Pub Date : 2025-09-16DOI: 10.1016/j.cemconres.2025.108042
Fangmin Shen , Guojian Liu , Yunsheng Zhang , Cheng Liu
Sulfate attack can impair the chloride-binding capacity of Friedel's salt (FS) in cementitious materials by inducing the release of its bound chloride ions (Cl−). However, the atomic-level understanding of this reaction remains unclear. In this study, ab initio molecular dynamics (AIMD) is employed to elucidate the molecular-scale exchange kinetics of SO₄2−/Cl− at the FS/sulfate solution interface. The results demonstrate that SO₄2− weakens both the electrostatic binding of Cl− to the [Ca₂Al(OH)₆]+ layer and its hydrogen bonding with water in the [Cl·2H₂O]− layer through charge redistribution effect, thereby facilitating Cl− release and subsequent SO₄2− substitution. Furthermore, the dynamic reconstruction of hydrogen bond (H-bond) network within the FS anion-binding layer is a critical mechanism for interfacial restabilization after anion exchange. First-principles calculations confirm the significant thermodynamic spontaneity of the SO₄2−/Cl− exchange, highlighting both the ionic competitive advantage and binding stability of SO₄2−.
{"title":"Molecular insights into sulfate-induced chloride release from Friedel's salt","authors":"Fangmin Shen , Guojian Liu , Yunsheng Zhang , Cheng Liu","doi":"10.1016/j.cemconres.2025.108042","DOIUrl":"10.1016/j.cemconres.2025.108042","url":null,"abstract":"<div><div>Sulfate attack can impair the chloride-binding capacity of Friedel's salt (FS) in cementitious materials by inducing the release of its bound chloride ions (Cl<sup>−</sup>). However, the atomic-level understanding of this reaction remains unclear. In this study, ab initio molecular dynamics (AIMD) is employed to elucidate the molecular-scale exchange kinetics of SO₄<sup>2−</sup>/Cl<sup>−</sup> at the FS/sulfate solution interface. The results demonstrate that SO₄<sup>2−</sup> weakens both the electrostatic binding of Cl<sup>−</sup> to the [Ca₂Al(OH)₆]<sup>+</sup> layer and its hydrogen bonding with water in the [Cl·2H₂O]<sup>−</sup> layer through charge redistribution effect, thereby facilitating Cl<sup>−</sup> release and subsequent SO₄<sup>2−</sup> substitution. Furthermore, the dynamic reconstruction of hydrogen bond (H-bond) network within the FS anion-binding layer is a critical mechanism for interfacial restabilization after anion exchange. First-principles calculations confirm the significant thermodynamic spontaneity of the SO₄<sup>2−</sup>/Cl<sup>−</sup> exchange, highlighting both the ionic competitive advantage and binding stability of SO₄<sup>2−</sup>.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108042"},"PeriodicalIF":13.1,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145067799","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 : 2025-09-16DOI: 10.1016/j.cemconres.2025.108038
Julian L. Stapper , Quin R.S. Miller , Russell L. Detwiler , Mohammad Javad Abdolhosseini Qomi
Belite-rich cement is a promising low-carbon material, yet the limited hydraulic reactivity of its primary component, dicalcium silicate (-Ca2SiO4), still poses a challenge. This study introduces a new approach to examining the reaction kinetics and acceleration strategies for low-reactivity materials like -Ca2SiO4 using quasi in situ X-ray diffraction (XRD). By simultaneously analyzing pre-cured and fresh samples, the method reduces measurement time at the expense of lowering temporal resolution. Applying this technique to hydrating -Ca2SiO4 pastes from 21 to 80 °C provides insight into the underlying temperature-dependent dissolution process and its apparent activation energy (AAE). The estimated AAE of 49 ± 3 kJ/mol aligns with existing data and supports the view that the rate-limiting step of belite hydration may change based on the physical properties of the material. By offering phase-specific and time-resolved data, this method serves as a useful tool in devising science-informed strategies to accelerate hydration of belite-rich cements.
