Mixture Design of Pavement Surface Course Considering the Performance of Skid Resistance and Disaster Proof in Road Tunnels

Incidents may arise in road tunnels, in particular at the tunnel entrance and exit. Investigation conducted in the road tunnels in the provinces of Guizhou and Yunnan in China showed that the concrete pavement surface skid resistance decreased rapidly inside the tunnels and was significantly different from that outside the tunnels. Pavement surface skid resistance is one of the most important factors that affect travel safety, in particular wet weather skidding accidents. Countermeasures are necessary to enhance the skid resistance on concrete pavements in tunnels. The writers made an effort to investigate possible pavement surfaces to provide long-lasting skid resistance, including porous concrete surface and open graded friction course (OGFC) surface. Porous concrete was paved directly on the regular concrete pavement and OGFC was paved on the existing surface of concrete pavement to provide sufficient skid resistance. Accelerated abrasion devices have been developed to evaluate the skid resistances of the porous concrete and OGFC, respectively. Regular asphalt materials will burn easily and emit toxic gas in fire, which may reduce the survival rate for tunnel users involved in fire accidents. Fire-retardant asphalt has been developed to reduce the tendency of asphalt materials to burn and reduce emission.