Home | ENGINEERING | Types of Failure in flexible pavements

Civil - Highway Planning and Alignment - Design Of Flexible And Rigid Pavements

Types of Failure in flexible pavements

   Posted On :  25.07.2016 08:29 am
Types of Failure in flexible pavements

The major flexible pavement failures are fatigue cracking, rutting, and thermal cracking. The fatigue cracking of flexible pavement is due to horizontal tensile strain at the bottom of the asphaltic concrete.

Flexible pavements

 

Flexible pavements will transmit wheel load stresses to the lower layers by grain-to-grain transfer through the points of contact in the granular structure (see Figure 19:1). The wheel load acting on the pavement will be distributed to a wider area, and the stress decreases with the depth. Taking advantage of this stress distribution characteristic, flexible pavements normally has many layers. Hence, the design of flexible pavement uses the concept of layered system. Based on this, flexible pavement may be constructed in a number of layers and the top layer has to be of best quality to sustain maximum compressive stress, in addition to wear and tear. The lower layers will experience lesser magnitude of stress and low quality material can be used. Flexible pavements are constructed using bituminous materials. These can be either in the form of surface treatments (such as bituminous surface treatments generally found on low volume roads) or, asphalt concrete surface courses (generally used on high volume roads such as national highways). Flexible pavement layers reflect the deformation of the lower layers on to the surface layer (e.g., if there is any undulation in sub-grade then it will be transferred to the surface layer). In the case of flexible pavement, the design is based on overall performance of flexible pavement, and the stresses produced should be kept well below the allowable stresses of each pavement layer.

 

Types of Failure in flexible pavements

 

The  major  flexible  pavement   failures   are  fatigue  cracking,   rutting,   and   thermal cracking. The fatigue cracking of flexible pavement is due to horizontal tensile strain at the bottom of the asphaltic concrete. The failure criterion relates allowable number of load repetitions to tensile strain and this relation can be determined in the laboratory fatigue test on asphaltic concrete specimens. Rutting occurs only on flexible pavements as indicated by permanent deformation or rut depth along wheel load path. Two design methods have been used to control rutting: one to limit the vertical compressive strain on the top of subgrade and other to limit rutting to a tolerable amount (12 mm normally). Thermal cracking includes both low-temperature cracking and thermal fatigue cracking.


Tags : Civil - Highway Planning and Alignment - Design Of Flexible And Rigid Pavements
Last 30 days 54 views
Related words :

What is Types of Failure in flexible pavements Define Types of Failure in flexible pavements Definition of Types of Failure in flexible pavements where how meaning of Types of Failure in flexible pavements lecturing notes for Types of Failure in flexible pavements lecture notes question and answer for Types of Failure in flexible pavements answer Types of Failure in flexible pavements study material Types of Failure in flexible pavements assignment Types of Failure in flexible pavements reference description of Types of Failure in flexible pavements explanation of Types of Failure in flexible pavements brief detail of Types of Failure in flexible pavements easy explanation solution Types of Failure in flexible pavements wiki Types of Failure in flexible pavements wikipedia how why is who were when is when did where did Types of Failure in flexible pavements list of Types of Failure in flexible pavements school assignment college assignment Types of Failure in flexible pavements college notes school notes kids with diagram or figure or image difference between Types of Failure in flexible pavements www.readorrefer.in - Read Or Refer

​TOP MENU

OTHER SUGEST TOPIC

Recent New Topics :