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IS 1206:2020 is the Indian Standard (BIS) for methods for testing tar and bituminous materials — viscosity. IS 1206 provides viscosity test methods for bitumen — the primary grading parameter for VG (Viscosity Grade) bitumen per IS 73. Absolute viscosity at 60°C determines the VG grade (VG-10, VG-20, VG-30, VG-40). Kinematic viscosity at 135°C indicates mixing/compaction temperature.
Methods for determining viscosity of bitumen by various methods including capillary, rotational, and orifice viscometers.
VG = Viscosity Grade. 30 indicates the absolute viscosity range at 60°C is 2400-3600 Poise. Higher VG number = stiffer bitumen. VG-30 is the standard grade for most Indian highways.