Determining the shear stress in a gyratory compacting machine

The Marshall Compaction Method has been used to prepare asphalt mixture samples in laboratories for many years, despite its technical disadvantages. It has since been replaced by the Gyratory Compacting Machine, which came about when the SuperPave mix design method was introduced. Shaft reaction to a specimen with a vertical pressure equal to 600 kPa under a determined angle-applied load is determined, and the specimen is compacted by vertical pressure and mould shear pressure simultaneously. One of the benefits of this new method is that the specimen height is measurable during the compaction procedure in this machine. Since the weight and height are known in the compaction procedure, the specimen density and air void fractions can be determined during the test. During this research study, equilibrium equations were used, and the specimen forces were presented to determine the shear stress in the Gyratory Compacting Machine. The results showed that there is a direct relationship between the shear stress and the mixture rutting resistance. Therefore, by determining the specimen shear stress during mixture preparation, the rutting potential can be measured simultaneously.These results offer the potential for cost and time saving in laboratory experiments, and allow an insight and extra degree of confidence in the experimental methods.