Mix design and performance evaluation of coloured slurry seal mixture containing natural iron oxide red pigments

The use of durable coloured surface treatment can be one of the best cost reduction strategies for road maintenance. The purpose of this study was to investigate the feasibility of applying natural iron oxide red pigments in a slurry seal mix design in order to change the colour of this type of asphalt and evaluate its performance. In this regard, first, the physical and chemical properties of the rock and pigment materials were evaluated. Then, 4 different mixtures containing 0, 3, 6, and 9% pigment as filler replacement by dry weight of total aggregate with three different levels of bitumen emulsion were used. The design results indicated that the mixture containing 9% of the pigment had the best performance among the mixtures. According to the results, red iron oxide pigment would improve adhesion of bitumen emulsion to rock aggregate, abrasion resistance, and also vertical deformation.