Faris M. Jassim
Civil Department, Technical College, Erbil
Abstract:
Shear strength of the asphalt mixture (Marshall Stability) decreases as the percentage of rounded particles increases, which makes the mixture more susceptible to Permanent Deformation. According to SORB[1] specifications revised 2004 (R9), for prepare bitumen base layer for Hawler- Perda Highway project (new direction), the max. nominal size, (25.4 mm) of aggregate at three different crushed boulders levels: 0% (all was rounded), 50%, and 100% (more than one fracture face), added to Two different asphalt penetration grade types (40-50), and (60-70) were used to prepare the specimens. Specimens were prepared a total of 108 specimens for performance evaluation tests. It has been shown that Crushed boulders mixtures have marshall stiffness value more than 250% (100% crushing), increase VMA (voids in mineral aggregate) more than 130%, and to increase the resistance of moisture damage 135% in comparison with rounded mixtures respectively.
Keywords: Crushed aggregate, HMA performance, Hot mix asphalt, Marshall design method.
References
1-SORB "Iraqi Standard Specifications For Roads And Bridges", (2007) Revised Edition.
2-Hicks, R.G., S. Albright, and J.R. Lundy. "Evaluation of Percent Fracture and Gradation on Behavior of Asphalt Concrete and Aggregate Base", (1985) Transportation Research Institute, Oregon State University, Corvallis, Oregon.
3-Wedding, P.A., and R.D. Gaynor, Effects of Using Crushed Gravel as the Fine and Coarse Aggregate in Dense Graded Bituminous Mixtures, (1961). Association of Asphalt Paving Technologists, Volume 30.
4-Cross, S.A., and E.R. Brown, Selection of Aggregate Properties to Minimize Rutting of Heavy Duty Pavements, (1992). American Society for Testing and Materials, Philadelphia.
5-BONNOT J. "Asphalt Aggregate Mixtures", (1986) Transportation Research Record, U.S.A., 1096, pp.42-5.
