Petrochemicals & Petroleum Products #3086017

Multigrade bitumen is a chemically modified bitumen that has the properties of a hard paving grade bitumen at high service temperatures coupled with the properties of a soft paving grade bitumen at low temperatures (i.e. it has properties that span multiple grades). Multigrade bitumens provide improved resistance to deformation and reduce the detrimental effects of high service temperatures, whilst providing reduced stiffness at low service temperatures than exhibited by a similar normal paving grade bitumen.

BITUMINA is currently setting up its Multigrade engineering and modification facilities and we hope to be able to provide you with Multigrade Bitumens as of 2013.

At this time we do not supply Multigrade Bitumen, however may assist you in transfer of technology and supply of relevant equipment for production of this superb bitumen (asphalt).

Multigrade Bitumen

• Is a bitumen with a positive penetration index
• Is a less pavement temperature sensitive binder
• Has a higher modulus at elevated temperatures
• Is less brittle in the cold
• In many cases performs like a PMB without the addition of polymers
• Subsequently it has no elastic recovery
• Is used e.g. in Australia, France and Poland

Bitumen is cutback by adding controlled amounts of petroleum distillates such as kerosene. This is done to reduce the viscosity of the bitumen temporarily so it can penetrate pavements more effectively or to allow spraying at temperatures that are too cold for successful sprayed sealing with neat bitumen. The materials used to cutback bitumen will evaporate after application to leave the remaining material similar in hardness to the original bitumen.

Applications of Cutback Bitumen in Bituminous (asphalt) Pavement Construction and Maintenance:Prime and Tack Coating

The process of priming involves applying a low viscosity binder to a prepared but usually unbound aggregate base. It is intended to be absorbed by the top layers of the base and provide a surface more easily wetted by a subsequent bituminous covering. The primer will be able to carry traffic for a short time (although this practice is uncommon) and help control dust. Generally, primers are applied at rates between 0.5 and 1.4 L/m2. Cutback bitumens suitable for priming are also used for tack coats, which are applied to an underlying surface to help with the adhesion of subsequent asphalt layer. A typical application rate is between 0.2 and 0.4 L/m2.

Prime Sealing

Where temperatures are too cool for an effective priming operation, or where traffic is likely to upset a primed surface before the final seal can be sprayed, a primer seal can be used to give adequate protection of the pavement for periods of up to 6 to 12 months. Cutback bitumens suitable for primer sealing can also be used in the manufacture of pre-mix asphalt, which is used in patch repairs.

Spray Sealing

Cutback bitumens are used extensively in sprayed sealing applications, particularly in cooler weather where they provide improved initial stone retention due to their lower viscosity. Typically, a single application of the appropriate cutback bitumen is sprayed onto the primed pavement onto which aggregate is laid.

Bitumen is a black or dark-colored (solid, semi-solid, viscous), amorphous, cementitious material that can be found in different forms, such us rock asphalt, natural bitumen, tar and bitumen derived from oil, which is referred to as petroleum bitumen.

Currently most of the roads globally are paved with bitumen. Today the worlds demand for bitumen accounts for more than 100 million tons per year which is approximately 700 million barrels of bitumen consumed annually.

Petroleum bitumen is typically referred to as bitumen or asphalt. In Europe for instance bitumen means the liquid binder. In North America, on the other hand the liquid binder is referred to as asphalt, or asphalt cement.

Origin

In general the term bituminous materials is used to denote substances in which bitumen is present or from which it can be derived. Bituminous substances comprise of primarily bitumens and tars.

Bitumen occurs in nature in several forms: hard one - easily crumbled bitumen in rock asphalt and softer, more viscous material which is present in tar sands and asphalt 'lakes'. Another way in which bitumen can be obtained is through petroleum processing in this manner the bitumen is essentially the residue yielded through a distillation process of petroleum. Although bitumen can be found in natural form, the world currently relies for all purposes on petroleum. The material has been produced in this way for over a hundred years.

Tars on the other hand do occur in nature. Tars derive as condensates from the processing of coal (at very high temperatures), petroleum, oil-shale, wood or other organic materials. Pitch is produced when a tar is partially distilled so that the volatile components have evaporated.

Often coal tar is confused with bitumen however they are two entirely chemically different products and should not be mistaken. For the distinction drawn between petroleum bitumen and coal tar see the distinction table below:

Viscosity Grade Bitumen (Asphalt)

AASHTO Designation: M 226-80 (2008)

ASTM Designation: ASTM D3381-09

Viscosity Grade Bitumen (Asphalt) is a standard grade Bitumen usually used as aPaving Grade Bitumensuitable for road construction and for the production of asphalt pavements with superior properties. This grade of Bitumen is mainly used in the manufacture ofhot mix asphalt for bases and wearing courses, and possesses characteristics and qualities unique sand quite different from other agents. They achieve very flexible and tenacious connections with other materials due mainly to viscoelastic response of bitumen, which behaviour depends on how fast charges are applied.

Viscosity Grade Bitumen supplied by BITUMINA is petroleum grade bitumen, manufactured from fractional / vacuum distillation of crude oil, which practical appliance and behaviour varies according to its temperature. The Bitumen supplied by BITUMINA is produced from vacuum residue (short residue) feedstock.

Viscosity Grade bitumens are specified by the methods described in ASTM Standard D3381-09 and AASHTO M226-80 (2008). Viscosity Graded specifications covers bitumen (asphalt) graded by Viscosity at 60 C (140 F).

There are two methods of grading:

• Standard Viscosity Grade Bitumen (AC-Grades), in which the Viscosity of the standard bitumen (asphalt) is measured at 60 C (140 F).
• RTFOT Viscosity Grade Bitumen (AR-Grades), in which the Viscosity of bitumen (asphalt) is measured at 60 C (140 F) after the roll on thin film oven test.

Viscosity grade bitumens have a thermoplastic property which causes the material to soften at high temperatures and to harden at lower temperatures. This unique temperature/ viscosity relationship is important when determining the performance parameters such as the adhesion, rheology, durability and application temperatures of bitumen. In the Viscosity Graded Bitumen specifications further special emphasizes is placed on the Bitumen ductility.

Standard Viscosity Grade Bitumen Binders include:

• Viscosity Grade Bitumen AC-2.5
• Viscosity Grade Bitumen AC-5
• Viscosity Grade Bitumen AC-10
• Viscosity Grade Bitumen AC-20
• Viscosity Grade Bitumen AC-30
• Viscosity Grade Bitumen AC-40

RTFOT Viscosity Grade Bitumen Binders include:

• Viscosity Grade Bitumen AR-1000
• Viscosity Grade Bitumen AR-2000
• Viscosity Grade Bitumen AR-4000
• Viscosity Grade Bitumen AR-8000
• Viscosity Grade Bitumen AR-16000