Improving the Mechanical Properties of Recycled Asphalt Pavement Mixtures Using Steel Slag and Silica Fume as a Filler

Due to its environmental and economic advantages, the use of recycled materials in asphalt mixes is witnessing increased interest, where the properties of those mixes are significantly affected by the properties of the recycled materials in them. This paper discusses the results of an experimental study conducted to evaluate the performance of recycled asphalt mixtures made with reclaimed asphalt pavement aggregate (RAP). These mixtures were also prepared with two filler additives, namely steel slag (SS) and silica fume (SF), at four different percentages by weight of the aggregate. A total number of 234 mixtures were tested. The laboratory results indicated the effectiveness of using such additives as a filler material. The Marshall stability showed improvement for mixes prepared with steel slag ranging from 11.73 to 32.73 kN as the RAP level increased; the highest stability load was recorded for the 75% RAP with a 50% steel slag mix. On the other hand, the silica fume depicted variance in its strength, yet the maximum load value of 31.02 kN was for the 75% RAP with 100% silica fume. The use of steel slag in the presence of water decreased the stability results, while satisfying the ASTM standards.

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