ce/papers最新文献_第9页

Quellverhalten von Portland- und Hochofenzementstein bei unterschiedlichen Temperaturen 同时气温偏高的波特兰和高音部的失常状态

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2918

Falk Wagemann, Frank Schmidt-Döhl, Amir Rahimi

{"title":"Quellverhalten von Portland- und Hochofenzementstein bei unterschiedlichen Temperaturen","authors":"Falk Wagemann, Frank Schmidt-Döhl, Amir Rahimi","doi":"10.1002/cepa.2918","DOIUrl":"https://doi.org/10.1002/cepa.2918","url":null,"abstract":"<div>\u0000 \u0000 <p>Zementgebundene Baustoffe quellen bei permanenter Wasserlagerung, d. h., sie erfahren eine zeitabhängige Volumenzunahme. Wesentlich für das Quellverhalten zementgebundener Baustoffe ist der volumetrische Anteil an Zementstein. Für Bereiche, in denen Betonbauteile permanent einer Wasserumgebung ausgesetzt sind, wie zum Beispiel bei Gründungen im Grundwasser, kann das Quellverhalten ggf. die Tragwirkung verbessern, da sich Bauteile im Boden infolge des Quelldruckes verspannen. Dieser Beitrag untersucht das Quellverhalten von Zementstein aus CEM I und CEM III/B mit w/z-Werten von 0,3 und 0,5 bei 10 °C und 20 °C betrachtet. Zusätzlich wurden im Rahmen der Untersuchungen Zementsuspensionen verpresst, um Filtrationseffekte abzubilden. Neben dem Quellmaß zu verschiedenen Zeitpunkten (1, 3, 5, 7, 14, 28 und 56 Tage) wurde der Hydratationsgrad und Gehalt an Calciumhydroxid mit Hilfe der Thermogravimetrie und die Porosität mittels Quecksilberdruckporosimetrie als Materialkennwerte bestimmt. Die Untersuchungsmethoden erlauben einen Rückschluss von Porosität und Hydratphasenausbildung auf das Quellverhalten der untersuchten Zementsteine zu ziehen. Bei beiden Zementarten führen niedrigere Lagerungstemperaturen zu höheren Quellmaßen.</p>\u0000 </div>","PeriodicalId":100223,"journal":{"name":"ce/papers","volume":"6 6","pages":"1091-1100"},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cepa.2918","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502482","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: 0

Erratum to: Changes to the lambda model for fatigue loads on steel railway bridges in Europe 对欧洲钢铁路桥梁疲劳荷载lambda模型的修改的勘误

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.3013

引用次数: 0

Preventing Alkali-Silica Reaction in Concrete 防止混凝土中的碱-硅反应

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2935

Jason H. Ideker, Thano Drimalas, Kevin J. Folliard, Ardalan Ghanizadeh, Anuj Parashar, Krishna Siva Teja Chopperla, April Snyder, Michael D.A. Thomas

{"title":"Preventing Alkali-Silica Reaction in Concrete","authors":"Jason H. Ideker, Thano Drimalas, Kevin J. Folliard, Ardalan Ghanizadeh, Anuj Parashar, Krishna Siva Teja Chopperla, April Snyder, Michael D.A. Thomas","doi":"10.1002/cepa.2935","DOIUrl":"https://doi.org/10.1002/cepa.2935","url":null,"abstract":"<div>\u0000 \u0000 <p>Alkali-silica reaction continues to be a challenging durability issue for portland cement-based concrete. While myriad of preventive options is known to reduce the risk of ASR, changes in availability and consistency of materials make either prescriptive or performance-based approaches difficult to develop and then quickly adapt. In general, the research community has supported industry with practical solutions based on empirically derived relationships, mostly from accelerated test methods and to a lesser extent realistic exposure/field structures. It is time to increase the level of science behind our approach. The research team represented in this talk is investigating a new methodology that combines the alkali availability needed to initiate ASR (aggregate specific) with the available alkali from the total cementitious blend. The relationship between reactivity of a supplementary cementitious material and the ASR expansion is also explored. This keynote lecture will: 1) Explore performance-based testing versus prescriptive approaches and why a hybrid approach should be considered ASR prevention; 2) Evaluate the relationship between accelerated laboratory tests, outdoor exposure blocks and field structures; 3) Examine the use of “non-traditional” supplementary cementitious materials and/or chemical admixtures to prevent alkali-silica reaction; 4) Propose future research needs and; 5) Make recommendations for how best to prevent alkali-silica reactivity following the proposed approach.</p>\u0000 </div>","PeriodicalId":100223,"journal":{"name":"ce/papers","volume":"6 6","pages":"1101-1109"},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cepa.2935","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502537","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: 0

