Page 41 - Lecture Notes DCC3113

Cutback Classification

Cutbacks are divided into two classifications, Rapid-Curing (RC) and Medium-Curing (MC) depending
on the solvent used. They are further defined by a number which indicates the minimum kinematic
viscosity (fluidity) of the cutback.

Rapid Curing (RC)
• It has been used for the tack coat and surface treatment.
• Produced by mixing the bitumen with petrol.

Medium Curing (MC)
• Produced by mixing the bitumen with kerosene.
• It has been used for prime coat and cold mix for the patching work.

Slow Curing (SC)
• Produced by mixing the bitumen with the diesel.
• It has been used especially for the prime coat, cold mix for patching work and dust control.

Grades and Properties

Table 3-2: Grades and Properties for cut-back bitumen

Penetration of
Grade Curing Speed Viscosity
Residue
MC 30 Medium 30-60 120- 150
MC 70 Medium 70-140 120 -150
MC 250 Medium 250- 500 120 -150
MC 800 Medium 800- 1600 120- 150
MC 3000 Medium 3000- 6000 120- 150
RC 70 Rapid 70-140 80- 120
RC 250 Rapid 250-500 80- 120
RC 800 Rapid 800- 1600 80- 120
RC 3000 Rapid 3000- 6000 80- 120

* Kinematic Viscosity at 140 deg F ( 60 deg C), in Centistokes , Penetration of Residue at 77 deg F (25
deg C) , 100 grams, 5 seconds.

Bitumen emulsion

Bitumen Emulsions have being developed and exponentially increased sinned they were
created in 1900. Bitumen emulsion usually consists of bitumen droplets suspended in water. The
bitumen particle charge can be positive (cationic), negative (anionic), or uncharged (non-ionic)
depending on the emulsifier employed. The binder can be either a bitumen, cutback, or modified
bitumen. Bitumen emulsions are used largely in road surfacing applications, such as surface dressing,
cold mixtures and slurry seals.

They are primarily used for tack coats for use in between hot mix asphalt layers and prime coats for
thin hot mix surfacing layers or a chip seal pavements.

Bitumen emulsions are divided into three categories:
 Anionic with negatively charged globules
 Cationic with positively charged globules
 Non-ionic with neutral globules.

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