AC-20 Viscosity Graded Asphalt Cement / Bitumen

Viscosity Graded Bitumen / Asphalt Cement

Viscosity Graded Bitumen, also known as viscosity asphalt cement, is a type of bitumen that is regulated and classified by the viscosity grade of the product. The required grade is determined based on the characteristics of the wearing course or asphalt concrete that will be used for the road project. Each type of viscosity-graded cement is ideal for different types of weather and traffic conditions. 

Basically, based on the use, traffic, resilient modulus, and climatic conditions, the hot-mixed asphalt specifications are defined, hence the type of bitumen required to meet such standards. 

AC-20 Asphalt / Bitumen Norms and AASHTO Standard Specification

 The Standard Specification for Viscosity-Graded Asphalt Cement can be found in the AASHTO M-226-80 (2008) norm, which states the basic principles and standards for this type of bitumen, and also AC-20, specifically. 

This specification covers asphalt binders graded by viscosity at 60°C (140°F) for use in pavement construction. Following are the three tables exhibited in the AASHTO Norm, where the AC-20 bitumen specification can be found.

Production and Manufacturing of AC-20

This type of asphalt is mainly manufactured from refined bitumen from petroleum. This base refined bitumen is then analyzed in order to determine the required processes to achieve the product’s standards according to the previously stated norm. Sometimes, these building materials products may be manufactured from natural bitumen, but it is not as common.  Most commonly, this is a petroleum product that is manufactured from the refinery process of such. It is a semi-solid hydrocarbon product that is created by blending petroleum fractions through the process of fractional distillation. The resulting material is then modified with additives to create a binder that has specific viscosity characteristics and meets certain performance requirements in order to produce optimal asphalt concrete or hot-mixed asphalt. 

Packing and Utilization

At Pro-Road, we deliver our bitumen products and ship them worldwide generally packed in 1000-1300kg big bags. Big bag or bitumen-bag (bitu~bag) packing provides a cost-effective alternative to shipping and storing bitumen or asphalt cement products. These bags are later melted and fed to the hot mix plant with the Pro-Road Asmelt equipment.