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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

CORROSION OF CONCRETE BY SULFATE IONS - PART II

CHLORIDE IONS ARE NOT ONLY NOT INIMICAL BUT EXTEND THE RESISTANCE TO SULFATE ATTACK WHEN COMBINED WITH ALKALINE CATIONS SUCH AS SODIUM AND POTASSIUM. THE PRESENCE OF 3000-5000 PPM CHLORIDE DOUBLES THE TOLERANCE OF SULFATE ION. CHLORIDES OF METALS FORMING BASES WEAKER THAN LIME CORRODE CONCRETE BY SOLUBILIZING CALCIUM CHLORIDE. MOST ACID SALTS ATTACK CEMENT AT PH BELOW 6. SOME ORGANIC COMPOUNDS ATTACK CONCRETE BECAUSE OF CONTAINED ACIDITY WHILE OTHERS ATTACK THE CEMENT DIRECTLY. SELECTION OF A SUITABLE GRADE OF CONCRETE, SURFACE TREATMENT, CORROSION RESISTANT COATINGS, OR ISOLATION OF ENVIRONMENT BY PROTECTIVE WALLS ARE SOME OF THE PROTECTIVE MEASURES THAT MAY BE ADOPTED. ACTIVE MEASURES AGAINST CORROSION WOULD INCLUDE DRAINAGE OR NEUTRALIZATION OF THE AGGRESSIVE WATERS. SPRAYED CONCRETE MAY BE APPLIED USING FERRARI-TYPE CEMENT, AND WATER-GLASS (SODIUM OR POTASSIUM METASILICATE) CAN BE APPLIED IN MULTIPLE TREATMENTS TO FORM CALCIUM SILICATE, FILLING AND SEALING PORES. CALCIUM FLUORIDE IS HIGHLY INSOLUBLE AND A CORROSION RESISTANT SEAL CAN BE DEVELOPED BY TREATMENT WITH SODIUM FLUROIDE OR SODIUM SILICON FLUORIDE AND MAGNESIUM SILICONE FLUORIDE. A PORE-FREE ENAMEL-LIKE SURFACE IS FORMED BY COMBINED PRODUCTS OF CALCIUM FLUORIDE AND SILICA GEL. IF NO ORGANIC SOLVENT ACTION IS ANTICIPATED IN THE EXPOSURE, 3-COAT APPLICATIONS OF BITUMINOUS PAINTS OR HEAVY ASPHALTIC MASTICS ARE SUITABLE BARRIERS. THE NEED FOR SPECIFICATION OF CEMENTS FOR KNOWN LEVELS OF SULFATE CONTAMINATION UNDER SPECIFIED CONDITIONS IS INDICATED.

  • Authors:
    • Dillon, C P
  • Publication Date: 1973-8

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  • Accession Number: 00214277
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 17 1973 12:00AM