Why Adhesion Promoters?

Bitumen is used in road construction industry due to its adhesive property. However, bitumen has low chemical affinity towards aggregates, while aggregates have high affinity to water. Wetting of aggregates is difficult in the presence of dust or water-wet aggregate as it is difficult for the oily bitumen to displace the present water.

Water may also enter into the pavement structure, by way of capillary action from subgrade, rainfall seeping through cracks and shoulders, or by the action pressing and pumping effect of the water caused by the front and back tyres of vehicles. The presence of water compromises the adhesion between the aggregate and the bitumen, resulting in stripping. This causes moisture induced damage thereby resulting in premature failure of the road. Therefore, bitumen additives are used to improve the adhesion between the aggregate and bitumen, which is vital for maintaining a longer pavement service life.

Adhesion Promoters, also known as Antistripping agents, are additives generally added into hot bitumen. Upon addition, they migrate to the aggregate bitumen interface, where they act as binding agents/glue, thereby increasing and reinforcing the adhesion between the aggregate surface and the bitumen, thus preventing the penetration of water into the aggregate surface. The choice of adhesion promoters depend on factors such as the type of the aggregate and bitumen being used.

ZycoTherm is a next generation Antistripping agent that reacts with the residual moisture on the aggregate surface, to provide better wetting and coating of bitumen. It forms a permanent chemical bond with the aggregate and improves the adhesion between the bitumen and aggregate. The permanence of the bond formed ensures that the adhesive property does not deplete over time.

ZycoTherm is compatible with all aggregate and bitumen types, works at significantly lower dosages and is an environment friendly additive that is non-corrosive and odour-free.

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