STUDIES OF THE PROCESSES OF CEMENT HARDENING IN THE COURSE OF LOW-PRESSURE STEAM CURING OF CONCRETE

THE PROBLEM OF FINDING THE OPTIMUM TECHNOLOGICAL CONDITIONS FOR THE RAPID HARDENING OF CONCRETE IS OF PRIMARY IMPORTANCE FOR THE PRODUCTION OF REINFORCED-CONCRETE UNITS. RESULTS ARE CONSIDERED OF INVESTIGATIONS ON THE LOW-PRESSURE STEAM CURING OF CONCRETES MADE WITH CEMENTS OF VARIOUS MINERALOGICAL COMPOSITIONS. AS A RESULT OF THESE STUDIES, THE KINETICS OF THE CHEMICAL REACTIONS DURING THE STEAM TREATMENT, THE INFLUENCE OF BOTH THE CURING CYCLE AND THE HUMIDITY CONDITIONS AT ELEVATED TEMPERATURES, AND THE ROLE OF THE MINERALOGICAL COMPOSITION OF THE CEMENT ARE ESTABLISHED. THE STUDIES REPORTED WERE MADE ON EIGHT CEMENTS OF VARIOUS MINERALOGICAL COMPOSITIONS AND HAVING SPECIFIC SURFACES NEAR 3000 SQ CM/GR. THE SAMPLES OF NEAT CEMENT PASTE, AT WATER-CEMENT RATIO 0.27, WERE CURED AT ATMOSPHERIC PRESSURE AND A TEMPERATURE OF 80 C ACCORDING TO A CYCLE OF PRETREATMENT, HEATING, STEAM CURING, AND COOLING. THE FOLLOWING CONCLUSIONS WERE MADE' /1/ PORTLAND CEMENTS CONTAINING NEAR 45 PERCENT C3S AND NEAR 10 PERCENT C3A SHOULD BE CONSIDERED THE MOST SUITABLE FOR LOW-PRESSURE STEAM TREATMENT OF CONCRETE, /2/ STEAM TREATMENT CAUSES NOT ONLY A MORE RAPID GAIN IN STRENGTH OF THE CEMENT PASTE, BUT ALSO SPEEDS UP THE COMBINATION OF WATER BY CEMENT INTO NEW COMPOUNDS, /3/ IN THE COURSE OF STEAM TREATMENT, FORMATION OF HYDROSULFOCOMPOUNDS IN CEMENT PASTE TAKES PLACE UP TO 60 C, /4/ THE HIGHEST RATE OF ALL THE HARDENING PROCESSES IS OBSERVED DURING THE FIRST 3-4 HOURS FOR CEMENTS HIGH IN C3A, AND IN THE FIRST 5-6 HOURS FOR CEMENTS HIGH IN ALITE AND OF MODERATE C3A CONTENT, /5/ STEAM TREATMENT CAUSES THE FORMATION IN THE PASTE OF MORE COARSELY CRYSTALLINE HYDRATES COMPARED WITH THOSE PRODUCED ON NORMAL HARDENING, /6/ IN ORDER TO OBTAIN THE MAXIMUM POSSIBLE STRENGTH OF A CONCRETE ON STEAM TREATMENT, THE RATE OF HEATING SHOULD NOT EXCEED 20 C PER HOUR, /7/ WITH MASSIVE CONCRETE UNITS IT IS POSSIBLE TO USE MORE RAPID HEATING RATES, PROVIDED THE PERIOD OF ISOTHERMAL HEATING IS REDUCED, WHILE FOR THIN UNITS IT IS ADVISABLE TO HAVE GRADUAL HEATING AND COOLING AND MORE PROLONGED ISOTHERMAL HEATING, AND /8/ FOR CONCRETES OF PLASTIC MIXES MADE WITH CEMENTS OF MODERATE C3A CONTENT, THE MOST FAVORABLE TEMPERATURE OF ISOTHERMAL HEATING ON STEAM TREATMENT IS IN THE RANGE OF 60-70 C.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/sr/sr90/90-036.pdf
• Supplemental Notes:
  • Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Corporate Authors:

  Highway Research Board (HRB)

  Washington, DC   
• Authors:
  • Budnikov, P P
  • Erschler, E Y
• Publication Date: 1966

Media Info

• Media Type: Print
• Features: Figures; Photos; References; Tables;
• Pagination: pp 431-446
• Monograph Title: Symposium on structure of Portland cement paste and concrete
• Serial:
  • Highway Research Board Special Report
  • Issue Number: 90
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Cement; Chemical reactions; Concrete; Concrete hardening; Cooling; Crash investigation; Hardness; Heating (Structures); Humidity; Portland cement; Production; Reinforced concrete; Samples; Steam curing; Studies; Surface treating; Water cement ratio
• Old TRIS Terms: Water pastes ratio
• Subject Areas: Highways; Materials; Safety and Human Factors;

Filing Info

• Accession Number: 00212453
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Dec 12 1994 12:00AM