ETTRINGITE, THAUMASITE AND WOODFORDIT

Studies have found that the thermal decomposition of ettringite in water suspensions at temperatures above 110, 190 and 280 deg. C is as follows: C6ASH32 110 - C4ASH12 + H:H =190 = C3AH6 + CS + H:280 = C4A3H3 + CH + H where C=CaO; A = A1203; S=SO3; and H = H20. It was also found that ettringite had the formula Ca6 (A1 (OH)6)2.(SO4)3.25.7H23. Investigation have revealed that deterioration of a soil-cement pavement resulted from the formation f Thaumasite Ca6 (S1(OH)6)2.24 H20(SO4)2(CO3)2 or a solid solution of it with ettringite. Further studies show that damage to a concrete tunnel lining was the result of formation of Thaumasite and Woodfordit CA6A11.5 (SO4.SiO2 CO3).(OH)10.5 15 H20. The composition of si-ettringite has been found to be Ca6 (Si(OH)6)2 (SO4)3 24H20.

• Corporate Authors:

  United States Gypsum Company

  Department No. 119-7, 101 South Wacker Drive
  Chicago, IL  United States  60606

  United States Gypsum Company

  Chemicals Division Department 125-4, 101 South Wacker Drive
  Chicago, IL  United States  60606
• Publication Date: 1976-10

Media Info

• Pagination: p. 3-4
• Serial:
  • SO3 Abstracts and Newsletter
  • Volume: 13
  • Issue Number: 2
  • Publisher: United States Gypsum Company

Subject/Index Terms

• TRT Terms: Aluminum compounds; Calcium compounds; Chemical composition; Concrete; Decomposition; Durability; Ettringite; Pavements; Soil cement; Sulfur compounds
• Subject Areas: Highways; Materials; Pavements;

Filing Info

• Accession Number: 00149614
• Record Type: Publication
• Files: TRIS
• Created Date: Apr 13 1977 12:00AM