Bonding in cementitious materials with asphalt-coated particles: Part II – Cement-asphalt chemical interactions. (15th January 2017)

• Record Type: Journal Article
• Authors: Brand, Alexander S.; Roesler, Jeffery R.
• Is Part Of: Construction & building materials. Volume 130(2017)
• Page Start: 182
• Page End: 192
• Publication Date: 2017-01-15
• Subjects: Reclaimed asphalt pavement -- Concrete -- Interfacial transition zone -- Bond improvement -- Interfacial bond test -- Surface free energy; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2016.10.013
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Asphalt cohesion is the dominant failure mode between asphalt and cement. Chemical treatments to RAP can increase interfacial bond energy between asphalt and cement. Higher ITZ porosity is the reason for reduced modulus in concrete with RAP aggregates. Asphalt cohesion failure is the primary reason for reduced mechanical properties in concrete with RAP. Abstract: Reclaimed asphalt pavement (RAP), when used as an aggregate in concrete, will reduce bulk concrete strength and modulus. While Part I of this study investigated the properties of the interfacial transition zone (ITZ), Part II focuses on the nature of the cement-asphalt bond. Several chemical oxidative treatments of the asphalt were found to improve the interfacial cement-asphalt bond energy without affecting the ITZ porosity and size. Based on surface free energy measurements, the failure mode was estimated to occur preferentially as asphalt cohesion rather than cement-asphalt adhesion or ITZ cohesion. Based on the findings from Parts I and II, RAP aggregates reduce concrete strength and modulus because of: (1) the higher porosity in the ITZ, which produces a lower bulk modulus and allows for easier crack initiation, and (2) the preferential asphalt cohesion failure, which occurs rather than adhesive failure of the cement-asphalt interface or cohesive failure of the ITZ.