THE INFLUENCE OF VARIOUS SULPHATES UPON THE SETTING AND HARDENING OF CEMENTS

WITH REFERENCE TO THE RESULTS OF LITERATURE STUDIES AND NUMEROUS INVESTIGATIONS CONDUCTED AT THE INSTITUT FUR GESTEINSHUTTENKUNDE (INSTITUTE FOR ROCK PRODUCTS TECHNOLOGY), THE ARTICLE DESCRIBES THE EFFECT OF THE SULPHATE CONTENT, IN TERMS OF TYPE AND QUANTITY, UPON THE SETTING AND HARDENING OF CEMENTS. THE FORMATION OF AN ENVELOPE OF ETTRINGITE-LIKE PHASES ON THE SURFACE OF THE ALUMINOFERRITIC PHASES OF THE CLINKER AND THE ALUMINA IN THE GRANULATED BLASTFURNACE SLAB OR THE POZZOLANA IS THE CAUSE OF THE RETARDATION OF SETTING WHEN SULPHATE IS ADDED TO CEMENTS CONFORMING TO THE GERMAN STANDARD SPECIFICATIONS DIN 1164 AND DIN 1167 RESPECTIVELY. ONLY WHEN THE SULPHATE CONCENTRATION IN THE DISSOLVED PHASE FALLS SHORT OF THE CONCENTRATION NEEDED TO FORM ETTRINGITE WILL THE INITIALLY FORMED ETTRINGITE-LIKE PHASES BE CONVERTED INTO MONOSULPHATE HYDRATES OR THE SOLID SOLUTIONS THEREOF WITH TETRACALCIUM ALUMINOFERRITE HYDRATES, THE ALUMINOFERRITIC PHASE BEING CONSUMED IN THIS PROCESS OF CONVERSION. THIS INTERPRETATION OF THE SETTING RETARDATAON ALSO MAKES POSSIBLE AN EXPLANATION FOR THE OPTIMIZATION OF THE STRENGTH DEVELOPMENT BY THE ADDITION OF SULPHATE, INASMUCH AS THE FORMATION OF ETTRINGITE IS ASSOCIATED WITH SWELLING AND SHOULD VERY LARGELY HAVE BEEN COMPLETED AT THE END OF THE SETTING PROCESS. IN CONTRAST WITH THIS, IN THE CASE OF SUPERSULPHATED CEMENT THE FORMATION OF ETTRINGITE TAKES PLACE WITHOUT BEING ACCOMPANIED BY SWELLING AND CONTRIBUTES TO THE STRENGTH. THE USE OF PURE OR GYPSUM-CONTAINING ANHYDRITE INSTEAD OF DIHYDRATE RESULTS IN SOME INSTANCES IN A MARKED IMPROVEMENT OF THE TECHNOLOGICAL PROPERTIES OF THE CEMENTS CONFORMING TO DIN 1164, DIN 1167 AND DIN 4210, AS THE HYDRATION IS ACCELERATED THE CAUSE OF THIS IS THE LOWER RATE OF SOLUTION OF THE ANHYDRITE AND ITS SMALLER SPECIFIC VOLUME. /AUTHOR/

• Supplemental Notes:
  • Vol 57, No 4, PP 175-179
• Authors:
  • Ludwig, U
• Publication Date: 1968-4

Media Info

• Serial:
  • Zement-Kalk-Gips

Subject/Index Terms

• TRT Terms: Cement; Concrete curing; Concrete hardening; Ettringite; Hardness; Pozzolanic action; Reviews; Sulfates
• Old TRIS Terms: Anhydrites
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00212624
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 1 1994 12:00AM