Effect of binder type and application rate on asphalt layer bonding evaluated by LCB test

Bonding between asphalt layers is a crucial factor affecting the durability and mechanical response of flexible pavements. The effect of tack coat application on this bonding has been extensively studied, with several factors influencing the degree of bonding achieved. These include the type of tack coat, application rate, temperature, and moisture, among others. This study evaluated the effect of binder type and application rate on the interface shear strength of bituminous layers made of asphalt concrete type MDC-19, using the Laboratorio de Caminos de Barcelona (LCB) shear test. Two types of asphalt emulsions, CRL-1 and CRL-1hm (conventional and modified with polymers, respectively), were used as tack coats at five residual application rates. The results of the study showed that the CRL-1hm tack coat developed a higher shear strength than the CRL-1 tack coat. Additionally, there was a variation in strength with an increase in application rate, leading to the determination of an optimum rate. These findings demonstrate the importance of binder type and application rate in achieving optimal bonding between asphalt layers, with potential benefits for the longevity and performance of pavements. Overall, this research provides valuable insights for pavement engineers seeking to optimize the bonding between asphalt layers. The study highlights the potential of modified emulsions, such as CRL-1hm, and the importance of carefully considering the application rate to achieve the desired bonding performance.