The advantages of Modified Bitumen in road works are summarized below :
The selection criteria for grade of modified bitumen shall be based on atmospheric temperature as shown below:
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
ADVANTAGES OF ON SITE PROCESSING PLANT FOR VG 40 GRADE BITUMEN AND EMULSIONS
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