Pub Date : 2025-01-30DOI: 10.1016/j.cemconres.2025.107805
Tiao Wang , Yuqian Zheng , Hao Qian , Zhenguo Shi , Satya Medepalli , Jin Zhou , Fuqiang He , Tetsuya Ishida , Dongshuai Hou , Gaozhang Zhang , Zhengwu Jiang , Zhengning Zhou , Wei Zhang
This study quantitatively examines the impact of aluminum (Al) in C–A–S–H gel2 on the chloride binding capacity of blended cement paste containing supplementary cementitious materials (SCMs). The experimental results show that Al incorporation does not influence the physical chloride binding of C–A–S–H gel, which is governed by its Ca/Si ratio. However, in the presence of Cl− ions, the OH− ligands that stabilize high-coordination AlVI species3 (specifically [AlO₂(OH)₄]5−) can be replaced by Cl− ions. This replacement leads to the leaching of AlVI species from the C–A–S–H gel and an increase in OH− ion concentration in the solution. The released Al3+ ions then interact with Ca2+ and Cl− ions in the pore solution to form Friedel's salts (Fs), which further promotes the leaching of AlVI species. Consequently, the chemical chloride binding capacity of the cement paste increases as the Al/Si ratio of the C–A–S–H gel rises, along with refinements in paste microstructure.
{"title":"Effects of Al in C–A–S–H gel on the chloride binding capacity of blended cement paste","authors":"Tiao Wang , Yuqian Zheng , Hao Qian , Zhenguo Shi , Satya Medepalli , Jin Zhou , Fuqiang He , Tetsuya Ishida , Dongshuai Hou , Gaozhang Zhang , Zhengwu Jiang , Zhengning Zhou , Wei Zhang","doi":"10.1016/j.cemconres.2025.107805","DOIUrl":"10.1016/j.cemconres.2025.107805","url":null,"abstract":"<div><div>This study quantitatively examines the impact of aluminum (Al) in C–A–S–H gel<span><span><sup>2</sup></span></span> on the chloride binding capacity of blended cement paste containing supplementary cementitious materials (SCMs). The experimental results show that Al incorporation does not influence the physical chloride binding of C–A–S–H gel, which is governed by its Ca/Si ratio. However, in the presence of Cl<sup>−</sup> ions, the OH<sup>−</sup> ligands that stabilize high-coordination Al<sup>VI</sup> species<span><span><sup>3</sup></span></span> (specifically [AlO₂(OH)₄]<sup>5−</sup>) can be replaced by Cl<sup>−</sup> ions. This replacement leads to the leaching of Al<sup>VI</sup> species from the C–A–S–H gel and an increase in OH<sup>−</sup> ion concentration in the solution. The released Al<sup>3+</sup> ions then interact with Ca<sup>2+</sup> and Cl<sup>−</sup> ions in the pore solution to form Friedel's salts (Fs), which further promotes the leaching of Al<sup>VI</sup> species. Consequently, the chemical chloride binding capacity of the cement paste increases as the Al/Si ratio of the C–A–S–H gel rises, along with refinements in paste microstructure.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107805"},"PeriodicalIF":10.9,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-30DOI: 10.1016/j.cemconres.2025.107792
Andreas Alhede , Jelke Dijkstra , Alessandro Tengattini , Karin Lundgren
Characterising steel corrosion at the steel-concrete interface and linking it to concrete damage is challenging due to limitations of current non-destructive techniques. This study combines electrical resistance measurements, full-field image-based analyses and analytical techniques to comprehensively characterise steel corrosion and damage in small-scale specimens.
X-ray and Neutron Computed Tomography of two reinforced mortar samples, before and after accelerated corrosion, were used to examine corrosion morphology, interfacial voids, and estimate volumetric strain in the corrosion layer. Inductively Coupled Plasma Mass Spectrometry was employed to measure iron isotope concentrations in water surrounding the specimens.