{"title":"Quantifying the effect of temperature on belite hydration kinetics through quasi in situ XRD","authors":"Julian L. Stapper , Quin R.S. Miller , Russell L. Detwiler , Mohammad Javad Abdolhosseini Qomi","doi":"10.1016/j.cemconres.2025.108038","DOIUrl":"10.1016/j.cemconres.2025.108038","url":null,"abstract":"<div><div>Belite-rich cement is a promising low-carbon material, yet the limited hydraulic reactivity of its primary component, dicalcium silicate (<span><math><mi>β</mi></math></span>-Ca<sub>2</sub>SiO<sub>4</sub>), still poses a challenge. This study introduces a new approach to examining the reaction kinetics and acceleration strategies for low-reactivity materials like <span><math><mi>β</mi></math></span>-Ca<sub>2</sub>SiO<sub>4</sub> using <em>quasi in situ</em> X-ray diffraction (XRD). By simultaneously analyzing pre-cured and fresh samples, the method reduces measurement time at the expense of lowering temporal resolution. Applying this technique to hydrating <span><math><mi>β</mi></math></span>-Ca<sub>2</sub>SiO<sub>4</sub> pastes from 21 to 80 °C provides insight into the underlying temperature-dependent dissolution process and its apparent activation energy (AAE). The estimated AAE of 49 ± 3 kJ/mol aligns with existing data and supports the view that the rate-limiting step of belite hydration may change based on the physical properties of the material. By offering phase-specific and time-resolved data, this method serves as a useful tool in devising science-informed strategies to accelerate hydration of belite-rich cements.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108038"},"PeriodicalIF":13.1,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145072128","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 : 2025-09-15DOI: 10.1016/j.cemconres.2025.108041
Xingdong Lv , Zhuofan Gao , Lu Yang , Fazhou Wang
This paper investigated the inhibition effects and mechanisms of organic phosphonic acids (OPAs) with distinct functional groups on triclinic tricalcium silicate (C3S) clinker hydration. In particular, the effects of three representative OPAs, namely ATMP, HEDP, and PBTC on adsorption/complexation behavior, hydration products, and microstructure characteristics of C3S clinker were studied. OPAs retardation of the C3S clinker hydration was governed by synergistic interactions of electrostatic adsorption, and cationic complexation, potentially involving intermolecular self-polycondensation. ATMP primarily relied on Ca2+ complexation through its [–C-PO(OH)2] groups, forming low-solubility precipitates that inhibited hydration. HEDP combined strong complexation with intermolecular self-polycondensation, driven by its [–C–PO(OH)2] and (–OH) groups, generating dense three-dimensional polymers that enhanced steric hindrance, while PBTC operated through surface adsorption and self-polycondensation. The revealed retardation efficiency hierarchy (HEDP > PBTC > ATMP) arose from functional group synergy: the maximal inhibition was provided by synergy of [–C–PO(OH)2] and (–OH) groups, a weaker one-by that of [–C–PO(OH)2] and (–COOH) groups, while isolated [–C–PO(OH)2] groups had the minimal retarding capacity.
{"title":"Retardation mechanisms and microstructure evolution of triclinic tricalcium silicate induced by three different organic phosphonic acids","authors":"Xingdong Lv , Zhuofan Gao , Lu Yang , Fazhou Wang","doi":"10.1016/j.cemconres.2025.108041","DOIUrl":"10.1016/j.cemconres.2025.108041","url":null,"abstract":"<div><div>This paper investigated the inhibition effects and mechanisms of organic phosphonic acids (OPAs) with distinct functional groups on triclinic tricalcium silicate (C<sub>3</sub>S) clinker hydration. In particular, the effects of three representative OPAs, namely ATMP, HEDP, and PBTC on adsorption/complexation behavior, hydration products, and microstructure characteristics of C<sub>3</sub>S clinker were studied. OPAs retardation of the C<sub>3</sub>S clinker hydration was governed by synergistic interactions of electrostatic adsorption, and cationic complexation, potentially involving intermolecular self-polycondensation. ATMP primarily relied on Ca<sup>2+</sup> complexation through its [–C-PO(OH)<sub>2</sub>] groups, forming low-solubility precipitates that inhibited hydration. HEDP combined strong complexation with intermolecular self-polycondensation, driven by its [–C–PO(OH)<sub>2</sub>] and (–OH) groups, generating dense three-dimensional polymers that enhanced steric hindrance, while PBTC operated through surface adsorption and self-polycondensation. The revealed retardation efficiency hierarchy (HEDP > PBTC > ATMP) arose from functional group synergy: the maximal inhibition was provided by synergy of [–C–PO(OH)<sub>2</sub>] and (–OH) groups, a weaker one-by that of [–C–PO(OH)<sub>2</sub>] and (–COOH) groups, while isolated [–C–PO(OH)<sub>2</sub>] groups had the minimal retarding capacity.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108041"},"PeriodicalIF":13.1,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060019","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 : 2025-09-15DOI: 10.1016/j.cemconres.2025.108039
