Climate change is primarily driven by increasing CO2 emissions and carbonation of cementitious materials is a promising effective technique. Conventional methods for assessing carbonation depth are limited by underlying principles and destructive sampling. Therefore, this study proposes employing a hyperspectral camera to non-invasively extract spectral signatures from carbonated concrete and evaluate carbonation depth using color images analyzed by Spectral Angle Mapper (SAM) algorithm. Initially, CaCO3–Ca(OH)2 mixed powders were used to simulate the hyperspectral behavior of carbonated cement paste. Subsequent experiments were performed on the spit sections of concrete cores at varying detection depths, followed by on-site inspections of the inner surfaces of concrete holes. The relative depth of the characteristic absorption peaks progressively increased with measurement depth, which can be attributed to the combined effects of Ca(OH)2 and CaCO3 on the hyperspectral characteristics of carbonated concrete, with Ca(OH)2 playing a more predominant role. The SAM color images accurately depicted the actual distribution and morphology of the carbonation front, highlighting its tortuosity and spatial specificity. The carbonation depth was also measured and comparatively analyzed with phenolphthalein tests. This study primarily verifies the applicability of hyperspectral imaging (HSI) for carbonation depth assessment and underscores its technological advantages.
{"title":"Spectral Characterization and Carbonation Depth Visualization of Concrete Using Hyperspectral Imaging","authors":"Yancheng Wang, Yuzhe Wang, Ryoma Kitagaki, Dayoung Oh, Haruka Takahashi, Kazutoshi Shibuya, Takahiro Ohkubo, Atsushi Teramoto, Yuya Suda, Ippei Maruyama","doi":"10.1016/j.cemconcomp.2026.106498","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2026.106498","url":null,"abstract":"Climate change is primarily driven by increasing CO<ce:inf loc=\"post\">2</ce:inf> emissions and carbonation of cementitious materials is a promising effective technique. Conventional methods for assessing carbonation depth are limited by underlying principles and destructive sampling. Therefore, this study proposes employing a hyperspectral camera to non-invasively extract spectral signatures from carbonated concrete and evaluate carbonation depth using color images analyzed by Spectral Angle Mapper (SAM) algorithm. Initially, CaCO<ce:inf loc=\"post\">3</ce:inf>–Ca(OH)<ce:inf loc=\"post\">2</ce:inf> mixed powders were used to simulate the hyperspectral behavior of carbonated cement paste. Subsequent experiments were performed on the spit sections of concrete cores at varying detection depths, followed by on-site inspections of the inner surfaces of concrete holes. The relative depth of the characteristic absorption peaks progressively increased with measurement depth, which can be attributed to the combined effects of Ca(OH)<ce:inf loc=\"post\">2</ce:inf> and CaCO<ce:inf loc=\"post\">3</ce:inf> on the hyperspectral characteristics of carbonated concrete, with Ca(OH)<ce:inf loc=\"post\">2</ce:inf> playing a more predominant role. The SAM color images accurately depicted the actual distribution and morphology of the carbonation front, highlighting its tortuosity and spatial specificity. The carbonation depth was also measured and comparatively analyzed with phenolphthalein tests. This study primarily verifies the applicability of hyperspectral imaging (HSI) for carbonation depth assessment and underscores its technological advantages.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-08DOI: 10.1016/j.cemconcomp.2025.106275
Shao-bo Geng, Chen Zhang, Hui Zhang, Lu Hai, Bo-Tao Huang, Yun-shan Han, Chuan-xin Du, Yu-jie Huang
The advent of 3D printed concrete (3DPC) has transformed construction industrialization, especially in the context of intelligent construction. Nevertheless, conventional cement-based printable materials, mainly composed of extrusion-adapted mortar without coarse aggregates, exhibit low stiffness, high shrinkage cracking potential, and excessive cement dependence, compromising sustainability and increasing carbon footprints. This study introduces the first use of coal gangue as a sustainable coarse aggregate in 3D printed coal gangue concrete (3DP-CC), offering an innovative strategy for upcycling coal mining waste into printable construction materials. We systematically perform uniaxial compression, three-point bending, interlayer bonding tests, and micro X-ray CT to evaluate the multi-scale mechanical behaviour of 3DP-CC with varying coal gangue contents. Key findings include: (1) Pore structure evolves with coal gangue content, with total porosity first decreasing (to 1.8% at 10% content) then increasing (to 3.4% at 40% content), driven by aggregate skeleton and fine aggregate filling; (2) 3DP-CC’s compressive strength anisotropy is reduced compared to printed mortar due to aggregate interlocking, whereas flexural strength anisotropy increases as a result of pore accumulation and weak interlayers; at equal coarse aggregate content, 3DP-CC exhibits lower compressive anisotropy than printed natural aggregate concrete; (3) Compressive and flexural strengths increase initially and peak at 10%–20% coal gangue content, with values in all directions surpassing those of printed concrete with 40% natural aggregate. This work quantifies relationships between coal gangue content, structural anisotropy, and fracture resistance, offering actionable insights for industrial upcycling of coal wastes and addressing key challenges in eco-friendly 3D concrete printing.
