EARLY HYDRATION REACTIONS OF ABNORMAL SETTING PORTLAND CEMENT

HYDRATION PRODUCTS OF QUICK-SETTING HIGH-ALKALI PORTLAND CEMENT PASTES AFTER 1/4 TO 15 MINUTES OF CURING WERE MEASURED BY DIFFERENTIAL THERMAL ANALYSIS. RESULTS ON CEMENT WITH AND WITHOUT AERATION IN PRESENCE AND ABSENCE OF CARBON DIOXIDE REVEALED FORMATION OF THE SO-CALLED 270 C PHASE IMMEDIATELY UPON GAGING. THE REPORT DESCRIBES THE IDENTIFICATION OF THE 270 C PHASE AS SYNGENITE AND ITS ROLE IN QUICK SETTING OF CEMENTS. THE DATA SUPPORT THE CONCLUSION THAT THE QUICK SET OF A CEMENT IS CAUSED BY LACK OF ADEQUATE AMOUNTS OF CALCIUM HYDROXIDE NEEDED FOR RAPID ETTRINGITE FORMATION AND STABILIZATION. PREVENTION OF QUICK SET AND STABILIZATION OF THE INITIALLY FORMED ETTRINGITE CAN BE ACHIEVED BY HEMIHYDRATE ADDITION. THE BENEFICIAL EFFECT OF HEMIHYDRATE IS INTERPRETED AS BEING DUE TO THE INCREASED CALCIUM HYDROXIDE CONCENTRATION RESULTING FROM THE REACTION OF CALCIUM SULFATE WITH THE ALKALI HYDROXIDES RELEASED FROM THE ALKALI-BEARING CEMENT MINERALS. /AUTHOR/

• Supplemental Notes:
  • Vol 3, No 3, PP 517-537
• Authors:
  • Jugovic, Z T
  • Gillam, J L
• Publication Date: 1968-9

Media Info

• Serial:
  • Journal of Materials
  • Publisher: American Society for Testing and Materials (ASTM)

Subject/Index Terms

• TRT Terms: Aeration; Alkali; Calcium; Carbon dioxide; Concrete curing; Differential thermal analysis; Ettringite; Hydration; Hydroxides; Portland cement; Soil stabilization; Sulfates
• Uncontrolled Terms: Stabilization
• Old TRIS Terms: Alkalies; Reaction; Syngenite
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00213259
• Record Type: Publication
• Files: TRIS
• Created Date: Dec 30 1994 12:00AM