Increase in physical and mechanical properties of decorative concretes for the post-war restoration of residential and public buildings in the Kharkiv region with the addition of highly dispersed calcite (chalk) 增加装饰混凝土的物理和机械性能，用于哈尔科夫地区住宅和公共建筑的战后修复，添加高度分散的方解石(白垩)

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2793

Svitlana Chepurna, Olena Dudka, Yevhenii Chepurnyi

{"title":"Increase in physical and mechanical properties of decorative concretes for the post-war restoration of residential and public buildings in the Kharkiv region with the addition of highly dispersed calcite (chalk)","authors":"Svitlana Chepurna, Olena Dudka, Yevhenii Chepurnyi","doi":"10.1002/cepa.2793","DOIUrl":"https://doi.org/10.1002/cepa.2793","url":null,"abstract":"<p>During the war active, a huge number of residential and public buildings were destroyed not only in Kharkiv and the region, but throughout Ukraine. For the restoration of destroyed buildings, new types of cement will be needed to look for and will be created decorated concretes based on them that would provide high operational and technological properties of constrictions and will be focused on local materials. Carbonate additive such as highly dispersed calcite (chalk) can be used for as local additive for concrete due to significant reserves are located in Kharkiv region. In the article research on the impact of joint action additive of highly dispersed calcite (chalk) and natural pigment (ocher) is presented by physical and mechanical properties such as density, strength, water resistance, and frost resistance. It has been established that, depending on the percentage of highly dispersed calcite (chalk), the physical and mechanical properties are changed irregularly. On the basis of the conducted researches it was established that the optimal amount of the addition of high-fossil chalk, which provides increased frost resistance and corrosion resistance of concrete in an aggressive environment, containing chlorides, sulfates and magnesium ions, is from 10 % to 30 %. In addition, it increases density, compressive strength, stretching strength at bending. At the same time, it should be noted at an increased amount of fine chalk to 40% leads to a decrease in physical and mechanical characteristics. But the introduction of plasticizer in the amount of 0.5% leads to increased compressive strength and, accordingly, increases the positive qualities of chalk. The concrete compositions that getting with high decorative and operational properties are allowed to use them for the restoration of the city and increase in urban space.</p>","PeriodicalId":100223,"journal":{"name":"ce/papers","volume":"6 6","pages":"1429-1433"},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502559","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}

引用次数: 0

Shotcrete 3D Printing - Interaction of nozzle geometry, homogeneity and hardened concrete properties 喷射混凝土3D打印-喷嘴几何形状、均匀性和硬化混凝土特性的相互作用

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2818

Niklas Freund, Martin David, David Böhler, Inka Mai, Stefan Ullmann, Klaus Dröder, Dirk Lowke

{"title":"Shotcrete 3D Printing - Interaction of nozzle geometry, homogeneity and hardened concrete properties","authors":"Niklas Freund, Martin David, David Böhler, Inka Mai, Stefan Ullmann, Klaus Dröder, Dirk Lowke","doi":"10.1002/cepa.2818","DOIUrl":"https://doi.org/10.1002/cepa.2818","url":null,"abstract":"<div>\u0000 \u0000 <p>Shotcrete 3D Printing (SC3DP) applies concrete layer by layer using a wet-spray process. The resulting hardened concrete properties of the applied SC3DP layers (e.g. height, width or mechanical strength) are largely dependent on the selected material and process parameters. In this context, the nozzle geometry is an important influencing parameter. During printing, the velocity of the shotcrete jet is significantly influenced by the nozzle outlet diameter. Therefore, in the present study, the effect of the nozzle outlet diameter (15 - 30 mm) is investigated with regard to the resulting layer homogeneity, i.e. local density and aggregate distribution in the cross-section, and hardened concrete properties, i.e. flexural strength. By analysing the manufactured specimens, an uneven distribution of the aggregate is observed horizontally across the cross-section of the layers. An accumulation of aggregate is present in the core of the layer resulting in a cement paste-rich region in the edge areas. This leads to increased local densities in the core of the specimen. The application of the concrete with small nozzle outlet diameters results in the highest local densities and the highest flexural strength.</p>\u0000 </div>","PeriodicalId":100223,"journal":{"name":"ce/papers","volume":"6 6","pages":"746-754"},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cepa.2818","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502569","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: 0