The results revealed delayed transport of corrosion products relative to mortar cracking. The volumetric expansion coefficients of corrosion products (3.84 and 3.90) align with previous research, and the risk of pitting corrosion correlated with the void size. Overall, the measurements obtained through the various techniques closely aligned with visual observations, providing a robust dataset for calibrating corrosion models.
{"title":"Characterisation of steel corrosion and matrix damage in reinforced mortar combining analytical, electrical and image-based techniques","authors":"Andreas Alhede , Jelke Dijkstra , Alessandro Tengattini , Karin Lundgren","doi":"10.1016/j.cemconres.2025.107792","DOIUrl":"10.1016/j.cemconres.2025.107792","url":null,"abstract":"<div><div>Characterising steel corrosion at the steel-concrete interface and linking it to concrete damage is challenging due to limitations of current non-destructive techniques. This study combines electrical resistance measurements, full-field image-based analyses and analytical techniques to comprehensively characterise steel corrosion and damage in small-scale specimens.</div><div>X-ray and Neutron Computed Tomography of two reinforced mortar samples, before and after accelerated corrosion, were used to examine corrosion morphology, interfacial voids, and estimate volumetric strain in the corrosion layer. Inductively Coupled Plasma Mass Spectrometry was employed to measure iron isotope concentrations in water surrounding the specimens.</div><div>The results revealed delayed transport of corrosion products relative to mortar cracking. The volumetric expansion coefficients of corrosion products (3.84 and 3.90) align with previous research, and the risk of pitting corrosion correlated with the void size. Overall, the measurements obtained through the various techniques closely aligned with visual observations, providing a robust dataset for calibrating corrosion models.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107792"},"PeriodicalIF":10.9,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143056927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-29DOI: 10.1016/j.cemconres.2025.107801
Paulo R. de Matos , José S. Andrade Neto , Carlos E.M. Campos , Ruben Snellings , Robert E. Dinnebier , Ana P. Kirchheim
A comprehensive investigation of the phase composition of eight commercial clinkers was conducted through state-of-the-art synchrotron (SXRD) and laboratory (LXRD) X-ray diffraction, and supporting techniques. Challenges involved in polymorph and minor phase quantification, and the effects of foreign ions on the clinker chemistry were addressed. SXRD yielded higher C3S and lower C2S contents than LXRD, besides higher C3S M3. Visual identification of C3S predominant polymorphs did not always match the Rietveld results for LXRD. Using orthorhombic-C3A in the refinement of samples that did not have this polymorph led to an underestimation of C4AF and α′H-C2S. Axial divergence made the quantification of β-C2S inaccurate for non-monochromatic LXRD. C3S formation was governed by the sulfate/magnesium ratio and Na2Oeq content rather than LSF, while C3S polymorphism was governed by the sulfate/magnesium + alkali ratio. Optimal chemistry ranges were proposed for maximizing C3S formation. C3A polymorphism was generally controlled by the sulfate/alkali ratio.