Zhenghao Li , Jing Yu , Jiajia Zhou , Christopher K.Y. Leung
The meso-level pore structure of Strain-Hardening/Engineered Cementitious Composites (SHCC/ECC) critically governs cracking strength distribution, and consequently the tensile performance. While pore distributions are typically attributed to matrix flowability, this relationship remains rarely quantified for SHCC. This study addresses this gap by linking material processing parameters, realistic pore structures, and tensile cracking behaviors of SHCC. Using X-ray computed tomography (X-CT), the 3D meso-level pore information (including porosity, size distribution, shape factors, and spatial distribution) of SHCC specimens was analyzed and correlated with matrix flowabilities. Mechanisms governing pore formation during mixing and casting were discussed. A statistically derived correlation between meso-level pore structures and matrix flowability was established and applied to predict cracking strength distributions. This correlation demonstrated improved agreement with experimental results over conventional methods. These findings advance the modeling and optimization of SHCC by providing a quantitative framework to account for matrix flowability effects.
{"title":"Meso-level pore structures of Strain-Hardening Cementitious Composites (SHCC): Correlation with matrix flowability and application in micromechanical modeling","authors":"Zhenghao Li , Jing Yu , Jiajia Zhou , Christopher K.Y. Leung","doi":"10.1016/j.cemconres.2025.108039","DOIUrl":"10.1016/j.cemconres.2025.108039","url":null,"abstract":"<div><div>The meso-level pore structure of Strain-Hardening/Engineered Cementitious Composites (SHCC/ECC) critically governs cracking strength distribution, and consequently the tensile performance. While pore distributions are typically attributed to matrix flowability, this relationship remains rarely quantified for SHCC. This study addresses this gap by linking material processing parameters, realistic pore structures, and tensile cracking behaviors of SHCC. Using X-ray computed tomography (X-CT), the 3D meso-level pore information (including porosity, size distribution, shape factors, and spatial distribution) of SHCC specimens was analyzed and correlated with matrix flowabilities. Mechanisms governing pore formation during mixing and casting were discussed. A statistically derived correlation between meso-level pore structures and matrix flowability was established and applied to predict cracking strength distributions. This correlation demonstrated improved agreement with experimental results over conventional methods. These findings advance the modeling and optimization of SHCC by providing a quantitative framework to account for matrix flowability effects.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108039"},"PeriodicalIF":13.1,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145067798","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 : 2025-09-14DOI: 10.1016/j.cemconres.2025.108030
Karam Mawas, Mehdi Maboudi, Markus Gerke
Given the substantial growth in the use of additive manufacturing in construction (AMC), it is necessary to ensure the quality of printed specimens, which can be much more complex than conventionally manufactured parts. This study examines the various aspects of geometry and surface quality control in 3D concrete printing (3DCP), with a particular emphasis on deposition-based methods, specifically extrusion and shotcrete 3D printing (SC3DP). A comprehensive overview of existing quality control (QC) methods and strategies is provided and preceded by an in-depth discussion. Four categories of data capture technologies are investigated and their advantages and limitations in the context of AMC are discussed. Additionally, the effects of environmental conditions and the properties of objects on data capture are also analyzed. The study extends to automated data capture planning methods for different sensors. Furthermore, various quality control strategies are explored across different stages of the fabrication cycle of the printed object including: (i) During printing, (ii) Layer-wise, (iii) Pre-assembly, and (iv) Assembly. In addition to reviewing the methods already applied in AMC, we also address various research gaps and future trends and highlight potential methodologies from adjacent domains that could be transferred to AMC.
