EXPERIMENTS WITH ALKALI-SILICA REACTIVE CONSTITUENTS OF SAND -GRAVEL AGGREGATE

A PILOT SERIES OF EXPERIMENTS INVESTIGATED THE EFFECT OF ALKALI-SILICA REACTIVE CONSTITUENTS IN A SAND-GRAVEL AGGREGATE IN THE SEALED MOIST-STORAGE AND THE CONROW CYCLE MORTAR BAR EXPANSION TESTS. THE HIGH ALKALI-SILICA REACTIVE SAND-GRAVEL USED PRODUCED DELETERIOUS EXPANSION IN BOTH THE SEALED MOIST-STORAGE AND THE CONROW CYCLE MORTAR BAR TEST. THE ALKALI-SILICA REACTIVE PARTICLES WERE REMOVED FROM THE AGGREGATE, AND THE PROCESSED AGGREGATE WAS TESTED. THE REMOVAL OF THE ALKALI-SILICA REACTIVE PARTICLES REDUCED EXPANSION IN THE SEALED MOIST-STORAGE TEST TO WITHIN SEVERAL TEST LIMITS. IN THE CONROW CYCLE TEST, EXPANSION WAS REDUCED BUT A SIGNIFICANT AMOUNT OF EXPANSION REMAINED. THE REMAINING EXPANSION APPEARS TO BE DUE TO THE CHARACTERISTIC CEMENT-AGGREGATE REACTION OF SAND-GRAVEL AGGREGATES. THE SMALL AMOUNT OF ALKALI REACTIVE MATERIAL REMAINING IN THE AGGREGATE MIGHT CONTRIBUTE TO THIS EXPANSION. THE ALKALI REACTIVE CONSTITUENTS WERE BLENDED WITH AN INNOCUOUS SOUTH PLATTE RIVER AGGREGATE WHICH DOES NOT PRODUCE DELETERIOUS EXPANSION IN EITHER OF THE TESTS. THE BLENDED SOUTH PLATTE RIVER AGGREGATE PRODUCED SOME EXPANSION IN BOTH THE TESTS. THESE TESTS INDICATE THAT ALKALI-SILICA REACTION IS A MAJOR FACTOR IN THE CEMENT-AGGREGATE REACTION WITH ALKALI-SILICA REACTIVE SAND-GRAVEL AGGREGATES. THE PROBLEM OF CEMENT- AGGREGATE REACTION WITH NONALKALI-REACTIVE SAND-GRAVEL AGGREGATES REQUIRES FURTHER INVESTIGATION. THESE TESTS ALSO INDICATE THAT THE CONROW CYCLE MORTAR BAR EXPANSION TEST IS SENSITIVE TO ALKALI-SILICA REACTION.

Media Info

  • Media Type: Print
  • Features: References; Tables;
  • Pagination: pp 41-49
  • Monograph Title: Aggregates for concrete
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00206231
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Nov 18 1994 12:00AM