{"title":"Polymorph and minor phase quantification in Portland clinker by X-ray powder diffraction analysis: Addressing challenges and foreign ion effects","authors":"Paulo R. de Matos , José S. Andrade Neto , Carlos E.M. Campos , Ruben Snellings , Robert E. Dinnebier , Ana P. Kirchheim","doi":"10.1016/j.cemconres.2025.107801","DOIUrl":"10.1016/j.cemconres.2025.107801","url":null,"abstract":"<div><div>A comprehensive investigation of the phase composition of eight commercial clinkers was conducted through state-of-the-art synchrotron (SXRD) and laboratory (LXRD) X-ray diffraction, and supporting techniques. Challenges involved in polymorph and minor phase quantification, and the effects of foreign ions on the clinker chemistry were addressed. SXRD yielded higher C<sub>3</sub>S and lower C<sub>2</sub>S contents than LXRD, besides higher C<sub>3</sub>S M<sub>3</sub>. Visual identification of C<sub>3</sub>S predominant polymorphs did not always match the Rietveld results for LXRD. Using orthorhombic-C<sub>3</sub>A in the refinement of samples that did not have this polymorph led to an underestimation of C<sub>4</sub>AF and α′<sub>H</sub>-C<sub>2</sub>S. Axial divergence made the quantification of β-C<sub>2</sub>S inaccurate for non-monochromatic LXRD. C<sub>3</sub>S formation was governed by the sulfate/magnesium ratio and Na<sub>2</sub>O<sub>eq</sub> content rather than LSF, while C<sub>3</sub>S polymorphism was governed by the sulfate/magnesium + alkali ratio. Optimal chemistry ranges were proposed for maximizing C<sub>3</sub>S formation. C<sub>3</sub>A polymorphism was generally controlled by the sulfate/alkali ratio.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107801"},"PeriodicalIF":10.9,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.cemconres.2025.107808
Weiqiang Guo, Ya Wei
This paper employs the discrete element method (DEM) to simulate the nanoindentation creep of calcium-silicate-hydrate (C-S-H), focusing on indentation deformation, particle interactions, and stress transmission paths. The Rate Process Theory (RPT), previously utilized in the creep modeling of cohesive soils and other granular materials, is proposed to simulate C-S-H creep. Due to the nanometer size of C-S-H particles, the critical time step in DEM simulations is very small. Therefore, a time-scaling algorithm is used to match the DEM simulation time with the physical time in laboratory tests, accelerating the simulation time by a factor of 1 × 108. C-S-H particle assemblies with specific packing densities are generated using Particle Flow Code (PFC3D, version 5.0), with coordination numbers and cohesion forces controlled by the stress-servo of PFC walls. Virtual nanoindentations using a Berkovich indenter are conducted on C-S-H particle assemblies with three different packing densities (0.74, 0.64, and 0.58), followed by parameters calibration. Results show that the DEM + RPT method can capture the scaling relations between the indentation modulus, hardness, and contact creep modulus of C-S-H particle assemblies and the packing density. Furthermore, DEM simulations reveal particle rearrangement under Berkovich and flat-tip indenters, highlighting that different indenter types lead to distinct creep kinetics in C-S-H, with the Berkovich indenters experimentally capturing long-term creep and flat-tip indenters measuring short-term creep.
{"title":"Discrete element modeling on nanoindentation creep behavior of C-S-H under berkovich and flat-tip indenters","authors":"Weiqiang Guo, Ya Wei","doi":"10.1016/j.cemconres.2025.107808","DOIUrl":"10.1016/j.cemconres.2025.107808","url":null,"abstract":"<div><div>This paper employs the discrete element method (DEM) to simulate the nanoindentation creep of calcium-silicate-hydrate (C-S-H), focusing on indentation deformation, particle interactions, and stress transmission paths. The Rate Process Theory (RPT), previously utilized in the creep modeling of cohesive soils and other granular materials, is proposed to simulate C-S-H creep. Due to the nanometer size of C-S-H particles, the critical time step in DEM simulations is very small. Therefore, a time-scaling algorithm is used to match the DEM simulation time with the physical time in laboratory tests, accelerating the simulation time by a factor of 1 × 10<sup>8</sup>. C-S-H particle assemblies with specific packing densities are generated using Particle Flow Code (PFC3D, version 5.0), with coordination numbers and cohesion forces controlled by the stress-servo of PFC walls. Virtual nanoindentations using a Berkovich indenter are conducted on C-S-H particle assemblies with three different packing densities (0.74, 0.64, and 0.58), followed by parameters calibration. Results show that the DEM + RPT method can capture the scaling relations between the indentation modulus, hardness, and contact creep modulus of C-S-H particle assemblies and the packing density. Furthermore, DEM simulations reveal particle rearrangement under Berkovich and flat-tip indenters, highlighting that different indenter types lead to distinct creep kinetics in C-S-H, with the Berkovich indenters experimentally capturing long-term creep and flat-tip indenters measuring short-term creep.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107808"},"PeriodicalIF":10.9,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.cemconres.2025.107810
