24 results
Search Results
2. Model of hydrated Portland cement paste based on paper submitted to Munich symposium
- Author
-
Feldman, R. F. and Sereda, P. J.
- Subjects
Béton ,Concrete - Published
- 1969
3. Reply by the authors to contribution by S. Chatterji and J. W. Jeffery on the paper 'The influence of CaSO4-2H2O upon hydration character of 3CaOAl2O3'
- Author
-
Feldman, R. F. and Ramachandran, V. S.
- Subjects
Béton ,Concrete - Published
- 1967
4. A preliminary study on thermal moisture transfer in concrete
- Subjects
cement stone ,diffusion ,mass transfer ,concrete ,thermal moisture diffusion ,thermal moisture transfer ,drying ,nuclear reactor ,moisture transfer ,porous solids - Abstract
The paper is a brief preliminary study of moisture transfer due to temperature differences in concrete made in this laboratory. The investigations on the phenomenon in concrete seem to be very scarce, although it appears to be of significance for moisture transfer in non-isothermal concrete structures, e.g. in the biological concrete shields of nuclear reactors. In the paper, an introduction to the theory of thermal moisture transfer in capillary porous colloidal solids, a simple examination of the significance of the phenomenon in moist concrete under temperature gradient as well as the results of a preliminary test series on cement stone have been presented.
- Published
- 1970
5. A preliminary study on thermal moisture transfer in concrete
- Author
-
Pihlajavaara, Sven and Tiusanen, K.
- Subjects
cement stone ,diffusion ,mass transfer ,concrete ,thermal moisture diffusion ,thermal moisture transfer ,drying ,nuclear reactor ,moisture transfer ,porous solids - Abstract
The paper is a brief preliminary study of moisture transfer due to temperature differences in concrete made in this laboratory. The investigations on the phenomenon in concrete seem to be very scarce, although it appears to be of significance for moisture transfer in non-isothermal concrete structures, e.g. in the biological concrete shields of nuclear reactors. In the paper, an introduction to the theory of thermal moisture transfer in capillary porous colloidal solids, a simple examination of the significance of the phenomenon in moist concrete under temperature gradient as well as the results of a preliminary test series on cement stone have been presented.
- Published
- 1970
6. Effect of organic surface agents on properties of hydrated cement compacts
- Author
-
J. Hosek and P. J. Sereda
- Subjects
Materials science ,mechanical properties ,propriete mecanique ,Indentation hardness ,surfactants ,law.invention ,chemistry.chemical_compound ,Adsorption ,law ,Béton ,General Materials Science ,Composite material ,Civil and Structural Engineering ,Cement ,Mechanical property ,ciment hydrate ,General Engineering ,hydrated cement ,Sorption ,Building and Construction ,Portland cement ,Oleic acid ,chemistry ,adsorption ,Mechanics of Materials ,Solid mechanics ,agent de surface ,Concrete - Abstract
This paper reports the treatment of bottle-hydrated portland cement with organosilanes, oleic acid and octadecylamine intended to reduce the sorption of water and the corresponding dimensional changes. Compacts were made from the treated hydrated cement powder to simulate cement paste and allow measurements of sorption-dimensional change characteristics and microhardness. It was found that organochlorosilanes are not suitable for the treatment because the HCl released during the reaction produced undesirable side effects and in some cases increased the adsorption and expansion of the cement. Hexamethyldisilazane was more effective, reducing adsorption by 10 to 20%. Oleic acid was effective at concentrations as high as 25% by weight, but serious loss in mechanical property of microhardness was experienced.
- Published
- 1968
7. The impact insulation assessent of covered concrete floors
- Author
-
Ford, R. D., Hothersall, D. C., and Warnock, A. C. C.
