Inverted Pavement-Paving the Way for a Sustainable and Decarbonizing Hong Kong

Inverted pavement (IP) refers to an unconventional flexible pavement structure that consists of a well compacted unbound aggregate base (UAB) layer sandwiched between two stiffer layers: an upper layer of thin asphalt concrete (AC) and a lower layer of cement-treated based (CTB). Compared to conventional flexible pavement (CP), IP involves the placement of a thinner asphalt concrete layer, resulting in reduced usage of asphalt materials and lower greenhouse emissions (GHGs). Additionally, the UAB layer between the AC layer and CTB layer helps mitigate reflective cracks since the stress concentration that typically originates from the CTB layer is dissipated within the UAB layer, contributing to increased durability compared to traditional semi-rigid pavements. Consequently, the cost-effective inverted pavement serves as an appealing alternative to CP.