Bin Zeng , Xumin Zhuang , Shaojie Jia , Wenjin Han , Jingkui Zhong , Liwu Mo , Toshiharu Kishi
Widely used hydration promoters primarily improve the early strength of steel slag supplementary cementitious materials (SCMs) but offer limited enhancement to later strength and fail to mitigate early hydration inhibition by steel slag (SS). This study introduces a novel organic hydration promoter, Triethanolamine-Gallate (TG), synthesized by modifying gallic acid with triethanolamine. TG imparted hydrophobicity to the SS composite cement powder, enhanced fluidity and increased initial and final setting times, and moderated hydration rate but improved overall hydration efficiency of SS composite cement. At 28d, the compressive strength of PS-TG-0.05% (PS was 70% PC and 30% SS) mortar was 21.1% and 13.3% higher than that of PS-Control and PS-TEA-0.05% mortar, respectively. TG promoted the transformation of C3S, C2S, C4AF, Ca2FexAl2-xO5 and CaCO3 into more C-S-H and Mc (monocarboaluminate), especially the new iron-containing Mc. TG also significantly refined the pores and reduced the cumulative pore volume of the SS composite cement.
{"title":"Effects of Triethanolamine-Gallate on the workability, hydration and microstructure of steel slag supplementary cementitious materials","authors":"Bin Zeng , Xumin Zhuang , Shaojie Jia , Wenjin Han , Jingkui Zhong , Liwu Mo , Toshiharu Kishi","doi":"10.1016/j.cemconres.2025.107810","DOIUrl":"10.1016/j.cemconres.2025.107810","url":null,"abstract":"<div><div>Widely used hydration promoters primarily improve the early strength of steel slag supplementary cementitious materials (SCMs) but offer limited enhancement to later strength and fail to mitigate early hydration inhibition by steel slag (SS). This study introduces a novel organic hydration promoter, Triethanolamine-Gallate (TG), synthesized by modifying gallic acid with triethanolamine. TG imparted hydrophobicity to the SS composite cement powder, enhanced fluidity and increased initial and final setting times, and moderated hydration rate but improved overall hydration efficiency of SS composite cement. At 28d, the compressive strength of PS-TG-0.05% (PS was 70% PC and 30% SS) mortar was 21.1% and 13.3% higher than that of PS-Control and PS-TEA-0.05% mortar, respectively. TG promoted the transformation of C<sub>3</sub>S, C<sub>2</sub>S, C<sub>4</sub>AF, Ca<sub>2</sub>Fe<sub>x</sub>Al<sub>2-x</sub>O<sub>5</sub> and CaCO<sub>3</sub> into more C-S-H and Mc (monocarboaluminate), especially the new iron-containing Mc. TG also significantly refined the pores and reduced the cumulative pore volume of the SS composite cement.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107810"},"PeriodicalIF":10.9,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.cemconres.2025.107807
Jiaxin Chen, Johann Plank
Behavior of different PCEs (MPEG (methacrylate ester), HPEG (methallyl ether), EPEG (2-hydroxyethyl poly(ethylene glycol) vinyl ether) based PCE) in NaOH-/Na2SiO3-activated two-part slag binders was investigated. In both activator solutions their solubility follows the order MPEGHPEGEPEG according to “cloud point” method. GPC chromatograms confirmed that at RT all PCEs don't decompose in activator solutions, independent of activator concentration and exposure time (1h/1d). “Mini-slump” tests confirmed the highest dispersing effectiveness of HPEG PCE, and the least for MPEG PCE. No PCE could disperse Na2SiO3-activated slag when PCE was dissolved in mixing water. Adsorption tests demonstrated non-Langmuir behavior in NaOH and almost no adsorption in Na2SiO3 pastes. DLS measurements revealed that in 1–2 M NaOH and 0.25 M Na2SiO3, decreased steric size (Rh) of PCE molecules was noted, indicating the coiling of PCE polymers. At very high activator dosages (3 M NaOH and 1 M Na2SiO3), remarkably increased Rh values due to the agglomeration of several PCE molecules was observed. Apparently, PCE effectiveness in AAS is strongly controlled by its solved conformation in AAS pore solution.
