Disadvantages Of Replacement Management System

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Pavement Management System Assignment -1- Sarah Jamal Abbas GS47746 Q1: Pavement Distress: is an indication of poor pavement performance and a sign of failure. Bitumen hardening: is influenced under the atmosphere and there are so many important factors that affect the bitumen hardening such as: • Oxidation. • Volatilization. • Steric or physical factors. • Exudation of oils. Types of failure modes related to bitumen hardening: Cracking: can be defined as a set of interconnected cracks caused by fatigue failure of the pavement surface. It includes many types as well: • Block cracking: Interconnected cracks which can divide the pavement surface into rectangular segments. Block cracking normally can be found highly over the pavement area. The…show more content…
SO controlling the temperature and the bitumen content are very important. • The thickness of the bitumen layer significantly affects the hardening. So increasing the thickness of the binder layer will reduce the viscosity of the bitumen and that will reduce the hardening as well. • Controlling the duration of mixing will lead to reduction in the degree of hardening. • The selection of the type of mixer that is used also affects the hardening during mixing. Since modern drum mixer, with counter flow drum mix and double drum configurations with high mixing quality will reduce the hardening of bitumen compared with older drum mixer. • During the storage, reducing the amount of oxidation by reducing the amount of free air at the top of the silo will reduce the hardening. So the silo should be as full as possible, and the entry and discharge gates should be tied up in a way so no additional openings where the air can enter the…show more content…
Then a reduction of the asphalt binder will be achieved. • Selecting the proper thickness of the asphalt binder will affect and reduce the hardening rate. • Selecting the proper compactor will affect the amount of the air voids that must be within the design, which will lead to a reduction of the degree of the hardening. • Penetration of the bitumen in the base layer affect the hardening rates. During in-service: The behavior of the bitumen hardening that occurs during mixing will be lesser during hot storage and transportation, paving and subsequent service. This type of behavior is called long term ageing • The mixtures’ voids content must be as low as possible to reduce the rate of hardening of the asphalt binder. • Controlling bitumen content (bitumen film thickness) has a significant impact in the speed of bitumen hardening rate on the road. So increasing the bitumen layer thickness will reduce the hardening rate. The figure below shows the ageing of bitumen during mixing, subsequently during storage, transportation and application and in

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