{"title":"Upcycling coal gangue coarse aggregates into 3D printed concrete: Multi-scale mechanisms of fracture behaviour","authors":"Shao-bo Geng, Chen Zhang, Hui Zhang, Lu Hai, Bo-Tao Huang, Yun-shan Han, Chuan-xin Du, Yu-jie Huang","doi":"10.1016/j.cemconcomp.2025.106275","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106275","url":null,"abstract":"The advent of 3D printed concrete (3DPC) has transformed construction industrialization, especially in the context of intelligent construction. Nevertheless, conventional cement-based printable materials, mainly composed of extrusion-adapted mortar without coarse aggregates, exhibit low stiffness, high shrinkage cracking potential, and excessive cement dependence, compromising sustainability and increasing carbon footprints. This study introduces the first use of coal gangue as a sustainable coarse aggregate in 3D printed coal gangue concrete (3DP-CC), offering an innovative strategy for upcycling coal mining waste into printable construction materials. We systematically perform uniaxial compression, three-point bending, interlayer bonding tests, and micro X-ray CT to evaluate the multi-scale mechanical behaviour of 3DP-CC with varying coal gangue contents. Key findings include: (1) Pore structure evolves with coal gangue content, with total porosity first decreasing (to 1.8% at 10% content) then increasing (to 3.4% at 40% content), driven by aggregate skeleton and fine aggregate filling; (2) 3DP-CC’s compressive strength anisotropy is reduced compared to printed mortar due to aggregate interlocking, whereas flexural strength anisotropy increases as a result of pore accumulation and weak interlayers; at equal coarse aggregate content, 3DP-CC exhibits lower compressive anisotropy than printed natural aggregate concrete; (3) Compressive and flexural strengths increase initially and peak at 10%–20% coal gangue content, with values in all directions surpassing those of printed concrete with 40% natural aggregate. This work quantifies relationships between coal gangue content, structural anisotropy, and fracture resistance, offering actionable insights for industrial upcycling of coal wastes and addressing key challenges in eco-friendly 3D concrete printing.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144797434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The widespread application of engineered cementitious composites (ECC) necessitates addressing two critical challenges: excessive shrinkage deformation and prohibitive economic costs. Incorporating coarse aggregates (CAs) into ECC (CA-ECC) presents an effective solution strategy for these limitations. In civil and hydraulic engineering applications where shear-dominated failure prevails under complex loading conditions, establishing the correlation between CA content and the damage evolution characteristics as well as failure mechanisms of CA-ECC under shear stress states becomes imperative. This investigation examines the multiaxial shear performance of CA-ECC through the multiaxial shear tests considering four CA contents and five axial compression ratios. The digital image correlation technique was employed to analyze the damage evolution, complemented by microstructural characterization to elucidate the mechanisms of CA on shear performance of CA-ECC. The results indicate that increasing the CA content and axial compression ratio can both cause CA-ECC to crack prematurely, with the cracks increasing significantly. A positive correlation exists between CA content and shear strength enhancement, peaking at 36.91% improvement with 30% CA content. Notably, maximum peak shear displacement (33.86% increase) was achieved at 10% CA content. However, high axial compression can weaken the improving effect of CA on the shear performance of CA-ECC. Furthermore, the increase in CA content expands its interfacial transition zones, alters the fiber distribution characteristics, and consequently changes the failure mechanism of CA-ECC. Finally, a modified damage constitutive model of CA-ECC was proposed in this article, which was demonstrated to accurately predict the shear mechanical properties of CA-ECC.
