Use of steel slag in pavement surface materials is an environmentally sustainable method of creating a valuable and useful resource out of something which would otherwise be regarded as a waste product.
Steelphalt has developed a range of asphalt products incorporating steel slag aggregate. Whilst there are examples of these materials that have been in service for almost two decades, the products are not currently exploited to their full capacity despite their significant environmental credentials. A contributory factor is that steel slag aggregates do not typically perform as well in laboratory tests designed to examine polish resistance as they apparently do in-service.
TRL was commissioned to assess the skid resistance performance of steel slag asphalt. The assessment included inspections, SCRIM testing and laboratory experiments.
This report considers SCRIM data collected on 18 in-service roads which have been surfaced with Steelphalt materials. In general, for all products investigated, the skid resistance measured is above the normal Investigatory Level (IL) for all non-event dual carriageway and non-event single carriageway sites.
For higher risk site categories the performance is mixed: the skid resistance was above IL on a large majority of the junction approaches measured, while for those below IL, the difference was small; the results for categories requiring a higher IL are inconclusive owing to the small amount of data available.
The site inspections found that the durability of most of the Steelphalt products inspected is above average.
The work concludes that Steelphalt products can be used with confidence in non-event situations, and can be used successfully in some high risk locations by applying engineering judgement regarding the target level of skid resistance and the likely traffic levels.

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