Morphological and nanomechanical analyses of ground tire rubber-modified asphalts

Abstract

Automobile industries produce more than 5.2 million tons of scrapped tires each year in the United States. Disposal of such a huge amount of waste scrapped tires has become a serious environmental issue. Scopes to use scrapped tires in the form of Ground Tire Rubber (GTR) in pavement industry have been analyzed in recent years. The GTR has potential to improve hot mix asphalt's performance from the view points of stiffness, resilience and shock absorbance properties. On the other hand, in recent years, researchers have attempted to explain performance of asphalt in terms of its nanomechanical characteristics. In this study, the PeakForce Quantitative Nanomechanical Mapping (PFQNM TM) mode of an atomic force microscope has been employed to find basic nanomechanistic properties and the morphology of GTRmodified asphalt binders. A performance grade (PG) binder (PG 64-22) modified with two different grades of GTR (Mesh #30 and Mesh #40) samples have been evaluated in this study. Nanomechanical properties such as adhesion, energy dissipation, deformation, and DMT (Derjaguin, Muller, and Toporov) modulus for the GTR-modified binders have been quantified. Each sample was scanned for three different (5 9 5, 10 9 10, and 20 9 20 lm) areas. The PFQNM TM analyses revealed distinct microstructures and grain distributions among tested additive modified binder samples. Two distinct phases, namely Catana and Peri-phase, were observed in GTR-modified samples, although the DMT moduli were found to be in a close range in these areas. The neat binder showed another phase, named Perpetua, which was missing from the GTRmodified samples. It was observed that modification of asphalt by addition of GTR considerably changes the mechanistic properties of the base binder.

Comparing Micro- and Macro-Level Rheological Properties of Polymeric and Reclaimed Asphalt Pavement-Modified Asphalt Binders

“…A similar decreasing trend in deformation values was also noticed for all binders evaluated in this study. These low deformation values observed after the aging indicated that PAV-aged samples become stiffer than other binders (36), which agrees with the micro-level DMT modulus values. It is also found that the binders modified with PPA plus SBS showed the lowest deformation, whereas unmodified (control) binders from both sources showed the highest deformation whatever the aging condition.…”

“…The deformation value (Table 2) indicates the depth of penetration and is also a relative measure of material's hardness (36). All tested PAV-aged samples had a lower deformation than their corresponding unaged and RTFO-aged binders.…”

“…For this reason, the DMT modulus has been adopted. Some researchers (e.g., [36]) suggested using the DMT modulus of asphalt binder for characterization purposes as it considers the adhesion values of the material, while the Young's modulus does not consider the material's adhesion properties. The PFQNMä mode of the Bruker Dimension AFM facilitates capturing ''DMT Modulus'' while oscillating the cantilever well below resonance, resulting in a continuous series of force-distance curves (37).…”

Violin Varnishes: Microstructure and Nanomechanical Analysis

“…Actually, Infra-red specular reflection and diffuse-transflection techniques have been reported as a method for in situ non-destructive analyses of varnishes on historical violins with a view to indicate state of degradation of varnishes [ 25 , 26 ]. A recent paper on modified asphalt binders [ 27 ] and on bamboo fibre cell walls and their composites has demonstrated the value of these additional data as basic nanomechanistic properties, adhesion, energy dissipation, and deformation of the modified asphalt binders were determined [ 28 ].…”

Nanoscale Quantification of Moisture Susceptibility of Paving Asphalts

“…In recent years, several researchers studied the qualitative characterization of the microscopic properties of the asphalt binders [8][9][10]. Moreover, the AFM technology was used to investigate the surface morphology as well as the micromechanical properties such as DMT (Derjaguin, Muller, and Toropov) modulus, adhesion, deformation, and energy dissipation of the asphalt binders [11][12][13][14][15][16]. These researchers described three distinct phases namely, dispersed phase (Catana), interstitial phase (Peri-phase), and matrix (Para-phase) to characterize the morphological clusters, which were also used in this study.…”