Standard Tar Viscometer

Viscosity is calculated indirectly by redwood viscometer (which is used to find the viscosity of oil) is used to find the viscosity of bituminous material, after modifying the diameter of the orifice. The behavior and properties of oil and bitumen are different but same procedure and criteria is used to find the viscosities of both the materials the bituminous material is tested alone presence of aggregates is neglected the test is conducted at standard temperature which neglects the practical condition of variation in the temperature assumption made while using the redwood viscometer about type of flow affects the results proper control over the binder viscosity has to be exercised not only at each and every stage of construction but also during service period of the pavement It can be said that low valve of viscosity indicates high fluidity which may not provided binding action but may just lubricate the movement of aggregate.