Surface Energy Measurement of Asphalt and Its Application to Predicting Fatigue and Healing in Asphalt Mixtures

Abstract

Cohesive and adhesive bonding within the asphalt—aggregate system are directly related to the surface energy of the asphalt. The thermodynamic changes in the surface energy of adhesion and cohesion are related to the de-bonding of the interface between asphalt and aggregate and to cracks that may occur within the mastic, respectively. However, it is also true that thermodynamic changes in the surface energy are required to heal a fracture between the surfaces of the asphalt and the aggregate or within the mastic. The methodology and testing protocol for measuring the surface energy of asphalt are presented. Both the surface energy of dewetting (fracture) and the surface energy of wetting (healing) can be obtained from the contact angle measurement with the Wilhelmy plate method. Ten asphalts were tested; surface energies varied substantially as a function of asphalt composition and the level of aging to which the asphalt was subjected. By using thermodynamic theory, the adhesion and cohesion bonding energy within the asphaltaggregate systems were further analyzed. This analysis has the potential to select the most compatible asphalt—aggregate combination for mixtures. The surface energy is also a very important parameter in the fatigue and healing analysis of the asphalt pavement.

Stochastic finite element analysis of moisture damage in hot mix asphalt

“…The presence of water reduces the surface energy of the system since aggregate surfaces have a stronger preference for water than asphalt (Majidzadeh and Brovold 1968). The adhesive bond strengths were calculated by Cheng et al (2002) by measuring the surface energies of components, the asphalt-aggregate interface, in the presence of water and when under dry conditions.…”

“…The salt solution moves from an area of high concentration to an area of low concentration. Cheng et al (2002) show that there is a considerable amount of water that diffuses through the asphalt cement and asphalt mastics can hold a significant amount of water.…”

“…The cohesive strength of a mastic is weakened due to the presence of water through increased saturation and void swelling or expansion Al-Swailmi 1992, Little andJones 2003). Cheng et al (2002) showed that the cohesive strength can be damaged in various mixtures by the diffusion of water into asphalt mastics.…”

“…The tests are summarized in Table 2-1. Kennedy et al (1984) Rolling Bottle Isacsson and Jorgensen (1987) Net Adsorption SHRP-A-341 (Curtis et al 1993) Surface Energy Thelen (1958) Cheng et al (2002) Pneumatic Pull-Off Youtcheff and Aurilio (1997) *No longer available as ASTM standard.…”

Chemically modified bitumens with enhanced rheology and adhesion properties to siliceous aggregates

“…To that end, the surface energy theory can explain adhesion and cohesion bonds according to both aggregate and binders physico-chemical properties [13,16,17]. Based on surface energy measurements, Cheng et al [18] pointed out that the affinity of the aggregates for water is far greater than that for bitumen. As a result, water is able to replace (strip) the bitumen from the aggregate surface, with the rate of replacement dependent on the aggregate-bitumen bond strength in the presence of water.…”