CEMENT最新文献

{"title":"Early age reaction of slag in composite cement: Impact of sulphates and calcite","authors":"Sam Adu-Amankwah ,&nbsp;Leon Black ,&nbsp;Liu Xianfeng ,&nbsp;Pengkun Hou ,&nbsp;Maciej Zajac","doi":"10.1016/j.cement.2023.100085","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100085","url":null,"abstract":"<div><p>Ground granulated blast furnace slag (GGBS) is an important supplementary cementitious material (SCM) for producing low carbon and durable concrete. There are however questions around the early age reactivity of GGBS and the factors that influence this. To elucidate the fundamental mechanisms controlling the early age reactivity and particularly the influence of anionic species, simplified systems comprising GGBS and calcium hydroxide were examined in the presence of limestone, anhydrite, or both at 4:1 SCM-to-activator ratio. Limestone and GGBS were considered as SCMs, but calcium hydroxide and anhydrite were considered as activators. Multiple techniques, including isothermal calorimetry, thermogravimetry, X-ray diffraction, electron microscopy, mass balance calculation and mercury intrusion porosimetry were used to study hydration and microstructure. The results show that GGBS hydration commences immediately in the alkaline media provided by calcium hydroxide. Sulphates and limestone influence hydration through reactions with aluminates to form ettringite and carboaluminates, but prevalence of macro-capillary pores in sulphate containing binders sustains diffusion-controlled hydration. Consequently, optimization of the alumina to sulphate and carbonate ratios is essential for exploiting the pore solution and space filling effects in composite cements.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"14 ","pages":"Article 100085"},"PeriodicalIF":0.0,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194575","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}

{"title":"Investigation of alkali-silica reaction on mortars with alternative binder systems: Alkali activated Slags and Celitement","authors":"Julia T. Sonntag ,&nbsp;Ravi A. Patel ,&nbsp;David Alós Shepherd ,&nbsp;Frank Dehn","doi":"10.1016/j.cement.2023.100078","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100078","url":null,"abstract":"<div><p>This study investigates the resistance against alkali-silica reaction (ASR) of two alternative binder systems, alkali-activated slag (AAS) and Celitement (Celite). Experimental studies on expansion and mechanical strength are carried out. Coupled kinetic and equilibrium thermodynamic modeling is used to clarify the role of binder chemistry on ASR. It was observed that under accelerated conditions OPC based mortars were more susceptible to ASR compared to AAS and Celite-based mortars. Based on experimental and modeling results, a correlation is shown between the dissolution of silica and the degree of expansion, but no correlation was found between the predicted amount of ASR products and the measured degree of expansion. Finally, the expansion degree could only be correlated with the reduction in compressive and flexural tensile strength for ASR-exposed samples.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"13 ","pages":"Article 100078"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50191467","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}

{"title":"Cold Water Extraction for determination of the free alkali metal content in blended cement pastes","authors":"Maxime Ranger ,&nbsp;Marianne Tange Hasholt","doi":"10.1016/j.cement.2023.100079","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100079","url":null,"abstract":"<div><p>In this work, Cold Water Extraction (CWE) was performed on blended cement pastes to extract the pore solution and determine the free alkali metal content. To better understand CWE results, the reactivity of cementitious materials was also investigated, complemented by TGA and quantitative XRD analysis. The study aimed at being generic to assess the suitability of the methods, and included 9 SCMs with various compositions: limestone, coal fly ash, two calcined clays, two biomass ashes, sewage sludge ash, crushed brick and glass beads.</p><p>The study highlighted the importance of assessing the reactivity of SCMs in parallel to performing CWE, as this contributes to a more certain interpretation of the results. In general, results obtained with CWE were consistent with the existing literature about the effect of binder composition on the free alkali metal content. From a practical view, CWE and SCM reactivity tests could be performed with basic laboratory equipment and appeared to be applicable to both traditional and alternative SCMs.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"13 ","pages":"Article 100079"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50191469","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}

{"title":"Thermal activation of inert basaltic materials to create supplementary cementitious materials","authors":"Ying Wang,&nbsp;Prannoy Suraneni","doi":"10.1016/j.cement.2023.100082","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100082","url":null,"abstract":"<div><p>The concrete industry faces an urgent need to identify new supplementary cementitious material (SCM) sources. One class of materials available in large volumes are basaltic materials, which are often stockpiled in landfills as a waste product from quarries and granule operations. Reactivity testing on some such materials has shown them to be inert. The thermal activation of basaltic fines, and their mixtures with fly ash and limestone was therefore evaluated in a furnace using different process variables. Physical and chemical characterization using X-ray diffraction, Fourier transform infrared spectroscopy, and electron microscopy was performed on the raw and thermally activated materials. The reactivity of the resulting materials was directly measured. Heating beyond 1300 °C and cooling results in complete amorphization for the tested materials and resulted in the highest reactivity. Thus, the activation of basaltic fines into SCMs is feasible, although optimization to reduce temperatures is needed.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"13 ","pages":"Article 100082"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50191470","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}

