Use of Surface Energy to evaluate Adhesion of Bituminous Crack Sealants to Aggregates

Problem statement: The performance of bituminous sealants in the field is partly controlled by properties and strength of the sealant-aggregate interface. The thermodynamic work of adhesion represents energy required for reversible separation of the two materials at the interface. The study of fracture includes the energy required for both reversible and irreversible processes during separation. Excess of work of facture over work of adhesion represents the energy consumed by irreversible processes in the specimen during loading and fracture. In addition, adhesion strength is related to the properties of constitutive components. Approach: The objective of this study was to measure or predict adhesion of hot-poured bituminous-based sealant to aggregates of different chemical composition. In order to accomplish, the study of fracture and the thermodynamic work of adhesion were estimated for 14 hot-poured bituminous-based sealants with two types of aggregate: Limestone and quartzite. The work of adhesion for each sealant-aggregate system was calculated from the contact angle measurements of system components at corresponding sealant installation temperature. Results: In general, limestone showed better adhesion to hot-poured crack sealant than quartzite. Interfacial parameters such as contact angles and surface tensions were successfully used to differentiate between sealants. Conclusion/Recommendation: The findings were in agreement with preliminary testing results of 14 sealants using a newly developed fixture in the direct-tension testing machine. Provided the sealant has an appropriate viscosity to fill the crack, as the sealant surface tension decreases, its adhesion strength increases.