Bitumen is a naturally occurring in hydrocarbon, as typically found in asphalt, tar, pitch and asphaltite. A class of manufactured, amorphous, solid, semi-solid or viscous, cementitious materials. Oxidized bitumen 75/25 materials are typically obtained from asphalt or coal tar, asphalt can be found in nature or obtained as a by-product of crude oil refining, and coal tar and pitch are produced by cracking distillation of coal.

Polymer modified bitumen 75/25

On the majority of roads, conventional bitumen grades possess satisfactory adhesion and mechanical properties for use in asphalt pavements for the vast majority of traffic and climatic conditions that are encountered. However, demands made on roads increase year by year and, in some cases, the limits of performance of conventional bitumen 75/25 have been reached mainly due to Increases in rainfall and temperature variations, Increases in axle weight, tyre pressures and freight movement and leading to a higher maintenance requirement and consequent increased costs for road owners

role of bitumen 75/25 modifiers in asphalt pavements

Traditional bitumens, derived from the distillation and/or blowing of crude oils, possess adequate performance characteristics, but increasing the high temperature performance can sometimes lessen the low temperature performance properties of the bitumen 75/25. The development of steps to counter this effect has been the incentive that has driven the early stages of the development of pmbs for use in roads. Modified binders are binders whose properties have been changed by the use of a chemical agent that, when added to the original bitumen, alters its chemical structure and physical and/or mechanical properties. As the bituminous binder is responsible for the visco-elastic behaviour of asphalts, it plays a large part in determining many aspects of road performance, particularly resistance to deformation and cracking, the two most common reasons for the structural failure of thicker pavements.

specification of bitumen 75-25