly-Ash-Enhanced Composite Concrete
Fly ash is commonly used as a partial replacement for cement. Although extensive research has been conducted on mixed design schemes for fly ash concrete, these studies commonly overlook carbonation durability, which may lead to an insufficient service life. This study investigates the strength deve...
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MDPI AG
2025-02-01
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| author | Bo Yang Yu Dong Xiao-Yong Wang |
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| description | Fly ash is commonly used as a partial replacement for cement. Although extensive research has been conducted on mixed design schemes for fly ash concrete, these studies commonly overlook carbonation durability, which may lead to an insufficient service life. This study investigates the strength development and optimal low-carbon design of composite concrete that incorporates fly ash. Initially, a regression analysis was performed to assess the compressive strength of concrete with various fly ash (FA) to FA plus cement (C) mass ratios (FA/(C + FA)), ranging from 0% to 55%, and water-to-binder mass ratios (W/(C + FA)), between 0.30 and 0.50 in the following different stages: early-term (3 and 7 days), mid-term (28 and 56 days), and long-term (90 and 180 days). The correlation coefficient between the predicted and actual strength values was 0.98208. The parameter analysis indicates that, for a given FA/(C + FA) ratio or curing duration, the relative strength of the concrete increases more rapidly with a lower W/(C + FA) ratio. Following this, with the water content held constant at 170 kg/m<sup>3</sup>, the CO<sub>2</sub> emissions of the cementitious materials in the concrete and the CO<sub>2</sub> emissions per unit of concrete strength were calculated. As the FA/(C + FA) ratio increased from 0% to 55%, the CO<sub>2</sub> emissions per unit of strength decreased. Similarly, reducing the W/(C + FA) ratio from 0.50 to 0.30 also lowers the CO<sub>2</sub> emissions per unit of strength. Finally, a genetic algorithm was employed for the optimization of the low-carbon design. As the water content decreases and the concentration of CO<sub>2</sub> increases, the critical design strength of the concrete must also increase to meet the requirements for carbonation durability. The fly ash replacement rate in each optimized mix design reached the maximum allowable replacement rate. Compared with considering only the carbon emissions of materials, the optimal mix ratios for each case remain unchanged when accounting for transportation and production processes; only the corresponding carbon emissions differ. |
| format | Article |
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| spelling | doaj-art-17d3b9c2f13e4e84af1c2ec2a9f947aa2025-08-20T02:44:45ZengMDPI AGBuildings2075-53092025-02-0115453210.3390/buildings15040532Analysis of the Strength Development, CO<sub>2</sub> Emissions, and Optimized Low-Carbon Design of Fly-Ash-Enhanced Composite ConcreteBo Yang0Yu Dong1Xiao-Yong Wang2Department of Integrated Energy and Infra System, Kangwon National University, Chuncheon-Si 24341, Republic of KoreaSchool of Architecture and Design, Harbin Institute of Technology, Key Laboratory of Cold Region Urban and Rural Human Settlement Environment Science and Technology, Ministry of Industry and Information Technology, Harbin 150001, ChinaDepartment of Integrated Energy and Infra System, Kangwon National University, Chuncheon-Si 24341, Republic of KoreaFly ash is commonly used as a partial replacement for cement. Although extensive research has been conducted on mixed design schemes for fly ash concrete, these studies commonly overlook carbonation durability, which may lead to an insufficient service life. This study investigates the strength development and optimal low-carbon design of composite concrete that incorporates fly ash. Initially, a regression analysis was performed to assess the compressive strength of concrete with various fly ash (FA) to FA plus cement (C) mass ratios (FA/(C + FA)), ranging from 0% to 55%, and water-to-binder mass ratios (W/(C + FA)), between 0.30 and 0.50 in the following different stages: early-term (3 and 7 days), mid-term (28 and 56 days), and long-term (90 and 180 days). The correlation coefficient between the predicted and actual strength values was 0.98208. The parameter analysis indicates that, for a given FA/(C + FA) ratio or curing duration, the relative strength of the concrete increases more rapidly with a lower W/(C + FA) ratio. Following this, with the water content held constant at 170 kg/m<sup>3</sup>, the CO<sub>2</sub> emissions of the cementitious materials in the concrete and the CO<sub>2</sub> emissions per unit of concrete strength were calculated. As the FA/(C + FA) ratio increased from 0% to 55%, the CO<sub>2</sub> emissions per unit of strength decreased. Similarly, reducing the W/(C + FA) ratio from 0.50 to 0.30 also lowers the CO<sub>2</sub> emissions per unit of strength. Finally, a genetic algorithm was employed for the optimization of the low-carbon design. As the water content decreases and the concentration of CO<sub>2</sub> increases, the critical design strength of the concrete must also increase to meet the requirements for carbonation durability. The fly ash replacement rate in each optimized mix design reached the maximum allowable replacement rate. Compared with considering only the carbon emissions of materials, the optimal mix ratios for each case remain unchanged when accounting for transportation and production processes; only the corresponding carbon emissions differ.https://www.mdpi.com/2075-5309/15/4/532fly ashCO<sub>2</sub> concentrationstrengthCO<sub>2</sub> emissionsoptimal design |
| spellingShingle | Bo Yang Yu Dong Xiao-Yong Wang Analysis of the Strength Development, CO<sub>2</sub> Emissions, and Optimized Low-Carbon Design of Fly-Ash-Enhanced Composite Concrete Buildings fly ash CO<sub>2</sub> concentration strength CO<sub>2</sub> emissions optimal design |
| title | Analysis of the Strength Development, CO<sub>2</sub> Emissions, and Optimized Low-Carbon Design of Fly-Ash-Enhanced Composite Concrete |
| title_full | Analysis of the Strength Development, CO<sub>2</sub> Emissions, and Optimized Low-Carbon Design of Fly-Ash-Enhanced Composite Concrete |
| title_fullStr | Analysis of the Strength Development, CO<sub>2</sub> Emissions, and Optimized Low-Carbon Design of Fly-Ash-Enhanced Composite Concrete |
| title_full_unstemmed | Analysis of the Strength Development, CO<sub>2</sub> Emissions, and Optimized Low-Carbon Design of Fly-Ash-Enhanced Composite Concrete |
| title_short | Analysis of the Strength Development, CO<sub>2</sub> Emissions, and Optimized Low-Carbon Design of Fly-Ash-Enhanced Composite Concrete |
| title_sort | analysis of the strength development co sub 2 sub emissions and optimized low carbon design of fly ash enhanced composite concrete |
| topic | fly ash CO<sub>2</sub> concentration strength CO<sub>2</sub> emissions optimal design |
| url | https://www.mdpi.com/2075-5309/15/4/532 |
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