Innovative high-strength, high-permeability concrete for large-scale applications in permeable subgrade of highway tunnel

The durability of concrete roads in mountainous regions may be reduced due to underground water infiltration and surface water erosion within highway tunnels. A promising solution is the use of pervious concrete as a drainage subgrade layer to drain away the water, and then to prevent water-induced pavement damage of pavement. For pervious concrete to be an ideal drainage layer for high-traffic loads, it must have compressive strength and permeability coefficient exceeding 25 MPa and 15 mm/s, simultaneously. However, traditional pervious concrete tends to emphasize either in high-strength or high-permeability, depending on its porosity. This study introduces an innovative proportion design method of pervious concrete, which enables higher compressive strength and permeability coefficient by adjusting its skeleton structure, and thus catering to high-traffic load applications. In addition, the workability and setting time of pervious concrete were optimized according to the local environmental conditions, facilitating large-scale and efficient paving of the drainage subgrade. As a result, a drainage subgrade layer with a 28-day compressive strength of 26.43 MPa and permeability coefficient of 18.86 mm/s was successfully applied in a highway tunnel. This study provides a theoretical framework and technical support for widespread application of pervious concrete in drainage subgrade of high-traffic load road.