SP-220: Autogenous Deformation of Concrete最新文献

Effect of Cement Type on Autogenous Deformation of Cement-Based Materials 水泥类型对水泥基材料自变形的影响

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13149

P. Lura, Ye Guang, K. Breugel

引用次数: 11

"Quantifying Volume Change, Stress Development, and Cracking Due to Early-Age Autogenous Shrinkage" 量化体积变化、应力发展和早期自收缩引起的开裂

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13147

B. Pease, A. Hossain, J. Weiss

{"title":"\"Quantifying Volume Change, Stress Development, and Cracking Due to Early-Age Autogenous Shrinkage\"","authors":"B. Pease, A. Hossain, J. Weiss","doi":"10.14359/13147","DOIUrl":"https://doi.org/10.14359/13147","url":null,"abstract":"In this study, three different methods (acoustic emission testing, a restrained ring test, and non-contact lasers) are used to measure autogenous shrinkage and its effect on concrete. Experimental efforts to quantify autogenous volume changes, stress development, and cracking in low water-to-cement ratio mixtures are described. A non-contact laser was used to measure length changes from the time that the mortar was placed in the forms. An analytical solution was used to illustrate how the restrained ring test could be used to quantify the level of residual stress that develops from the time of casting. Piezoelectric sensors were used to measure the acoustic activity that develops in the mortar. It is hypothesized that this acoustic activity is generated by microcracking at the aggregate interface caused by differential shrinkage. Length change measurements show an initial period of shrinkage before setting, a slight expansion during setting, and continued shrinkage after final set. The residual stresses were observed to develop several hours after the time of set, suggesting that some movement may be permitted while the structure of the paste is developing. Acoustic activity occurred 1 or 2 hours after the development of residual stress. This suggests that, for microcracking to occur, some critical strain or stress level needs to be reached.","PeriodicalId":148502,"journal":{"name":"SP-220: Autogenous Deformation of Concrete","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128652231","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: 6

Why Does Ultrahigh-Performance Concrete (UHPC) Exhibit Such Low Shrinkage and Such Low Creep? 超高性能混凝土(UHPC)为何表现出如此低的收缩和徐变?

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13155

P. Acker

{"title":"Why Does Ultrahigh-Performance Concrete (UHPC) Exhibit Such Low Shrinkage and Such Low Creep?","authors":"P. Acker","doi":"10.14359/13155","DOIUrl":"https://doi.org/10.14359/13155","url":null,"abstract":"Ductal is a non-brittle, fiber-reinforced, ultrahigh performance concrete. Recent experimental results from creep tests and indentation tests at a nanometer scale on Ductal show that only the one constituent of this composite, viscoplastic behavior of the cement hydrates, causes creep. Former creep tests on hydrated cement paste have shown a very high creep rate of the cement gel which decelerates very slowly (much more slowly than concrete creep). Furthermore, these results provide a clear explanation for the observations of a strong correlation between shrinkage and creep values. When hydration rate becomes negligible (typically after a few weeks), the dominant part of shrinkage is nothing but the viscoplastic response of the cement gel to the internal stress that is applied by the liquid phase on the pore surface. This statement nullifies the last argument against the explanation of shrinkage by capillary tension, the so-called argument of reversibility. Creep aging, as well as the very low creep of high-strength concretes can be explained by the consumption of creep potential by the hygral stress. The strong coupling between shrinkage and creep suggested by the results has been observed qualitatively for many years but never before correctly analyzed.","PeriodicalId":148502,"journal":{"name":"SP-220: Autogenous Deformation of Concrete","volume":"170 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124148336","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: 21

From Chemical and Microstructural Evolution of Cement Pastes to the Development of Autogenous Deformations 从水泥浆体的化学和微观结构演变到自变形的发展

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13146

Baroghel-Bouny, P. Mounanga, A. Loukili, A. Khelidj

{"title":"From Chemical and Microstructural Evolution of Cement Pastes to the Development of Autogenous Deformations","authors":"Baroghel-Bouny, P. Mounanga, A. Loukili, A. Khelidj","doi":"10.14359/13146","DOIUrl":"https://doi.org/10.14359/13146","url":null,"abstract":"This paper seeks to contribute to the understanding of physical and chemical mechanisms that are at the origin of the autogenous volume changes and cracking of cementitious materials, focusing on the first 24 hours. A micro-macro experimental study has been performed, from the end of mixing up to several months, on a set of plain cement pastes prepared with the same type I ordinary Portland cement and various water-to-cement ratios (W/C), and cured at various constant temperatures. Chemical shrinkage, volumetric and one-dimensional autogenous deformations have been measured and analyzed in relation to the hydration process and to the microstructural characteristics of the material. The effect of the curing temperature at early age (<24 hours) in the range 10-50 deg C, and of W/C in the range 0.25-0.60, have been investigated. The temperature-induced changes recorded on both the magnitude and the kinetics of volumetric autogenous shrinkage clearly show the irrelevance of using the usual maturity concept to describe such phenomena within the whole early-age period. In addition, a threshold is pointed out at about a degree of hydration of the cement = 7%, both defining the range where autogenous shrinkage is linearly related to degree of hydration of the cement and corresponding to the precipitation of calcium hydroxide. A W/C threshold also is pointed out both at the macro-level (autogenous deformations, etc.) and at the micro-level (characteristics of the hydration products, pore size distribution, etc.). The findings indicate the critical two-fold effect of calcium hydroxide: a chemical effect, in which the carbon hydroxide content of the cement past plays the role of a chemical indicator of the hydration process, and a microstructural effect, generated by large-sized carbon hydroxide crystals.","PeriodicalId":148502,"journal":{"name":"SP-220: Autogenous Deformation of Concrete","volume":"99 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114052705","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: 10

