Pub Date : 2025-04-13DOI: 10.1016/j.cemconres.2025.107899
Samuel De Carvalho Gomes , Quang Dieu Nguyen , Wengui Li , Arnaud Castel
This research investigates the influence of alkaline concentration and calcium content on the shrinkage mechanisms, carbonation resistance and reinforcement corrosion of alkali-activated concrete system composed of calcined clay and ground granulated blast furnace slag (GGBFS). An increase in Na2O% led to an improvement in the mechanical performance, pore structure refinement, reducing both accelerated and natural carbonation. However, the increase in alkaline concentration generated a greater shrinkage for mixtures with a higher proportion of GGBFS; the opposite was observed for mixtures with calcined clay as the dominant precursor. The results of 1-year of total shrinkage shows that the concrete containing high calcined clay and Na2O contents demonstrated the best performance. Importantly, there was no evidence of reinforcement corrosion observed after the carbonation front had reached the steel-concrete interface following 2 % CO2 accelerated carbonation exposure. This was attributed to the high pH values measured in the carbonated region of the alkali-activated concrete.
{"title":"Shrinkage and carbonation of alkali-activated calcined clay-ground granulated blast furnace slag (GGBFS) concrete","authors":"Samuel De Carvalho Gomes , Quang Dieu Nguyen , Wengui Li , Arnaud Castel","doi":"10.1016/j.cemconres.2025.107899","DOIUrl":"10.1016/j.cemconres.2025.107899","url":null,"abstract":"<div><div>This research investigates the influence of alkaline concentration and calcium content on the shrinkage mechanisms, carbonation resistance and reinforcement corrosion of alkali-activated concrete system composed of calcined clay and ground granulated blast furnace slag (GGBFS). An increase in Na<sub>2</sub>O% led to an improvement in the mechanical performance, pore structure refinement, reducing both accelerated and natural carbonation. However, the increase in alkaline concentration generated a greater shrinkage for mixtures with a higher proportion of GGBFS; the opposite was observed for mixtures with calcined clay as the dominant precursor. The results of 1-year of total shrinkage shows that the concrete containing high calcined clay and Na<sub>2</sub>O contents demonstrated the best performance. Importantly, there was no evidence of reinforcement corrosion observed after the carbonation front had reached the steel-concrete interface following 2 % CO<sub>2</sub> accelerated carbonation exposure. This was attributed to the high pH values measured in the carbonated region of the alkali-activated concrete.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107899"},"PeriodicalIF":10.9,"publicationDate":"2025-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824006","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 : 2025-04-12DOI: 10.1016/j.cemconres.2025.107895
Jae Hong Kim , In Kuk Kang , Tae Yong Shin , Chan Kyu Park
An automated experimental system enables precise evaluation of cement dispersant performance through rheological measurements of 230 mL mortar samples. Analysis of 129 mortar samples demonstrated comprehensive characterization of dispersant effects beyond traditional manual testing capabilities. Principal component analysis revealed distinct patterns in torque measurements, explaining the variance of the pattern and effectively capturing dispersant performance differences. The automated system achieved superior reproducibility with 7% coefficient of variance, which can be considered as the inherent variation of materials. Observation-informed learning extended the system's utility, successfully predicting flow and bleeding rate. Results confirmed superior performance of third-generation polycarboxylate dispersants while providing new insights into dosage-rheology relationships. This automated approach establishes a framework for more efficient and comprehensive evaluation of cement-based materials.
