Mechanical properties and freezing and thawing durability of concrete incorporating a ground granulated blast-furnace slag

Abstract

This paper gives the results of laboratory invstigations to determine the mechanical properties and freezing and thawing durability of concrete incorporating a granulated blast-furnace slag from a Canadian source. A series of fifteen 0.06 m3 concrete mixtures were made with water-to-(cement + slag) ratios (W/(C + S)) ranging from 0.70 to 0.45. The percentage of slag used as a partial replacement for normal portland cement ranged from 0 to 100% by weight. All mixtures were air entrained. A number of test cylinders and prisms were cast for determining the mechanical properties and freezing and thawing resistance of concrete.The test results indicate that the ground granulated blast-furnace slag can be used with advantage as a partial replacement for portland cement in concrete at 50% or lower replacement levels, especially at W/(C + S) of the order of 0.55 or lower. At 28 days, irrespective of the W/(C + S) and regardless of the percentage replacement of the cement by the slag investigated, the compressive strength of the concrete incorporating slag is comparable with that of the concrete made with normal portland cement. At all W/(C + S) and at all percentages of replacement, the flexural strength of the slag concrete is comparable with or greater than the corresponding strength of the control concrete. Durability of air-entrained slag concrete exposed to repeated cycles of freezing and thawing is satisfactory as evidenced by the high durability factors achieved. Key words: granulated slag, bleeding, time of setting, concrete, strength, freezing and thawing, shrinkage, creep, abrasion.