Journal Published Online: 01 July 1983
Volume 5, Issue 1

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



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.

Author Information

Carette, GG
Construction Materials Section, CANMET, Energy, Mines and Resources Canada, Ottawa, Canada
Malhotra, VM
Construction Materials Section, CANMET, Energy, Mines and Resources Canada, Ottawa, Canada
Pages: 11
Price: $25.00
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Stock #: CCA10244J
ISSN: 0149-6123
DOI: 10.1520/CCA10244J