Pub Date : 2025-04-03DOI: 10.1016/j.cement.2025.100139
Federica Boscaro , Diana Londono-Zuluaga , Peter Kruspan , Michael Plötze , Karen Scrivener , Robert J. Flatt
Burnt oil shale (BOS), obtained from the combustion of oil shale, is a promising supplementary cementitious material (SCM) based on its chemistry and mineralogy. This paper summarizes the use of BOS and its hydration in blended cements. It presents new data on the effect of combinations of alkali activators and Ca(NO3)2 in blended cements containing 50 % Portland cement (OPC) where BOS is combined with limestone, fly ash and ground granulated blast furnace slag. These chemical admixtures increase the slope of the correlation between compressive strength and heat of hydration of BOS containing mixes, providing an increase in compressive strength from 1 to 7 days for similar heat release to the control system. In contrast, the slope is not affected in absence of BOS. The change is due to a higher volume of hydrates from BOS increased hydration for a given C3S degree of hydration, likely from a less exothermic dissolution of BOS amorphous component. These admixtures increase the reactivity of both BOS and OPC at different curing times and depending on the type of alkali activator. They promote ettringite and portlandite precipitation, inducing a refinement of the microstructure, particularly around BOS particles. The information presented should pave the way to a broader and more effective use of BOS in blended cements with particularly low clinker contents.
{"title":"Phase assemblage and microstructure of burnt oil shale-containing blended cements","authors":"Federica Boscaro , Diana Londono-Zuluaga , Peter Kruspan , Michael Plötze , Karen Scrivener , Robert J. Flatt","doi":"10.1016/j.cement.2025.100139","DOIUrl":"10.1016/j.cement.2025.100139","url":null,"abstract":"<div><div>Burnt oil shale (BOS), obtained from the combustion of oil shale, is a promising supplementary cementitious material (SCM) based on its chemistry and mineralogy. This paper summarizes the use of BOS and its hydration in blended cements. It presents new data on the effect of combinations of alkali activators and Ca(NO<sub>3</sub>)<sub>2</sub> in blended cements containing 50 % Portland cement (OPC) where BOS is combined with limestone, fly ash and ground granulated blast furnace slag. These chemical admixtures increase the slope of the correlation between compressive strength and heat of hydration of BOS containing mixes, providing an increase in compressive strength from 1 to 7 days for similar heat release to the control system. In contrast, the slope is not affected in absence of BOS. The change is due to a higher volume of hydrates from BOS increased hydration for a given C<sub>3</sub>S degree of hydration, likely from a less exothermic dissolution of BOS amorphous component. These admixtures increase the reactivity of both BOS and OPC at different curing times and depending on the type of alkali activator. They promote ettringite and portlandite precipitation, inducing a refinement of the microstructure, particularly around BOS particles. The information presented should pave the way to a broader and more effective use of BOS in blended cements with particularly low clinker contents.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"20 ","pages":"Article 100139"},"PeriodicalIF":0.0,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143829562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.cement.2025.100136
A.A. Amadi , S.S. Kolo , A. Yusuf , F.E. Eze , U. Salihu
It is recognized that different cements have different properties and stabilization effectiveness for different applications. The challenge of using the right type of cement should be a concern for practitioners in civil engineering construction. In this study, an experimental testing programme was conducted to evaluate and compare the stabilizing effects of CEM I 42.5 N, CEM II/B-L 42.5 N and CEM III/A 42.5 N types of cement on some physical and mechanical properties of lateritic soil. Laboratory tests performed on soil mixtures containing the selected cements added to constitute 0, 3, 6, 9 and 12 % of the dry weight of the composite materials include the consistency and compaction tests determined on the basis of fresh mixtures. In addition, unconfined compressive strength (UCS) test on specimens compacted at optimum moisture conditions with the British Standard Light (BSL) compaction effort and cured for 7, 28 and 90 days was performed. In equal proportions, soil mixtures prepared with the different types of cements yielded comparable results in terms of reducing the plasticity index (PI) from values as high as 60 % in untreated