Dense Bituminous Macadam (DBM) or Bituminous Concrete (BC) layer Quantity / Compaction Factor value / Loose thickness calculation

Dense Bituminous  Macadam (DBM) or   Bituminous Concrete (BC)  quantity / Compaction Factor value for DBM or BC / Loose thickness of DBM or BC Layer 

In this article we shall discuss three important points about Dense Bituminous   Macadam (DBM) or Bituminous Concrete (BC)

1- How can we calculate the required DBM/BC quantity? 

2 -  What is value of compaction factor for DBM/BC?

3- How much loose thickness should be taken to get proper compacted layer thickness ? 

1- How can we calculate the required DBM/BC quantity?



Let us consider

Length of  DBM/BC layer (L) = 1 Km = 1000 Met.
Breadth of DBM/BC Layer (B)= 5 Met.
Thickness of DBM/BC Layer (T)  = 50 mm =0.050 Met.

Max. Dry Density (MDD) =2.441 Gram/ Cubic Centimeter = 2441KG/ Cubic metre

Note -  The value of MDD is calculated by conducting suitable test .

Then
Volume of DBM/BC Layer = ( Length of DBM/BC layer X Width of DBM/BC layer  X Thickness of DBM/BC Layer)

Volume of DBM/BC Layer = L X B X T Volume of DBM/BC Layer  = 1000 X 5 X 0.050
Volume of DBM/BC Layer    = 250 Cubic Metre

We Know That
Mass = Volume X Density
in this case -

Mass = Volume X MDD

Putting the value in the above Formula

Mass = 250 X 2441 Kg
Mass  = 6,10,250 Kg

To convert above quantity in Tonn
We Know That

1 Tonn = 1000 Kg
Then

Mass =(610250/ 1000) Tonn
Mass   = 610.250 Tonn


Hence required DBM/BC quantity is 610.25 Tonn. 




2 -  What is value of compaction factor for DBM/BC?

Density of Blended aggregate = 1.60 gram/cc  to 2.0 gram/cc
                  = 1600 - 2000 KG/ cubic metre

In this case
Let us consider

Density of Blended aggregate = 1.80 gram/cc = 1800 Kg / cubic metre

Value of Max. Dry Density (MDD) = 2.441 gram/cc = 2441 Kg/cubic metre

Compaction Factor = (Max.Dry Density/Density of Blended Aggregate )

        =2.441/ 1.80
        =1.3561= 1.36
Hence compaction factor = 1.36

3- How much loose thickness should be taken to get proper compacted layer thickness ? 

Compaction factor = 1.36
Thickness of DBM/BC Layer  = 50 mm

Hence

 Loose thickness of DBM/BC Layer = ( Compacted layer thickness X Compaction Factor )
 = 50 X 1.36
 =68 mm

Hence Loose Thickness of DBM/BC Layer is 68 mm. 

Thanks a lot 
Mukesh Kumar
 Gyan of engineering