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Different types of bitumen and applications

Bitumen has excellent adhesive qualities provided the conditions are favourable. However in presence of water the adhesion does create some problems. Most of the aggregates used in road construction possess a weak negative charge on the surface. The bitumen aggregate bond is because of a weak dispersion force. Water is highly polar and hence it gets strongly attached to the aggregate displacing the bituminous coating.

The factors influencing aggregate bitumen adhesion are plenty and some of the factors influencing this property are as below:

External: Rainfall, Humidity, Water pH, Presence of salts, Temperature,

Temperature cycle, Traffic, Design, Workmanship, Drainage

Aggregate: Mineralogy, Surface texture, Porosity, Dirt, Durability, Surface area, Absorption, Moisture content, Shape, Weathering

Bitumen: Rheology, Constitution

Mix: Void content, Permeability, Bitumen content, Bitumen film thickness, Filler type, Aggregate grading, Mix type. The above list is only indicative and not exhaustive.

Based on the fundamental Engineering Properties: VG system is based on fundamental engineering parameter i.e. actual performance on road and not on the empirical properties. Bitumen VG 30 , bitumen VG 10 and bitumen VG 40 are the most common types of bitumen VG grade. Bitumen VG 30 has wider applications that other types.

Takes care of low as well high temperature: Viscosity is measured at 60º C and 135ºC which takes care of both low and high temperature susceptibility of the Bitumen, which is not possible with Penetration value at 25ºC. Hence, road contractors can have better understanding of Bitumen performance in the field. Any two same Viscosity Grade Bitumen would give similar rutting performance in hot summer unlike Penetration Grade bitumen. Greater Mix in ease design: Greater ease of handling to customers as

Viscosity value at two different temperature is available, which would enable users to measure accurate mixing and compaction temperature. Minimum specified Kinematic Viscosity Value at 135ºC helps to minimize the potential of tender mixes during construction. Less no. of tests save time and cost: IS-73-2006 has only 7 tests to evaluate a sample compared to 14 tests in Penetration Grade system. This reduces time, bitumen price and cost of testing without sacrificing the quality.

Longer Durability: The pavement made from VG Bitumen will have better performance, because Viscosity value at 135ºC gives sufficient idea about mixing and compaction temperature and as a result pavement life is improved. Takes higher Traffic: Penetration test was developed in the era of significantly lower pavement loading. In the past, truck weights were less than 30 tons with tyre pressure of 75 PSI. Today truck weight has increased to 35 tons a with tyre pressure of 125 PSI and increased traffic with extreme weather conditions. Therefore, to cope up with these changes shift from PEN Grade to VG Grade is required. There are many bitumen properties which can be tested. All these tests replicate the actual field conditions in different ways and based on the type, bitumen price will be different.

Viscosity at 135OC is a fair indicator of the ability of bitumen to coat the aggregates properly. In order to get best coating the viscosity has to be optimum. Too viscous bitumen would result in inadequate and non-uniform coating of the aggregates. Very low viscosity would again result in inadequate coating as the bitumen will tend to bleed. Therefore viscosity at 135OC is a true reflection of the quality of bond that is likely to be formed with the aggregate.

Various testing equipments like Capillary Viscometer, Cup Viscometer, Tar Viscometer, etc. can be used for testing the viscosity. Viscosity at 60OC is a very good indicator of the resistance of bitumen to melting/flowing on the road. It is considered to be replacement test for Softening Point test. Some specifications have replaced softening point test with Viscosity at 60OC. However, at many places both the tests are carried out as both the tests are empirical and have their own limitations for bitumen manufacturers.

Bitumen suppliers in Malaysia

Ket Bilietai , Ket Testai , ket bilietai nemokamai