Cement science - is it simple?

• Autorzy: Bensted J.

Warianty tytułu

PL

Czy nauka o cemencie jest nauką prosta?

• Języki publikacji: EN PL

Abstrakty

EN

Cement science is often introduced in a simple way. In the chemistry of cement a simplified means of representing oxides and compounds that have effectively been "built up" from oxides has been introduced. Relatively few chemical equations are used to demonstrate the reactions of Portland, blended, high alumina, sulphoaluminate and various other cements. The reactions of ferrite phase are commonly ignored as though they are of no consequence. Under certain conditions designated accelerators start to retard or designated retarders begin to accelerate: the situation appears to be less easy. False set, flash set and air set are all not simple phenomena. The complicated effect of gypsum on the quality of cement is also discussed.

PL

Nauka o cemencie często jest uważana za naukę prostą. W chemii cementu stosowany jest uproszczony sposób zapisu tlenków i związków "zbudowanych" z tlenków. Stosunkowo niewiele równań chemicznych jest używanych do przedstawiania reakcji cementów portlandzkich, z dodatkami, glinowych, siarczanoglinianowych i innych. W przypadku cementu portlandzkiego i cementu glinowego reakcje fazy żelazianowej są powszechnie pomijane, jakby nie miały żadnych konsekwencji. Sytuację komplikuje to, że w niektórych przypadkach domieszki przyspieszające wiązanie działają opóźniająco, a opóźniacze - przyspieszająco. Także fałszywe wiązanie, błyskawiczne wiązanie i wiązanie powietrzne nie są zjawiskami prostymi. Rozważono również skomplikowany wpływ gipsu na jakość cementu.

Słowa kluczowe

PL

cement; mineralogia; hydratacja; gips; chemia cementu

• Wydawca: Fundacja Cement, Wapno, Beton
• Czasopismo: Cement Wapno Beton
• Rocznik: 2001
• Tom: R. 6/68, nr 1
• Strony: 6--19
• Opis fizyczny: Bibliogr. 40 poz., tab.

Twórcy

autor

Bensted J.

