Abstract
Rutting potential of stone mastic asphalt with varying aggregate gradations was assessed in the past mainly by uniaxial compression testing which is not the only test to predict its true performance in the field. Dynamic testing and accelerated wheel tracking test are considered the most suitable laboratory test procedures. Four stone mastic asphalt mixtures were prepared in this study using PG 58-22 binder, Viatop plus CT-40 fiber and four aggregate gradations with nominal maximum sizes of 9.5 mm, 12 mm, 19 mm and 25.4 mm. To access the effects of aggregate gradations, single type of bitumen, filler and fiber was used. Mixtures were tested and evaluated under both type of testing procedures at different temperature levels. A regression model was developed using wheel tracker test data to ascertain significant parameters that are directly influencing the rut depth. The statistics of the model shows an excellent degree of determinacy of 0.92 and a relative accuracy of 0.29. Sigmoidal functions using Witczak equations were determined from dynamic modulus master curves for characterization of mixes and compared with previous studies. Correlation between the wheel tracking factor and a dynamic modulus factor was also established at three frequency levels. The study reveals that a reasonable relationship exists between the wheel tracking factor and dynamic modulus factor for stone mastic asphalt mixtures
Highlights
Stone mastic asphalt (SMA) generally consists of gap graded aggregate gradation bonded by mastic, which is combination of mineral filler, bitumen and a fiber (Brown et al 1997)
Different methodologies have so far been used with different techniques and testing methods especially dynamic creep testing, wheel tracking test, dynamic modulus test, imaging technique, and voids in coarse aggregates (VCA) to ascertain SMA mixtures rut potential (Apeagyei 2011; Goh et al 2011; Hafeez et al 2009; Masad 2004; Pouget et al 2014; Retherford, McDonald 2013; Seo et al 2007; Sivilevičius 2011; Su et al 2008; Watson 2003)
Other parameters like air voids, bitumen content and the voids in mineral aggregate vary in a narrow range in the mixtures and have no significant effect on the model
Summary
Stone mastic asphalt (SMA) generally consists of gap graded aggregate gradation bonded by mastic, which is combination of mineral filler, bitumen and a fiber (Brown et al 1997). Addition of filler and fiber in a SMA mixture mainly reduces the binder drain. The stabilizing agents may be fibers (more effective in drain down) or modifiers (more resistant to rutting of SMA in the laboratory wheel tracking test). Different methodologies have so far been used with different techniques and testing methods especially dynamic creep testing, wheel tracking test, dynamic modulus test, imaging technique, and voids in coarse aggregates (VCA) to ascertain SMA mixtures rut potential (Apeagyei 2011; Goh et al 2011; Hafeez et al 2009; Masad 2004; Pouget et al 2014; Retherford, McDonald 2013; Seo et al 2007; Sivilevičius 2011; Su et al 2008; Watson 2003).
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