Pavement Valuation of Bond Between Bituminous Pavement Layers

The interlayer bonding between the pavement layers in modern multi-layered flexible pavements is crucial for ensuring long-term performance. Poor bonding can lead to significant pavement distresses, such as premature fatigue, top-down cracking, potholes, and surface delamination. One common issue caused by inadequate bonding is slippage failure, especially in areas with frequent heavy vehicle acceleration, deceleration, or turning. Tack coats, typically made from bituminous emulsions or binders, are applied between pavement layers to enhance bonding. This study focuses on evaluating the bond strength at the interface between pavement layers using laboratory testing. Special attachments were fabricated for the Marshall Loading Frame to measure the bond performance between Bituminous Concrete (BC) and Dense Bituminous Macadam (DBM) layers. The tests involved 100 mm and 150 mm diameter specimens using two common emulsions, CMS-2 and CRS-1, applied at varying rates (0.20 kg/m², 0.25 kg/m², and 0.30 kg/m²) at a temperature of 25°C. The results indicate that CRS-1 provides superior interface bond strength compared to CMS-2. The optimal application rate for both emulsions was found to be 0.25 kg/m², aligning with MORT&H specifications.