{"title":"A review on geometry and surface inspection in 3D concrete printing","authors":"Karam Mawas, Mehdi Maboudi, Markus Gerke","doi":"10.1016/j.cemconres.2025.108030","DOIUrl":"10.1016/j.cemconres.2025.108030","url":null,"abstract":"<div><div>Given the substantial growth in the use of additive manufacturing in construction (AMC), it is necessary to ensure the quality of printed specimens, which can be much more complex than conventionally manufactured parts. This study examines the various aspects of geometry and surface quality control in 3D concrete printing (3DCP), with a particular emphasis on deposition-based methods, specifically extrusion and shotcrete 3D printing (SC3DP). A comprehensive overview of existing quality control (QC) methods and strategies is provided and preceded by an in-depth discussion. Four categories of data capture technologies are investigated and their advantages and limitations in the context of AMC are discussed. Additionally, the effects of environmental conditions and the properties of objects on data capture are also analyzed. The study extends to automated data capture planning methods for different sensors. Furthermore, various quality control strategies are explored across different stages of the fabrication cycle of the printed object including: (i) During printing, (ii) Layer-wise, (iii) Pre-assembly, and (iv) Assembly. In addition to reviewing the methods already applied in AMC, we also address various research gaps and future trends and highlight potential methodologies from adjacent domains that could be transferred to AMC.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108030"},"PeriodicalIF":13.1,"publicationDate":"2025-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057199","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 : 2025-09-12DOI: 10.1016/j.cemconres.2025.108034
Yanjie Tang , Katrin Schollbach , Zixing Liu , Sieger van der Laan , Wei Chen , H.J.H. Brouwers
This study investigates the hydration behavior of basic oxygen furnace (BOF) slag in phosphate solutions across different pH levels, focusing on hydration kinetics, microstructure, and strength development. Acidic phosphate solutions trigger rapid dissolution via acid-base reactions, resulting in lower heat release, while alkaline phosphates promote sustained dissolution-precipitation reactions, prolonging hydration and increasing cumulative heat. The buffering effect of H2PO4−/HPO42− prolongs induction periods and inhibits hydrogarnet and layered double hydroxides (LDHs) formation. At early stages, C2S hydration is more pronounced in acidic solutions, whereas higher pH enhances late-stage hydration of C2S, brownmillerite, and wuestite, forming C-S-H, hydrogarnet, and LDHs. Despite similar porosities (11.9–13.9 %), strengths vary from 37.7 to 66.9 MPa due to a higher proportion of capillary pores and a larger average pore size at a low pH (pH at 4.2). The findings support using phosphate-rich wastewater to activate BOF slag, reducing phosphate discharge while developing low-carbon, cement-free binders.
{"title":"Phosphate-activated basic oxygen furnace (BOF) slag: Understanding pH-driven hydration and strength development","authors":"Yanjie Tang , Katrin Schollbach , Zixing Liu , Sieger van der Laan , Wei Chen , H.J.H. Brouwers","doi":"10.1016/j.cemconres.2025.108034","DOIUrl":"10.1016/j.cemconres.2025.108034","url":null,"abstract":"<div><div>This study investigates the hydration behavior of basic oxygen furnace (BOF) slag in phosphate solutions across different pH levels, focusing on hydration kinetics, microstructure, and strength development. Acidic phosphate solutions trigger rapid dissolution via acid-base reactions, resulting in lower heat release, while alkaline phosphates promote sustained dissolution-precipitation reactions, prolonging hydration and increasing cumulative heat. The buffering effect of H<sub>2</sub>PO<sub>4</sub><sup>−</sup>/HPO<sub>4</sub><sup>2−</sup> prolongs induction periods and inhibits hydrogarnet and layered double hydroxides (LDHs) formation. At early stages, C<sub>2</sub>S hydration is more pronounced in acidic solutions, whereas higher pH enhances late-stage hydration of C<sub>2</sub>S, brownmillerite, and wuestite, forming C-S-H, hydrogarnet, and LDHs. Despite similar porosities (11.9–13.9 %), strengths vary from 37.7 to 66.9 MPa due to a higher proportion of capillary pores and a larger average pore size at a low pH (pH at 4.2). The findings support using phosphate-rich wastewater to activate BOF slag, reducing phosphate discharge while developing low-carbon, cement-free binders.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108034"},"PeriodicalIF":13.1,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043000","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 : 2025-09-10DOI: 10.1016/j.cemconres.2025.108031
