Published Online: 25 July 2013
Page Count: 19
Graduate Student, Dept. of Civil Engineering, North Dakota State Univ., Fargo, ND
Associate Professor, Dept. of Civil Engineering, North Dakota State Univ., Fargo, ND
Ph.D. Candidate, Dept. of Civil Engineering, North Dakota State Univ., Fargo, ND
(Received 2 January 2012; accepted 18 June 2013)
In the current research, the introduction of a new selecti\ton approach for crumb-rubber-modified asphalts (CRMA), based on their rutting and permanent deformation resistance, is carried out. This new approach involves selecting CRMA according to their rheological properties [complex modulus (G*) and phase angle (δ) values] by utilizing a proposed three-dimensional (3D) parametric diagrams approach. This was carried out for the different asphalt and crumb-rubber (CR) types investigated. Three-dimensional parametric diagrams for both the G* and δ were constructed through controlling the interaction time, speed, and temperature for the CRMA synthesis. This was carried out to illustrate the combined effect of interaction speed and temperature, with the increase of interaction time, on the produced rutting and permanent deformation resistance properties of CRMA. It was found that, for all the asphalt types investigated, the utilization of a high interaction mixing speed of 50 Hz with a medium interaction temperature (190°C) for the mixing of cryogenic processed CR with asphalt produced the best results in terms of complex modulus (G*) and phase angle (δ) values. For ambient processed CR, on the other hand, the utilization of a low interaction temperature (160°C), with both interaction speeds utilized (10 and 30 Hz), produced enhanced properties (G* and δ) for the CRMA. Based on the results obtained in this research, the new selection approach presents an efficient way to provide an expected profile for the asphalt in-service required properties with relation to their synthesis conditions.
Paper ID: ACEM20120058