للكاتبين Ibrahim F. El-Demary1, Laila S. Radwan2, Hassan T. Abdelwahab2
1Hamza and Associates, Giza, Egypt
2Highway, Airport and Traffic Engineering
Public Works Department, Faculty of Engineering, Cairo University, Giza, Egypt
The main objective of this research is to investigate the effect of mix components on
pavement friction. Mix components include asphalt content, aggregate type, and mix
gradation (dense versus open). Three locally-produced aggregates (dolomite, basalt, and
gravel) having different physical and engineering properties were selected to represent a wide
range of properties of available aggregates in Egypt. The British Pendulum was used to
measure the pavement coefficient of friction. Test slabs were prepared using two different
methods of compactions (static and dynamic). The coefficient of friction was measured under
two different surface conditions (wet versus dry) and two temperatures (25 C, 50 C).
Results showed that the coefficient of friction varies among the three aggregate types included
in the study. The average measured BPN for dry dense mix gradation at 25 C were 81, 76,
and 79 for dolomite, basalt, and gravel, respectively. Open-graded mix has a higher
coefficient of friction than dense-graded mix. Results showed significant deterioration in
coefficient of friction due to the change of surface condition (wet versus dry). The average
measured BPN of dry surface was reduced by about 30% due to the surface wet condition.
Coefficient of friction also varied between samples made of natural and crushed particles.
The measured BPN for dry-dense mix gradation at 25 Cْ were 77 and 87 for the natural and
crushed particles, respectively.