Effect of Lab. Compaction Effort on Evaluation of Modified HMA Specimens

Abstract

The only way to estimate the future performance of any asphalt pavement is reached through the laboratory test which was made for evaluating its expected lifetime. For that purpose the laboratory compaction considered as the main important factor that influence the expected lifetime of any asphalt pavement. In this study we evaluated the effect of compaction effort on the performance properties of asphalt pavement through examining two compaction methods which are the Marshall hammer compactor and the Superpave gyratory compactor (SGC), that conducted the best method which provides the best simulation of what really happen in the field compaction, through making many of laboratory tests involving the volumetric properties and the performance properties for the both methods. Two types of modifiers were used with two percentages which are polypropylene (1% and 2%) by weight of total mix,  and hydrated lime (1% and 2% ) by weight of the total mix as replacer part of the filler content, and then the results were compared for evaluating the most simulating method to the field compaction for control and modified mixes. The results showed that the Superpave gyratory compactor provide the best simulation to the field compaction compering to the Marshall Compaction method, The mixes compacted by using SGC have lower optimum asphalt content than those prepared by Marshall compaction method by about (1% and 2%) for binder and base course respectively. The volumetric and performance properties of mixes prepared by using the SGC were better than those of mixes prepared by Marshall compaction method.

Keywords: Superpave Gyratory Compactor, Marshall Hammer, Indirect Tensile Strength, Tensile Strength Ratio