TOPICS IN CONCRETE TECHNOLOGY-MIXTURES CONTAINING INTENTIONALLY ENTRAINED AIR

AIR BUBBLES ARE INTENTIONALLY ENTRAINED IN CONCRETE TO PROTECT HARDENED CONCRETE FROM FROST ACTION, OR SOMETIMES TO IMPROVE WORKABILITY. AIR-ENTRAINING AGENTS ARE EITHER SURFACTANTS OR INSOLUBLE HYDROPHOBIC COLLOIDS FORMED IN THE MIXTURE BY REACTION WITH CALCIUM HYDROXIDE; SUCH AGENTS STABILIZE BUBBLES PRODUCED MECHANICALLY BY STIRRING OR KNEADING. AIR CAN BE ENTRAINED IN WATER, IN WET AGGREGATE, OR IN CEMENT PASTE. THE QUANTITY ENTRAINED IN PASTE DEPENDS MAINLY ON PASTE CONSISTENCY AND STIRRING PROCEDURE; THE QUANTITY IN CONCRETE DEPENDS ON EMULSIFICATION IN PASTE AND ON THE AGGREGATE SCREEN EFFECT, WHICH IS RELATIVELY LARGE IN LEAN MIXTURES. AIR BUBBLES CAN BE USED TO REPLACE AN EQUAL SOLID VOLUME OF SAND, WITH LITTLE OR NO EFFECT ON SLUMP. /PCA/

• Authors:
  • Powers, T C
• Publication Date: 0

Media Info

• Serial:
  • Portland Cement Assoc R & D Lab Bull
  • Issue Number: 0

Subject/Index Terms

• TRT Terms: Air; Air entraining agents; Bubbles; Concrete hardening; Entrained air; Frost protection; Pastes; Workability
• Uncontrolled Terms: Hardened concrete
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00213614
• Record Type: Publication
• Source Agency: Portland Cement Association
• Report/Paper Numbers: No 174
• Files: TRIS
• Created Date: Jun 1 1970 12:00AM