Shengnan Sha, Yuliang Wang, Hailong Ye
The presence of montmorillonite (MMT) as an impurity in aggregates and limestone diminishes the plasticization efficacy of polycarboxylate ether (PCE) superplasticizers in fresh cement pastes. Despite extensive research efforts to elucidate the mechanisms behind the reduced efficacy of PCE in cementitious systems with MMT and to design tailored PCE molecules with enhanced MMT tolerance, quantitative insights into PCE behavior, specifically surface adsorption and intercalation, within cement pastes containing MMT remain ambiguous. In this work, a delayed addition method was employed to investigate how two PCEs with different side-chain lengths (P-1000 and P-3000) influence the flowability of cement-MMT pastes through quantification of their adsorption and intercalation behavior. The results indicate that approximately 1 g of MMT necessitates an additional 3 g of water to achieve the equivalent fluidity as the plain mixture without MMT. The maximum adsorption of PCE on MMT in cement-MMT pastes was approximately 35 mg/g, below the threshold (∼40 mg/g) required for intercalation. This demonstrates that the reduction in fluidity primarily arises from the extensive surface adsorption driven by the high specific surface area of MMT, which decreases the availability of PCE for effective dispersion of cement particles.
蒙脱土（MMT）作为杂质存在于骨料和石灰石中，降低了聚羧酸酯醚（PCE）高效减水剂在新鲜水泥浆中的增塑效果。尽管进行了大量的研究，以阐明PCE在含MMT的胶凝体系中效率降低的机制，并设计出具有增强MMT耐受性的定制PCE分子，但在含MMT的水泥浆中，PCE行为的定量分析，特别是表面吸附和插层，仍然不明确。在这项工作中，通过量化两种不同侧链长度的pce （P-1000和P-3000）的吸附和插层行为，采用延迟添加方法研究了它们如何影响水泥- mmt膏体的流动性。结果表明，大约1 g MMT需要额外的3 g水才能达到与不加MMT的普通混合物相当的流动性。水泥-MMT膏体中PCE在MMT上的最大吸附量约为35 mg/g，低于插入所需的阈值（~ 40 mg/g）。这表明流动性的降低主要是由MMT的高比表面积驱动的广泛表面吸附引起的，这降低了PCE对水泥颗粒有效分散的可用性。
{"title":"Quantifying the impact of montmorillonite on water demand and polycarboxylate superplasticizer efficiency in cement pastes","authors":"Shengnan Sha, Yuliang Wang, Hailong Ye","doi":"10.1016/j.cemconres.2025.108031","DOIUrl":"10.1016/j.cemconres.2025.108031","url":null,"abstract":"<div><div>The presence of montmorillonite (MMT) as an impurity in aggregates and limestone diminishes the plasticization efficacy of polycarboxylate ether (PCE) superplasticizers in fresh cement pastes. Despite extensive research efforts to elucidate the mechanisms behind the reduced efficacy of PCE in cementitious systems with MMT and to design tailored PCE molecules with enhanced MMT tolerance, quantitative insights into PCE behavior, specifically surface adsorption and intercalation, within cement pastes containing MMT remain ambiguous. In this work, a delayed addition method was employed to investigate how two PCEs with different side-chain lengths (P-1000 and P-3000) influence the flowability of cement-MMT pastes through quantification of their adsorption and intercalation behavior. The results indicate that approximately 1 g of MMT necessitates an additional 3 g of water to achieve the equivalent fluidity as the plain mixture without MMT. The maximum adsorption of PCE on MMT in cement-MMT pastes was approximately 35 mg/g, below the threshold (∼40 mg/g) required for intercalation. This demonstrates that the reduction in fluidity primarily arises from the extensive surface adsorption driven by the high specific surface area of MMT, which decreases the availability of PCE for effective dispersion of cement particles.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108031"},"PeriodicalIF":13.1,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145026712","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 : 2025-09-05DOI: 10.1016/j.cemconres.2025.108033
Pascal Boustingorry
Thixotropy, the property of a fluid to decrease in apparent viscosity under stress and recover its viscosity upon stress relief with observable kinetics, is a crucial characteristic in the behavior of cement pastes in addition to plasticity - the presence of a yield stress, or shear-thinning. This phenomenon has significant implications for the workability, stability, and overall performance of cement-based materials. Understanding thixotropy in cement pastes is particularly important for optimizing the placement and finishing processes in concrete construction, as well as for the development of advanced materials with tailored rheological properties. From concrete placement to additive manufacturing, it is an influential feature of cementitious pastes that scales up to the full-scale material. While numerous studies linked the admixture adsorption kinetics to the slump evolution, this paper aims at illustrating how thixotropy and structural buildup kinetics are affected. A first result