Waterproof and Antiscour Properties of Asphalt-Based Composite Seals for Airfield Base Layer

A new type of three-layer waterproof structure was developed to reduce the scour problem of concrete slabs by paving an asphalt-based composite seal layer between the cement-stabilized base and the cement concrete pavement. The asphalt-based composite seal layer consists of an upper layer (microsurfacing), a transition layer (microsurfacing), and a bottom layer (synchronous chip seal). A new construction method was proposed to guide the construction of the asphalt-based composite seal layer. The waterproof and antiscouring properties of the asphalt-based composite seal layer were evaluated by a permeability test, a high-resolution industrial computed tomography (CT) scanner, a scouring test, and a direct shear test. The permeability test showed that the three-layer structure possessed good waterproofing properties. The CT scans results showed that the asphalt-based composite seal layer was very dense due to effective compaction during the construction process. The scouring test indicated that the scouring resistance of the asphalt-based composite seal layer was much better than that of the cement-stabilized base. The results showed that the asphalt-based composite seal possessed decent resistance to scour and could effectively protect the base from the threat of scour. The cost analysis results showed that the proposed asphalt-based composite seal layer has a more competitive unit price compared with an asphalt concrete layer.