Unit Processes of Shrinkage Behavior Based on Dynamical Analysis of Cement Paste in Different Maturity 基于不同成熟度水泥浆动力分析的收缩行为单元过程

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13151

E. Tazawa

{"title":"Unit Processes of Shrinkage Behavior Based on Dynamical Analysis of Cement Paste in Different Maturity","authors":"E. Tazawa","doi":"10.14359/13151","DOIUrl":"https://doi.org/10.14359/13151","url":null,"abstract":"The relationship between drying and shrinkage phenomena is not simple in the case of hardened cement paste. Although it is sometimes true that weight loss causes reduction in length of hardened cement paste, increase in length followed by weight loss due to evaporation can be observed in special cases. This paper analyzes the relationship between weight loss and drying shrinkage using type I Portland cement, as measured by ASTM method. This analysis shows that unit processes involved in these physical phenomena are not as simple as can be stated by Fick's diffusion theory. Depending on duration of underwater curing or degree of hydration, unit processes are drastically varied, suggesting that variation in microstructure gives rise to quite different situations for desiccation and deformation. Based on these models, relation and interaction between drying shrinkage and autogenous shrinkage is discussed. Chemical shrinkage occurs when water molecules are changed into a part of solid with reduced free volume due to bonding energy that depresses the molecules' thermal fluctuation. Chemical shrinkage provides the main driving force for autogenous shrinkage since self-desiccation is generated by the chemical shrinkage. Loss of liquid due to evaporation or conversion of liquid water into solids are both equivalent in the sense that liquid water is lost from a interstitial space of hardened cement paste. It is impossible to separate drying shrinkage and autogenous shrinkage because evaporation and self-desiccation can take place at the same location.","PeriodicalId":148502,"journal":{"name":"SP-220: Autogenous Deformation of Concrete","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132377075","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

Assessment of Water Migration Distance in Internal Curing of High-Strength Concrete 高强混凝土内养护过程中水迁移距离的评价

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13157

S. Zhutovsky, K. Kovler, A. Bentur

引用次数: 14

Measuring Non-Drying Bulk Shrinkage of Cement Paste and Mortar Using Archimedes' Principle 用阿基米德原理测定水泥浆和砂浆的非干燥体积收缩率

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13148

K. Douglas, K. Hover

引用次数: 2

Test Device for Studying the Early-Age Stresses and Strains in Concrete 混凝土早期应力应变研究试验装置

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13153

J. Charron, B. Bissonnette, J. Marchand, M. Pigeon

引用次数: 11

Controlling Plastic and Autogenous Shrinkage in High-Performance Concrete Structures by an Early Water Curing 早期水养护控制高性能混凝土结构的塑性收缩和自收缩

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13150

P. Aitcin, G. Haddad, R. Morin

{"title":"Controlling Plastic and Autogenous Shrinkage in High-Performance Concrete Structures by an Early Water Curing","authors":"P. Aitcin, G. Haddad, R. Morin","doi":"10.14359/13150","DOIUrl":"https://doi.org/10.14359/13150","url":null,"abstract":"This paper discusses the technique and benefits of early water curing to control plastic and autogenous shrinkage in high performance concrete. High-performance concrete is very vulnerable to early cracking because it does not bleed, is subject to autogenous shrinkage, has low water/binder ratio, and is subject to thermal shrinkage. Fog spraying is most appropriate for controlling plastic shrinkage. Among the different means already available to fight early autogenous shrinkage, external water curing is a very efficient one. Water curing must be extended for 7 days. At the present state of the technology, concretes having a water/cement ratio of 0.36 are more robust against early cracking when an external water curing is used. Early water curing is easy to implement and control. The City of Montreal has specified the use of early water curing procedure for the last three years and has noticed an improvement in the quality of high performance concrete structures. The cost of early water curing has been estimated at 0.1 to 1.5% of the total construction cost of concrete structures, which represents a profitable investment over the long-term.","PeriodicalId":148502,"journal":{"name":"SP-220: Autogenous Deformation of Concrete","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115291975","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: 6

Shrinkage and Creep of High-Performance Self-Compacting Concrete (HPSCC) 高性能自密实混凝土(HPSCC)的收缩徐变

SP-220: Autogenous Deformation of Concrete Pub Date : 2004-03-01 DOI: 10.14359/13156

B. Persson

{"title":"Shrinkage and Creep of High-Performance Self-Compacting Concrete (HPSCC)","authors":"B. Persson","doi":"10.14359/13156","DOIUrl":"https://doi.org/10.14359/13156","url":null,"abstract":"This paper describes an experimental investigation of the fresh properties, strength and elastic modulus, shrinkage, and creep in high-performance self-compacting concrete (HPSCC). Optimizations were performed on a laboratory scale according to an ideal grading of the particles in the fresh concrete for SCC, with high strength, high durability in marine environment or with fire spalling safety. SCC was introduced in the full-scale production of beams and piles. The results showed high slump flow and robustness that allowed for a reasonable variation of the water-cement ratio (w/c), keeping the fresh concrete properties within the limits of the full-scale production even at elevated temperature. The early strength development was extremely high even though w/c was slightly higher in the SCC than in vibrated concrete (NC). Internal frost resistance was improved for SCC compared with NC but the chloride migration was larger in SCC with limestone powder than in NC. Spalling of the concrete during fire, especially in low w/c concrete, was avoided by use of polypropylene fibers. The elastic modulus was slightly smaller in SCC than in NC due to lower aggregate content in SCC than in NC. Creep, shrinkage, salt frost scaling and sulfate resistance did not differ much from the corresponding properties of NC.","PeriodicalId":148502,"journal":{"name":"SP-220: Autogenous Deformation of Concrete","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122066952","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