of the present work on adsorption is that full superplasticizer consumption is observed at low dosages and beyond five minutes of observation, which does neither correspond to polymer capture by early hydrates nor comply to Langmuir-like mechanisms. Simultaneously to adsorption measurements, rheology flow curves were acquired and modeled according to a simple framework based on a time-evolving structural parameter. The fitted model parameters were then compared to the adsorbed amounts over time. The observations show that after the moment of full polymer consumption, structural buildup strongly accelerates while the ultimate dispersion state of the suspensions drops sharply. On the other hand, as long as enough polymer remains in solution to fuel further adsorption, the ultimate dispersion degree is high and structural buildup remains slow. This work sheds a different light on the role of superplasticizers, which behave as thixotropy-mitigators as much as pure dispersants through their adsorption kinetics.
{"title":"Free superplasticizer concentration is a key influencer of the instantaneous thixotropy rates of cementitious pastes","authors":"Pascal Boustingorry","doi":"10.1016/j.cemconres.2025.108033","DOIUrl":"10.1016/j.cemconres.2025.108033","url":null,"abstract":"<div><div>Thixotropy, the property of a fluid to decrease in apparent viscosity under stress and recover its viscosity upon stress relief with observable kinetics, is a crucial characteristic in the behavior of cement pastes in addition to plasticity - the presence of a yield stress, or shear-thinning. This phenomenon has significant implications for the workability, stability, and overall performance of cement-based materials. Understanding thixotropy in cement pastes is particularly important for optimizing the placement and finishing processes in concrete construction, as well as for the development of advanced materials with tailored rheological properties. From concrete placement to additive manufacturing, it is an influential feature of cementitious pastes that scales up to the full-scale material. While numerous studies linked the admixture adsorption kinetics to the slump evolution, this paper aims at illustrating how thixotropy and structural buildup kinetics are affected. A first result of the present work on adsorption is that full superplasticizer consumption is observed at low dosages and beyond five minutes of observation, which does neither correspond to polymer capture by early hydrates nor comply to Langmuir-like mechanisms. Simultaneously to adsorption measurements, rheology flow curves were acquired and modeled according to a simple framework based on a time-evolving structural parameter. The fitted model parameters were then compared to the adsorbed amounts over time. The observations show that after the moment of full polymer consumption, structural buildup strongly accelerates while the ultimate dispersion state of the suspensions drops sharply. On the other hand, as long as enough polymer remains in solution to fuel further adsorption, the ultimate dispersion degree is high and structural buildup remains slow. This work sheds a different light on the role of superplasticizers, which behave as thixotropy-mitigators as much as pure dispersants through their adsorption kinetics.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108033"},"PeriodicalIF":13.1,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996049","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 : 2025-09-04DOI: 10.1016/j.cemconres.2025.108029
Jianhui He , Mai Zhang , Zhenbin Lei , Ji Liu , Yulian Deng , Jinhai Lu , Lu Yang , Fazhou Wang
High ferrite Portland cement (HFPC), a low-carbon alternative to ordinary Portland cement with reduced C3S and C3A alongside elevated C4AF and C2S, exhibits insufficient early- and mid-term strength development due to sluggish hydration kinetics. To address this limitation, the synergistic effects of Q phase (Ca20Al26Mg3Si3O68) clinker (0–12 wt%) and gypsum (0–8 wt%) on the hydration regulation, mechanical properties and microstructure evolution of HFPC were systematically investigated. Results demonstrate that a hybrid formulation containing 6 wt% Q phase clinker and 4 wt% gypsum achieves a 1-day compressive strength comparable to pure HFPC while significantly enhancing the 28-day strength to over 90 MPa. Gypsum addition was found to mitigate the early-stage hydration retardation induced by Q phase, primarily by promoting the nucleation and stabilization of ettringite. This synergy elongates C-(A-)S-H chains and enhances chloride binding than HFPC, with concurrent porosity reduction and pore size distribution homogenization collectively boosting mechanical and durability performance.