Effects of the Chemical Composition of Synthetic Slags Compared to an Average Blast Furnace Slag 合成炉渣与普通炉渣化学成分的比较

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2933

Luis Schnürer, Alisa Machner

{"title":"Effects of the Chemical Composition of Synthetic Slags Compared to an Average Blast Furnace Slag","authors":"Luis Schnürer, Alisa Machner","doi":"10.1002/cepa.2933","DOIUrl":"https://doi.org/10.1002/cepa.2933","url":null,"abstract":"<div>\u0000 \u0000 <p>To study the effect of the main oxides and the minor components in slags on their reactivity as SCM, various glasses were synthesized to stepwise imitate a commercial slag of average chemical composition. First, a glass was produced from the main oxides CaO, Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub>. In a second step, the minor components MgO, Fe<sub>2</sub>O<sub>3</sub>, Na<sub>2</sub>O and K<sub>2</sub>O were added separately to the main oxide mix. A selection of two synthetic glasses was tested for their compressive strength contribution (up to 90 days) by substituting 20 wt.% of cement. After all testing times, the synthetic slags achieved a strength similar to that of the commercial product. The reactivities determined by heat flow calorimetry (R<sup>3</sup> test) correlate with the calculation of NBO/T and the results of <sup>29</sup>Si MAS NMR showing that a decreased degree of polymerization enhances the reactivity. Apart from that, FTIR spectroscopy and <sup>27</sup>Al MAS NMR indicate a similar structure of the original and the synthetic slags.</p>\u0000 </div>","PeriodicalId":100223,"journal":{"name":"ce/papers","volume":"6 6","pages":"181-188"},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cepa.2933","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502598","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: 0

Ultra-high performance alkali-activated slag as a reusable mold for light metal casting 超高性能碱活性渣作为轻金属铸造的可重复使用模具

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2772

Janna Link, Alexander Wetzel, Sebastian Müller, Bernhard Middendorf

引用次数: 0

Optimisation and prediction of compressive properties for concrete containing recycled aggregates and rice husk ash using response surface methodology (RSM) 利用响应面法(RSM)优化和预测含再生骨料和稻壳灰混凝土的抗压性能

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2872

Wenzhuo Ma, Yutong Wang, Liang Huang, Libo Yan, Bohumil Kasal

{"title":"Optimisation and prediction of compressive properties for concrete containing recycled aggregates and rice husk ash using response surface methodology (RSM)","authors":"Wenzhuo Ma, Yutong Wang, Liang Huang, Libo Yan, Bohumil Kasal","doi":"10.1002/cepa.2872","DOIUrl":"https://doi.org/10.1002/cepa.2872","url":null,"abstract":"<div>\u0000 \u0000 <p>Rice husk ash (RHA), an agricultural by-product, has been added as supplementary cementitious material (SCM) in concrete mixture to improve the compressive properties of recycled aggregate concrete (RAC) in recent years. This study aimed to optimise the mixture design of RAC considering two variables: the replacement ratio (wt.%) of recycled aggregate (RA) to natural aggregate (NA) with three levels (0%, 50% and 100%) and the replacement ratio (wt.%) of RHA to cement with three levels (0%, 10% and 20%). Compression test was implemented at concrete age of 28 days based on the full factorial experiment. By means of response surface methodology (RSM), the optimised RA replacement ratio and RHA replacement ratio can be calculated with respect to the compressive strength and E-modulus at 28 days, and vice versa the compressive strength and E-modulus at 28 days of RAC containing RHA can also be predicted. According to response surface modelling, the compressive strength reaches the maximum value when the RA replacement ratio is 0% and the RHA replacement ratio is 7%, and the E-modulus would reach the maximum when the RA replacement ratio is 17% and the RHA replacement ratio is 7%. The determination coefficient (R<sup>2</sup>) and adjusted coefficient (R<sup>2</sup><sub>adj</sub>) for the compressive strength model are 0.9632 and 0.9544 respectively, and for the E-modulus model are 0.9319 and 0.9157 respectively, showing that the models developed by RSM are relatively well correlated with the experimental results.</p>\u0000 </div>","PeriodicalId":100223,"journal":{"name":"ce/papers","volume":"6 6","pages":"1009-1014"},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cepa.2872","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502613","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: 0

