Evaluation of moisture susceptibility of foamed warm asphalt produced by water injection using surface free energy method

Abstract

Foamed warm asphalt are widely used to lower the mixing and paving temperature of asphalt mixtures. However, due to the foaming water addition, moisture damage is one of the main worries. The objective of this paper was evaluate the moisture damage of foamed warm asphalt using surface free energy (SFE) method. Contact angles were measured to estimate the surface free energy components, work of cohesion and adhesion, spreading coefficient and energy ratios (ER1, ER2). The results showed that foamed warm asphalt had lower total surface free energy, but had higher acid base SFE component compared unfoamed asphalt. Foaming water did not seem to have significant effects on the total SFE of asphalt. The work of cohesion and ER1 decreased after foamed, while the work of adhesion, spreading Coefficient (SC) and ER2 increased after foamed. Analysis base on surface free energy results reflected that the wettability and work of adhesion had an improvement after foamed, while the foaming water weakened the work of debonding.