Mechanical Properties, Durability, and Drying Shrinkage of Portland Cement Concrete Incorporating Silica Fume

    Volume 5, Issue 1 (July 1983)

    ISSN: 0149-6123

    CODEN: CCAOAD

    Page Count: 11


    Carette, GG
    Materials engineer and head, Construction Materials Section, CANMET, Energy, Mines and Resources Canada, Ottawa,

    Malhotra, VM
    Materials engineer and head, Construction Materials Section, CANMET, Energy, Mines and Resources Canada, Ottawa,

    Abstract

    Portland cement is a highly energy intensive material, therefore, considerable effort is being made to find substitutes for partially replacing cement in concrete. Silica fume, a byproduct in the manufacture of ferrosilicon and silicon metal is one possible substitute. Results are given of a preliminary investigation to determine the strength, freezing and thawing characteristics, and drying shrinkage of concrete incorporating various percentages of silica fume.

    Eighteen 0.06-m3 air-entrained concrete mixes were made incorporating 0 to 30% silica fume as a partial replacement for cement. Some mixes were proportioned to have constant slump with water to cementitious materials ratio (W/C + S) ranging from 0.64 to 0.84 whereas others were proportioned to have a constant W/C + S of 0.40; the latter incorporated a superplasticizer. Cylinder and prism specimens were cast for determining the mechanical properties and durability of concrete.

    Test data indicate that silica fume when used in concrete as a partial replacement for cement performs as a highly efficient pozzolanic material. Notwithstanding the extreme fineness of silica fume (20 000 m2/kg) and, hence, its high water demand, the compressive strength of constant slump concrete incorporating up to 30% silica fume is comparable with or higher than the strength of control concrete.

    Superplasticized concrete mixes having a W/C + S maintained at 0.40 indicate some increase in compressive strength at all ages regardless of the percentage of silica fume.

    Concrete prisms incorporating 0 to 15% silica fume (W/C + S = 0.40) perform satisfactorily when subjected to 300 cycles of freezing and thawing; however, prisms incorporating 20 to 30% silica fume and large dosages of superplasticizer show excessive expansion and relatively low dynamic moduli after 300 cycles. The drying shrinkage of concrete incorporating silica fume is generally comparable with that of control concrete regardless of the W/C + S.


    Paper ID: CCA10244J

    DOI: 10.1520/CCA10244J

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    Author
    Title Mechanical Properties, Durability, and Drying Shrinkage of Portland Cement Concrete Incorporating Silica Fume
    Symposium , 0000-00-00
    Committee C01