Core Cutting in Asphalt Road | Lab Report for Core Cutting

 Core Cutting in Asphalt/Premix/DBM

 

Core cutting is traditional method of quality control. In this method, the surface of road, either Asphalt or Premix or DBM is chopped with the help of rotary driller. The driller consists of cylindrical drill bit of 15 cm diameter. Drilling is held to the depth greater than overlay thickness. A cylindrical bituminous cake is drawn out with the help of levers. 

Objective of Core Cutting:

• To identify the thickness of the overlay. 
• To determine the bitumen content in the overlay.
• To determine the compaction of the overlay.

How to Determine Thickness of Asphalt from Core Cutting Method?

• Once the cylindrical cake cutout from bituminous road is drawn, the thickness between the tack layer and surface can be measured with the help of ruler or digital vernier caliber. 

How to Determine Bitumen Content of Asphalt from Core Cutting Method? 

• The method is called Bitumen Extraction Test. The bituminous cake is crushed, weighted and dissolved in carbon bisulphide chloroform. Undissolved aggregate is weighted after centrifugal process. Thus the difference in weight determines the bitumen content.

How to Determine the Compaction of Asphalt from Core Cutting Method?

• The method is called water replacement or buoyancy method. In the civil laboratory, the cutout from core cutting is washed and additional portion beyond tack layer is removed with the help of solvent like CS2CHCl3 or petrol gasoline. The thickness and the weight of the chunk in air is measured. The chunk is then weighted in water. The amount of water displaced is the volume of the sample. Thus density of Asphalt = wt in air / (wt in air - wt in water). The compaction percentage of the road surface = density of asphalt/2.359.