{"title":"Automated experimentation for evaluating cement dispersant performance","authors":"Jae Hong Kim , In Kuk Kang , Tae Yong Shin , Chan Kyu Park","doi":"10.1016/j.cemconres.2025.107895","DOIUrl":"10.1016/j.cemconres.2025.107895","url":null,"abstract":"<div><div>An automated experimental system enables precise evaluation of cement dispersant performance through rheological measurements of 230 mL mortar samples. Analysis of 129 mortar samples demonstrated comprehensive characterization of dispersant effects beyond traditional manual testing capabilities. Principal component analysis revealed distinct patterns in torque measurements, explaining the variance of the pattern and effectively capturing dispersant performance differences. The automated system achieved superior reproducibility with 7% coefficient of variance, which can be considered as the inherent variation of materials. Observation-informed learning extended the system's utility, successfully predicting flow and bleeding rate. Results confirmed superior performance of third-generation polycarboxylate dispersants while providing new insights into dosage-rheology relationships. This automated approach establishes a framework for more efficient and comprehensive evaluation of cement-based materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107895"},"PeriodicalIF":10.9,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824005","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 : 2025-04-11DOI: 10.1016/j.cemconres.2025.107894
Ruoxi Yang, Jiaqi Li
The significant global CO2 emissions from the cement industry coerces the development of alternative, low-carbon cement. Reactive MgO cement is a promising candidate, reacting with CO2 to form hydrated magnesium carbonates. This high-pressure X-ray diffraction study investigates the intrinsic mechanical properties of artinite, a binding phase in reactive MgO cement. Artinite remains structurally resolved up to 6.45 GPa hydrostatic pressure, beyond which the critical diffraction peak (310) is illegible. The bulk modulus of artinite was determined to be 46.3 and 47.7 GPa using the 2nd-order and 3rd-order Birch-Murnaghan Equation of State, respectively. When including applied hydrostatic pressures up to 9.35 GPa, the calculated bulk modulus significantly varied due to the weak intensity of (310) peak, highlighting the impact of data quality and analysis on calculating intrinsic mechanical properties. The experimental results are important for validating computational studies of reactive MgO cement and providing inputs to micromechanics modeling.
{"title":"Probing the intrinsic mechanical properties of artinite using high-pressure X-ray diffraction for reactive MgO cement","authors":"Ruoxi Yang, Jiaqi Li","doi":"10.1016/j.cemconres.2025.107894","DOIUrl":"10.1016/j.cemconres.2025.107894","url":null,"abstract":"<div><div>The significant global CO<sub>2</sub> emissions from the cement industry coerces the development of alternative, low-carbon cement. Reactive MgO cement is a promising candidate, reacting with CO<sub>2</sub> to form hydrated magnesium carbonates. This high-pressure X-ray diffraction study investigates the intrinsic mechanical properties of artinite, a binding phase in reactive MgO cement. Artinite remains structurally resolved up to 6.45 GPa hydrostatic pressure, beyond which the critical diffraction peak (310) is illegible. The bulk modulus of artinite was determined to be 46.3 and 47.7 GPa using the 2nd-order and 3rd-order Birch-Murnaghan Equation of State, respectively. When including applied hydrostatic pressures up to 9.35 GPa, the calculated bulk modulus significantly varied due to the weak intensity of (310) peak, highlighting the impact of data quality and analysis on calculating intrinsic mechanical properties. The experimental results are important for validating computational studies of reactive MgO cement and providing inputs to micromechanics modeling.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107894"},"PeriodicalIF":10.9,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143816435","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 : 2025-04-11DOI: 10.1016/j.cemconres.2025.107892
Zeyu Zhou , Ellina Bernard , Barbara Lothenbach
Cements based on hydrated magnesium carbonates are an alternative binder system with high CO2 sequestration ability. The present study examines the effect of silica, a by-product of MgO production from magnesium-silicate rocks, in MgO/nesquehonite binders. A high Mg/Si ratio of 3 was used to allow the formation of both the hydrous carbonate-containing brucite (HCB) phase and the magnesium silicate hydrate (M-S-H) phase. HCB formed within the first day. Its quantity was reduced during the formation of M-S-H and stabilized until the complete reaction of silica. Low quantities of nesquehonite, ≤10 wt%, accelerated M-S-H formation, while ≥16 wt% hindered it. CO2 quantification showed that up to 12 g of CO2 per 100 g dry cement could be sequestered. MgO/silica/nesquehonite mortars with 10 wt% of nesquehonite and a water/cement ratio of 0.65 exhibited overall good mechanical strength, achieving 23 MPa at 2 days and 36 MPa at 182 days.