state to 5.05 %, 7.05 % and 8.2 % respectively for CEM I, CEM II and CEM III at 12 % cement content. Addition of cement also increased both the maximum dry unit weight (γdmax) and optimum moisture content (OMC) of the soil with CEM I cement having the greatest effect while CEM III cement affected the γdmax of the soil the least. For example, when compacted with BSH effort, CEM I achieved γdmax = 1.95 kN/m3 and OMC = 25 %, while for CEM III, γdmax = 1.63 kN/m3 and OMC = 22.6 % compared to γdmax of 1.53 kN/m3 and OMC of 21.1 % for the untreated soil. Regardless of the cement type, there was an overall improvement in the strength properties of the lateritic soil represented by a range of 11 – 14 times for UCS and 31 - 62 folds for E50 at 12 % cement after 90 days curing duration in comparison with the untreated soil. While strength gain was higher in CEM I based mixtures at early (7 day) age (1635.44, 1622.85 and 1599.55 kN/m2 for CEM I, CEM II and CEM III respectively at 12 % cement content), CEM III provided superior strength improvement at the long term (90 day) curing period (2566.25 compared to 2444.58 and 2465.77 kN/m2 respectively for CEM I and CEM II at 12 % cement content). Using the variance analysis (ANOVA) at a significance level (α) of 0.05, the influence of cement type was statistically confirmed for the liquid limit, optimum moisture content and UCS at 28 and 90 days curing ages.
{"title":"Stabilization characteristics of cemented lateritic soil produced with selected cement types","authors":"A.A. Amadi , S.S. Kolo , A. Yusuf , F.E. Eze , U. Salihu","doi":"10.1016/j.cement.2025.100136","DOIUrl":"10.1016/j.cement.2025.100136","url":null,"abstract":"<div><div>It is recognized that different cements have different properties and stabilization effectiveness for different applications. The challenge of using the right type of cement should be a concern for practitioners in civil engineering construction. In this study, an experimental testing programme was conducted to evaluate and compare the stabilizing effects of CEM I 42.5 N, CEM II/B-L 42.5 N and CEM III/A 42.5 N types of cement on some physical and mechanical properties of lateritic soil. Laboratory tests performed on soil mixtures containing the selected cements added to constitute 0, 3, 6, 9 and 12 % of the dry weight of the composite materials include the consistency and compaction tests determined on the basis of fresh mixtures. In addition, unconfined compressive strength (UCS) test on specimens compacted at optimum moisture conditions with the British Standard Light (BSL) compaction effort and cured for 7, 28 and 90 days was performed. In equal proportions, soil mixtures prepared with the different types of cements yielded comparable results in terms of reducing the plasticity index (PI) from values as high as 60 % in untreated state to 5.05 %, 7.05 % and 8.2 % respectively for CEM I, CEM II and CEM III at 12 % cement content. Addition of cement also increased both the maximum dry unit weight (γ<sub>dmax</sub>) and optimum moisture content (OMC) of the soil with CEM I cement having the greatest effect while CEM III cement affected the γ<sub>dmax</sub> of the soil the least. For example, when compacted with BSH effort, CEM I achieved γ<sub>dmax</sub> = 1.95 kN/m<sup>3</sup> and OMC = 25 %, while for CEM III, γ<sub>dmax</sub> = 1.63 kN/m<sup>3</sup> and OMC = 22.6 % compared to γ<sub>dmax</sub> of 1.53 kN/m<sup>3</sup> and OMC of 21.1 % for the untreated soil. Regardless of the cement type, there was an overall improvement in the strength properties of the lateritic soil represented by a range of 11 – 14 times for UCS and 31 - 62 folds for E<sub>50</sub> at 12 % cement after 90 days curing duration in comparison with the untreated soil. While strength gain was higher in CEM I based mixtures at early (7 day) age (1635.44, 1622.85 and 1599.55 kN/m2 for CEM I, CEM II and CEM III respectively at 12 % cement content), CEM III provided superior strength improvement at the long term (90 day) curing period (2566.25 compared to 2444.58 and 2465.77 kN/m<sup>2</sup> respectively for CEM I and CEM II at 12 % cement content). Using the variance analysis (ANOVA) at a significance level (α) of 0.05, the influence of cement type was statistically confirmed for the liquid limit, optimum moisture content and UCS at 28 and 90 days curing ages.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100136"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.cement.2025.100137
Mahipal Kasaniya, Michael DA Thomas, Ted Moffatt, Ashlee Hossack
