CEMENT Pub Date : 2021-09-01 DOI: 10.1016/j.cement.2021.100011

J. Goergens, F. Goetz-Neunhoeffer

{"title":"Temperature-dependent late hydration of calcium aluminate cement in a mix with calcite – Potential of G-factor quantification combined with GEMS-predicted phase content","authors":"J. Goergens, F. Goetz-Neunhoeffer","doi":"10.1016/j.cement.2021.100011","DOIUrl":"https://doi.org/10.1016/j.cement.2021.100011","url":null,"abstract":"<div>In continuation of earlier work on early hydration, this study evaluates the late hydration of CAC and CaCO3 using QXRD and thermodynamic modelling at different temperatures. Experiments were performed at 5, 23, 40 and 60 °C for up to one year. As stated in the preceding study, C2AHX might act as a precursor for monocarbonate in early hydration, and thus no or only little monocarbonate should form at temperatures below 20 °C. At 5 °C, monocarbonate starts precipitating after 7 d and remains alongside CAH10. At all other investigated temperatures, monocarbonate is the dominant hydrate phase. Primarily formed CAH10 at 23 °C is visible up to 14 d but then becomes unstable with respect to monocarbonate. At 23 °C and 40 °C the thermodynamically stable phase assemblage is reached within one year. However, the precipitation of C3AH6 is detected in all samples at 60 °C, which results from an insufficient w/CAC ratio for carbonate-AFm in the paste due to the inevitable evaporation of mixing water for this condition. However, C3AH6 can partly be “re-converted” at 60 °C when the sample is subsequently stored under water and monocarbonate is stable again.</div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"5 ","pages":"Article 100011"},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cement.2021.100011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90006586","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}

引用次数: 7

Evaluation of corn straw ash as supplementary cementitious material: Effect of acid leaching on its pozzolanic activity 玉米秸秆灰作为补充胶凝材料的评价:酸浸对其火山灰活性的影响

CEMENT Pub Date : 2021-06-01 DOI: 10.1016/j.cement.2021.100007

Charles Prado Ferreira de Lima, Guilherme Chagas Cordeiro

{"title":"Evaluation of corn straw ash as supplementary cementitious material: Effect of acid leaching on its pozzolanic activity","authors":"Charles Prado Ferreira de Lima, Guilherme Chagas Cordeiro","doi":"10.1016/j.cement.2021.100007","DOIUrl":"10.1016/j.cement.2021.100007","url":null,"abstract":"<div>The use of biomass ash is an environmentally friendly practice in the search for sustainable construction materials. This study aimed to produce pozzolanic ash from corn straw with a high amorphous silica content, low carbon content, and high specific surface area via controlled acid leaching, two-step burning, and grinding. The effect of pretreating corn straw on the properties of the material was assessed by comparative analysis with corn straw and rice husk ashes produced without acid pretreatment. To this end, characterization data, hydration heat, chemically bound water, and portlandite consumption in pastes, and mortar compressive strength were used to evaluate the pozzolanicity of the ashes. The results indicated that all the ashes exhibited pozzolanic behavior and that the leaching process significantly improved the physical and chemical properties of corn straw ash, with reduction in portlandite content. The calorimetric results showed a change in hydration kinetics with an increase in ash in the cement mixes. Moreover, the compressive strength of leached corn straw ash-based mortars was greater than that of the other mortars, primarily for high levels of cement replacement (20 and 30% by mass).</div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"4 ","pages":"Article 100007"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cement.2021.100007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"111284388","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}

引用次数: 16

The effective volumes of waters of crystallization & the thermodynamics of cementitious materials 结晶水的有效体积&胶凝材料的热力学

CEMENT Pub Date : 2021-03-01 DOI: 10.1016/j.cement.2021.100004

Leslie Glasser

{"title":"The effective volumes of waters of crystallization & the thermodynamics of cementitious materials","authors":"Leslie Glasser","doi":"10.1016/j.cement.2021.100004","DOIUrl":"10.1016/j.cement.2021.100004","url":null,"abstract":"<div>Hydrates are significant components of cements and concrete. We examine the effective volumes of waters of crystallization for these materials, where the “effective volumes” are the difference per water molecule between the formula volume of the hydrate and of its parent anhydrate. These effective volumes cover a small range around 15 cm3 mol−1 (≅ 23 Å3 per water molecule), unlike the wider range for general inorganic materials.We also examine the thermodynamic properties of the cementitious phase, which follow the generally observed correlation of relating to their molar volumes. We establish “effective” additive oxide parameters for enthalpy and for molar volume, which are useful in confirming experimental values and in predicting as-yet undetermined values. Their Debye temperatures approximate to 600 K; this Debye temperature is well above ambient temperature and suggests that the vibrational modes of these cementitious phases are only partially excited and that the materials are hard. Ferrate-containing materials generally have a lower Debye temperature (∼273 K) implying that they may be softer than other cementitious materials.These observations may be useful in checking for errors in data and anomalies in behavior among related cementitious materials.</div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"3 ","pages":"Article 100004"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cement.2021.100004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"96790825","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}

引用次数: 4

Assessing condition of concrete affected by internal swelling reactions (ISR) through the Damage Rating Index (DRI) 用损伤等级指数(DRI)评价混凝土内膨胀反应(ISR)影响条件

CEMENT Pub Date : 2020-06-01 DOI: 10.1016/j.cement.2020.100001

L.F.M. Sanchez , T. Drimalas , B. Fournier

引用次数: 8

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