Advanced Cement Based Materials最新文献_第3页

Microstructural changes due to elevated temperature in cement based grouts 水泥基灌浆温度升高引起的微观结构变化

Advanced Cement Based Materials Pub Date : 1998-10-01 DOI: 10.1016/S1065-7355(98)00016-9

Danielle Palardy , Maria Onofrei , Gerard Ballivy

{"title":"Microstructural changes due to elevated temperature in cement based grouts","authors":"Danielle Palardy , Maria Onofrei , Gerard Ballivy","doi":"10.1016/S1065-7355(98)00016-9","DOIUrl":"10.1016/S1065-7355(98)00016-9","url":null,"abstract":"<div><p>The durability of type K and H cement based grouts under conditions potentially found to be in high level nuclear waste repositories was studied. Tests have been carried out to determine the effects of temperature on the hydraulic conductivity and the leaching resistance of the grouts. Measurements of mercury intrusion porosimetry and scanning electron microscopy with energy dispersive X-ray analysis have been used to investigate the changes in the pore structures of both grouts as function of leaching and permeating time. Type K and type H cement based grouts, made with low water to cementitious materials ratio, silica fume, and superplasticizer, were exposed to high temperature and pressure. Preliminary results indicate that both hydraulic properties and leaching behavior of the grouts investigated are affected by the increase in temperature. However, data show that leaching rate and hydraulic conductivity of the grouts decrease with time. The results showed clearly that chemical reactions, presumably accelerated by the elevated temperatures (100°C), led to the formation of a precipitate in the microcracks and on the surface of the leached specimens. This precipitate is likely the cause of the observed decrease in the hydraulic conductivity and leaching rate.</p></div>","PeriodicalId":100028,"journal":{"name":"Advanced Cement Based Materials","volume":"8 3","pages":"Pages 132-138"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1065-7355(98)00016-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80844560","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: 12

Cl−, SO42−, and PO43− distribution in concrete slabs ponded by corrosion-inhibitor-added deicing salts Cl−、SO42−和PO43−在掺入缓蚀剂和除冰盐的混凝土板中的分布

Advanced Cement Based Materials Pub Date : 1998-10-01 DOI: 10.1016/S1065-7355(98)00012-1

Ji-Won Jang , Mark G. Hagen , Glenn M. Engstrom , Iwao Iwasaki

{"title":"Cl−, SO42−, and PO43− distribution in concrete slabs ponded by corrosion-inhibitor-added deicing salts","authors":"Ji-Won Jang , Mark G. Hagen , Glenn M. Engstrom , Iwao Iwasaki","doi":"10.1016/S1065-7355(98)00012-1","DOIUrl":"10.1016/S1065-7355(98)00012-1","url":null,"abstract":"<div><p>Deicing chemicals are mixed with corrosion inhibitors to reduce rebar corrosion in bridge decks. The corrosion inhibitors are thought to penetrate into concrete to the depth of the rebars and form the passive film on the rebar surface. In a previous study, it was found that corrosion-inhibitor-added deicing salts interacted with 3% NaCTadded concrete and produced precipitates through chemical reactions. The amounts of precipitates produced was dependent on the type and concentration of corrosion-inhibitor-added deicing salts. In this investigation, the precipitates formed by chemical reactions between concrete and corrosion-inhibitor-added deicing salts were identified by using chemical analysis and X-ray diffraction methods. The distributions of Cl<sup>−</sup>, SO<sub>4</sub><sup>2−</sup>, and PO<sub>4</sub><sup>3−</sup> in concrete slabs ponded with corrosion-inhibitor-added deicing salts were determined by chemical analyses of powder samples obtained from the slabs. The major precipitates were calcium and/or magnesium phosphates as major chemical compounds and gypsum as a minor component. High concentrations of phosphate were observed at the top portion of concrete slabs when the deicing chemicals contained phosphate inhibitors. Voids were observed at the interface of aggregate and mortar in the concrete slabs tested with the deicing salts solutions containing corrosion inhibitors.</p></div>","PeriodicalId":100028,"journal":{"name":"Advanced Cement Based Materials","volume":"8 3","pages":"Pages 101-107"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1065-7355(98)00012-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88919508","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: 11