{"title":"Effect of nesquehonite and silica on magnesia-silicate‑carbonate cements","authors":"Zeyu Zhou , Ellina Bernard , Barbara Lothenbach","doi":"10.1016/j.cemconres.2025.107892","DOIUrl":"10.1016/j.cemconres.2025.107892","url":null,"abstract":"<div><div>Cements based on hydrated magnesium carbonates are an alternative binder system with high CO<sub>2</sub> sequestration ability. The present study examines the effect of silica, a by-product of MgO production from magnesium-silicate rocks, in MgO/nesquehonite binders. A high Mg/Si ratio of 3 was used to allow the formation of both the hydrous carbonate-containing brucite (HCB) phase and the magnesium silicate hydrate (M-S-H) phase. HCB formed within the first day. Its quantity was reduced during the formation of M-S-H and stabilized until the complete reaction of silica. Low quantities of nesquehonite, ≤10 wt%, accelerated M-S-H formation, while ≥16 wt% hindered it. CO<sub>2</sub> quantification showed that up to 12 g of CO<sub>2</sub> per 100 g dry cement could be sequestered. MgO/silica/nesquehonite mortars with 10 wt% of nesquehonite and a water/cement ratio of 0.65 exhibited overall good mechanical strength, achieving 23 MPa at 2 days and 36 MPa at 182 days.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107892"},"PeriodicalIF":10.9,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143816436","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 : 2025-04-08DOI: 10.1016/j.cemconres.2025.107893
Maxime Ranger , Marianne Tange Hasholt , Ole Mejlhede Jensen
Cement pastes made with ternary binders containing Portland cement, calcined smectitic clay and limestone were subjected to chloride migration and diffusion. Microstructural changes due to chloride ingress were studied by mercury intrusion porosimetry and SEM back-scattered electron image analysis, while chemical changes were investigated via chloride binding isotherms complemented by thermogravimetric analysis, X-ray diffraction and SEM-EDS. Chloride binding parameters were taken as inputs in a chloride diffusion model, to process chloride profiles obtained in diffusion experiments.
Refinement of the pore structure was observed for pure Portland cement samples in migration. No changes were observed in diffusion, nor with ternary blends. Moreover, ternary blends lead to more chloride binding compared to Portland cement, mainly due to more Friedel's salt. Effective diffusion coefficients, purely linked to transport properties, obtained from migration and diffusion experiments agree well. Conversely, apparent diffusion coefficients may differ by a factor two. Implications regarding chloride ingress are discussed.
{"title":"Chloride ingress parameters derived from migration and diffusion tests for systems with calcined smectitic clay and limestone","authors":"Maxime Ranger , Marianne Tange Hasholt , Ole Mejlhede Jensen","doi":"10.1016/j.cemconres.2025.107893","DOIUrl":"10.1016/j.cemconres.2025.107893","url":null,"abstract":"<div><div>Cement pastes made with ternary binders containing Portland cement, calcined smectitic clay and limestone were subjected to chloride migration and diffusion. Microstructural changes due to chloride ingress were studied by mercury intrusion porosimetry and SEM back-scattered electron image analysis, while chemical changes were investigated via chloride binding isotherms complemented by thermogravimetric analysis, X-ray diffraction and SEM-EDS. Chloride binding parameters were taken as inputs in a chloride diffusion model, to process chloride profiles obtained in diffusion experiments.</div><div>Refinement of the pore structure was observed for pure Portland cement samples in migration. No changes were observed in diffusion, nor with ternary blends. Moreover, ternary blends lead to more chloride binding compared to Portland cement, mainly due to more Friedel's salt. Effective diffusion coefficients, purely linked to transport properties, obtained from migration and diffusion experiments agree well. Conversely, apparent diffusion coefficients may differ by a factor two. Implications regarding chloride ingress are discussed.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107893"},"PeriodicalIF":10.9,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143791965","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 : 2025-04-05DOI: 10.1016/j.cemconres.2025.107891
Hamideh Mehdizadeh , Tung-Chai Ling
Alkaline solid wastes, such as recycled concrete fines, can integrate with CO2 to produce high-purity vaterite CaCO3 via leaching‑carbonation mineralization. This study aims to examine the stability and nucleation effects of the metastable vaterite relative to stable conventional calcite in cement paste systems. To better elucidate the underlying mechanisms, their influence in the pure C3S/C3A phase systems was also comparatively studied. The results indicate that vaterite accelerates the hydration rate of C3S and C3A phases, resulting in the formation of both crystalline and amorphous calcium silicate hydrates, as well as carbonate-Am phases, within the first 12 h of hydration. The spherical morphology of vaterite facilitates a more uniform distribution of hydration products, leading to particle encapsulation and reduced nucleation effects at later ages (> 7 days). Overall, vaterite blended cement pastes exhibit 40% higher early strength at 7 days and comparable long-term mechanical properties to those made with calcite.