This paper presents the quantification of the pozzolanic reactivity of pozzolans examined in terms of compressive strength, bound water and electrical resistivity. The pozzolans studied included natural pozzolans, glass pozzolans and fly ash that were ground to four fineness levels or median particle sizes (d50) of approximately 3, 5, 10 and 15 µm. Quantitative X-ray diffraction was employed to determine the amorphous content of pozzolans. The UNB lime-reactivity test and a modified ASTM C311 activity with portland cement test were performed in mortars. In these two tests, bulk electrical resistivity measurements were conducted before measuring compressive strength. Additionally, pastes were prepared for bound water in accordance with the R3 test or ASTM C1897. While the pozzolanic reactivity for all materials tested generally improves with the fineness, one pozzolan could demonstrate a very different rate of pozzolanicity improvements compared to that of others. Bulk electrical resistivity provides a reliable assessment of pozzolanic reactivity and can help differentiate pozzolanic and pozzolanic-hydraulic materials when used in conjunction with compressive strength. The modified ASTM C311 test is also found to be suitable and effective in rapidly distinguishing pozzolans, especially slow reactive ones, from inert materials at 7 days. A novel amorphous-fineness index derived by combining the amorphous content and fineness of pozzolans to reasonably predict the pozzolanic reactivity and limitations of the index are discussed.
{"title":"Significance of fineness of pozzolans in determining pozzolanic reactivity","authors":"Mahipal Kasaniya, Michael DA Thomas, Ted Moffatt, Ashlee Hossack","doi":"10.1016/j.cement.2025.100137","DOIUrl":"10.1016/j.cement.2025.100137","url":null,"abstract":"<div><div>This paper presents the quantification of the pozzolanic reactivity of pozzolans examined in terms of compressive strength, bound water and electrical resistivity. The pozzolans studied included natural pozzolans, glass pozzolans and fly ash that were ground to four fineness levels or median particle sizes (d<sub>50</sub>) of approximately 3, 5, 10 and 15 µm. Quantitative X-ray diffraction was employed to determine the amorphous content of pozzolans. The UNB lime-reactivity test and a modified ASTM <span><span>C311</span><svg><path></path></svg></span> activity with portland cement test were performed in mortars. In these two tests, bulk electrical resistivity measurements were conducted before measuring compressive strength. Additionally, pastes were prepared for bound water in accordance with the R<sup>3</sup> test or ASTM <span><span>C1897</span><svg><path></path></svg></span>. While the pozzolanic reactivity for all materials tested generally improves with the fineness, one pozzolan could demonstrate a very different rate of pozzolanicity improvements compared to that of others. Bulk electrical resistivity provides a reliable assessment of pozzolanic reactivity and can help differentiate pozzolanic and pozzolanic-hydraulic materials when used in conjunction with compressive strength. The modified ASTM <span><span>C311</span><svg><path></path></svg></span> test is also found to be suitable and effective in rapidly distinguishing pozzolans, especially slow reactive ones, from inert materials at 7 days. A novel amorphous-fineness index derived by combining the amorphous content and fineness of pozzolans to reasonably predict the pozzolanic reactivity and limitations of the index are discussed.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100137"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.cement.2025.100138
Qi Luo , Xinyu Zhang , Junchao Yu , Guoqing Geng
This study systematically investigates the impact of varying metakaolin contents on the compressive strength and microstructure of hardened limestone calcined clay cement (LC3) paste. The findings reveal that increasing metakaolin content intensifies the aluminum sulfate reaction peak and accelerates its onset, while decreasing metakaolin leads to higher total calcium hydroxide (Ca(OH)₂) and calcium carbonate (CaCO₃) levels in the system. A specific threshold of 70 % metakaolin content is identified as optimal for pozzolanic activity; excess metakaolin remains unreacted. The addition of metakaolin refines the pore structure, reduces harmful large pores, and promotes the formation of ettringite and other hydration products, enhancing mechanical properties. Notably, a sample with 70 % metakaolin content exhibits higher compressive strength than one with 100 % metakaolin, indicating that metakaolin containing 30 % impurities (referred to as sand powder) demonstrates superior mechanical performance. These results support the development of LC3 as a commercially viable and eco-friendly alternative to Ordinary Portland Cement (OPC).
