Hot-mix asphalt that contains nickel slag aggregate: Laboratory evaluation of use in highway construction

Air-cooled (AC) nickel slag is evaluated for highway construction applications as an aggregate in hot-mix asphalt (HMA). The AC nickel slag is a liquid coproduct of nickel production that is solidified under ambient conditions. The laboratory evaluation program, which was carried out to determine the characteristics of the AC nickel slag, included physical and mechanical properties testing, petrographic examinations, and HMA mixture designs. Accelerated laboratory testing was completed on the mixtures by using an asphalt pavement analyzer to assess their performance characteristics. Additional testing included autoclave disruption tests for free lime and free magnesia, chemical and mineralogical analyses, polished stone value, and aggregate abrasion value. This study indicated that suitably processed nickel slag was environmentally, mineralogically, and physically stable. From the accelerated laboratory testing that was completed, it was concluded that the AC nickel slag was suitable for use as coarse and fine aggregates in HMA. The use of nickel slag in a highway construction is also presented.