Effects of SARA fractions on low temperature properties of asphalt binders

Abstract: In order to achieve better reuse of asphalt, it is necessary to quantitatively characterize the aging degree of asphalt. Conventional methods such as Dynamic Shear Rheometer (DSR), Fourier Transform Infrared Spectroscopy (FTIR), and Gel Permeation Chromatography (GPC) have been used to evaluate the aging degree of asphalt from different angles. In order to develop a more comprehensive and straightforward method to distinguish asphalt aging degree, a potential new technique namely Spectrophotometry was introduced in this study. Eight asphalts at three aging states were tested by UV–Vis spectrophotometer and DSR to obtain the absorption and rheological data, respectively. The two-component method was used to analyze the component change at different aging states. Gray Relational Analysis (GRA) and R-cluster analysis were used to demonstrate the consistency of different evaluation systems. Linear regression was used to show the feasibility of using asphalt absorbance data to characterize the rheological properties during the aging procedure. The results indicated that it was the asphaltene incensement during the aging procedure who contributed to the rheological property and asphalt absorbance change during the aging procedure. Meanwhile, the statistical analysis indicated that spectrophotometry could be effectively introduced to characterize asphalt aging degree and rheological properties by preparing a 2 g/L “toluene-heptane” asphalt suspension and testing the asphalt absorbance area from 700 nm to 900 nm.

Abstract: The aim of this study was to characterize the chemical, molecular, and rheological properties of different asphalt emulsions including a newly introduced tire-rubber modified asphalt emulsion (CRS-...

Abstract: Thermal or low temperature cracking is among the most common distresses in asphalt pavements, occurring in cold regions and exerting a detrimental effect on the quality and life of the pavement. Ha...

Abstract: The environmental factors, such as the ultraviolet (UV) radiation, water, acid, alkali and salt, can cause significant negative impacts on the bitumen. Therefore, multi-factors coupling ageing test is closer to the actual service conditions of bitumen. Nine groups of coupling-condition ageing tests (UV radiation and the acidic, alkaline and neutral solutions) were conducted on the bitumen (Pen60/80). The conditioning times were 3, 6 and 9 days. After the test, the coupling hazards and its mechanism of these environmental factors on bitumen were analyzed. In detail, the transition of the appearance, physical and rheological properties of bitumen was characterized, the results show that coupled conditions have much more serious negative impacts on the performance of bitumen. In addition, to reveal the mechanism of negative impacts, the chemical functional groups and components of bitumen were studied, meanwhile the pH value, organic carbon content and chemical functional groups of the residual solutions were also analyzed, indicating that the coupled ageing mechanism mainly includes three channels, they are the excitation and break of bituminous molecules, the dissolution and leach of the organic component in the solutions, and the catalytic action of the alkali metal ions.

Abstract: The use of reclaimed asphalt pavement (RAP) is believed to contribute significantly towards overall energy conservation and environmental protection efforts. However, the recycling of aged binder f...

Abstract: The use of bitumen as a construction material dates back to antiquity. The materials in use then were mostly naturally occurring in contrast to modern bitumens which have become highly technical artificial materials. This article reviews the current understanding of bitumen structure and the consequences in terms of properties, with a strong emphasis on the rheological properties. The links between chemistry, structure and mechanical properties are highlighted in the framework of an updated colloidal picture of bitumen. It shows that a simple solvation parameter allows quantifying the effect of the asphaltenes on the rheological properties of bitumen. This appears as a promising approach in order to understand more complex phenomena such as bitumen ageing or the diffusion of rejuvenating oils into an older bitumen. From this structural modelling, the effect of several modifiers, such as polymers, acids or mineral fillers, is explained using fundamental results from the mechanics of colloidal suspensions and multiphase materials through the Palierne model. Thus, relevant parameters describing polymer-bitumen or mineral fillers-bitumen interactions can be extracted, as detailed from literature data. In the case of mineral filler, volume fraction is the key parameter but particle size comes also into play when fine fillers are considered. In the case of polymer-modified bitumens, the swelling extent of the polymer controls all other parameters of importance: volume fraction of dispersed phase and mechanical properties of both dispersed and continuous phases. In addition, interesting rheological features due to droplet shape relaxations are described in polymer-modified bitumens. Although a general picture of bitumen structure is shown to emerge, the many fundamental points that remain to be addressed are discussed throughout the paper.

Abstract: Publisher Summary This chapter examines the literature dealing with the chemical composition of asphalt and changes in composition during environmental aging that affect durability-related properties. The characterization of the chemical functional types gives a fundamental approach to the relationships between asphalt composition and asphalt properties, and the performance of asphalts and asphalt-aggregate mixtures. Differences in the quality of asphalts depend on their crude oil sources because different crude oils have different chemical compositions. A durable asphalt is defined as one that (a) possesses the physical properties necessary to produce the desired initial product performance properties, and (b) is resistant to changes in physical properties during long-term, in-service environmental aging. Durability is determined by the physical properties of the asphalt, which are determined directly by chemical composition.

Abstract: The present study gives a new understanding about bitumen's colloidal behavior, related to its chemical composition, microscopic structure and rheological properties. Bitumens possess a strong temperature dependence of rheological properties, governed by the interaction of the individual constituents. Much importance is given to the colloidal index of the bitumen, based on the ratio of the four main chemical components (asphaltenes, resins, aromatics, saturates). Increasing one of these constituents fundamentally changes the structure and the rheological behavior of bitumen. Therefore, a gel bitumen contains high asphaltene/resin concentrations, leading to a network structure with high rigidity and elasticity (high IG ∗ I , low δ), whereas a sol bitumen possesses a high resin/asphaltene ratio, forming domains of coherent asphaltene micelles which lead to a good time-temperature equivalence in the Black space but also high viscous behavior.

Abstract: The chemical and structural analyses of a series of petroleum resins are reported. The data allow feasible representation to be made of the chemical and physical structure of bitumen and crude oils.