- Subjects
sound insulating ,Floors ,isolation acoustique ,Planchers ,beton ( materiau) ,floor coverings ,concrete ( materials) ,Béton ,revetement de sol ,plancher ,bruit d'impact ,impact sounds ,Concrete - Abstract
The standard tapping machine is the most commonly used source for impact insulation testing of floors and floor coverings. In this paper the stages of the transmission of impact noise through a floor are considered. The force spectrum of the hammer impulse is calculated digitally. By assuming that the cushioning effect of the floor covering can be separated from the concrete floor on which it is laid, it is possible to predict the sound field produced by the tapping machine. It is necessary to know the sound field produced by the tapping machine on the bare floor and the force spectra of the hammer on the bare and the covered floor. The predicted results agree well with measured cases. This validates the definition of the behaviour of a floor covering in terms of impact insulation improvement when used on concrete slab floors. It also shows that impact insulation improvement can be calculated from a knowledge only of the hammer impact spectrum. An ageing or hardening process which occurs after successive hammer blows on soft floor coverings is also described.
- Published
- 1974
8. Downdrag measuremetns on 270-ft compostie piles
- Author
-
Bozozuk, M. and Labrecque, A.
- Subjects
instrumentation ,marine clay ,argile marine ,bearing piles ,evaluation ,embankments ,talus ,skin friction ,surface friction ,deformation modulus ,curing (hydration) ,frottement superficiel ,fondation sur pieux ,downdrag ,concrete ,pile friction ,composite piles ,highway embankment ,electroosmosis ,pile foundations ,module de deformation - Abstract
The Quebec autoroute on the North Shore of the St. Lawrence River between Montreal and Quebec City traverses deep deposits of compressible marine clay. One of the overpass structures at Berthierville is supported on twelve 39-in. (1 m) diameter reinforced concrete piles, which pass through 270 ft (82 m) of soil and finally rest on shale bedrock. The paper presents measurements of settlement and pore water pressures in the soil at various depths under the fill, and of axial deformations in two of the piles. It provides a set of relatively rare field observations on which to base an approximate evaluation of the rate and magnitude of negative skin friction development under the described field conditions.
- Published
- 1969
9. Contribution to the topics and discussions in the Conference on Frontiers in Research and Practice in Plain Concrete. University of Illinois, September 8 - 11, 1970
- Subjects
cement paste ,carbonation ,shrinkage ,research policy ,futurology ,moisture ,deformation ,concrete ,drying ,strength - Abstract
The Conference on Frontiers in Research and Practice in Plain Conerete was held at the University of Illinois Conference Center. Robert Allerton Park. Monticello., Illinois, USA, from September 8 through 11, 1970. The program consisted of a series of introductory lectures and discussion on topics pertinent to conerete research. The topics and the discussion leaders were as follows: 1) The Engineering Challenge to Conerete Georg Verbeck, Portland Cement Association 2) Recent Developments in Understanding the Matrix of Conerete Brady Williamson, University of California 3) Mechanics of Conerete (stress and strain of multiphase materials). The Strength of Conerete as a Multiphase Material Joseph Glucklich, Israel Institute of Technology 4) Effeet of Extreme Environments on Concrete (wetting and drying; low and high temperature), Peter Smith, Ontario Department of Highways 5) Moisture Migration in Conerete Hubert Hilsdorf, University of Illinois 6) Recent Developments in Cements, Paul Klieger, Portland Cement Association The Conference was concerned with plain conerete - as opposed to reinforced concrete, and with research - as opposed to structural design or construction practice. The aim of the presentations and discussions in the conference were to contribute to the understanding of the fundamental nature of plain concrete. The presentation of new developments and new concepts was emphasized without undue review of previously published observations and analyses. The purpose of the conference was to bring together scientists and engineers, engaged in basic research and use of plain conerete and in allied fields, to exehange ideas in a free and informal atmosphere. The list of the participants has been influded as an appendix. The papers of this publication are the contributions distributed by the author to the participants in the above mentioned conference. Report on the Conference will be published by the University of Illinois in due time, probably during the first half of 1971.
- Published
- 1970
10. Pathology of construction: the causes of cracking of concrete
- Author
-
Levy, J. P. and National Research Council of Canada. Division of Building Research
- Subjects
fissuration ,crackings (breaking) ,concrete ,béton - Abstract
Although of a general nature, this paper summarizes the causes of cracking in concrete and makes specific reference to more detailed studies.
