Main properties of bitumen & aggregate

It can be termed as the building block of the pavements without which all the pavement materials would behave independently and thus will be deemed useless.

Almost ninety percent of bitumen is used in road construction by bitumen suppliers. It is usually available in dark colors ranging from brown to black. The main purpose of bitumen in flexible pavements is to strongly bind and hold the other pavement components together and provide a smooth and leveled surface for the moving vehicles. Bitumen is a naturally occurring material and is found in large quantities in the solid or semi-solid forms of petroleum. It is also manufactured artificially in vast amounts globally. Bitumen mixed with some other materials has always been used as a sealant and adhesive material over the ages. It was also widely used in the waterproofing of boats and ships as it is insoluble in water. The highest applications of bitumen are found in the construction field for the construction of roads, airports etc., in the hydraulic field for the construction of water tanks, dams, bridges etc., is also used in battery making, tyre making and the thermal and acoustic insulation purposes. Types of Bituminous Materials:

Depending upon the temperature and other factors various types of bitumen are found and used throughout the world.

Cutback Bitumen: Cut-back bitumens are those which are prepared with the addition of a volatile to reduce the thickness of the binder.

Fluxed Bitumen: Fluxed bitumens are those bitumen that are prepared by the addition of relatively non-volatile oils to reduce the viscosity of the binder

Modified Bitumen: Modified bituminous binder are those whose properties such as cohesive strength, adhesive property, elasticity or viscosity have been modified by the use of one or combined chemical agents.

Different Types of Bitumen, their Properties and Uses

There are different types of bitumen available with different properties, specifications and uses based on the requirements of the consuming industry. To buy bitumen one should consider these matters.

The specification of bitumen also shows variation with the safety, solubility, physical properties, and durability.

To understand the performance of the bitumen when it is on service, the design of the physical properties of the material is highly essential. The standard testing methods are carried out to grade bitumen.

Types of Bitumen and their Properties and Uses

The bitumen can be classified into the following grade types:

- Penetration Grade Bitumen (bitumen 60/70)

- Oxidized Bitumen Grades

- Cut Back Bitumen

- Bitumen Emulsion

-  Polymer Modified Bitumen

Penetration Grade Bitumen

The penetration grade bitumen is refinery bitumen that is manufactured at different viscosities. The penetration test is carried out to characterize the bitumen, based on the hardness. Thus, it has the name penetration bitumen.

The penetration bitumen grades range from 15 to 450 for road bitumen. But the most commonly used range is 25 to 200. This is acquired by controlling the test carried out i.e. the distillation process.

The partial control of fluxing the residual bitumen with the oils can help in bringing the required hardness. The table below shows the penetration grade bitumen’s test carried out as per BS EN 12591. This test is for bitumen that is for road application.

Table.1. Paving Grade Bitumen Specification As per BS EN 12591