Application of the synthetic wax to improve the foamed bitumen parameters used in half-warm bituminous mixtures

Abstract

The need for bitumen modification allowing lower asphalt production temperatures is a direct result of economic and environmental issues. Compared with the traditional Hot Mix Asphalt (HMA) technology, foamed bitumen used in the Warm and Half Warm Mix Asphalt (WMA, HWMA) processes provides an approximately 30-40 °C reduction in operating temperatures. This paper analyses the effect of the Fischer-Tropsch (FT) wax modifier on foamed bitumen parameters. The evaluation is focused on the basic properties of the binder and the parameters of the bituminous foam. The tests were performed on 35/50 and 50/70 penetration grade binders for road construction, modified with 0.5% to 2.5% FT wax, added with an increment of 0.5% relative to the bitumen mass. The following basic parameters were evaluated (before the foaming process): penetration, Fraass breaking point and softening point. The bitumen foam parameters were measured at the foaming water content (FWC) in the range from 1.5% to 4.0% with an increment of 0.5%. The tests allowed determining optimal application ranges for the FT and the FWC to produce asphalt at lower temperatures.