One of the main areas of pavement failure is at interfaces where two dissimilar layers are brought into contact. Examples of such interfaces are those between a subgrade and an overlying asphalt cement base course, or those between two asphalt layers such as a base course and surface course. If pavement interfaces are not compatibilized with each other, they can affect load transfer between the two layers and lead to premature pavement failure. Bond coats, typically in the form of prime and tack coats, are a critical requirement for ensuring uniform transfer of load from one pavement layer to the next.
Typical reasons for bond coat failures are excess dust, incomplete / spotty coverage, excessive tracking, water intrusion and poor bond strength as measured via tensile and shear tests. While the cost of a bond coat is relatively low as compared to the overall cost of the pavement, a poor quality bond coat can lead to accelerated pavement damage.
Technologies that improve coverage, tracking resistance, bond strength and moisture resistance are the need of the hour and will be critical in ensuring that pavements of the future do not fail due to poor bond coats.
TerraPrime is a cationic bitumen emulsion additive that enables a deeply penetrative prime coat that is track resistant and waterproof. It forms a permanent chemical bond between the prime coat and soil base, thereby enabling high bond strengths, track resistance and lower residual bitumen contents.
TerraPrime modified emulsions form a durable chemical bond between the bitumen and the underlying surface. The permanent anchoring of the bitumen ensures improved and homogenous load transfer between the various layers of the pavement, while significantly reducing the potential of the bitumen to track and be prone to moisture damage.
TerraPrime is also designed to reduce the surface tension of Cationic Slow Setting type emulsions significantly. This leads to improved wetting and coverage properties, deeper penetration in to the soil / aggregate base, quicker setting times (1-2 hours vs. 6-8 hours), and reduced droplet size of the emulsion.
Bond coat additive for bound layers (Prime Coats)
NanoTac is a cationic bitumen emulsion additive that addresses the problems mentioned above, by creating a permanent chemical bond between the bitumen emulsion and the underlying surface. Due to the formation of a permanent chemical bond, the tack coat is resistant to tracking, has very high bond strength and can be used to lower residual bitumen content. The permanent anchoring of the bitumen ensures improved and homogenous load transfer between the various layers of the pavement, and ensures that the primary objective of a bond coat is met.
NanoTac also reduces the surface tension of cationic emulsions significantly. This leads to improved wetting and coverage properties, quicker setting times and reduced droplet size of the emulsion.
This has important ramifications with respect to the quality of tack coat that is sprayed out of the distributor.