8/9/2019 Evaluation of Steel Slag Fine Aggregate in Hot Asphalt Mixtures

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ABSTRACT

Since a considerable amount of steel slag is produced in the southwestern part ofPennsylvania around Pittsburgh, where natural fine aggregate sources are limited, anevaluation was undertaken to determine the feasibility of using "cured" steel slag fineaggregate in hot-mix asphalt (HMA) mixtures. The objectives of this work were to (1) correlate

fine aggregate expansions to the "parent" coarse aggregate expansions, (2) determineproperties of dense-graded Pennsylvania ID-2 wearing course mixtures made with varioussources of steel slag and crushed limestone fine aggregate, and (3) recommend appropriatespecifications and test criteria for implementing the use of steel slag fine aggregate, ifjustifiable. Expansive characteristics of the steel slag aggregates were determined byPennsylvania Test Method 130. HMA mixtures made with steel slag aggregates andlimestone aggregate (control) were subjected to hot-water conditioning and Lottman freeze-and-thaw conditioning to determine potential problems, such as swell and moisture-induceddamage. An excellent correlation existed between the average total expansion of the fineaggregate fraction and that of the "parent" coarse aggregate. No significant problems withswell and moisture-induced damage were noted in HMA mixtures containing steel slag fineaggregate and limestone coarse aggregate. Specifications and test criteria wererecommended for the use of steel slag fine aggregate in HMA mixtures.