{"title":"Sustainability of concretes with binary and ternary blended cements considering performance parameters","authors":"Gisela Cordoba ,&nbsp;Manuel Barquero ,&nbsp;Viviana Bonavetti ,&nbsp;Edgardo F. Irassar","doi":"10.1016/j.cement.2023.100077","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100077","url":null,"abstract":"<div><p>This paper examines the sustainability of cementitious materials and concrete. Although the environmental impact of these materials is often evaluated based on their CO₂ emissions per ton of cement or m³ of concrete, incorporating performance parameters into sustainability indices is crucial for a more comprehensive assessment. This study evaluates the sustainability of concretes with and without supplementary cementitious materials (SCM), considering compressive strength and durability performance as performance parameters. Results show that the most sustainable concretes have the highest compressive strength and best durability performance. Furthermore, the importance of using locally available materials is highlighted, as transporting SCM over long distances can outweigh the benefits of using them as a replacement for Portland cement.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"13 ","pages":"Article 100077"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50191141","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}

{"title":"Effects of graphene nanoplatelets inclusion on microstructure and mechanical properties of alkali activated binders","authors":"Jarvis Devon,&nbsp;Emily Hacking,&nbsp;Kyra Wilson,&nbsp;Monica F. Craciun,&nbsp;Raffaele Vinai","doi":"10.1016/j.cement.2023.100080","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100080","url":null,"abstract":"<div><p>This paper presents a study investigating for the first time the effects of the inclusion of graphene nanoplatelets (GNPs) on the mechanical and microstructural properties of alkali activated binders produced with fly ash and slag and using superplasticizer for the GNPs dispersion in the mixing water. Compressive strength and water absorption of mortar cubes, flexural strength of mortar beams, X-ray computer tomography scanning and mercury intrusion porosimetry, Fourier transform infrared spectroscopy, scanning electron microscopy with Energy Dispersive X-Ray Spectroscopy, and X-ray diffraction, were carried out on samples cured either at room temperature or at 40 °C. Results showed that the inclusion of GNPs at a dosage of 0.05% provided a considerable increase in compressive strength at both curing conditions. Microstructural observations suggested that the presence of GNPs improved the formation of hydrated gel, and the research demonstrated through porosity measurements the shift from the capillary to the gel pore region due to the inclusion of GNPs. This study represents a step forward in understanding the effects of GNPs inclusion on alkali activated binder microstructure.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"13 ","pages":"Article 100080"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50191468","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}

{"title":"Environmental assessment in concrete pole industries","authors":"Nathalie Barbosa Reis Monteiro ,&nbsp;José Machado Moita Neto ,&nbsp;Elaine Aparecida da Silva","doi":"10.1016/j.cement.2023.100076","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100076","url":null,"abstract":"<div><h3>Purpose</h3><p>Companies that manufacture poles generate several negative environmental impacts, whose extent needs to be assessed to find ways to mitigate them.</p></div><div><h3>Methods</h3><p>In this research, Life Cycle Assessment (LCA) was used as a methodology to measure the potential environmental impacts throughout the poles' life cycle. Primary data (amount of cement, gravel, sand, steel rebars, energy, water) were collected from industries located in Teresina, Piauí, Brazil, and information from the Ecoinvent 3.7.1 database (transport, solid waste, liquid effluents, particulate matter) was used.</p></div><div><h3>Results and discussion</h3><p>The literature addresses pole production from a different perspective, making this study relevant to disseminate the life cycle thinking in concrete pole production. However, the literature points to a correlation trend for ecotoxicity and human toxicity indicators, as well as the results found in this research. Waste disposal stands out as an important source of impact for these industries, confirming the necessity of efficient management of these materials at the end of their lifespan and during the production process. The scenario analysis showed that is possible to reduce the potential impacts of these industries.</p></div><div><h3>Conclusion</h3><p>The reuse of waste within the industry itself is feasible (using a shredder for this purpose) and can contribute to decreasing the extraction of natural deposits in various production processes related to the poles' life cycle and reducing their accumulation in the environment. The use of inputs from closer suppliers is a strategy that contributes to mitigating the potential impact of gaseous emissions, reducing the impact that generates global warming and climate change. In addition, other papers show viable alternatives in different scenarios, based on complex laboratory studies. Nevertheless, his approach shows how impacts can be mitigated with the adoption of simple actions such as the reuse of effluents and residues from these industries. It is possible to redefine the production process through a scenario close to the ideal, bringing environmental sustainability to the sector.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"13 ","pages":"Article 100076"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50191140","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}