{"title":"High ferrite Portland cement: Synergistic influence of Q phase and gypsum on hydration kinetics","authors":"Jianhui He , Mai Zhang , Zhenbin Lei , Ji Liu , Yulian Deng , Jinhai Lu , Lu Yang , Fazhou Wang","doi":"10.1016/j.cemconres.2025.108029","DOIUrl":"10.1016/j.cemconres.2025.108029","url":null,"abstract":"<div><div>High ferrite Portland cement (HFPC), a low-carbon alternative to ordinary Portland cement with reduced C<sub>3</sub>S and C<sub>3</sub>A alongside elevated C<sub>4</sub>AF and C<sub>2</sub>S, exhibits insufficient early- and mid-term strength development due to sluggish hydration kinetics. To address this limitation, the synergistic effects of Q phase (Ca<sub>20</sub>Al<sub>26</sub>Mg<sub>3</sub>Si<sub>3</sub>O<sub>68</sub>) clinker (0–12 wt%) and gypsum (0–8 wt%) on the hydration regulation, mechanical properties and microstructure evolution of HFPC were systematically investigated. Results demonstrate that a hybrid formulation containing 6 wt% Q phase clinker and 4 wt% gypsum achieves a 1-day compressive strength comparable to pure HFPC while significantly enhancing the 28-day strength to over 90 MPa. Gypsum addition was found to mitigate the early-stage hydration retardation induced by Q phase, primarily by promoting the nucleation and stabilization of ettringite. This synergy elongates C-(A-)S-H chains and enhances chloride binding than HFPC, with concurrent porosity reduction and pore size distribution homogenization collectively boosting mechanical and durability performance.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108029"},"PeriodicalIF":13.1,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144987700","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 : 2025-09-04DOI: 10.1016/j.cemconres.2025.108032
Hongqian Lian , Tao Ding
Current extrusion-based 3D printing technologies for concrete are ill suited for constructing complex geometric structures featuring curved or inclined surfaces. In this study, one 3D concrete printing model based on computational fluid dynamics (CFD) was established. The concrete fluid model was simulated via the Bingham rheological model. After validating the model's accuracy through experimental data, the effects of variables such as the inclination angle, printing speed, and layer height on the deformation of 3D printed concrete structures with inclined angles was investigated. Our findings reveal that both the layer height and inclination angle exert the most significant influence on the deformation and stability of concrete structures, whereas increasing the printing speed exacerbates deformation. Within the parameter range explored in this study, an increase in the inclination angle markedly enhances the deformation of the concrete structure. Furthermore, reducing the layer height substantially mitigates deformation and improves structural stability.
{"title":"Deformation of inclined concrete 3D printing: A computational fluid dynamics analysis","authors":"Hongqian Lian , Tao Ding","doi":"10.1016/j.cemconres.2025.108032","DOIUrl":"10.1016/j.cemconres.2025.108032","url":null,"abstract":"<div><div>Current extrusion-based 3D printing technologies for concrete are ill suited for constructing complex geometric structures featuring curved or inclined surfaces. In this study, one 3D concrete printing model based on computational fluid dynamics (CFD) was established. The concrete fluid model was simulated via the Bingham rheological model. After validating the model's accuracy through experimental data, the effects of variables such as the inclination angle, printing speed, and layer height on the deformation of 3D printed concrete structures with inclined angles was investigated. Our findings reveal that both the layer height and inclination angle exert the most significant influence on the deformation and stability of concrete structures, whereas increasing the printing speed exacerbates deformation. Within the parameter range explored in this study, an increase in the inclination angle markedly enhances the deformation of the concrete structure. Furthermore, reducing the layer height substantially mitigates deformation and improves structural stability.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"199 ","pages":"Article 108032"},"PeriodicalIF":13.1,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144987636","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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