{"title":"Which factors impact the effectiveness of PCEs in alkali-activated slag cements?","authors":"Jiaxin Chen, Johann Plank","doi":"10.1016/j.cemconres.2025.107807","DOIUrl":"10.1016/j.cemconres.2025.107807","url":null,"abstract":"<div><div>Behavior of different PCEs (MPEG (methacrylate ester), HPEG (methallyl ether), EPEG (2-hydroxyethyl poly(ethylene glycol) vinyl ether) based PCE) in NaOH-/Na<sub>2</sub>SiO<sub>3</sub>-activated two-part slag binders was investigated. In both activator solutions their solubility follows the order MPEG<span><math><mo>></mo></math></span>HPEG<span><math><mo>></mo></math></span>EPEG according to “cloud point” method. GPC chromatograms confirmed that at RT all PCEs don't decompose in activator solutions, independent of activator concentration and exposure time (1h/1d). “Mini-slump” tests confirmed the highest dispersing effectiveness of HPEG PCE, and the least for MPEG PCE. No PCE could disperse Na<sub>2</sub>SiO<sub>3</sub>-activated slag when PCE was dissolved in mixing water. Adsorption tests demonstrated non-<em>Langmuir</em> behavior in NaOH and almost no adsorption in Na<sub>2</sub>SiO<sub>3</sub> pastes. DLS measurements revealed that in 1–2 M NaOH and 0.25 M Na<sub>2</sub>SiO<sub>3</sub>, decreased steric size (R<sub>h</sub>) of PCE molecules was noted, indicating the coiling of PCE polymers. At very high activator dosages (3 M NaOH and 1 M Na<sub>2</sub>SiO<sub>3</sub>), remarkably increased R<sub>h</sub> values due to the agglomeration of several PCE molecules was observed. Apparently, PCE effectiveness in AAS is strongly controlled by its solved conformation in AAS pore solution.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107807"},"PeriodicalIF":10.9,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the growing emphasis on reducing CO2 emissions, new hydraulic binders are gaining attention. Understanding the hydration products of these new binders is crucial. This study investigates mixed Al/Fe-CO3 AFm hydrates. This research proposes two methods to synthesize CO3-AFm phases with varying proportions of trivalent Al3+ and Fe3+ cations, followed by a thorough characterization of the samples. Results showed that Al-rich samples crystallized only in the triclinic P1 space group, whereas the Fe-containing CO3-AFm phase crystallized in both the triclinic P1 and trigonal R space groups. A complete solid solution between the two end-members (Ca2Al(OH)6⋅(CO3)0.5⋅2.5H2O and Ca2Fe(OH)6⋅(CO3)0.5⋅2.5H2O) was confirmed with triclinic symmetry, whereas a partial solid solution was observed for the rhombohedral Ca2Al1-xFex(OH)6⋅(CO3)0.5⋅3H2O higher hydrate with ∼0.33 ≤ x ≤ 1. This study enhances the characterization of Al/Fe-mixed CO3-AFm phases that develop during the hydration of binders containing iron and aluminum, offering crucial insights for developing new sustainable construction materials.
