Bitumen & Aggregate

Bitumen, being the cheapest binder available, finds extensive use in road construction. However, the physical and chemical properties of bitumen vary from refinery to refinery. Similarly, there is a vast variety of aggregate available in India. For eg. Marble, limestone, basalt, sandstone, granite, quartzite etc. These are classified as acidic or alkaline. They may also be classified as hydrophilic (water loving) or hydrophobic ( water hating). These aggregate have different characteristics, properties, stripping values etc. Furthermore, due to the vast number of roads and highway projects, good quality aggregate is not always easily available. In India the Ministry of Road Transport and Highways has specified permissible stripping value of aggregate as 5% only, when tested as per IS 6241:1971. Any aggregate which has stripping value of more than 5% should either not be used in road construction or suitable remedial measure(such as addition of anti- stripping agent in bitumen) should be taken to bring the stripping value within permissible limit. Surface texture, porosity and absorption properties of aggregate also effect the adhesion to bitumen. In majority of the cases, the bitumen-aggregate bond is not sufficiently strong and complete by itself. Antistripping agent, Super-Bond XS , is the most effective and economical solution for providing a strong, durable and lasting binder-aggregate bond