Subject index to volume 7 第七卷的主题索引

Advanced Cement Based Materials Pub Date : 1998-10-01 DOI: 10.1016/S1065-7355(98)80002-3

引用次数: 0

Author index to volume 8 第8卷作者索引

Advanced Cement Based Materials Pub Date : 1998-10-01 DOI: 10.1016/S1065-7355(98)80003-5

引用次数: 0

Multiscale Analytical/Numerical Theory of the Diffusivity of Concrete 混凝土扩散系数的多尺度解析/数值理论

Advanced Cement Based Materials Pub Date : 1998-09-01 DOI: 10.1016/S1065-7355(98)00010-8

Edward J. Garboczi , Dale P. Bentz

{"title":"Multiscale Analytical/Numerical Theory of the Diffusivity of Concrete","authors":"Edward J. Garboczi , Dale P. Bentz","doi":"10.1016/S1065-7355(98)00010-8","DOIUrl":"10.1016/S1065-7355(98)00010-8","url":null,"abstract":"<div><p>The ionic diffusivity of a concrete is a function of its microstructure at many length scales, ranging from nanometers to millimeters. The microstructure is largely controlled by the initial concrete mixture proportions and the ultimate curing conditions. Linking a property like ionic diffusivity to the microstructure then requires a multiscale approach. A multiscale microstructural computer model for ionic diffusivity has been previously developed. This model has been developed specifically to compute the chloride diffusivity of concretes with various mixture proportions and projected degrees of hydration. The three key parts of this model were dependent on large-scale supercomputer-magnitude simulations to: (1) determine the total volume of interfacial zones for a given aggregate distribution; (2) simulate the hydrated cement paste microstructure around a typical aggregate; and (3) compute the effect of the aggregates and interfacial zones on the overall diffusivity of the concrete. The key feature of this model is that one can approximately take into account the redistribution of cement paste between interfacial transition zone regions and bulk paste regions, and its important effect on overall concrete diffusivity. In the present article, we review the previously developed model and show how analytical equations can accurately replace the large scale computer simulations of parts (1) and (3). This accomplishment will make the model more usable by those who do not have access to supercomputer computing power.</p></div>","PeriodicalId":100028,"journal":{"name":"Advanced Cement Based Materials","volume":"8 2","pages":"Pages 77-88"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1065-7355(98)00010-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90091989","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: 195

Solvent Replacement Studies of Hydrated Portland Cement Systems: The Role of Calcium Hydroxide 水合硅酸盐水泥体系的溶剂替代研究:氢氧化钙的作用

Advanced Cement Based Materials Pub Date : 1998-09-01 DOI: 10.1016/S1065-7355(98)00008-X

James J Beaudoin , Ping Gu , Jacques Marchand , Basile Tamtsia , Robert E Myers , Zheng Liu

引用次数: 64

Extruded Fiber Reinforced Cement Pressure Pipe 挤压纤维增强水泥压力管

Advanced Cement Based Materials Pub Date : 1998-09-01 DOI: 10.1016/S1065-7355(98)00006-6

Corina Aldea , Shashi Marikunte , Surendra P Shah

{"title":"Extruded Fiber Reinforced Cement Pressure Pipe","authors":"Corina Aldea , Shashi Marikunte , Surendra P Shah","doi":"10.1016/S1065-7355(98)00006-6","DOIUrl":"10.1016/S1065-7355(98)00006-6","url":null,"abstract":"<div><p>Extrusion is a plastic-forming method that is suitable not only for flat shapes, but also for structural shapes, such as I-sections, channels, pipes, and hollow and solid tubes. The advantage of introducing extrusion into cement product processing is that the materials are formed under high shear and compressive forces resulting in composites with improved performance. This article presents research results on extruded fiber reinforced cement pipe and flat sheet. A pipe die was designed and developed specifically for extrusion of cement based materials. Three different mix proportions were selected by varying the fiber type (polyvinyl alcohol and alkali-resistant glass), admixture type (silica fume, metakaolin, and latex), and their proportions to study their influence on the properties of extruded fiber reinforced cement pipes and thin sheets. Extruded cement pipes were tested for hydrostatic burst strength, bearing strength, and flexural performance. Thin sheets were tested for tensile and flexural performance. The test results indicated that polyvinyl alcohol fibers in the presence of silica fume and latex provide a suitable reinforcing effect, and silica sand provides good surface finish.</p></div>","PeriodicalId":100028,"journal":{"name":"Advanced Cement Based Materials","volume":"8 2","pages":"Pages 47-55"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1065-7355(98)00006-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85970073","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: 49