- Published
- 1955
11. An investigation of internal stresses in concrete
- Author
-
Nielsen, K. and National Research Council of Canada. Division of Building Research
- Subjects
coarse aggregates ,strain ,gros granulats ,stresses ,dilatation contraction ,expansion contraction ,concrete ,contrainte (mécanique) ,dimensional stability ,déformation ,béton ,stabilité dimensionnelle - Abstract
This paper includes the study of the following problems: The local stress concentration in the large particles of the coarse aggregate in non-reinforced concrete during setting and as a result of conversion of water. Stress and deformation patterns in specimens of non-reinforced concrete under constant load and constant elongation, respectively, i. e., stress and deformation patterns due to contraction and relaxation, respectively.
- Published
- 1956
12. A Reactive aggregate undetected by ASTM tests
- Author
-
Swenson, E. G.
- Subjects
coarse aggregates ,expansion ,fissuration ,crackings (breaking) ,essai ,tests ,Béton ,gros granulat ,dilatation ,Concrete - Abstract
In the course of a Canadian investigation, a dolomitic limestone coarse aggregate has been found that produces excessive expansion and cracking in concrete. Despite the observed influence of cement alkalis, the results of the ASTM Test Method C289 on the limestone were negative. The results of the ASTM mortar bar test were also negative but indicated some alkali-reactivity in the limestone. This brief paper is intended to provide for the benefit of those concerned with the use of the standard tests for alkali- aggregate reaction a record of this Canadian experience with an apparently unusual case of cement-aggregate reaction for which the standard tests were not effective.
- Published
- 1957
13. Thermal properties of concrete at elevated temperatures
- Author
-
Harmathy, T. Z.
- Subjects
Portland cement ,bulk density ,porosity ,béton (matériau) ,thermal properties ,lightweight aggregates ,résistance au feu ,thermogravimetry ,fire resistance ,dilatometry ,physical properties ,dehydration reactions ,ciment Portland ,true density ,enthalpy ,tobermorite gel ,Béton ,propriété thermique ,thermal conductivity ,specific heat ,concrete (materials) ,propriété physique ,concrete aggregates ,elevated temperatures ,Concrete - Abstract
The practice of regarding the thermal properties of concrete as constants may lead to serious errors in heat flow calculations. Because of the physicochemical instability of concrete it is very difficult to procure valid experimental information. In this paper theoretical considerations are presented which, together with some experimental data, will make the assessment of the thermal properties of concrete possible. The calculation procedure is illustrated by examples., Reprinted from: ASTM Journal of Materials, v. 5, no. 1, March 1970, p. 47-74. ISSN: 0022-2453
- Published
- 1970
14. The behaviour of concrete products and precast reinforced concrete members in a fire
- Author
-
Wierig, H. J. and National Research Council Of Canada. Division Of Building Research
- Subjects
Floors ,precast concrete ,Murs ,Poteaux de béton ,prestressed concrete ,Walls ,Planchers ,résistance au feu ,béton précontraint ,béton armé ,fire resistance ,reinforced concrete ,fire resistance test ,béton préfabriqué ,Concrete columns ,Béton ,essai de résistance au feu ,Concrete - Abstract
This paper, a translation of an extensive German article, reviews the behaviour of concrete and reinforced concrete in fire and discusses by means of examples the fire related properties of concrete and concrete products, particularly concrete masonry and precast concrete. It deals separately with structural parts of buildings, such as floors, beams, walls and columns. It is shown that it is now possible to build concrete, reinforced concrete and prestressed concrete structures of almost any desired fire resistance. Even in relatively slender precast concrete construction considerable fire resistance periods can be achieved.