{"title":"Hydration and strength of cement paste containing metastable vaterite derived from recycled concrete fines and CO2","authors":"Hamideh Mehdizadeh , Tung-Chai Ling","doi":"10.1016/j.cemconres.2025.107891","DOIUrl":"10.1016/j.cemconres.2025.107891","url":null,"abstract":"<div><div>Alkaline solid wastes, such as recycled concrete fines, can integrate with CO<sub>2</sub> to produce high-purity vaterite CaCO<sub>3</sub> via leaching‑carbonation mineralization. This study aims to examine the stability and nucleation effects of the metastable vaterite relative to stable conventional calcite in cement paste systems. To better elucidate the underlying mechanisms, their influence in the pure C<sub>3</sub>S/C<sub>3</sub>A phase systems was also comparatively studied. The results indicate that vaterite accelerates the hydration rate of C<sub>3</sub>S and C<sub>3</sub>A phases, resulting in the formation of both crystalline and amorphous calcium silicate hydrates, as well as carbonate-Am phases, within the first 12 h of hydration. The spherical morphology of vaterite facilitates a more uniform distribution of hydration products, leading to particle encapsulation and reduced nucleation effects at later ages (> 7 days). Overall, vaterite blended cement pastes exhibit 40% higher early strength at 7 days and comparable long-term mechanical properties to those made with calcite.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107891"},"PeriodicalIF":10.9,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777122","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 : 2025-03-31DOI: 10.1016/j.cemconres.2025.107872
Elisabeth John , Cordula Jakob , Ursula Pott , Mona Sando
Isothermal heat flow calorimetry evaluates heat development during binder reactions. It distinguishes between in situ calorimetry, where mixing occurs within the device, and ex situ calorimetry, involving externally mixed samples. Despite ex situ calorimetry being a standard method in binder research, in situ calorimetry is underutilized. This paper aims to promote its adoption by summarizing challenges related to repeatability and reproducibility and offering solutions. The initial section addresses repeatability issues caused by preventable errors, providing a structured guide for experimental design. It was found that water leakage had minimal impact, and sample size is crucial for data robustness. The second section examines operational challenges, revealing that frictional heating, affecting recorded heat, can be minimized with an optimized mixing protocol. The final part highlights that significant errors in measured data stem from signal delay and heat loss, offering methods to correct these issues for improved reproducibility in in situ calorimetric experiments.
{"title":"Repeatability and reproducibility challenges of isothermal heat flow calorimetry with in situ mixing","authors":"Elisabeth John , Cordula Jakob , Ursula Pott , Mona Sando","doi":"10.1016/j.cemconres.2025.107872","DOIUrl":"10.1016/j.cemconres.2025.107872","url":null,"abstract":"<div><div>Isothermal heat flow calorimetry evaluates heat development during binder reactions. It distinguishes between in situ calorimetry, where mixing occurs within the device, and ex situ calorimetry, involving externally mixed samples. Despite ex situ calorimetry being a standard method in binder research, in situ calorimetry is underutilized. This paper aims to promote its adoption by summarizing challenges related to repeatability and reproducibility and offering solutions. The initial section addresses repeatability issues caused by preventable errors, providing a structured guide for experimental design. It was found that water leakage had minimal impact, and sample size is crucial for data robustness. The second section examines operational challenges, revealing that frictional heating, affecting recorded heat, can be minimized with an optimized mixing protocol. The final part highlights that significant errors in measured data stem from signal delay and heat loss, offering methods to correct these issues for improved reproducibility in in situ calorimetric experiments.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107872"},"PeriodicalIF":10.9,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143737214","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 : 2025-03-31DOI: 10.1016/j.cemconres.2025.107883
Antonela Di Salvo Barsi, Mónica A. Trezza, Edgardo F. Irassar
This study examines the stability of dolomitic filler (DF), both in isolation and in interaction with supplementary cementitious materials (SCMs), when immersed in water media at different pH at 40 °C. Additionally, the interaction of DF with Portland cement (PC) is analyzed. In the presence of SCMs or PC, results reveal that DF undergoes dedolomitization in alkaline environments, which confirms the absence of brucite in this process. As corroboration, the volumetric stability of mortar bars containing 20 wt% DF is demonstrated and the compressive strength remained after immersion in pore water at 40 °C for 5 years.
