Effect of synthetic and functionalized waxes on bituminous binders: From the glassy state to the intermediate viscoelastic domain. (1st April 2017)

• Record Type: Journal Article
• Authors: Merusi, Filippo; Filippi, Sara; Polacco, Giovanni
• Is Part Of: Construction & building materials. Volume 136(2017)
• Page Start: 541
• Page End: 555
• Publication Date: 2017-04-01
• Subjects: Warm-Mix Asphalt -- Bitumen -- Wax -- Rheology -- Viscoelasticity -- Differential Scanning Calorimetry -- Colloidal structure -- Morphology; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2017.01.062
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Synthetic and amidic functionalized waxes were used to modify a base bitumen. Rheological experiments were analysed in the domain of time, temperature and stress. The invariance in glass transition requires that wax does not modify maltenic phase. The existence of a structured and interconnected physical network was argued. Linear viscoelasticity depends on the degree of residual crystallinity. Abstract: A 50/70 bitumen was modified with five different commercial waxes, including Fischer-Tropsch, Montan and functionalized waxes. Thermal and morphological properties were investigated through Differential Scanning Calorimetry (DSC) and polarized optical microscopy (POM). Dynamic and continuous rheological tests were carried out to analyse the mechanical response of wax-modified bitumens (WMB). Theories behind possible mechanisms of asphalt/wax interaction are discussed. The entire frequency/temperature domain was divided into two macro-regions. The first one covers the glassy state, with independent waxy structures, where the bitumen mainly determines the mechanical response. The second macro region develops along the intermediate viscoelastic domain and propagates towards high temperatures/low frequencies. Within this domain, all WMB exhibits a complex mechanical response, with gel-like characteristics, thus suggesting the existence of physical networks and interconnections between contiguous wax crystalline segments.