INVESTIGATION OF METHODS FOR DETERMINING THE ALKALI CONTENT OF OLD CEMENTS

This investigation attempts to determine the extent of errors, induced by various forms of acid and neutral extraction of the cement content of the hardened concrete, upon the alkali content contributed by the cement. Four common New Zealand volcanic rocks (Basalt, Andesite, and Dacite) and a Greywacke were chosen to represent the types of aggregates likely to be present in concretes undergoing the alkali aggregate reaction. The following concrete extraction methods were tested: a) dilute nitric acid; b) hot water; and c) picric acid. Total alkali levels, and sodium and potassium levels were measured, as were the concentrations of trace alkalis such as lithium, rubidium and caesium. The results showed that: a) acid extraction methods cannot be used to determine cement alkalis of basalt aggregate because the large amount of alkalis contributed by the basalt cause unacceptable errors; b) the dilute nitric acid extraction method can be used for andesite, dacite and rhyolite aggregates; and c) it is not possible to use the level of trace alkalis to correct for the errors contributed by the extraction of alkalis form aggregates in acid solution. (TRRL)

• Corporate Authors:

  Department of Scientific & Industrial Research, NZ

  Chemistry Division
  Petone,   New Zealand 
• Authors:
  • Milestone, N B
  • St John, D A
  • Baxter, N I
• Publication Date: 1990

Language

• English

Media Info

• Features: References;
• Pagination: 8 p.

Subject/Index Terms

• TRT Terms: Aggregates; Alkali; Alkali aggregate reactions; Basalt; Cement; Cement content; Concrete; Volcanic aggregates; Volcanic rock
• Old TRIS Terms: Alkalies
• ITRD Terms: 4577: Aggregate; 7353: Alkali; 4183: Basalt; 4758: Cement; 7163: Chemical analysis; 4755: Concrete; 6440: Error; 4122: Felspar; 7198: Potassium; 7197: Sodium; 5937: Structure (physicochem)
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00609465
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Files: ITRD, TRIS
• Created Date: Jun 30 1991 12:00AM