New experimental methods to monitor and characterize asphalt rubber binders

• Author(s): Peralta, J. ; Silva, Hugo Manuel Ribeiro Dias da ; Pais, Jorge C.
• Date: 2010
• Persistent ID: http://hdl.handle.net/1822/17446
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Asphalt rubber; Density; Sphere production simulator; Basket drainage method
• Document Type: Conference Object
• Language: English

Description

The need for continuous quality improvement of the road pavements, leads to the development of new binders, such as asphalt rubber (AR). AR is produced by the digestion of crumb rubber from used tires on bitumen. The resulting AR is a heterogeneous material with high viscosity. The study of this product during its production is essential due to the sudden and sharp increase in the volume of AR in this phase. Knowledge of the extent of this phenomenon has obvious implications in the design of the AR production equipment. In addition, to predict the performance of the AR in the pavement, its components (i.e. bitumen and rubber) should be analyzed separately. Thus, the objective of this paper is to present new experimental methods for the evaluation of the referred parameters, namely: i) a method to control the AR density during its production; ii) a modified “basket drainage method” to separate the swelled rubber from the residual bitumen after the AR production and; iii) a “sphere AR production simulator” (SARPS) method developed to reproduce the bitumen aging during the AR production (without the contribution of the rubber interaction). The effectiveness of these procedures was assessed by applying conventional CEN tests in the different bituminous materials obtained with the previous methods (base bitumen, sphere bitumen, residual bitumen and AR). SARPS method, combined with the “basket drainage method”, was found to be a simple and effective way to monitor rubber-bitumen interaction. SARPS was also a simple and adequate method to evaluate the aging of bitumen during AR production. Finally, it was also possible to assess the evolution of the bitumen, rubber and AR densities during the AR binder production.