mohammad mohammad karimi

It has been spent big amouts of budget for design,build and maintenance of roads in all over the world.Many of the failures occurring in pavements are as results of different vehicle loads,environmental changes and poor maintenance strategies.One of the important issues that creates cracks in concrete pavement and reduces pavement loading capacity is thermal stresses caused by temperature gradients and combined streeses due to temperature gradient and traffic loads.Factors such as solar radiation,temperature changes and etc. cause thermal stresses in pavements. These stresses , alone or in combination with traffic loading, can lead to cracks in the surfaces of the pavement, which can gradually lead to the removal and destruction of concrete pavement. Therefore, research on effective parameters of this issue seems necessary. Until the advent of the finite element method, these categories of researches were carried out experimentally, which, due to their hardiness, over time, gave their place to numerical methods. In this paper, the Abqus software is used to model three-dimensional roller compacted concrete pavement and to investigate the response of this pavement under the combination of traffic and thermal loading.

Flexible pavements is subjected to various combinations of repeated loading and varying environmental conditions that lead to their cracking. Induce healing technology of asphalt pavements under the electromagnetic radiation with electrically conductive particles is a novel method to heal the existing cracks of asphalt concrete materials. This research characterizes the mechanical and induced heating behavior of steel wool fiber (SWF) modified asphalt concrete considering induced healing technology. A microwave device was used to provide inductive heating in specimens. The electrical resistivity, Induce heating and healing and indirect tensile strength test were conducted on 0.2 and 1.5 (wt)% SWF modified asphalt concretes. The results indicated that SWF as a conductive component significantly decreased the electrical resistivity of asphalt concrete materials and is a potentially powerful additive for induction heating and healing purpose. Experimental tests demonstrated that not only the addition of 0.2 (wt)% SWF meets both the heating and healing requirements, but also it had considerably less negative effects on the mechanical performance of asphalt concrete comparing to the conventional 1.5% of SWF.

Aging phenomenon affects pavement performance that results in reduced flexibility of the pavement. Aging can cause asphalt binder stiffness in asphalt mixes and increases the risk of cracking. Cracks can be healed by the induction heating method. The ability of asphalt binder in flowing and filling cracks plays a dominant role in the induced healing of asphalt mixes. With this regard, activated carbon (AC) is added to asphalt concrete in order to enhance the electromagnetic radiation absorption of mixes. In order to apply age conditioning, both the control and modified asphalt concrete samples were kept in oven for 5 days at 85℃. It was found that heating rate of activated carbon modified asphalt mixes is 55 percent greater than control mixes. From the results of this study, effects of asphalt concrete aging was determined by induced healing index. In addition, repeated breaking-healing cycles were applied through indirect tensile testing to investigate the induced healing properties of asphalt mixes. This was through peak load and fracture energy criteria. In addition, effect of sample dimensions on heating rate and damage level were investigated on induced healing index of asphalt concrete. It can be concluded that increased asphalt concrete aging and increased breaking-healing cycles resulted in decreased induced healing index. Result reveals that combination effects of aging and breaking healing cycles resulted in 48 percent reduction in healing index. In addition, testing results confirmed that AC as a conductive component has potential of induction heating healing and increasing aging resistance of asphalt mixes.