{"title":"Influence of metakaolin content on the microstructure and strength in hardened LC3 paste","authors":"Qi Luo , Xinyu Zhang , Junchao Yu , Guoqing Geng","doi":"10.1016/j.cement.2025.100138","DOIUrl":"10.1016/j.cement.2025.100138","url":null,"abstract":"<div><div>This study systematically investigates the impact of varying metakaolin contents on the compressive strength and microstructure of hardened limestone calcined clay cement (LC<sup>3</sup>) paste. The findings reveal that increasing metakaolin content intensifies the aluminum sulfate reaction peak and accelerates its onset, while decreasing metakaolin leads to higher total calcium hydroxide (Ca(OH)₂) and calcium carbonate (CaCO₃) levels in the system. A specific threshold of 70 % metakaolin content is identified as optimal for pozzolanic activity; excess metakaolin remains unreacted. The addition of metakaolin refines the pore structure, reduces harmful large pores, and promotes the formation of ettringite and other hydration products, enhancing mechanical properties. Notably, a sample with 70 % metakaolin content exhibits higher compressive strength than one with 100 % metakaolin, indicating that metakaolin containing 30 % impurities (referred to as sand powder) demonstrates superior mechanical performance. These results support the development of LC<sup>3</sup> as a commercially viable and eco-friendly alternative to Ordinary Portland Cement (OPC).</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100138"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1016/j.cement.2025.100135
Sarah Danieli , José S. Andrade Neto , Erick Grünhäuser Soares , Thainá Faria Oliveira , Bruna L.F. Brito , Ana Paula Kirchheim
Portland cement is one of the most used materials in the world. Despite the environmental harm its production causes, it will most likely continue dominating the market, given its remarkable characteristics and widespread use worldwide with high consumer acceptance. Improvements in the energy demand, equipment efficiency, and intensification of alternative materials have been proposed to mitigate the large amount of CO2 emissions during the clinker process. However, even if applied, only some extent of the CO2 emitted could be avoided since the most significant portion comes from the limestone decomposition, which cannot be avoided, fitting the cement industry into the list of hard-to-abate industries. In this scenario, new companies are developing and improving indispensable carbon capture technologies and CO2 reapplication in new processes. With the advance of carbon market regulation, the technologies that prove to be the most efficient will have a competitive advantage in this new economy. This study reviews the current carbon capture scenario in cement and concrete production and highlights the leading companies emerging in this sector, exploring the main aspects of their processes, technology readiness levels (TRL), real-world achievements, scalability, suitability for achieving net-zero emissions, credibility, feasibility, opportunities, and limitations.