{"title":"Dedolomitization of dolostone filler: Modifying the course of Mg with SCM","authors":"Antonela Di Salvo Barsi, Mónica A. Trezza, Edgardo F. Irassar","doi":"10.1016/j.cemconres.2025.107883","DOIUrl":"10.1016/j.cemconres.2025.107883","url":null,"abstract":"<div><div>This study examines the stability of dolomitic filler (DF), both in isolation and in interaction with supplementary cementitious materials (SCMs), when immersed in water media at different pH at 40 °C. Additionally, the interaction of DF with Portland cement (PC) is analyzed. In the presence of SCMs or PC, results reveal that DF undergoes dedolomitization in alkaline environments, which confirms the absence of brucite in this process. As corroboration, the volumetric stability of mortar bars containing 20 wt% DF is demonstrated and the compressive strength remained after immersion in pore water at 40 °C for 5 years.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107883"},"PeriodicalIF":10.9,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143737215","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 : 2025-03-29DOI: 10.1016/j.cemconres.2025.107882
Piumika W. Ariyadasa , Allan C. Manalo , Weena Lokuge , Vasantha Aravienthan , Andreas Gerdes , Jonas Kaltenbach
Alkali-activated geopolymers are increasingly studied as alternatives to Ordinary Portland Cement (OPC) concrete for use in challenging service environments. Low-calcium geopolymers have been advocated to mitigate Microbial-Induced Concrete Corrosion (MICC) in sewer pipes; however, their broader acceptance as a repair material for sewer rehabilitation remains to be established. This study evaluated the degradation mechanism of low-calcium fly ash-based geopolymer (FAGP) repair mortar under laboratory-simulated sewer conditions by exposing it to varying concentrations of sulphuric acid (pH 0.5, 1, and 4) for extended durations. The corrosion of the mortar samples was assessed based on visual changes, mass loss, residual mechanical strength, pore evolution, and ion transport over three exposure durations. Comparative analysis with OPC counterparts served as a benchmark. The degradation of FAGP and OPC due to acid exposure appears to escalate with both acid concentration and exposure. However, FAGP displayed superior performance by maintaining their shape and retaining approximately 30% of mechanical strength even after 3000 h of exposure under highly aggressive sewer conditions at pH 0.5. In contrast, OPC fails to endure acid exposure beyond 2000 h. The loss of matrix integrity primarily stems from ion leaching, supported by Scanning Electron Microscopy and Mercury Intrusion Porosimetry analysis, which revealed the creation of intrinsic pores facilitating the ingress of sulphate ions into the matrix. X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy patterns indicate no significant phase alterations, confirming this phenomenon. In conclusion, this study demonstrated that FAGP mortar is more resilient and durable in mild to aggressive sewer conditions than OPC.
