Thickness determination of bituminous layers

The determination of bituminous layer thickness is carried out with respect to design ESAL and design CBR value. A number of nomographs (design charts) have been developed, for each distinct base/sub-base thickness (400, 300 and 200 mm) and for each MAAT (13°C, 16°C and 19°C), for two penetration grade bitumen (50/70 and 40/50 pen). 

By choosing the appropriate nomograph, the total thickness of asphalt layers is easily determined. 

It is noted that when MAAT is between the values taken for the development of the nomographs, the thickness of the asphalt layers is determined by linear extrapolation. 

In all cases, thickness of the asphalt layers determined is rounded up to the next 5 mm. 

The type of bituminous mixture for which the thickness is determined is dense asphalt concrete mixture with 40/50 or 60/70 pen graded bitumen. 

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