![]() The temperature of bitumen tested was such that, it favors human body temperature. Based on the test conducted, the sample was either accepted or rejected. It was carried out by experienced US inspectors. This was the time when no penetration test was developed. But raveling is caused after a duration showing the inadequacy of the structure.įig.3: Fatigue Crack formed in Bitumen pavement after certain ageįollowing are the different methods used for grading of bitumenĭuring the 19th century, chewing was the method used to determine the stiffness i.e. These damages are caused after five to ten years of service life i.e. The stiffness determination of bitumen at 25 degrees will help us to find the maximum stiffness that is needed to resist the damages like fatigue cracking or raveling. ![]() The average annual temperature of an asphalt pavement during a year is almost near to 25 degree Celsius. Here the stiffness is determined in terms of viscosity.įig.2: Rutting Damage Caused in Bituminous Pavement Just after few period of construction ![]() Based on this value, a minimum stiffness value for the binder can be maintained. The determination of stiffness at 60 degrees will be more useful in bringing adequate resistance in the summer season. Here the possible failure caused will be rutting. The temperature 60 degree Celsius is similar to a temperature of the bituminous pavement on an extremely summer day. Here the stiffness in terms of kinetic viscosity must be determined. To have proper mixing and compaction temperatures for asphalt mixtures, it is necessary to find the stiffness of bitumen. This state makes them be easily mixed with aggregates. This temperature would give bitumen possess a motor oil form thin in layers. The temperature of 135 degrees is near to those temperatures at which the bitumen mix is used for mixing and compacting during the construction. The above explanation of bitumen A and B are from the estimates obtained for three temperatures 25, 60 and 135 degree Celsius as shown in figure-1. The bitumen stiffness at a lower temperature is also an essential criterion to have resistance against thermal cracking. But at 60 degree Celsius the condition is reversed. For example, if we have bitumen A and B, bitumen B at 25 oC is stiffer than bitumen A at the same temperature. This will also give a way to compare different binders of bitumen. A temperature at which the grading of bitumen can be carried out. The figure below explains this, where it is observed that bitumen A and Bitumen B have different relationships with temperature.įig.1: Graph representing relationship between temperature and stiffness for different bitumenĭue to these variations, it was necessary to fix a test temperature. The bitumen type varies based on their origin as well as a method of refining. The correlation between the bitumen stiffness and temperature varies with the type of bitumen employed.
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