{"title":"Shaping a sustainable path: Exploring opportunities and challenges in carbon capture and utilization in cement and concrete industry","authors":"Sarah Danieli , José S. Andrade Neto , Erick Grünhäuser Soares , Thainá Faria Oliveira , Bruna L.F. Brito , Ana Paula Kirchheim","doi":"10.1016/j.cement.2025.100135","DOIUrl":"10.1016/j.cement.2025.100135","url":null,"abstract":"<div><div>Portland cement is one of the most used materials in the world. Despite the environmental harm its production causes, it will most likely continue dominating the market, given its remarkable characteristics and widespread use worldwide with high consumer acceptance. Improvements in the energy demand, equipment efficiency, and intensification of alternative materials have been proposed to mitigate the large amount of CO<sub>2</sub> emissions during the clinker process. However, even if applied, only some extent of the CO<sub>2</sub> emitted could be avoided since the most significant portion comes from the limestone decomposition, which cannot be avoided, fitting the cement industry into the list of <em>hard-to-abate</em> industries. In this scenario, new companies are developing and improving indispensable carbon capture technologies and CO<sub>2</sub> reapplication in new processes. With the advance of carbon market regulation, the technologies that prove to be the most efficient will have a competitive advantage in this new economy. This study reviews the current carbon capture scenario in cement and concrete production and highlights the leading companies emerging in this sector, exploring the main aspects of their processes, technology readiness levels (TRL), real-world achievements, scalability, suitability for achieving net-zero emissions, credibility, feasibility, opportunities, and limitations.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100135"},"PeriodicalIF":0.0,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-04DOI: 10.1016/j.cement.2025.100134
Nicholas Benjamin Petersen , Ashish Bastola , Pavan Akula , John Rushing
Rapid stabilization of weak soil offers a promising option for quick infrastructure development and soil repair. The interaction between the rapid stabilizer and the soil is critical in defining its strength and durability. This study investigates the physicochemical effects of using Calcium Sulfoaluminate (CSA) cement-based stabilizers for rapid stabilization of weak clays, focusing on early age (<1 day) reaction kinetics and its effect on the short-term and long-term engineering characteristics. Geochemical modeling is proposed to model the chemical kinetics and predict the formation of strength-enhancing products in the stabilized soil mixtures. The study investigates the unconfined compression strength and durability (cyclic wetting and drying) of stabilized soil. Results showed stabilizers with a higher proportion (50 wt. percentage or more) of CSA (CSA-rich) achieved up to 80 % of the 28–day strength in 60 min after stabilization. Mineralogical characterization using X-Ray Diffraction, Thermogravimetric Analysis, and Scanning Electron Microscopy, identified Ettringite in CSA-rich stabilizers and Calcium-Silicate-Hydrates (C-S-H) in stabilizers with a higher (50 wt. percentage or more) proportion of Portland Cement (PC-rich) stabilizers as key strength-enhancing products. Integrating the modeling results with the engineering and mineralogical characterization provided valuable insights into the rapid stabilization mechanisms of CSA cement.
{"title":"Physicochemical kinetics of rapid soil stabilization using calcium sulfoaluminate-based cements","authors":"Nicholas Benjamin Petersen , Ashish Bastola , Pavan Akula , John Rushing","doi":"10.1016/j.cement.2025.100134","DOIUrl":"10.1016/j.cement.2025.100134","url":null,"abstract":"<div><div>Rapid stabilization of weak soil offers a promising option for quick infrastructure development and soil repair. The interaction between the rapid stabilizer and the soil is critical in defining its strength and durability. This study investigates the physicochemical effects of using Calcium Sulfoaluminate (CSA) cement-based stabilizers for rapid stabilization of weak clays, focusing on early age (<1 day) reaction kinetics and its effect on the short-term and long-term engineering characteristics. Geochemical modeling is proposed to model the chemical kinetics and predict the formation of strength-enhancing products in the stabilized soil mixtures. The study investigates the unconfined compression strength and durability (cyclic wetting and drying) of stabilized soil. Results showed stabilizers with a higher proportion (50 wt. percentage or more) of CSA (CSA-rich) achieved up to 80 % of the 28–day strength in 60 min after stabilization. Mineralogical characterization using X-Ray Diffraction, Thermogravimetric Analysis, and Scanning Electron Microscopy, identified Ettringite in CSA-rich stabilizers and Calcium-Silicate-Hydrates (C-S-H) in stabilizers with a higher (50 wt. percentage or more) proportion of Portland Cement (PC-rich) stabilizers as key strength-enhancing products. Integrating the modeling results with the engineering and mineralogical characterization provided valuable insights into the rapid stabilization mechanisms of CSA cement.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100134"},"PeriodicalIF":0.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-31DOI: 10.1016/j.cement.2025.100133
Ana Bergmann , Leandro F.M. Sanchez
Alkali aggregate reaction (AAR) affected structures show reduced serviceability and premature distress in over 50 countries worldwide. Several laboratory test protocols have been proposed to evaluate the potential reactivity of aggregates by varying the conditions known to trigger and sustain the reaction. Among them, the most popular methods are the accelerated mortar bar test (AMBT) and the concrete prism test (CPT). Nevertheless, exposure site data, displaying the behaviour of concrete blocks exposed to real environmental conditions, has increased considerably recently, showing significant discrepancies between laboratory and concrete field performance. This study explores the reliability of laboratory tests, indicating moderate accuracy in predicting field performance for the AMBT and the CPT. The findings highlight an opportunity for recalibration of these methods through advanced analytical models that account for environmental conditions, alkali content, and the presence of SCMs to improve predictive accuracy. These measures will enhance concrete infrastructure safety by identifying risks associated with incorporating AAR-prone aggregates into new structures.
