CHEMICAL TREATMENTS AND ADDITIVES FOR CONTROLLING ALKALI REACTIVITY

The reactivity of certain aggregates with the alkalis in the cement paste is essentially a chemical activity. As such, it should be controllable with chemical additives. Current research is examining this possibility. A chemical additive to the mix water could be more closely controlled than mineral additives such as fly ash or silica fume. Alkali-silica(te) reactivity (ASR) involves dissolution of silica and formation of silica gel. The gel by itself is probably not harmful. Only when excess alkalis are present in the gel does it become deleteriously expansive through osmotic action. Any chemical treatments that will either reduce silica gel formation or reduce the osmotic pressures generated by alkalis would reduce the destructive potential of alkali reactivity. Some chemical groups have been found to reduce expansion caused by ASR. Among the anions, phosphates and nitrates are effective. Lithium and calcium cations were also found to work. However, not all varieties of these compounds are effective, and when effective, are not equally so with all ASR aggregates. (A)

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  • Corporate Authors:

    Elsevier Science Publishers

    Crown House, Linton Road
    Barking, Essex IG11 8JU,   England 

    Organisation for Economic Co-operation and Development (OECD)

    2, rue André Pascal
    Paris,   France  75775 Paris Cedex 16
  • Authors:
    • Hudec, P P
    • BANAHENE, N K
  • Publication Date: 1993

Language

  • English

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Filing Info

  • Accession Number: 00663471
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Aug 24 1994 12:00AM