Janak Shah and Aswin Kumar, Arizona State University
What is the economic and environmental case for the use of asphalt rubber?
IRF: What did your research identify as some of the main milestones in the progressive uptake of PPPs in the United States?
Janak Shah and Aswin Kumar: The primary purpose of using Asphalt Rubber (AR) in Hot Mix Asphalts (HMA) is that it significantly improves engineering properties over conventional paving grade asphalt. Asphalt rubber binders can be engineered to perform in any type of climate. Reducing the environmental influences of the highway infrastructure has received the increasing attentions recently. Application of crumb rubber in asphalt pavements overcomes the used tires disposal problem and achieves materials savings and environmental benefits, due to the reduction of raw material and extension of pavement service life. In addition, rubberized asphalt production is a highly energy consuming process due to a higher mixing temperature. However, the warm mixing technology can lower the mixing temperature of rubberized asphalt mixture, leading to approximately 20–25% of fuel savings. Moreover, the consumed energy of rubberized asphalt during maintenance phase is lower than that of conventional asphalt. In addition, the greenhouse gas emissions from the production and construction of rubberized asphalt mixtures are similar to those from hot mix asphalt, but their emissions of CO and CH4 are much lower. Meanwhile, the noise reduction is an environmentally friendly benefit. Rubberized asphalt technology as a green technology in term of lowering GHG emissions, saving energy and raw material and reducing noise level of pavement should be widely used to achieve economic and environmental sustainability.
IRF: What did you research identify as the most promising asphalt mixture characteristics for optimal pavement performance?
Janak Shah and Aswin Kumar:The direct pavement characteristics influencing pavement performance are roughness, rutting, skid resistance, reflectance, and tire-pavement noise. The pavement performance is just the outward manifestation of the pavement characteristics, whereas the structural behavior of the pavement can cause the change in pavement performance over time. The structural behavior of pavement is defined as the interactions between the physical characteristics and the mechanistic responses of the pavement structure and materials under the external loads including characteristics such as Pavement distresses, Pavement deformation, Materials properties and Mechanistic response. After extensive laboratory performance testing on rubber modified asphalt mixtures and evaluation of the results; stiffness, durability, fatigue resistance, moisture resistance and film thicknesses were identified as most crucial asphalt mixture characteristics for optimal pavement performance. When working with rubber modified asphalt mixtures, it is very important to maintain correct gradations and temperatures as they can have huge impact on the performance of the pavement.
IRF: As a researcher, what is the value of presenting your work at a Conference featuring a wide cross-action of actors from the public, private and academic sector?
Janak Shah and Aswin Kumar:Conferences set the right platform and stage on a global scale to present the research to critics, experts and fellow researchers from various regions of the same community. We have CEO's, Professors, Fellow Engineers and Industrial contractors. This enables us to receive feedback and actually know what type of technology or properties are required out in the real world. One such conference was the IRF Conference in Dubai during November 2017. We received feedback on our testing results, the audience showed interest on key parameters of strengths such as fatigue property and long-term performance durability. This sort of interaction between the academic sector and the Industry enables us to develop research and steer it towards more practical approach so that it can be adapted on a vast scale. As these presentations often represent the most cutting-edge programs and research, they provide valuable information to take back to your schools and organizations. This clearly demonstrates the nature of symbiotic relation among the various parties involved such as public, private and academic sectors.
IRF Global R2T Conference & Exhibition: November 19-22, 2019