{"title":"Multiaxial Shear Performance of Coarse-Aggregate ECC: Damage Evolution and Interfacial Characteristics","authors":"Lei Xie, Xinjian Sun, Zhenpeng Yu, Zetian Zhang, Xiaoli Xu, Kequan Yu","doi":"10.1016/j.cemconcomp.2025.106280","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106280","url":null,"abstract":"The widespread application of engineered cementitious composites (ECC) necessitates addressing two critical challenges: excessive shrinkage deformation and prohibitive economic costs. Incorporating coarse aggregates (CAs) into ECC (CA-ECC) presents an effective solution strategy for these limitations. In civil and hydraulic engineering applications where shear-dominated failure prevails under complex loading conditions, establishing the correlation between CA content and the damage evolution characteristics as well as failure mechanisms of CA-ECC under shear stress states becomes imperative. This investigation examines the multiaxial shear performance of CA-ECC through the multiaxial shear tests considering four CA contents and five axial compression ratios. The digital image correlation technique was employed to analyze the damage evolution, complemented by microstructural characterization to elucidate the mechanisms of CA on shear performance of CA-ECC. The results indicate that increasing the CA content and axial compression ratio can both cause CA-ECC to crack prematurely, with the cracks increasing significantly. A positive correlation exists between CA content and shear strength enhancement, peaking at 36.91% improvement with 30% CA content. Notably, maximum peak shear displacement (33.86% increase) was achieved at 10% CA content. However, high axial compression can weaken the improving effect of CA on the shear performance of CA-ECC. Furthermore, the increase in CA content expands its interfacial transition zones, alters the fiber distribution characteristics, and consequently changes the failure mechanism of CA-ECC. Finally, a modified damage constitutive model of CA-ECC was proposed in this article, which was demonstrated to accurately predict the shear mechanical properties of CA-ECC.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144792853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-06DOI: 10.1016/j.cemconcomp.2025.106279
Xujia You, Xiang Hu, Zhiqiang Xiao, Zain Ali Saleh Bairq, Wei Chen, Nemkumar Banthia, Caijun Shi
The carbonation curing of cement-based materials has been widely recognized as one of the most promising technologies for CO2 storage and utilization. Calcium carbonate is the main carbonation product of cement-based materials, which includes three anhydrous polymorphs: cubic calcite, needle-like aragonite, and amorphous vaterite. Products composed of aragonite with a large aspect ratio are inclined to develop whisker-like structures, which confer enhanced flexural strength and toughness. In this paper, a thermodynamic model for the formation of different CaCO3 polymorphs during the aqueous carbonation with organic additives that selectively promote aragonite formation is proposed. The effects of four organic additives including polyacrylic acid (PAA), polyacrylamide (PAM), polyvinyl alcohol (PVA) and monoethanolamine (MEA) on the proportion of different CaCO3 polymorphs produced during carbonation were quantified. By comparing the literature data and experimental results with the modelling output, the average error of the model for the four different organic additives (PAA, PAM, PVA, MEA) is 2.70%, 4.61%, 3.05% and 3.71% respectively. Through calculation, the thermodynamic mechanism of the selective adsorption of organic additives on the surface of aragonite has been revealed. The carbonation parameters, including temperature, CO2 input and additives concentration have been found to specifically affect the polymorphs of CaCO3 in three aspects: 1) adjusting the effective concentration of organic additives adsorbed on the surface of calcium carbonate; 2) altering the difference in surface energy and critical nucleation Gibbs free energy between aragonite and calcite; 3) regulating the reduction in surface energy attributed to per mole organic additive.