{"title":"The monocarbonate Ca2Al1-xFex(OH)6·½CO3·nH2O AFm system","authors":"Aurore Lechevallier , Yunge Bai , Antoine Rochelet , Rodolphe Thirouard , Mohend Chaouche , Evelyne Prat , Jérôme Soudier , Guillaume Renaudin","doi":"10.1016/j.cemconres.2025.107804","DOIUrl":"10.1016/j.cemconres.2025.107804","url":null,"abstract":"<div><div>With the growing emphasis on reducing CO<sub>2</sub> emissions, new hydraulic binders are gaining attention. Understanding the hydration products of these new binders is crucial. This study investigates mixed Al/Fe-CO<sub>3</sub> AFm hydrates. This research proposes two methods to synthesize CO<sub>3</sub>-AFm phases with varying proportions of trivalent Al<sup>3+</sup> and Fe<sup>3+</sup> cations, followed by a thorough characterization of the samples. Results showed that Al-rich samples crystallized only in the triclinic <em>P</em>1 space group, whereas the Fe-containing CO<sub>3</sub>-AFm phase crystallized in both the triclinic <em>P</em>1 and trigonal <em>R</em><span><math><mover><mn>3</mn><mo>¯</mo></mover><mi>c</mi></math></span> space groups. A complete solid solution between the two end-members (Ca<sub>2</sub>Al(OH)<sub>6</sub>⋅(CO<sub>3</sub>)<sub>0.5</sub>⋅2.5H<sub>2</sub>O and Ca<sub>2</sub>Fe(OH)<sub>6</sub>⋅(CO<sub>3</sub>)<sub>0.5</sub>⋅2.5H<sub>2</sub>O) was confirmed with triclinic symmetry, whereas a partial solid solution was observed for the rhombohedral Ca<sub>2</sub>Al<sub>1-<em>x</em></sub>Fe<sub><em>x</em></sub>(OH)<sub>6</sub>⋅(CO<sub>3</sub>)<sub>0.5</sub>⋅3H<sub>2</sub>O higher hydrate with ∼0.33 ≤ <em>x</em> ≤ 1. This study enhances the characterization of Al/Fe-mixed CO<sub>3</sub>-AFm phases that develop during the hydration of binders containing iron and aluminum, offering crucial insights for developing new sustainable construction materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107804"},"PeriodicalIF":10.9,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-18DOI: 10.1016/j.cemconres.2025.107790
Weizheng Shi , Zixiao Wang , Chaoqun Li , Qingya Sun , Weiqiang Wang , Shuxin Deng , Weijin Li , Aming Xie
This work prepares a novel cementitious material with high-temperature strengthening by adding titanium diboride (TiB2) powders into Portland cement. The influences of TiB2 on the physicochemical properties of paste samples before and after high-temperature treatment (the maximum is 900 °C) are investigated. Results indicated that the pore structure of hardened paste is refined after curing because of the filling effects of TiB2 micron powders. During the heating, the ceramic phases are formed from the outer layer to the inner layer in the hardened paste because of the high-temperature oxidability of TiB2, strengthening the matrix significantly (the highest compressive strength value increase is about 55.2% compared to the initial value). A random forest algorithm model analyses the contributions of matrix compositions and porosity on the compressive strength of hardened paste. The potential reaction mechanisms among the TiB2 and the main hydrates at high temperatures are suggested.