{"title":"Assessing the reliability of laboratory test procedures for predicting concrete field performance against alkali-aggregate reaction (AAR)","authors":"Ana Bergmann , Leandro F.M. Sanchez","doi":"10.1016/j.cement.2025.100133","DOIUrl":"10.1016/j.cement.2025.100133","url":null,"abstract":"<div><div>Alkali aggregate reaction (AAR) affected structures show reduced serviceability and premature distress in over 50 countries worldwide. Several laboratory test protocols have been proposed to evaluate the potential reactivity of aggregates by varying the conditions known to trigger and sustain the reaction. Among them, the most popular methods are the accelerated mortar bar test (AMBT) and the concrete prism test (CPT). Nevertheless, exposure site data, displaying the behaviour of concrete blocks exposed to real environmental conditions, has increased considerably recently, showing significant discrepancies between laboratory and concrete field performance. This study explores the reliability of laboratory tests, indicating moderate accuracy in predicting field performance for the AMBT and the CPT. The findings highlight an opportunity for recalibration of these methods through advanced analytical models that account for environmental conditions, alkali content, and the presence of SCMs to improve predictive accuracy. These measures will enhance concrete infrastructure safety by identifying risks associated with incorporating AAR-prone aggregates into new structures.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100133"},"PeriodicalIF":0.0,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.cement.2025.100132
Wena de Nazaré do Rosário Martel, Josée Duchesne, Benoît Fournier
The growing use of alkali-rich glass powder (GP) as a supplementary cementitious material (SCM) in concrete has led to a rising number of studies focused on the microstructure of cementitious matrices incorporating GP. Electron probe microanalyzer (EPMA) is commonly used to characterize cementitious materials. However, alkali migration induced by electron irradiation - a well-known phenomenon in inorganic materials - remains underexplored in this context. This migration often leads to underestimation of Na and K and overestimation of Si and Ca, thus compromising the analysis of key elements in cementitious hydrates, such as C-S-H. Due to the lack of a tailored protocol for EPMA analysis of alkali-rich SCMs, this study established analytical conditions to minimize errors in quantifying pozzolanic GP. Mixed glass culets and GP particles embedded in 7-year-old ternary concrete made with GP and silica fume were analyzed using ten different current densities by varying beam size, current, and the sub-counting method. The results show that alkali migration is highly sensitive to material composition and irradiation conditions. Na losses exceeded 70% as Ca and Si overestimation reached approximately 13% at current densities above 0.354 nA/μm². Literature-reported densities often surpass this threshold. At those conditions, the implementation of a sub-counting method effectively reduces the Na loss to 3%. However, it introduced a tendency for Na overestimation at lower current densities. Among all conditions, a beam diameter of 6 µm and a current of 10 nA, was the most accurate, reducing losses to under 2% and closely matching the reference glass analysis.