{"title":"Thermodynamic calculation of CaCO3 polymorphs from aqueous carbonation of Portland cement with the addition of organic additives","authors":"Xujia You, Xiang Hu, Zhiqiang Xiao, Zain Ali Saleh Bairq, Wei Chen, Nemkumar Banthia, Caijun Shi","doi":"10.1016/j.cemconcomp.2025.106279","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106279","url":null,"abstract":"The carbonation curing of cement-based materials has been widely recognized as one of the most promising technologies for CO<sub>2</sub> storage and utilization. Calcium carbonate is the main carbonation product of cement-based materials, which includes three anhydrous polymorphs: cubic calcite, needle-like aragonite, and amorphous vaterite. Products composed of aragonite with a large aspect ratio are inclined to develop whisker-like structures, which confer enhanced flexural strength and toughness. In this paper, a thermodynamic model for the formation of different CaCO<sub>3</sub> polymorphs during the aqueous carbonation with organic additives that selectively promote aragonite formation is proposed. The effects of four organic additives including polyacrylic acid (PAA), polyacrylamide (PAM), polyvinyl alcohol (PVA) and monoethanolamine (MEA) on the proportion of different CaCO<sub>3</sub> polymorphs produced during carbonation were quantified. By comparing the literature data and experimental results with the modelling output, the average error of the model for the four different organic additives (PAA, PAM, PVA, MEA) is 2.70%, 4.61%, 3.05% and 3.71% respectively. Through calculation, the thermodynamic mechanism of the selective adsorption of organic additives on the surface of aragonite has been revealed. The carbonation parameters, including temperature, CO<sub>2</sub> input and additives concentration have been found to specifically affect the polymorphs of CaCO<sub>3</sub> in three aspects: 1) adjusting the effective concentration of organic additives adsorbed on the surface of calcium carbonate; 2) altering the difference in surface energy and critical nucleation Gibbs free energy between aragonite and calcite; 3) regulating the reduction in surface energy attributed to per mole organic additive.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"95 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144792856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-05DOI: 10.1016/j.cemconcomp.2025.106277
Siyuan Bian, Yan Wang, Cheng Yao, Xue Xiang, Ruixing Wang
Extracellular polymeric substances (EPS), mainly composed of polysaccharides and proteins, are high-molecular compounds secreted during the metabolic process of bacteria. This study primarily examined the modification effects and influencing factors of EPS on the carbonation of low-calcium CO2 sequestration materials. The results indicate that EPS significantly enhanced the compressive strength of carbonated samples, from 2.21 MPa to 32.90 MPa, as well as the carbonation degree from 4.44 wt.% to 11.51 wt.%. Acidic amino acids in EPS can not only promote the leaching of Ca2+, but also adsorb free water in the system. Consequently, EPS may provide more nucleation sites, inducing the in-situ generation of amorphous calcium carbonate (ACC), and thus organic-inorganic carbonated composites were formed eventually, which improved the pore structure and carbonation degree of samples. The application of EPS has overcome the influence of unstable enzyme activity during the traditional microbial carbonation, achieving better and more stable carbonation effects.
{"title":"Inducing the formation of organic-inorganic carbonated composites via extracellular polymeric substances (EPS)-modified carbonation in low-calcium CO2 sequestration materials","authors":"Siyuan Bian, Yan Wang, Cheng Yao, Xue Xiang, Ruixing Wang","doi":"10.1016/j.cemconcomp.2025.106277","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106277","url":null,"abstract":"Extracellular polymeric substances (EPS), mainly composed of polysaccharides and proteins, are high-molecular compounds secreted during the metabolic process of bacteria. This study primarily examined the modification effects and influencing factors of EPS on the carbonation of low-calcium CO<sub>2</sub> sequestration materials. The results indicate that EPS significantly enhanced the compressive strength of carbonated samples, from 2.21 MPa to 32.90 MPa, as well as the carbonation degree from 4.44 wt.% to 11.51 wt.%. Acidic amino acids in EPS can not only promote the leaching of Ca<sup>2+</sup>, but also adsorb free water in the system. Consequently, EPS may provide more nucleation sites, inducing the in-situ generation of amorphous calcium carbonate (ACC), and thus organic-inorganic carbonated composites were formed eventually, which improved the pore structure and carbonation degree of samples. The application of EPS has overcome the influence of unstable enzyme activity during the traditional microbial carbonation, achieving better and more stable carbonation effects.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"731 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144787582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-31DOI: 10.1016/j.cemconcomp.2025.106265
