Effect of Additives Types and Contents on Permanent Deformation

Abstract

The permanent deformation (rutting) of asphalt concrete is considered one of the major distress that affect the performance of pavement structures. It is one of the major form of distress a bowel-shaped depression in the wheel paths gradually with increasing number of load applications. Heavy axle loadings besides high pavement summer temperature and high loading repetitions enhance the problem of rutting in Iraq. The asphaltic paving mixture is normally subjected to various detrimental types of distresses during its service life. These distresses are caused by load, weather, and construction practices, and /or deficient materials. Some of these serious distresses include rutting (permanent deformation), shoving, stripping, and fatigue cracking which finally may lead to completed failure of pavement at the same time. Such distresses will reduce the performance of asphalt pavements, which is not only causes inferior ride quality to motorists but also yields higher life-cycle cost. Some of the mentioned distresses are associated with the asphalt cement binder and can be controlled significantly by modifying the material with chemical additives The purpose of this study is to evaluate the effect of additives type and content on the permanent deformation out by preparing asphalt mixtures specimens using aggregate from Al-Nibaay State, (40-50) grade asphalt from dourah refinery and two types of additives Rubber with different content (1.5,3, 4.5, 6, 7.5 &9 )% by weight of asphalt and wool with different content (3, 6, 9,&12)% by weight of asphalt.