- Published
- 1968
15. Probabilistic study of reinforced concrete in bending
- Author
-
D. E. Allen
- Subjects
construction management ,théorie des probabilités ,Materials science ,yield strength ,business.industry ,résistance à la flexion ,General Engineering ,Probabilistic logic ,résistance à la rupture ,béton armé ,Bending ,Structural engineering ,reinforced concrete ,Reinforced concrete ,ductility tests ,probability theory ,flexural strength ,essai de ductilité ,Béton ,Statistical analysis ,contrôle des travaux ,business ,Concrete - Abstract
This paper summarizes the results of a probabilistic study of ultimate moment and ductility ratio of reinforced concrete. The results are of use in assessing existing design formulas and safety provisions.
- Published
- 1970
16. Interaction of concrete aggregates and Portland cement: situation in Canada
- Author
-
Swenson, E. G.
- Subjects
Portland cement ,bases (chemistry) ,fissuration ,rock types ,base (chimie) ,alkalis ,concrete admixtures ,expansion ,adjuvant ,ciment Portland ,crackings (breaking) ,North America ,Béton ,dilatation ,Amérique du Nord ,concrete aggregates ,Concrete - Abstract
Certain rock types, used as aggregate, react with alkalis in Portland cement to produce expansion and cracking of concrete. In Canada, several investigations of field problems have indicated a much wider occurrence of the phenomenon than was formerly thought to be the case. There are at least two different types of reaction involved. Methods of determining potential alkali-expansivity of concrete aggregate have been well developed and preventive measures have been established that are being used successfully in the field. The extra cost involved is relatively small and, in terms of added life to concrete, may be considered negligible. This paper is a brief review of the present situation in Canada.
- Published
- 1972
17. Portland cements in building construction
- Author
-
Swenson, E. G.
- Subjects
concrete admixtures ,Portland cement ,propriété des matériaux ,building materials ,ciment Portland ,adjuvants du béton ,properties of materials ,Béton ,matériau de construction ,Concrete - Abstract
The ready-mix concrete producer at times experiences problems with uniformity of his raw materials, and also with secondary properties. Portland cement is no exception. The sources of variations in the properties of Portland cement are discussed in this paper as well as the problems that such variations can create; some solutions to these problems are offered. Particular attention is given to the distinction that should be made between the minimum requirements of a general quality specification and the more rigid requirements of a purchase specification. Also noted is the accessibility of test data on secondary properties from the cement manufacturer.
- Published
- 1972
18. An Evaluation of Electrical Resistance Strain Gauges for use on Concrete Surfaces
- Author
-
Berwanger, C.
- Subjects
instrument de mesure électrique ,electrical measuring instruments ,résistance électrique (propriété) ,béton (matériau) ,electrical resistance ,bibliographies ,Béton ,concrete (materials) ,bibliographie ,Concrete - Abstract
This paper presents a review of literature on the use of electrical resistance strain gauges on concrete. Type of gauge, surface preparation, cement type and waterproofing techniques are tabulated. Investigations into the effect of aggregate size are reported and conclusions drawn in a preliminary way. A separate bibliography on Strain Gauges and Their Application 1940 to 1964 and a second bibliography on Electric Resistance Strain Gauges Applied to Concrete Surfaces have been combined in this publication., Cette communication présente une revue de la littérature sur l'usuage des appareils à mesurer les déformations unitaires sur le béton par résistance électrique. Le genre d' instruments, la préparation de la surface, le genere de ciment et les techniques d'étanchéité sont catalogués. Des résultats d'études sur l'effet de la grosseur de l'agrégat sone rapportés et certaines conclusions sont établies d'une facon préliminaire. Une bibliographie séparée sur les instruments à mesurer les déformations unitaires et leur application de 1940 à 1964 et une deuxième bibliographie sur ces instruments à résistance électrique appliquée aux surfaces de béton ont été combinées dans cette publication.
- Published
- 1968
- Full Text
- View/download PDF
19. Volume change, porosity and helium flow studies of hydrated Portland cement
- Author
-
Feldman, R. F.
