Approach to fatigue performance using Fénix test for asphalt mixtures Félix Pérez-Jiménez a , Gonzalo A. Valdés a,b , Ramón Botella a , Rodrigo Miró a,c,⇑ , Adriana Martínez a a Technical University of Catalonia, Barcelona, Spain b Universidad de La Frontera, Temuco, Chile c Jordi Girona 1–3, Módulo B1, 08034 Barcelona, Spain article info Article history: Received 17 March 2010 Received in revised form 3 June 2011 Accepted 18 June 2011 Available online 20 July 2011 Keywords: Asphalt mixture Fatigue Fracture Dissipated energy Direct tensile test Fénix test abstract Fatigue is one of the most common causes of damage in bituminous pavements. However, since fatigue characterization requires complex cyclic tests, this property is not usually taken into account when designing bituminous mixtures. The present study introduces a new methodology to assess fatigue behavior of bituminous mixtures by means of a simpler procedure based on a new fracture test called Fénix. Several bituminous mixtures were tested at the Road Research Laboratory of the Technical Univer- sity of Catalonia using the Fénix test and the three-point bending beam fatigue test, which complies with the new European standard UNE-EN 12697-24:2006. Results show that this new methodology assesses fatigue behavior of bituminous mixes by correlations between both tests. In addition, the procedure can be used to relate stiffness and dissipated energy parameters obtained in the cracking process, which allows the choice of mixtures with better fatigue performance considering the thermal conditions to which mixtures will be subjected during their service life. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Fatigue distress in bituminous mixtures is a complex phenom- enon that depends on several variables like component character- istics, pavement layer thickness and fabrication process, among others. Furthermore, external agents such as traffic and environ- mental conditions also have a strong influence in mixture behavior under fatigue conditions [1–3]. This distress is considered one of the most important problems in bituminous mixtures. It occurs when pavement is stressed to the limit of its service life by repetitive load applications [4]. The ability of bituminous mixes to accumulate damage allows gradual failure instead of fragile failure [5]. During the fatigue process, resistance decreases and material undergoes continuous degradation, result- ing in the formation of microcracks and eventual complete failure [6–8]. Cyclic tests to determine fatigue performance of bituminous mixtures are usually complex and time consuming. This property is not usually considered in mixture design. However, fatigue behavior is important enough to be defined in detail in order to know the actual performance of the mixture as a layer in the pave- ment structure. On the other hand, the complex microstructure of asphalt con- crete is related to aggregate gradation, properties of the aggregate– binder interface, rheological behavior and bitumen type, bitumen film thickness, thermal sensitivity of mixtures, void size distribu- tion, and interconnectivity of voids. Consequently, the fatigue property of asphalt mixtures is very complicated and sometimes difficult to predict [9]. In recent years some research has addressed the prediction of fatigue behavior of bituminous mixes using fewer assays or sim- pler test procedures which correlate the obtained mechanical properties with the fatigue properties of mixtures. However, results have not been fully satisfactory as no specific methods have been established, either because of the need for long, complex tests or the impossibility of obtaining correlations between the evalu- ated methodologies and fatigue procedures [10,11]. A previous study conducted at the Road Research Laboratory of the Technical University of Catalonia investigated fatigue failure of bituminous mixes by subjecting prismatic specimens to sinusoidal loading. The authors of the present work have used the results of that investigation, where correlations between modulus and fati- gue law slope, and between failure strain and ordinate at the origin of the fatigue law were obtained [12]. The work hypothesis of this paper is that fatigue law parameters can be estimated using a new direct tensile test called Fénix test [13,14] since this method deter- mines parameters related to both stiffness and strain. These rela- tionships are shown in the paper. Moreover, the Fénix test can determine dissipated energy in the cracking process. Many investigations have established this param- eter, obtained by monotonic tests, as a useful indicator for mixture characterization according to crack resistance [14–17]. Other 0950-0618/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.conbuildmat.2011.06.036 ⇑ Corresponding author at: Jordi Girona 1–3, Módulo B1, 08034 Barcelona, Spain. Tel.: +34 934017085; fax: +34 934017264. E-mail address: r.miro@upc.edu (R. Miró). Construction and Building Materials 26 (2012) 372–380 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat