Laboratory Evaluation on Steel Slag as Aggregate Replacement in Stone Mastic Asphalt Mixtures

The stone mastic asphalt (SMA) mixture has been used in many developed countries with the addition of by-product to reduce the consumption of aggregates in road construction. Recently, the Malaysian Public Works Department (PWD) has launched the new specifications on specialty mixture and surface treatment, including SMA. Therefore, this study was conducted to investigate the use of steel slag as an aggregate replacement in Malaysian SMA. Two types of mixes; namely SMA14 and SMA20 were used in this study. The Marshall Mix design method with 50 compaction efforts was used for the design mix for both mixes, where all the standards were referred to the PWD specification (JKR/SPJ/2008-S4). The performance of SMA14- and SMA20- steel slag mixtures was evaluated in terms of the resilient modulus, rutting and creep deformations, conducted by means of a universal testing machine (UTM) and a Wessex wheel tracking. Except for the water absorption test, it was observed that the strength and shape of the steel slag aggregate meet the PWD specification. In addition, the results also show that the use of steel slag improves the strength and resistance to rutting compared to the control SMA samples.