Properties and Characteristics of Vibratory-Compacted Bituminous Mixes

The purpose of this research was to investigate the feasibility of employing vibratory compaction to bituminous mixtures under laboratory controlled conditions, as a step in the direction of designing mixes utilizing dynamic properties determined by vibratory techniques. Three parameters are defined to characterize vibratory-compacted bituminous mixes: compaction force, Fc; mix stiffness factor, k, and mix damping coefficient, c. Use was made of the ASTM vibrating steel deck [ASTM Test for Relative Density of Cohesionless Soils (D 2049-69)] employing different surcharges and vibration amplitudes. The scope of testing included dense and open-graded mixes with asphalt contents, respectively, of 4.5 to 7.0 and 3.0 to 4.5%. On the basis of the analysis of the experimental data, it was concluded that bituminous mixtures can be characterized by dynamic parameters that are influenced by variations in amplitude and surcharge. These parameters are comparable to conventional Marshall properties and may be used as criteria for rational design of bituminous mixtures. For the purpose of developing final mix design criteria for a wider range of application using vibratory compaction in the laboratory, it is recommended that a vibrating system with varying frequencies, amplitudes, and surcharges be standardized.