Rheological Behavior and Its Chemical Interpretation of Crumb Rubber Modified Asphalt Containing Warm-Mix Additives

Abstract

The microstructure and chemical composition of asphalt binders have a significant effect on their rheological properties and, therefore, their performance as road paving binders. This study aims to investigate the effects of warm-mix asphalt (WMA) additives, organic type and chemical type, on the rheological properties and chemical internal structure of base asphalt and crumb rubber modified asphalt (CRMA). A set of dynamic shear rheometer (DSR) tests was conducted to obtain the rheological parameters (e.g., complex viscosity, complex modulus, phase angle) of asphalt binders. The flow activation energy was calculated from Arrhenius equation based on viscosity data to rank the thermal susceptibility. Black diagrams and master curves of complex modulus and phase angle were utilized to analyze the rheological properties. The molecular weight distributions of asphalt binders were inverted from the phase angle master curve to evaluate the molecular weight characteristics. It was found that the the addition of crumb rubber into base asphalt improves the rheological properties of enhanced modulus and elasticity. Organic and chemical types of WMA additives have different chemo-physical effects on both base asphalt and CRMA. Phase angle inversion method provides a powerful tool to monitor the molecular structure change and, therefore, the chemo-physical interactions of asphalt binders induced by modifications. Finally, there is a good correlation between flow activation energy and molecular weight.Recycling crumb rubber from end-of-life tires into asphalt paving has been applied for several decades for its tremendous economic and environmental benefits. It is reported that the incorporation of crumb rubber modifier (CRM) into asphalt binders can improve the overall performance of asphalt pavements (1, 2), such as improved aging and oxidation resistance, greater resistance to fatigue/thermal cracking and rutting, lower noise generation, higher skid resistance, and so forth. The above-improved performance of rubberized asphalt pavement relies on the interaction of CRM with asphalt. Depending on different interaction parameters (temperature, time and mixing rate, etc.), rubber-asphalt interaction is generally related to two mechanisms (3, 4): (a) swelling of CRM particles in asphalt matrix through absorbing the light aromatic oils of asphalt, and (b) degradation (devulcanization and depolymerization) of CRM through the release of its components into the liquid phase of asphalt.The improvement of the rheological properties of the rubberized asphalt binders has been observed after the interaction of CRM with asphalt (5). However, due to the high viscosity of rubberized binders, high mixing and compaction temperatures are required to achieve desirable workability and density of asphalt mixtures. In addition, the consequent high emissions and compromised work conditions during the construction process of rubberized asphalt pavement have been criticized (6). Warm-mix asphalt (WMA) technologies are developed to substantia...

Non-Newtonian Behaviors of Crumb Rubber-Modified Bituminous Binders

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Development and Characterization of Stable Polymer Formulations for Manufacturing Magnetic Composites

“…Activation energy is an indicator used to characterize the thermal susceptibility of materials. Materials with low activation energy were observed to be less susceptible to temperature changes [26,32]. Additionally, the chosen rheological additive (Disparlon 6900-20x) is PA based with a high melting point, which extends its activity to high temperature ranges [33].…”

Value-Added Application of Waste Rubber and Waste Plastic in Asphalt Binder as a Multifunctional Additive

“…By means of incorporating wastes into asphalt binder, a large amount of domestic garbage or industrial refuse can be consumed with environmental benefits [1,16,17,18,19]. Thus, attention has been focused on the possibility of using asphalt binder as an innovative waste treatment method [20,21,22]. Specifically, previous studies have demonstrated the feasibility of recycling various types of waste materials into asphalt materials, for instance, end-of-life vehicle tires [23], waste plastic [2,24], electronic waste powders [17], marble waste [25], waste bleaching clays [26], waste glass powder [27], waste wood resources [28], etc.…”