{"title":"Potential of spent fluid cracking catalyst (FCC) waste for low-carbon cement production. Effect of treatments to enhance reactivity","authors":"Z. Lei,&nbsp;S. Pavia","doi":"10.1016/j.cement.2023.100081","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100081","url":null,"abstract":"<div><p>Spent fluid cracking catalyst (FCC) waste is produced to convert petroleum crude oil into gasoline, and its main component is a reactive zeolite known as faujasite. This paper studies low-energy treatments to enhance reactivity. When untreated, the spent FCC has outstanding activity, and a fast set which delivered significant strength (6–10 MPa) and a high mechanical index (MI=14). Calcination (up to 800 °C) is not enough to amorphize the faujasite and increase reactivity. However, NaOH-fusion is highly efficient. Even at low temperature (450 °C), NaOH-fusion breaks down the zeolite structure, dissolving Si⁴⁺ that forms cementing hydrates with high Ca/Si and Si/Al ratios which delivered high strengths. NaOH-fusion at 450 °C totally amorphized the zeolite resulting in high strength (9–13 MPa) and outstanding MI&gt;22; superior to pozzolans, and closer to cementitious materials. Fusion at 600 °C reorganises some of the amorphous phase into a silicate whose hydrates provided the greatest strengths (over 16 MPa) and an outstanding MI of 24.</p><p>Na₂CO₃-fusion at 600 °C did not alter the spent FCC but provided CO₃²⁻ which formed calcite cements. These initially densified the matrix providing strength but lowered long-term strength and workability.</p><p>Acid-etching partially dissolved spent FCC particles which improved early activity but caused a loss of soluble Si⁴⁺ and Al³⁺ that reduced the ultimate strength. Due to the low organic matter in the spent FCC, oxidation did not increase reactivity.</p><p>The spent FCC is highly pozzolanic, it can safely reduce the embodied carbon of cements: concentrations of heavy metals are either traces or insignificant. Therefore, they can easily immobilise in a stable matrix.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"14 ","pages":"Article 100081"},"PeriodicalIF":0.0,"publicationDate":"2023-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194577","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}

{"title":"Leachate testing for delayed ettringite formation potential in cementitious systems","authors":"Benjamin J. Mohr ,&nbsp;M. Shariful Islam ,&nbsp;J. France-Mensah","doi":"10.1016/j.cement.2023.100060","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100060","url":null,"abstract":"<div><p>The aim of this research was to investigate the relation between leachate data and expansion due to delayed ettringite formation (DEF). These correlations have the potential for identifying the probability of delayed ettringite formation in a shorter time than the traditional method of monitoring expansion over time. Ions leached from the samples after heat curing of the cement paste were measured and the resultant data were used to calculate relative quasi-crystallization pressures within the cement microstructure. Potential relationships exist between these pressures, time to expansion initiation, and overall percent expansion of samples. The results indicate that sulfates and alkalis affect the onset and overall percent expansion observed. The calculated quasi-crystallization pressures strongly correlate with the observed overall percent expansion of mortar bars. Time to expansion initiation was negatively correlated with alkali content, indicating that cement with higher amounts of alkalis tends to expand at earlier ages. Overall, the leachate test corroborates earlier findings in the determination of DEF potential in cementitious materials and allows for the possible prediction of expansive behavior in 28 days or less using experimental results as opposed to cement composition.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"12 ","pages":"Article 100060"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50189480","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}

{"title":"Reactivity of waterglass in cementitious systems","authors":"Melissa McAlexander,&nbsp;Keshav Bharadwaj,&nbsp;W. Jason Weiss,&nbsp;O. Burkan Isgor","doi":"10.1016/j.cement.2023.100067","DOIUrl":"https://doi.org/10.1016/j.cement.2023.100067","url":null,"abstract":"<div><p>This research investigates the chemical reactivity of waterglass, a sodium silicate (Na₂O·<em>n</em>SiO₂·yH₂O). This research establishes a framework for thermodynamic modeling of waterglass systems that contain calcium hydroxide and potassium hydroxide. Conventional pozzolanic reactivity tests used for supplementary cementitious materials (e.g., fly ash) that rely on heat release and calcium hydroxide consumption cannot adequately capture the waterglass reactivity, primarily due to the high reaction rates. Capturing the heat released using isothermal calorimetry requires procedural changes in the testing protocol. Specifically, the test is modified by lowering the temperature of the test to slow the reaction rate and using internal mixing to capture the initial reaction. The heat release and calcium hydroxide consumption are used to quantify the reactivity. The theoretical relationship between heat, reactivity, and calcium hydroxide consumption is related to the molar ratio of SiO₂ to Na₂O, also known as the waterglass modulus (<em>n</em>). Thermodynamic modeling and X-ray powder diffraction results demonstrate that the mixtures react to produce Tobermorite-like calcium-silicate-hydrate (C–S–H, C/S = 1.42), which increases in amount with waterglass modulus. Finally, the developed approach demonstrates how the quantified reactivity is used in thermodynamic calculations to predict the reaction products and paste properties.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"12 ","pages":"Article 100067"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50189485","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}