- Subjects
Portland cement ,porosity ,porosité ,ciment Portland ,ciment hydraté ,Béton ,propriété mécanique ,hydrated cement ,helium ,hélium ,mechanical properties ,Concrete - Abstract
The mechanical properties of hydrated Portland cement, are largely dependent on its pore structure. This paper describes these relationships and shows the difficulties in firmly establishing them because of (a) the instability of the material under any form of stress and drying and (b) the existence of interlayer spaces which play an important part in volume stability and elastic moduli of the material. A new technique, the helium flow method, is described, where relative changes to the dimensions of very small pores, due to removal of sorbed water may be traced. This technique involves measuring the flow of helium as a function of time into the vacated spaces of the material as water is removed and returned. Simultaneously, volume change, porosity and density of the material are measured as a function of weight change. Results obtained by this technique are presented showing the unique behaviour of this "porosity" and how density of the sorbed water can be computed. Results that show the effect of this "porosity" on Young's modulus are also presented., RILEM/IUPAC 1973 International Symposium on Pore Structure and Properties of Materials, September 18, 1973, Prague, Czechoslovakia
- Published
- 1973
20. A model for hydrated Portland cement paste as deduced from sorption-length change and mechanical properties
- Author
-
R. F. Feldman and P. J. Sereda
- Subjects
Materials science ,Portland cement ,mechanical properties ,Thermodynamic equations ,law.invention ,Adsorption ,law ,Béton ,propriété mécanique ,General Materials Science ,Composite material ,Porosity ,Civil and Structural Engineering ,Cement ,ciment hydraté ,General Engineering ,Sorption ,hydrated cement ,Building and Construction ,Creep ,Mechanics of Materials ,ciment Portland ,adsorption ,Hydrate ,Concrete - Abstract
Recent findings in DBR and other laboratories has made it necessary here to revise the accepted model for hydrated portland cement paste. The model recognizes surface areas and porosities obtained by N2 adsorption as the most reliable values, and attributes many of the phenomena observed, to the behaviour of interlayer hydrate water. The bonds between and within individual “crystallites» are clearly defined; it is shown that the “inter-crystallite” bonds do not separate when exposed to physically adsorbed water. The paper describes some of the thermodynamic equations pertinent to the phenomena of adsorption, length change and creep, and some basic principles governing physical adsorption and types of hystereses. The results were obtained from two areas of work: A. Surface chemical experiments. B. Measurement of mechanical properties of compacted and cast systems of hydrated cement and gypsum. The experiments in (A) included sorption and length change scanning isotherms of water and methanol and led to the following conclusions: The experiments in (B) included measurements of modulus and strength versus relative humidity, and porosity, and led to the following conclusions
- Published
- 1969
21. Sorption and length-change scanning isotherms of methanol and water on hydrated Portland cement
- Author
-
Feldman, R. F.
- Subjects
Portland cement ,ciment Portland ,adsorption ,Béton ,hydratation ,isotherms ,hydration ,isotherme ,Concrete - Abstract
The practice of regarding the thermal properties of concrete as constants may lead to serious errors in heat flow calculations. Because of the physicochemical instability of concrete it is very difficult to procure valid experimental information. In this paper theoretical considerations are presented which, together with some experimental data, will make the assessment of the thermal properties of concrete possible. The calculation procedure is illustrated by examples., 5th International Symposium on the Chemistry of Cement: 1968, Tokyo, Japan
- Published
- 1970
22. Contribution to the topics and discussions in the Conference on Frontiers in Research and Practice in Plain Concrete. University of Illinois, September 8 - 11, 1970
- Author
-
Pihlajavaara, Sven
- Subjects
cement paste ,carbonation ,shrinkage ,research policy ,futurology ,moisture ,deformation ,concrete ,drying ,strength - Abstract