• Uniwersytet w Londynie

Bibliografia

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• 2. J. Bensted: The hydraulic calcium silicates. II Cemento 75 (3), 129-136 (1978).
• 3. J. Bensted: Hydration of Portland cement. 'Advances in Cement Technology', (Ed. S.N. Ghosh), pp. 307-347, Pergamon Press, Oxlord, New York (1983).
• 4. J. Bensted: 'Cements: Past, Present and Future'. Inaugural Lecture Series, The University ot Greenwich, 16 pp. Greenwich University Press, Dartford (1997).
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• 6. J. Bensted: High alumina cement - Present state of knowledge. Zement-Kalk-Gips 46 (9), 560-566 (1993).
• 7. J. Bensted: White and coIoured Portland cements. World Cement 24, No. 2, 13-19 (1993).
• 8. J. Bensted: White cement. Construction Repair 9, No. 2, 34 (1995).
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• 15. J. Bested: Effects of natural gypsum quality upon early Portland cement hydration. World Cement Research and Development, 26, No. 9, 97-104 (1995).
• 16. J. Bensted: Alcune applicazioni della termogravimetria al cemento portland. / Some applications of thermogravimetry to Portland cement. II Cemento 77 (3), 169-182 (1980).
• 17. J. Bensted: Cements containing by-product gypsums. SCI Lecture Paper Series No. 69, 1-10 (1996).
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• 19. M.R. Hawkins et al.: Alkali-silica reaction: minimising the risk of damage to concrete. Guidance notes and model clauses for specifications. Concrete Society Technical Report No. 30, 3rd Edition. The Concrete Society, Slough (1999).
• 20. J. Bensted: Chemical considerations of sulphate attack. World Cement Technology 12 (4), 178-184 (1981).
• 21. J. Bensted: Scientific background to thaumasite formation in concrete. World Cement Research 29 (No.11), 102-105 (1998).
• 22. Department of the Environment, Transport and the Regions: 'The thaumasite form of sulphate attack: Risks, diagnosis, remedial works and guidance on new construction'. Report of the Thaumasite Expert Group, DETR, London (1999).
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• 24. M. Collepardi: Degradation and restoration of masonry walls of historic buildings. Materials and Structures 23, 81-102 (1990).
• 25. J. Bensted: Thaumasite - background and nature in deterioration of cements, mortars and concretes. Cement and Concrete Composites 21, 117-121 (1999).
• 26. S.A. Hartshorn, J.H. Sharp and R.N. Swamy: Thaumasite formation in Portland-limestone cement. Cement and Concrete Research 29 (9), 1331-1340 (1999).
• 27. P. Kresse: Ausblühungen-Entstehungsmechanismus und Möglichkeiten ihrer Verhinderung. / Efflorescence - mechanism of occurrence and possibilities of prevention. Betonwerk und Fertigteil- Technik No. 3, 93-95 (1987).
• 28. J. Bensted: Changing concrete's colour. Urban Renewal 1 (No.1). 29-32 (1990).
• 29. J. Bensted: Efflorescence - A visual problem on buildings. Construction Repair 8 (No.1), 47-49 (1994).
• 30. J. Bensted: Oilwell cements - Some interesting scientific aspects. 'Advances in Cement Chemistry'. Proceedings of the International Colloquium held at Mogilany, 18-19 September 1997, (Ed. W. Kurdowski), pp. 105-115. Gorniczo-Hutnicza, Krakow (1997).
• 31. K.-H. Arens and M. Akstinat; 'Bundesministerium für Forschung und Technologie - Forschungsbericht T82-112. Verbesserung der Ringraumzementation in tiefen und übertiefen Bohrungen - Teil 2: Tiefbohrzemente und Additive'. (Federal Ministry for Research and Technology - Research Report T82-112. Improvement of casing cementation in deep and ultradeep wells - Part 2: Deep Well Cements and Additives). Fachinformationszentrum, Energie-Physik-Mathematik GmbH, Karlsruhe (1982).
• 32. J. Bensted: The S-curve effect in oilwell cement thickening. Proceedings of the 15th International Conference on Cement Microscopy, March 29 - April 1, 1993, Dallas, Texas, pp. 51-72. International Cement Microscopy Association, Duncanville, Texas (1993).
• 33. J. Bensted: S-curve effect in oilwell cement compressive strength development under hydrothermal conditions. Cement and Concrete Research 25 (2), 240-242 (1995).
• 34. J. Bensted: Retardation of cement slurries to 250°F. SPE Paper 23073: Offshore Europe 91 Proceedings 1, 379-386 (1991).
• 35. J. Bensted: Thickening behaviour of oilwell cement slurries with silica flour and silica sand additions. Chemistry and Industry (London) No. 18, 702-704 (1992).
• 36. J.S. Lota, J. Bensted, J. Munn and P.L. Pratt: Idratazione del cemento per pozzi petroliferi di Classe G a 20° ed a 5°C. / Hydration of Class G oilwell cement at 20°C and 5°C. L'lndustria Italiana del Cemento No. 725, 776-798 (1997).
• 37. J.S. Lota, J. Bensted and P.L. Pratt: Effect of sodium aluminate on Class G oilwell cement hydration at low and ambient temperatures. Proceedings of the 10th International Congress on the Chemistry of Cement, Gothenburg, Sweden, June 2-6, 1997. Vol. 3: Additives, Admixtures, Characterisation Techniques. Paper 3iii014, 8pp. Amarkai AB and Congrex Göteborg AB, Gothenburg (1997).
• 38. J.S. Lota, J. Bensted and P.L. Pratt: Hydration of Class G oilwell cement at 20°C and 5°C with calcium formate. Proceedings of the 21st International Conference on Cement Microscopy, ApriI 25-29, 1999, Las Vegas, Nevada, pp. 160-179. International Cement Microscopy Association, Duncanville, Texas (1999).
• 39. J.S. Lota, J. Bensted and P.L. Pratt: Hydration of Class G oilwell cement with additions of calcium chloride at 20°C and 5°C. Modern Concrete Materials: Binders, Additions and Admixtures, Proceedings of the International Conference held at the University of Dundee, Scotland, 8-10 September 1999, (Ed. R.K. Dhir and T.O. Dyer), pp. 411-418. Thomas Telford Publishers, London (1999).
• 40. J. Bensted: An examination of the normal setting of Portland cement containing borogypsum. Proceedings of the 6th International Conference on Cement Microscopy, March 26-29, 1984, Albuquerque, New Mexico, pp. 232-242. International Cement Microscopy Association, Duncanville, Texas (1984).