Laboratory evaluation of the effect of cement concrete overlays on the existing asphalt concrete pavement with different degrees of bonding

The utilisation of cement concrete overlays has been on the rise owing to the growing demand for the repair and enhancement of existing pavements, emphasising cost-effectiveness and prolonged overlay lifespan. The primary objective of this study is to ascertain the performance and scrutinise the impact of various types of separating layers on the mechanical parameters of cement concrete overlays. Upon the acquisition of requisite materials and the preliminary testing pertaining to the design of mixtures utilised in both asphalt concrete and cement concrete, three-layer samples were employed in pull-off tests and bending beam tests. These samples incorporated separating layers of different material types, namely AC60/70 neat bitumen (neat bitumen with Pen 60/70), AC85/100 neat bitumen (neat bitumen with Pen 85/100), bitumen emulsion (tack coat), polymer-modified bitumen, bituminous thin layer mixture, and a control sample without a separating layer. Subsequently, through a comparative analysis of the tensile strength and flexural strength results derived from the three-layer samples, the separating material demonstrating the highest and lowest potential for bonding was identified and compared through diverse diagrams. Furthermore, to ensure the reliability of the obtained results, a comparative analysis was conducted against the Darter and Barenberg criterion, along with average stress (mean fatigue).