随着富碱玻璃粉（GP）作为一种补充胶凝材料（SCM）在混凝土中的应用越来越广泛，越来越多的研究关注于含GP的胶凝基质的微观结构。电子探针微量分析仪（EPMA）是一种常用的胶凝材料表征方法。然而，电子辐照引起的碱迁移——无机材料中一个众所周知的现象——在这方面仍未得到充分的研究。这种迁移往往导致Na和K的低估和Si和Ca的高估，从而影响了胶结水合物中关键元素（如C-S-H）的分析。由于缺乏适合富碱SCMs的EPMA分析方案，本研究建立了分析条件，以尽量减少定量火山灰GP的误差。混合玻璃碎片和GP颗粒嵌入在由GP和硅灰制成的7年的三元混凝土中，通过不同的光束大小，电流和子计数方法，使用十种不同的电流密度进行分析。结果表明，碱迁移对材料组成和辐照条件高度敏感。当电流密度大于0.354 Na /μ²时，Ca和Si的高估约为13%，Na损失超过70%。文献报道的密度经常超过这个阈值。在这些条件下，子计数方法的实施有效地将Na损耗降低到3%。然而，在较低的电流密度下，它引入了Na高估的趋势。在所有条件下，光束直径为6µm，电流为10 nA是最准确的，将损耗降低到2%以下，与参考玻璃分析结果非常吻合。
{"title":"Optimization of microprobe analysis of cementitious materials incorporating glass powder under electron beam to avoid alkali migration","authors":"Wena de Nazaré do Rosário Martel, Josée Duchesne, Benoît Fournier","doi":"10.1016/j.cement.2025.100132","DOIUrl":"10.1016/j.cement.2025.100132","url":null,"abstract":"<div><div>The growing use of alkali-rich glass powder (GP) as a supplementary cementitious material (SCM) in concrete has led to a rising number of studies focused on the microstructure of cementitious matrices incorporating GP. Electron probe microanalyzer (EPMA) is commonly used to characterize cementitious materials. However, alkali migration induced by electron irradiation - a well-known phenomenon in inorganic materials - remains underexplored in this context. This migration often leads to underestimation of Na and K and overestimation of Si and Ca, thus compromising the analysis of key elements in cementitious hydrates, such as C-S-H. Due to the lack of a tailored protocol for EPMA analysis of alkali-rich SCMs, this study established analytical conditions to minimize errors in quantifying pozzolanic GP. Mixed glass culets and GP particles embedded in 7-year-old ternary concrete made with GP and silica fume were analyzed using ten different current densities by varying beam size, current, and the sub-counting method. The results show that alkali migration is highly sensitive to material composition and irradiation conditions. Na losses exceeded 70% as Ca and Si overestimation reached approximately 13% at current densities above 0.354 nA/μm². Literature-reported densities often surpass this threshold. At those conditions, the implementation of a sub-counting method effectively reduces the Na loss to 3%. However, it introduced a tendency for Na overestimation at lower current densities. Among all conditions, a beam diameter of 6 µm and a current of 10 nA, was the most accurate, reducing losses to under 2% and closely matching the reference glass analysis.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100132"},"PeriodicalIF":0.0,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1016/j.cement.2025.100131
Keshav Bharadwaj , O. Burkan Isgor , W. Jason Weiss
Accurate sorption/desorption isotherms for cementitious materials are important in predicting drying shrinkage, moisture transport, ionic transport, freezable water content, and the service life of concrete. This paper develops a framework for constructing water sorption isotherms for hydrated cementitious pastes from the outputs of thermodynamic modeling and a pore partitioning model (PPM). Thermodynamic modeling helps quantify the solid phases and pore space in the hydrated matrix. The PPM provides the volume of evaporable water in crystalline hydrates, the total volume of gel water, the volume of capillary water, and volume of pores due to chemical shrinkage. The sorption isotherm is constructed from information on the evaporable water present in individual phases at each RH, water adsorbed on C-S-H, water in pores with kelvin radius of 2–5 nm, capillary water, and water in pores due to chemical shrinkage and air voids. The Brunauer-Skalny-Bodor (BSB) model is used to calculate the water adsorbed on the C-S-H. This model predicts the sorption isotherms from the literature to within an error of 2–19 %. The areas for future work and the challenges in predicting the desorption isotherms are discussed.