Abdellatif Abidar, Rabah Hamzaoui, Othmane Bouchenafa, Sandrine Mansoutre, Céline Florence, Michael Paris, Laury Barnes Davin, Claire Capra, Bruno Classen
The primary objective of this study is to investigate the regeneration of hydraulic properties in hydrated cement pastes through thermal treatment between 400 °C and 800 °C, with a particular focus on the phase transformations and hydration mechanisms of the regenerated binders. This research is part of a broader effort to develop sustainable strategies for concrete recycling within a circular economy framework. Crushed cement paste, previously hydrated for 28 days, was thermally treated and characterized using 29Si nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) combined with Rietveld refinement.Results show that treatment at 600 °C leads to the formation of two C2S polymorphs (α'H-C2S and β-C2S), confirmed by both XRD and 29Si-NMR, associated with the complete decomposition of C–S–H phases. Binder hydration obtained between 600°C and 800°C required more water than ordinary Portland cement, likely due to the high reactivity of the free lime formed during thermal treatment. After 28 days of rehydration, a significant proportion of the belite formed is consumed. These findings demonstrate that heat-treated recycled cement pastes can behave as low-temperature belitic binders, offering a promising low-carbon alternative to conventional clinker production.
本研究的主要目的是研究水化水泥膏体在400°C至800°C之间进行热处理后水力性能的再生，特别关注再生粘合剂的相变和水化机制。这项研究是在循环经济框架内制定可持续混凝土回收战略的更广泛努力的一部分。粉碎后的水泥浆，事先水化28天，进行热处理，并使用29Si核磁共振（NMR）光谱和x射线衍射（XRD）结合Rietveld细化进行表征。结果表明：经XRD和29Si-NMR验证，在600℃的温度下，形成了两种C2S多晶（α′H-C2S和β-C2S），并伴有C - s - h相的完全分解。在600°C到800°C之间获得的粘结剂水化比普通硅酸盐水泥需要更多的水，这可能是由于在热处理过程中形成的游离石灰的高反应性。经过28天的补水，形成的belite的很大一部分被消耗掉了。这些发现表明，经过热处理的再生水泥浆可以作为低温褐铁矿粘结剂，为传统熟料生产提供了一种有前途的低碳替代品。
{"title":"Restoration of hydraulic properties in recycled cement pastes via thermal treatment","authors":"Abdellatif Abidar, Rabah Hamzaoui, Othmane Bouchenafa, Sandrine Mansoutre, Céline Florence, Michael Paris, Laury Barnes Davin, Claire Capra, Bruno Classen","doi":"10.1016/j.cemconcomp.2025.106265","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106265","url":null,"abstract":"The primary objective of this study is to investigate the regeneration of hydraulic properties in hydrated cement pastes through thermal treatment between 400 °C and 800 °C, with a particular focus on the phase transformations and hydration mechanisms of the regenerated binders. This research is part of a broader effort to develop sustainable strategies for concrete recycling within a circular economy framework. Crushed cement paste, previously hydrated for 28 days, was thermally treated and characterized using <sup>29</sup>Si nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) combined with Rietveld refinement.Results show that treatment at 600 °C leads to the formation of two C<sub>2</sub>S polymorphs (α'<sub>H</sub>-C<sub>2</sub>S and β-C<sub>2</sub>S), confirmed by both XRD and <sup>29</sup>Si-NMR, associated with the complete decomposition of C–S–H phases. Binder hydration obtained between 600°C and 800°C required more water than ordinary Portland cement, likely due to the high reactivity of the free lime formed during thermal treatment. After 28 days of rehydration, a significant proportion of the belite formed is consumed. These findings demonstrate that heat-treated recycled cement pastes can behave as low-temperature belitic binders, offering a promising low-carbon alternative to conventional clinker production.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144747737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Uneven distribution of chloride ions will cause macro-cell corrosion, which is typical but much more severe to reinforced concrete (RC) structures compared to micro-cell corrosion. In order to evaluate the electro-chemical characteristics of such macro-cell corrosion happening in actual RC structures, an integrated numerical platform including the coupled electric and chemical analysis has been developed. The platform had been successfully validated through an artificial electric field induced by external charge to obtain the accelerated macro-cell corrosion within a short period. In this paper, the application of integrated platform is conducted to chloride induced macro-cell corrosion with verification by long-term laboratory tests and in-service infrastructures in terms of the time-dependent chloride profile and corrosion characteristics. In addition, parametric analysis is conducted to further study the influence of chloride distribution as well as oxygen concentration on macro-cell effect. Results show that the uniformity of micro-cell corrosion even within a single rebar is found broken in either laboratory test or actual infrastructures. The polarization creates anode and cathode along the cross section of rebar, which is qualitatively captured by the numerical analysis. Meanwhile, the impact of adjacent rebars on the macro-cell corrosion of certain rebar, as well as the macro-cell properties within one rebar under the effect of single or multiple cover concrete cracks are also discussed in detail.
