Advantages

The advantages of Modified Bitumen in road works are summarized below :

• Lower susceptibility to daily and seasonal temperature variations.
• Higher resistance to deformation at elevated pavement temperature.
• Better age resistance properties.
• Better adhesion between aggregate and binder.
• Higher fatigue life of mixes.
• Delay of cracking and reflective cracking.
• Overall improved performance in extreme climatic conditions and under heavy traffic conditions.

The selection criteria for grade of modified bitumen shall be based on atmospheric temperature as shown below:

• PMB 120 / CRMB 50 : For temperature below 35°C.
• PMB 70 / CRMB 55 : For temperature between 35 to 45°C.
• PMB 40 / CRMB 60 : For temperature above 45°C.

Blending of Modifier with Bitumen 

Modifiers like EVA, PE and crumb rubber based products can be easily blended with the molten bitumen at 140 to 180°C using a suitable mechanical stirrer. The blending time is around 40 minutes.

SBS type modifiers are blended in shear type stirrers. Bitumen is heated to a temperature of 160°C when the modifier is added. The stirring is continued for 90 to 120 minutes. The blending can be done in central plant by proper industrial process.

Cost – Benefit Analysis 

Life Cycle costing is an economic evaluation technique in which all significant cost for construction and maintenance of roads are considered in terms of discounted cost over the period of time that the facility is required. Considering 1.5 times increase in life of overlay as provided by field trials, frequency of overlaying can be minimized. Comparing cost of 60/70 bitumen with modified bitumen, the later would be about 50% expensive at an independent blending unit and about 30% expensive at refinery. Assuming other component of the cost of construction would be same, the overall rise in cost of overlaying will be about 15 – 25% higher. For design life of 12 years, three renewals of 60/70 bitumen mix would be required while using modified bitumen only two renewals are sufficient for periodic maintenance.

ADVANTAGES OF BITUMINOUS MIX PRODUCED WITH VG 40 GRADE

• Improved temperature Susceptibility
• Improved Fatigue resistance
• Improved rutting resistance due to higher stiffness
• Longer lasting overlays resulting in enhanced Service life due to above
• Thinner structural pavements can be achieved (Reduction in thickness) due to High Resilient modulus of mix corroborated by IIT, Kharagpur.

ADVANTAGES OF ON SITE PROCESSING PLANT FOR VG 40 GRADE BITUMEN AND EMULSIONS

• Delivery of preheated Bitumen (On demand) eliminates heating of bitumen in storage tanks thereby saving on fuel.
• Impurities if any during transit eliminated due to Hydrogenation assuring a product which meets IS/IRC Specifications.
• In Emulsions eliminates transportation of water thereby saving on landed costs.