{"title":"Degradation mechanisms of low-calcium fly ash-based geopolymer mortar in simulated aggressive sewer conditions","authors":"Piumika W. Ariyadasa , Allan C. Manalo , Weena Lokuge , Vasantha Aravienthan , Andreas Gerdes , Jonas Kaltenbach","doi":"10.1016/j.cemconres.2025.107882","DOIUrl":"10.1016/j.cemconres.2025.107882","url":null,"abstract":"<div><div>Alkali-activated geopolymers are increasingly studied as alternatives to Ordinary Portland Cement (OPC) concrete for use in challenging service environments. Low-calcium geopolymers have been advocated to mitigate Microbial-Induced Concrete Corrosion (MICC) in sewer pipes; however, their broader acceptance as a repair material for sewer rehabilitation remains to be established. This study evaluated the degradation mechanism of low-calcium fly ash-based geopolymer (FAGP) repair mortar under laboratory-simulated sewer conditions by exposing it to varying concentrations of sulphuric acid (pH 0.5, 1, and 4) for extended durations. The corrosion of the mortar samples was assessed based on visual changes, mass loss, residual mechanical strength, pore evolution, and ion transport over three exposure durations. Comparative analysis with OPC counterparts served as a benchmark. The degradation of FAGP and OPC due to acid exposure appears to escalate with both acid concentration and exposure. However, FAGP displayed superior performance by maintaining their shape and retaining approximately 30% of mechanical strength even after 3000 h of exposure under highly aggressive sewer conditions at pH 0.5. In contrast, OPC fails to endure acid exposure beyond 2000 h. The loss of matrix integrity primarily stems from ion leaching, supported by Scanning Electron Microscopy and Mercury Intrusion Porosimetry analysis, which revealed the creation of intrinsic pores facilitating the ingress of sulphate ions into the matrix. X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy patterns indicate no significant phase alterations, confirming this phenomenon. In conclusion, this study demonstrated that FAGP mortar is more resilient and durable in mild to aggressive sewer conditions than OPC.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"194 ","pages":"Article 107882"},"PeriodicalIF":10.9,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725578","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 : 2025-03-25DOI: 10.1016/j.cemconres.2025.107879
Ziyu Chen , Tian Zhang , Yuxiang Wu , Ian Madsen , Jisheng Ma , Kwesi Sagoe-Crentsil , Adrian Neild , Wenhui Duan
The carbonation of cementitious calcium silicates, specifically tricalcium silicate (C₃S) and dicalcium silicate (C₂S), is crucial for Carbon Capture and Utilization (CCU) in reducing CO₂ emissions in the cement and concrete industry. Controlling these reactions, including the rate and phase evolution necessary for producing desirable carbonated products, poses significant challenges. A lack of continuous kinetic data has impeded the understanding of the mechanisms behind carbonation and its optimization to enhance efficiency. This study explores the effects of four amino acids—glycine, L-arginine, sarcosine, and l-serine—on the carbonation of calcium silicate using in-situ XRD for real-time data collection. It identified a three-stage carbonation process starting with an induction period. The presence of specific amino acids encouraged the formation of stable vaterite and denser microstructures, indicating their potential to enhance the mechanical properties and durability of cementitious materials.
{"title":"In-situ XRD study of the effects of amino acids on the carbonation kinetics of cementitious calcium silicates","authors":"Ziyu Chen , Tian Zhang , Yuxiang Wu , Ian Madsen , Jisheng Ma , Kwesi Sagoe-Crentsil , Adrian Neild , Wenhui Duan","doi":"10.1016/j.cemconres.2025.107879","DOIUrl":"10.1016/j.cemconres.2025.107879","url":null,"abstract":"<div><div>The carbonation of cementitious calcium silicates, specifically tricalcium silicate (C₃S) and dicalcium silicate (C₂S), is crucial for Carbon Capture and Utilization (CCU) in reducing CO₂ emissions in the cement and concrete industry. Controlling these reactions, including the rate and phase evolution necessary for producing desirable carbonated products, poses significant challenges. A lack of continuous kinetic data has impeded the understanding of the mechanisms behind carbonation and its optimization to enhance efficiency. This study explores the effects of four amino acids—glycine, L-arginine, sarcosine, and <span>l</span>-serine—on the carbonation of calcium silicate using in-situ XRD for real-time data collection. It identified a three-stage carbonation process starting with an induction period. The presence of specific amino acids encouraged the formation of stable vaterite and denser microstructures, indicating their potential to enhance the mechanical properties and durability of cementitious materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107879"},"PeriodicalIF":10.9,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688027","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}
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