A predictive and experimental method to assess bitumen emulsion wetting on mineral substrates

• Assessment of theoretical bitumen emulsion/mineral substrate work of adhesion.
• Study of wetting kinetics of bitumen emulsions onto mineral substrates.
• Influence of various parameters on bitumen emulsion wetting.
• Determination of experimental bitumen emulsion/mineral substrate work of adhesion.

This paper deals with wetting kinetics and adhesion of bitumen emulsions on mineral surfaces. To this purpose, four mineral substrates: gneiss, diorite, limestone and quartzite and three emulsions were tested. First, surface properties of the materials were determined and theoretical bitumen emulsion/mineral substrate work of adhesion was calculated. Second, bitumen emulsion/mineral substrate contact angles were measured as a function of time and images of emulsion droplets were taken to highlight drop shape evolution and water evaporation. Experimental bitumen emulsion/mineral work of adhesion was assessed using contact angle values and Young-Dupré equation usually employed for pure liquids. It was proved that quartzite has the highest surface energy, and gneiss has the lowest. The highest theoretical work of adhesion was noted with one of the emulsions studied and quartzite. However, error bars found for all the values were important. The calculation of experimental work of adhesion showed the same tendency as for theoretical work and error bars were lower. Consequently, Young-Dupré equation is valid for emulsion/substrate systems at short times.

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