INFLUENCE OF VARIOUS TYPES OF SULPHATE ON THE SETTING AND HARDENING OF CEMENT /IN GERMAN/

THE DELAY IN CEMENT SETTING BY THE FORMATION OF AN ETTRINGITE FILM AROUND TRICALCIUM ALUMINATE GRAINS IS EXPLAINED. THIS FILM DISINTEGRATES AND REFORMS MANY TIMES UNDER THE INFLUENCE OF INTERAL CRYSTALLIZATION PRESSURE, OR EXTERNAL OSMOSIS PRESSURE UNTIL THE COMPLETE ELIMINATION OF SULPHATE IONS IN THE SOLUTION. AT THIS STAGE DELAY CEASES TO OCCUR BECAUSE OF THE STRONG REACTION OF TRICALCIUM ALUMINATE WITH WATER. THE ETTRINGITE IS TRANSFORMED INTO WITHER HYDRATED CALCIUM MONOSULPHOALUMINATE OR MIXED CRYSTALS OF THE SERIES TRICALCIUM ALUMINATE AND TETRACALCIUM ALUMINATE. SIMILAR DELAY WAS OBSERVED IN CEMENT CONTAINING CLINKER OR TRASS. ELECTRON MICROSCOPY HAS PROVED TO BE THE OPTIMUM METHOD FOR STUDYING DELAY IN SETTING. KNOWLEDGE OF DELAY MECHANISM HAS BEEN APPLIED TO THE PROPORTIONING OF SULPHATE IN CEMENT THUS AVOIDING SWELLING DURING HYDRATION. THE USE OF ANLYDRITE INSTEAD OF GYPSUM LEADS TO A SHARP IMPROVEMENT IN THE HYDRATION OF TRASS OR SLAG CEMENT POSSIBLY BECAUSE OF ITS SLOWER APTITUDE TO SOLUBILITY AND OF ITS SMALLER SPECIFIC VOLUME. /LCPC/RRL/

• Supplemental Notes:
  • No 2, pp 81-90, 39 FIG, 5 TAB, 91 REF
• Authors:
  • Von, LUDWIG V
• Publication Date: 1968

Media Info

• Serial:
  • Zement-Kalk-Gips

Subject/Index Terms

• TRT Terms: Aluminates; Calcium compounds; Clinkers; Concrete curing; Concrete hardening; Ettringite; Hardness; Hydration; Slag cement; Sulfates
• Old TRIS Terms: Anlydrite
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00212885
• Record Type: Publication
• Source Agency: Road Research Laboratory /UK
• Files: TRIS
• Created Date: May 10 1971 12:00AM