DETERMINATION OF CHLORIDE IN HARDENED PORTLAND CEMENT PASTE, MORTAR, AND CONCRETE

THE SEVERE DISTRESS OBSERVED IN MANY PORTLAND CEMENT CONCRETE PAVEMENTS AND BRIDGE DECKS EXPOSED TO SEA WATER OR TO DEICING SALTS HAS RESULTED IN THE NEED FOR A SIMPLE AND ACCURATE METHOD FOR DETERMINING CHLORIDE CONTENT IN HARDENED CONCRETE. MOST AVAILABLE METHODS ARE INACCURATE EITHER BECAUSE VOLATILE CHLORIDE IS LOST OR BECAUSE THE TOTAL QUANTITY OF CHLORIDE ION IS NOT EXTRACTED. A METHOD IS PRESENTED IN WHICH THE TOTAL CHLORIDE ION CONTENT IS DETERMINED BY DISSOLVING THE SAMPLE IN 1+16 NITRIC ACID, FILTERING, AND TITRATING WITH SILVER NITRATE WITH THE AID OF A CHLORIDE-SELECTIVE ELECTRODE. VOLATILIZATION OF CHLORIDE DURING THE DIGESTION IS AVOIDED BY GENTLE HEATING AND CAREFUL CONTROL OF THE NITRIC ACID CONCENTRATION. THE TITRATION-ELECTRODE METHOD IS MORE PRECISE THAN METHODS WHICH USE THE ELECTRODE AS A DIRECT-READING INSTRUMENT AND OBVIATES THE NEED FOR CLOSE CONTROL OF SUCH VARIABLES AS IONIC STRENGTH AND PH REQUIRED IN DIRECT READING METHODS. THE ACCURACY OF THE METHOD IS ESTIMATED TO BE WITHIN 0.5 PERCENT OF THE CHLORIDE CONTENT. THE ESTIMATED SENSITIVITY IS 0.02 MG C1. /FHWA/

  • Corporate Authors:

    Federal Highway Administration

    Office of Research and Development, 1200 New Jersey Avenue, SE
    Washington, DC  USA  20590
  • Authors:
    • Berman, H A
  • Publication Date: 1972-9

Media Info

  • Pagination: 22 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00206531
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-RD-72- 12 Intrm Rpt.
  • Files: TRIS, USDOT
  • Created Date: Jun 5 1976 12:00AM