The influence of temperature and traffic on seal aggregate re-orientation in different binders.

Timon von Benecke & Daymen Gerber, University of Stellenbosch

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A major behavioural characteristic of surfacing seals includes aggregate re-orientation which involves the re-orientation of seal aggregates, onto their respective least dimensions, during and after construction, to ensure a lower risk of aggregate loss and adhesion problems.

The purpose of this investigation is to gain an understanding of the effect that traffic has on the re-orientation of surfacing seal aggregate. Variables that affect aggregate re-orientation include different binder types, rheological properties, different pavement temperatures and different aggregate matrices. The combination of these variables is measured and discussed to determine the optimal binder adjustment factors and conditions for aggregate re-orientation. This investigation tests eight different binders including 70/100 penetration grade bitumen, Cat65 emulsion, SC-E1, SC-E2, S-E1, S-E2, S-R1 and S-R2 at three different trafficking temperatures (10°C, 20°C and 30°C), two different aggregate matrices (shoulder-to-shoulder and over application) and simulated traffic going up to five thousand load repetitions per combination of variables. To simulate traffic, the Model Mobile Load Simulator Mk. 3 is used, after which a Laser Profilometer is used to record texture readings. The time between construction and testing was kept constant throughout. This study provides a better understanding of different factors that influence aggregate re-orientation, which could be implemented in practice immediately.