Use of Ash in Low-Volume Road Construction in South Africa

Sasol Chemical Industries produces large quantities of coarse clinker and fly ash as a by-product of the coal gasification process at their Sasolburg plant in South Africa. If this ash could be used as an aggregate in roads, the demand on natural reserves for aggregates would be reduced and an effective method of disposing of these materials would result. The ash is processed at a blending plant in Sasolburg and is marketed under the name Premamix. Trial sections were constructed using labor-based techniques with unstabilized and bitumen emulsion-treated Premamix as a base course material. As the Premamix is a lightweight material and is delivered at a specified moisture content (the optimum moisture content for compaction), it is ideal for labor-based construction of low-volume roads as only spreading and compaction of the layers are required. The trial sections were subjected to accelerated pavement testing with the heavy-vehicle simulator. Although high deflections were measured in the pavement structure, the Premamix performed well under trafficking, even after the base was soaked with water.