Medium Curing Cutback Bitumen
The Medium Curing Cutback bitumen is used in the flexible pavements for surface dressing, prime coating, and tack coating. The evaporation of the solvents will be at a moderate rate. This grade is used with aggregates for ensuring better workability in the mix.
The degree of evaporation in the medium curing cutback asphalt is intermediate because the kerosene is intermediate volatile liquid as compared to the naphtha and diesel. The degree of liquidity depends on the proportion in which the kerosene is mixed in the asphalt cement.
The medium-setting grades are designed for mixing with aggregates. Because these grades do not break immediately upon contact with aggregate, mixes using them can remain workable for extended periods of time and lend themselves to cold mix stockpiles.
The degree of liquidity developed in each case depends principally on the proportion of solvent to asphalt cement. To a minor degree, the liquidity of the cutback may be affected by the hardness of the base asphalt from which the cutback is made. The degree of fluidity results in several grades of cutback asphalt—some quite fluid at ordinary temperatures and others somewhat more viscous. The more viscous grades may require a small amount of heating to make them fluid enough for construction operations.
The medium-setting grades are designed for mixing with aggregates. Because these grades do not break immediately upon contact with aggregate, mixes using them can remain workable for extended periods of time and lend themselves to cold mix stockpiles.
The commonly used grades of MC Cutback Bitumen are:
- MC-30
- MC-70
- MC-250
- MC-800
- MC-3000
Applications of MC Cutback Bitumen
MC cutback bitumen is widely used in road construction and maintenance activities due to the equilibrium it offers between workability and curing rate.
One of its most prominent applications is in cold mix asphalt, which is quite convenient when patching and repairing roads in areas where hot mix asphalt is not a viable option. The slow evaporation of the solvent allows the mix to remain workable for extended periods before setting.
The second principal use of MC cutback bitumen is in prime coats, which are applied by spraying on unbound base surfaces before laying asphalt layers. The prime coat helps to stabilize the base and increase the bond between the base and asphalt layer.
Besides, patching of pavement is an effective application of MC cutback bitumen. With a longer workable time, it is suitable for repairing potholes and patching of damaged road sections, especially in remote areas where the hot mix plants are not nearby.
Lastly, MC cutback bitumen is used in surface dressing, a method of enhancing the durability of road surfaces by binding aggregates together. This enhances skid resistance and prolongs the life of roads.
The medium-volatility solvent evaporates after application, leaving the bitumen to form a strong, permanent bond with the surface or aggregates.