Effects of Polyvinyl Alcohol on Aggregate-Paste Bond Strength and the Interfacial Transition Zone 聚乙烯醇对骨料-膏体结合强度及界面过渡区的影响

Advanced Cement Based Materials Pub Date : 1998-09-01 DOI: 10.1016/S1065-7355(98)00009-1

Jae-Ho Kim , Richard E. Robertson

{"title":"Effects of Polyvinyl Alcohol on Aggregate-Paste Bond Strength and the Interfacial Transition Zone","authors":"Jae-Ho Kim , Richard E. Robertson","doi":"10.1016/S1065-7355(98)00009-1","DOIUrl":"10.1016/S1065-7355(98)00009-1","url":null,"abstract":"<div><p>Small amounts of polyvinyl alcohol (PVA) were added to cement paste in an attempt to increase the aggregate-paste bond strength. Specimens consisted of ordinary Portland cement mixed with PVA/water solutions and cast against ground surfaces of limestone and granite. The aggregate-paste bond strength after curing was tested in a wet state by three-point bending. The morphology of the interfacial transition zone was observed with scanning electron microscopy, and the composition was analyzed with infrared spectroscopy. The addition of 1.4 wt% PVA based on the mass of cement increased the strength for both limestone-paste and granite-paste bonds. The strength increase was about five-fold for limestone and nearly two-fold for granite. The failure mode also changed, from pure adhesive failure without PVA to cohesive failure of the aggregate with limestone and to a mixed cohesive failure of the paste and adhesive failure with granite. The gain in bond strength with the addition of PVA seems to arise from suppression of the porous interfacial transition zone and an inhibition of calcium hydroxide nucleation on the aggregate surface.</p></div>","PeriodicalId":100028,"journal":{"name":"Advanced Cement Based Materials","volume":"8 2","pages":"Pages 66-76"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1065-7355(98)00009-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82099241","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: 73

Quasi-Instantaneous and Long-Term Deformations of High Performance Concrete with Sealed Curing 高性能混凝土密封养护的准瞬时和长期变形

Advanced Cement Based Materials Pub Date : 1998-07-01 DOI: 10.1016/S1065-7355(98)00004-2

Bertil Persson

{"title":"Quasi-Instantaneous and Long-Term Deformations of High Performance Concrete with Sealed Curing","authors":"Bertil Persson","doi":"10.1016/S1065-7355(98)00004-2","DOIUrl":"10.1016/S1065-7355(98)00004-2","url":null,"abstract":"<div><p>This article outlines an experimental and numerical study on quasi-instantaneous and long-term deformations of high performance concrete subjected to sealed curing. For this purpose more than 100 cylinders and 400 cubes were made of eight concretes and studied in relation to creep and shrinkage, hydration, internal relative humidity, and compressive strength. One heat-cured concrete was studied at temperatures other than 20°C varying between −20°C and 60°C. Analyses were carried out of quasi-instantaneous deformation, short- and long-term basic creep, and autogenous shrinkage. Relationships were obtained between elastic modulus and creep compliance, and hydration, internal relative humidity, and compressive strength. New and original results are presented on relationships between autogenous shrinkage and internal relative humidity. Other results confirm and validate earlier findings of normal strength concrete regarding relationships between creep compliance, porosity, compressive strength, and maturity for high performance concrete. The project was carried out at Lund Institute of Technology between 1992 and 1996.</p></div>","PeriodicalId":100028,"journal":{"name":"Advanced Cement Based Materials","volume":"8 1","pages":"Pages 1-16"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1065-7355(98)00004-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87404089","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: 17

Interparticle Potential and Sedimentation Behavior of Cement Suspensions: Effects of Admixtures 水泥悬浮物的颗粒间电位和沉降行为:外加剂的影响

Advanced Cement Based Materials Pub Date : 1998-07-01 DOI: 10.1016/S1065-7355(98)00005-4

Christopher M Neubauer , Ming Yang , Hamlin M Jennings

引用次数: 96