{"title":"High-temperature strengthening of Portland cementitious materials by surface micro-ceramization","authors":"Weizheng Shi , Zixiao Wang , Chaoqun Li , Qingya Sun , Weiqiang Wang , Shuxin Deng , Weijin Li , Aming Xie","doi":"10.1016/j.cemconres.2025.107790","DOIUrl":"10.1016/j.cemconres.2025.107790","url":null,"abstract":"<div><div>This work prepares a novel cementitious material with high-temperature strengthening by adding titanium diboride (TiB<sub>2</sub>) powders into Portland cement. The influences of TiB<sub>2</sub> on the physicochemical properties of paste samples before and after high-temperature treatment (the maximum is 900 °C) are investigated. Results indicated that the pore structure of hardened paste is refined after curing because of the filling effects of TiB<sub>2</sub> micron powders. During the heating, the ceramic phases are formed from the outer layer to the inner layer in the hardened paste because of the high-temperature oxidability of TiB<sub>2</sub>, strengthening the matrix significantly (the highest compressive strength value increase is about 55.2% compared to the initial value). A random forest algorithm model analyses the contributions of matrix compositions and porosity on the compressive strength of hardened paste. The potential reaction mechanisms among the TiB<sub>2</sub> and the main hydrates at high temperatures are suggested.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107790"},"PeriodicalIF":10.9,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1016/j.cemconres.2025.107782
Yufeng Song , Jiaze Wang , Yinjie Huang , Jiawen Wang , Yitian Weng , Rui Ma , Kevin Seng Hong Pang , Shaoqin Ruan
This study explores the influence of incorporating recycled aggregate (RA) and CO2-pretreated recycled aggregate (CRA) in reactive magnesia concrete (RMC) formulations. Through comprehensive microscopic characterizations, the phase composition, carbonation degree, pore structure, and interfacial transition zone (ITZ) characteristics are examined in both interior and exterior regions of specimens. The findings highlight that RA and CRA contribute to a 28 d strength in RMC formulations 14% and 25% higher than that with NA, respectively. This enhancement is attributed to internal curing and significantly increased channels for CO2 diffusion within (C)RA specimens, leading to improvements in the modulus, hardness, and microstructures of the interior region—the traditionally weaker part in RMC-based concrete. Furthermore, a robust linear correlation is observed between ITZ characteristics, porosity, and compressive strength of CO2-cured specimens. Finally, utilizing different grades of RA improves the performance of RMC-based concrete to varying degrees while reducing costs, thus potentially expanding the application of RA in practical RMC-based concrete scenarios, regardless of RA quality.
{"title":"Effects of varying grades/pretreatments of recycled aggregates on the development of pore structures and ITZs within reactive magnesia cement (RMC) concrete","authors":"Yufeng Song , Jiaze Wang , Yinjie Huang , Jiawen Wang , Yitian Weng , Rui Ma , Kevin Seng Hong Pang , Shaoqin Ruan","doi":"10.1016/j.cemconres.2025.107782","DOIUrl":"10.1016/j.cemconres.2025.107782","url":null,"abstract":"<div><div>This study explores the influence of incorporating recycled aggregate (RA) and CO<sub>2</sub>-pretreated recycled aggregate (CRA) in reactive magnesia concrete (RMC) formulations. Through comprehensive microscopic characterizations, the phase composition, carbonation degree, pore structure, and interfacial transition zone (ITZ) characteristics are examined in both interior and exterior regions of specimens. The findings highlight that RA and CRA contribute to a 28 d strength in RMC formulations 14% and 25% higher than that with NA, respectively. This enhancement is attributed to internal curing and significantly increased channels for CO<sub>2</sub> diffusion within (C)RA specimens, leading to improvements in the modulus, hardness, and microstructures of the interior region—the traditionally weaker part in RMC-based concrete. Furthermore, a robust linear correlation is observed between ITZ characteristics, porosity, and compressive strength of CO<sub>2</sub>-cured specimens. Finally, utilizing different grades of RA improves the performance of RMC-based concrete to varying degrees while reducing costs, thus potentially expanding the application of RA in practical RMC-based concrete scenarios, regardless of RA quality.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"190 ","pages":"Article 107782"},"PeriodicalIF":10.9,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1016/j.cemconres.2025.107787
Tillmann Schramm, Jürgen Neubauer, Friedlinde Goetz-Neunhoeffer
{"title":"Corrigendum to “Influence of silica fume addition and content on the early hydration of calcium aluminate cement — The role of soluble silicon” [Cem. Concr. Res. 184 (2024) 107618]","authors":"Tillmann Schramm, Jürgen Neubauer, Friedlinde Goetz-Neunhoeffer","doi":"10.1016/j.cemconres.2025.107787","DOIUrl":"10.1016/j.cemconres.2025.107787","url":null,"abstract":"","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107787"},"PeriodicalIF":10.9,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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