Evaluation of Hydraulic Cement Concretes Containing Slag Added at the Mixer

About the report:

The study evaluated the effect of ground, granulated, iron slags on the properties of hydraulic cement concretes such as normally used in highway construction. Two cements with different alkali contents and two slags with different activity indices, 100 and 120, were used. Slags were used as replacements for portions of Portland cement at 40%, 50%, and 65% by weight. This final report presents data on the properties of the freshly mixed concrete and the test results on time of set, heat of hydration, compressive strength, flexural strength, permeability, resistance to freezing and thawing, length change values, and the results of petrographic examinations including data on air voids, carbonation, and hydration. The test results for the laboratory specimens indicate that mixtures with the slags exhibit delay in set and slower development of compressive strength early ages than do conventional mixtures but have equal or better strengths at Later ages. The incorporation of slag reduces the permeability of concrete considerably. It is concluded from this study that concretes in which up to 50% by weight of the cement has been replaced with a slag meeting the requirements of ASTM C989 and having a minimum activity index of 100 are satisfactory for use in highway construction.

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