{"title":"Numerical study of macro-cell corrosion on reinforced concrete induced by chloride attack","authors":"Yifang Ji, Zhao Wang, Sho Inose, Satoshi Tsuchiya, Tsutomu Yamamoto, Tetsuya Ishida, Koichi Maekawa","doi":"10.1016/j.cemconcomp.2025.106263","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106263","url":null,"abstract":"Uneven distribution of chloride ions will cause macro-cell corrosion, which is typical but much more severe to reinforced concrete (RC) structures compared to micro-cell corrosion. In order to evaluate the electro-chemical characteristics of such macro-cell corrosion happening in actual RC structures, an integrated numerical platform including the coupled electric and chemical analysis has been developed. The platform had been successfully validated through an artificial electric field induced by external charge to obtain the accelerated macro-cell corrosion within a short period. In this paper, the application of integrated platform is conducted to chloride induced macro-cell corrosion with verification by long-term laboratory tests and in-service infrastructures in terms of the time-dependent chloride profile and corrosion characteristics. In addition, parametric analysis is conducted to further study the influence of chloride distribution as well as oxygen concentration on macro-cell effect. Results show that the uniformity of micro-cell corrosion even within a single rebar is found broken in either laboratory test or actual infrastructures. The polarization creates anode and cathode along the cross section of rebar, which is qualitatively captured by the numerical analysis. Meanwhile, the impact of adjacent rebars on the macro-cell corrosion of certain rebar, as well as the macro-cell properties within one rebar under the effect of single or multiple cover concrete cracks are also discussed in detail.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144747745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-25DOI: 10.1016/j.cemconcomp.2025.106253
Kairui Duan, Ze Liu, Xiang Li, Jixiang Wang, Jingshen Zhang, Dongmin Wang
In this study, polyepoxysuccinic acid salt (PESA (Na), P) was employed to enhance the time-dependent flowability of the one-part sodium carbonate and carbide slag activated ground granulated blast furnace slag paste within 60 min. The action mechanism of P with different addition methods was revealed through pore solution chemistry, in-situ XRD, Zeta potential, etc. For the direct addition method, P (0.2 wt% to 0.3 wt%) could adsorb onto the ground granulated blast furnace slag (GBS) and carbide slag (CS), offering dispersibility and inhibiting the dissolution of carbide slag, thereby improving the initial flowability. Then, P lost its dispersible capability because it participated in the formation of calcite and gaylussite, inhibiting the growth of calcite along the (104) crystal plane and leading to the fast consumption of CO32- in the pore solution. 0.4 wt% P retained high CO32- while low OH- during the test period, delaying the chemical reaction between CS and sodium carbonate. For the delayed addition method, 0.1 wt%-0.3 wt% P significantly improved the flowability of the paste under high OH- concentrations within 60 min. In this case, calcite was allowed to precipitate in advance so that P was not consumed by calcite and gaylussite but adsorbed onto chemically inert calcite, GBS, and unreacted CS to provide strong dispersibility. Both addition methods promoted the formation of gaylussite with large molar volumes and a rough appearance, which was detrimental to the flowability. A modelled chemical system comprising "Na2CO3+Ca(OH)2" with and without P validated the investigated mechanisms.
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