Material-minimised construction with extruded textile reinforced concrete 材料最小化建筑与挤压纺织钢筋混凝土

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2827

Matthias Kalthoff, Cynthia Morales Cruz, Michael Raupach, Thomas Matschei

{"title":"Material-minimised construction with extruded textile reinforced concrete","authors":"Matthias Kalthoff, Cynthia Morales Cruz, Michael Raupach, Thomas Matschei","doi":"10.1002/cepa.2827","DOIUrl":"https://doi.org/10.1002/cepa.2827","url":null,"abstract":"<div>\u0000 \u0000 <p>The use of textile reinforced concrete (TRC) is particularly suitable for producing sustainable, material-minimised components, as it allows for a significant reduction in the amount of concrete cover required compared to steel reinforced concrete (SRC). Instead of steel, fibres made of glass, aramid or carbon are used as reinforcement, which are processed from rovings into textiles with a polymer or mineral impregnation. Among these, carbon reinforcements have the highest tensile strength and alkali resistance, making them the most durable in concrete and requiring less maintenance over time. An innovative approach is the production of TRC structures by means of extrusion, in which the stiff, fresh concrete is continuously pressed through a shaping mouthpiece, giving the product its final shape. Within the scope of the CRC/Transregio 280, a new mouthpiece was developed that enables the horizontal introduction of stiff, impregnated textiles. The carbon TRC produced in this process showed a textile stress of up to 4,000 MPa. Additionally, solutions are presented that allow the characterization of stiff, fresh concrete and technical limits for shaping fresh, extruded TRC elements. The potential of this new production method is illustrated through the example of a compound component made of extruded TRC elements.</p>\u0000 </div>","PeriodicalId":100223,"journal":{"name":"ce/papers","volume":"6 6","pages":"797-801"},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cepa.2827","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502617","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: 0

Temperature dependance of 3D printed concrete produced with copper tailings 铜尾矿3D打印混凝土的温度依赖性

ce/papers Pub Date : 2023-12-06 DOI: 10.1002/cepa.2829

Claudia Eugenin, Karla Cuevas, Ivan Navarrete

{"title":"Temperature dependance of 3D printed concrete produced with copper tailings","authors":"Claudia Eugenin, Karla Cuevas, Ivan Navarrete","doi":"10.1002/cepa.2829","DOIUrl":"https://doi.org/10.1002/cepa.2829","url":null,"abstract":"<p>3D printed concrete is being applied in an increasing amount worldwide. While in theory, there are environmental and economic benefits associated with using this technology, in practice, the amount of cement in printable concrete is much higher than in a conventional one, leading to increased environmental and economic costs. Furthermore, cement's performance relies heavily on climate variables, specifically temperature. One way to solve this issue is to include local alternative low-CO<sub>2</sub> materials, such as processed mine tailings, as cement replacement. This paper presents an experimental approach to assess the use of copper tailings as cement replacement in printable concrete under different ambient temperatures. Three levels of cement volume replacement have been researched. The copper tailings' rheological effect has been measured using standard printability tests and a rheometer. Four mixtures have been printed in a controlled-climate chamber to evaluate print-ability, buildability and extrudability. The mechanical effect has been assessed with compressive and flexural strength tests of samples collected from the printed specimens. The results show that copper tailings are a promising alternative to cement in printable concrete in countries where this by-product is abundant.</p>","PeriodicalId":100223,"journal":{"name":"ce/papers","volume":"6 6","pages":"802-811"},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502618","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}

引用次数: 0