- Adhesion: Bitumen's adhesive properties bind together all the components without affecting their properties in any way. A solid surface can be adhered to with bitumen in a fluid state depending on its nature. If water is present on the surface, adhesion will be inhibited.
- Resistance to Water: Water cannot dissolve bitumen, making this a good sealant. Bitumen is water-resistant. The bitumen or the filler may be able to absorb water under some conditions when the inorganic salts present in them are small.
-
Hardness: A penetration test is used to measure the hardness of bitumen. This test measures how deep a weighted needle can penetrate in bitumen after a certain amount of time and at a known temperature. Usually, 100g of weight is held for 5 seconds at 77° F. Permeation measures the hardness of a material. In general, hard coating asphalt produces 10 to 20 results, roofing asphalt 15 to 40 results, and waterproofing bitumen 100 to 200 results.
Road construction and some industrial applications use grades with penetrations greater than 40. For use in industrial applications, grades having penetrations under 40 are suitable. Lower grades like 60/70 are typically used in hot climates. - Viscosity and Flow: Bitumen's viscosity is important at both high and low temperatures. Its viscosity is affected by both the temperature at which bitumen is processed and the temperature at which it is applied. Temperature and stress conditions influence bitumen's flow properties significantly. Bitumen hardens as a result of deterioration or loss of its desirable characteristics. The result is a decrease in adhesive and flow properties as well as an increase in softening point temperature and thermal expansion coefficient.
-
Softening Point: The hardening point value should be higher than the pavement temperature for bitumen to be used at that place. Otherwise, bitumen in the layer gets softened and comes out.
During a known rate of heating of the test assembly, the softening point is the temperature at which a steel ball falls through the bitumen at a known distance. -
Ductility: A ductility test applies temperature below the bitumen's softening point to determine how much it will stretch. The temperature of 77 °F is used to test the performance of briquettes with a cross-sectional area of 1 in2. The duality of bitumen ranges from 0 to 150.
If ductility is present, these films and coatings will form properly. - Specific Gravity: Binders of different densities behave the same way. In mixed design, it is still valuable. Temperatures are set at 27o C.
-
Durability: The durability of the Bitumen refers to how long the Material will remain resistant to oxidative hardening over long periods of time. The bitumen on the road will harden as a result of the reaction with time.
Oxygen in the air will cause excessive hardening (poor durability) and surfacing failure, resulting in chipping and cracking. Maintaining the asphalt properly throughout the pavement's lifetime can extend its lifespan by as much as twenty years. - Versatility: As a result of its versatility property, Bitumen can be used in a wide range of applications due to its thermoplastic properties. It can easily be spread over the underlying pavement layers because it liquefies when heated and hardens into a solid mass when cooled.
- Economical: It is available at cheaper rates almost all over the world which makes it feasible and affordable in many applications.
- Strength: Though the coarse aggregates are the main load-bearing component in a pavement, bitumen or asphalt also play a vital role in distributing the traffic loads to the layers beneath.
Bitumen Properties
General Properties of Bitumen
- Most bitumen is colloidal in nature.
- Bitumen is thermoplastics.
- Bitumen is insoluble in water.
- They are highly impermeable to the passage of water.
- They are generally hydrophobic. They are chemically inert.
- Bitumen oxidizes slowly.
Chemical composition of bitumen
Bitumen can be divided in to the following three main fractions.
- Asphaltenes: Asphaltenes are insoluble in light hydrocarbon solvents, such as petroleum ether. Asphaltene fraction together with a part of the maltenes fraction forms the dispersed.
- Maltenes: Maltenes are soluble in hydrocarbon solvents. Maltenes consist of four elements namely nitrogen base, first acidifies, second a daffiness, and paraffin.
- Carbenes: Carbenes fraction is insoluble in carbon tetrachloride.