Steel Slag Aggregates in Bituminous Mixtures

摘要

The report covers the evaluation of steel slag from open hearth, basic oxygen, orelectric arc steel making processes used as an aggregate for bituminous asphalt mixes. Bituminous asphalt mixes demonstrate several good mix characteristics with steel slag aggregates. The characteristics include high stability, high skid resistance, longer heat retention after mixing, and ease of compaction without 'shoving' in front of a roller compactor. Steel slag aggregates are abundant in Pennsylvania due to the once large steel processing centers. However, steel slag aggregates have potential for volumetric expansion due to the fast occurring hydration of Calcium Oxide and the slower hydration of Magnesium Oxide found in steel slag. For this reason, steel slag aggregates were evaluated in a Pennsylvania FB-2 binder and wearing course and in a FJ-1 wearing course to determine any potential for blow-ups or pop-outs at the pavement surface. Laboratory test results indicated no problems with any of the steel slag bituminous mixes. Stell slag specimens demonstrated a higher percent retained tensile strength and stability with less stripping than limestone specimens. The percent swell of the steel slag specimens were also within tolerable limits. Field pavements also had no problems.