The Conference on Frontiers in Research and Practice in Plain Conerete was held at the University of Illinois Conference Center. Robert Allerton Park. Monticello., Illinois, USA, from September 8 through 11, 1970. The program consisted of a series of introductory lectures and discussion on topics pertinent to conerete research. The topics and the discussion leaders were as follows: 1) The Engineering Challenge to Conerete Georg Verbeck, Portland Cement Association 2) Recent Developments in Understanding the Matrix of Conerete Brady Williamson, University of California 3) Mechanics of Conerete (stress and strain of multiphase materials). The Strength of Conerete as a Multiphase Material Joseph Glucklich, Israel Institute of Technology 4) Effeet of Extreme Environments on Concrete (wetting and drying; low and high temperature), Peter Smith, Ontario Department of Highways 5) Moisture Migration in Conerete Hubert Hilsdorf, University of Illinois 6) Recent Developments in Cements, Paul Klieger, Portland Cement Association The Conference was concerned with plain conerete - as opposed to reinforced concrete, and with research - as opposed to structural design or construction practice. The aim of the presentations and discussions in the conference were to contribute to the understanding of the fundamental nature of plain concrete. The presentation of new developments and new concepts was emphasized without undue review of previously published observations and analyses. The purpose of the conference was to bring together scientists and engineers, engaged in basic research and use of plain conerete and in allied fields, to exehange ideas in a free and informal atmosphere. The list of the participants has been influded as an appendix. The papers of this publication are the contributions distributed by the author to the participants in the above mentioned conference. Report on the Conference will be published by the University of Illinois in due time, probably during the first half of 1971.
- Published
- 1970
23. Dimensional control in precast concrete large-panel building systems
- Author
-
National Research Council of Canada. Division of Building Research
- Subjects
construction par système ,dimensional tolerances ,panneau du béton préfabriqué ,Béton ,tolérance dimensionelle ,system building ,dimensional coordination ,coordination dimensionelle ,precast concrete panels ,Concrete - Abstract
The Division of Building Research has investigated, in the field, the leading "system housing" advances in urban building in Northern Europe. The results of these studies are already being used by some Canadian builders of large multi-family housing complexes and there is a rapidly developing interest in the subject. "System building" developments raise the critical question of precision in the manufacture of large-panel components, especially when these are highly prefinished and are assembled to form almost the complete building. This paper concerns the extensive statistical sampling of dimensional control and on problems in system building, by the consulting engineering firm Rastor OY, in Helsinki, Finland.
- Published
- 1970
24. The influence of CaSO4-2H2O upon hydration character of 3CaOAl2O3
- Author
-
Feldman, R. F. and Ramachandran, V. S.
- Subjects
cement ,differential thermal analysis ,concrete admixtures ,adjuvant ,gypse ,analyse thermique differentielle ,Béton ,hydratation ,ciment ,hydration ,gypsum ,Concrete - Abstract
This paper presents a quantitative interpretation of results of differential thermal analysis of hydration reactions at 2, 12, 23 and 52 degrees C of 3CaO.Al[2]O[3] mixed with 0, 0. 25, 2.5, 10 or 20% gypsum, and compares these with length changes obtained from the hydration of compacts of these mixtures. Estimates of the relative reaction rates from d.t. a. peak areas and measurement of length change during these reactions showed marked agreement, although interpretation had to be made with caution. It was concluded that the formation of ettringite (high sulpho-aluminate) had no direct effect upon reaction rate, but that the reactivity of 3CaO.Al[2]O[3] was reduced by the sorption of (SO[4])[2-] ions on active sites of its surface. Gypsum reduces the rate of conversion of the hexagonal hydro-aluminates to the cubic hexahydrate, probably also by sorption of (SO[4])[2-] ions, and thus is a second mechanism by which they can retard the normal hydration of 3CaO.Al[2]O[3]. The degree to which a given addition of gypsum retards the hydration of 3CaO.Al[2]O[3] at a particular temperature is affected by a balance between (1) the concentration of (SO[4])[2-] ions on and around the surface of the 3CaO.Al[2]O[3]; (2) the rate of reaction of (SO[4])[2-] ions with the hexagonal hydroaluminates; (3) the thickness of the hexagonal hydroaluminate layer around the 3CaO.Al[2]O[3] grain. Reactions at the various temperatures are discussed in terms of the above parameters.
- Published
- 1967
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