{"title":"Predicting sorption isotherms from thermodynamic calculations","authors":"Keshav Bharadwaj , O. Burkan Isgor , W. Jason Weiss","doi":"10.1016/j.cement.2025.100131","DOIUrl":"10.1016/j.cement.2025.100131","url":null,"abstract":"<div><div>Accurate sorption/desorption isotherms for cementitious materials are important in predicting drying shrinkage, moisture transport, ionic transport, freezable water content, and the service life of concrete. This paper develops a framework for constructing water sorption isotherms for hydrated cementitious pastes from the outputs of thermodynamic modeling and a pore partitioning model (PPM). Thermodynamic modeling helps quantify the solid phases and pore space in the hydrated matrix. The PPM provides the volume of evaporable water in crystalline hydrates, the total volume of gel water, the volume of capillary water, and volume of pores due to chemical shrinkage. The sorption isotherm is constructed from information on the evaporable water present in individual phases at each RH, water adsorbed on C-S-H, water in pores with kelvin radius of 2–5 nm, capillary water, and water in pores due to chemical shrinkage and air voids. The Brunauer-Skalny-Bodor (BSB) model is used to calculate the water adsorbed on the C-S-H. This model predicts the sorption isotherms from the literature to within an error of 2–19 %. The areas for future work and the challenges in predicting the desorption isotherms are discussed.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100131"},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-14DOI: 10.1016/j.cement.2025.100128
Pegah Farjad , Ahmed G. Mehairi , Fereshteh Meshkani , Roozbeh Mowlaei , Rahil Khoshnazar , Nashaat N. Nassar
Nanosilica particles are among the most studied nanomaterials in cementitious mixtures. However, literature on the effect of nanosilica particle size on the performance of these mixtures is still limited, with sometimes inconsistent findings. This study aims to address this gap by including the synthesis and application of different-sized nanosilica particles in one study. A uniform synthesis method was used to achieve nanosilica with four distinct average particle sizes (10, 35, 65, and 90 nm), covering the whole nanoscale range. The nanosilica particles were then fully characterized and utilized in cement paste at 1, 2, and 3 wt% of the cement. The compressive strength, heat evolution, microstructure, and rheological behaviour of the resultant pastes were investigated. The results revealed that the smallest particle size of nanosilica (10 nm) provided the highest compressive strength enhancement (over 100 % enhancement when used at 2 wt% of cement). The high pozzolanic reactivity of such small nanosilica particles at 2 wt%, together with their acceleration effect on cement hydration and densification of the paste microstructure, all contributed to this strength improvement. Overall, the enhancing effects of the nanosilica particles on the compressive strength of the pastes were less substantial when their particle size increased from 10 to 90 nm at any given concentration. All the nanosilica particles also increased the viscosity of the paste. This increasing effect was higher for smaller-sized nanosilica particles and at higher concentrations.
{"title":"Compressive strength and microstructural development of cement paste incorporating nanosilica with different particle sizes","authors":"Pegah Farjad , Ahmed G. Mehairi , Fereshteh Meshkani , Roozbeh Mowlaei , Rahil Khoshnazar , Nashaat N. Nassar","doi":"10.1016/j.cement.2025.100128","DOIUrl":"10.1016/j.cement.2025.100128","url":null,"abstract":"<div><div>Nanosilica particles are among the most studied nanomaterials in cementitious mixtures. However, literature on the effect of nanosilica particle size on the performance of these mixtures is still limited, with sometimes inconsistent findings. This study aims to address this gap by including the synthesis and application of different-sized nanosilica particles in one study. A uniform synthesis method was used to achieve nanosilica with four distinct average particle sizes (10, 35, 65, and 90 nm), covering the whole nanoscale range. The nanosilica particles were then fully characterized and utilized in cement paste at 1, 2, and 3 wt% of the cement. The compressive strength, heat evolution, microstructure, and rheological behaviour of the resultant pastes were investigated. The results revealed that the smallest particle size of nanosilica (10 nm) provided the highest compressive strength enhancement (over 100 % enhancement when used at 2 wt% of cement). The high pozzolanic reactivity of such small nanosilica particles at 2 wt%, together with their acceleration effect on cement hydration and densification of the paste microstructure, all contributed to this strength improvement. Overall, the enhancing effects of the nanosilica particles on the compressive strength of the pastes were less substantial when their particle size increased from 10 to 90 nm at any given concentration. All the nanosilica particles also increased the viscosity of the paste. This increasing effect was higher for smaller-sized nanosilica particles and at higher concentrations.</div></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"19 ","pages":"Article 100128"},"PeriodicalIF":0.0,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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