Experimental Research on Durability of Fly Ash Pavement Concrete and Mix Proportion Optimization

This paper focused on the optimization of the C40 fly ash concrete pavement, which was considered as a measure to accelerate the consumption of industrial solid wastes such as fly ash, committing to the goal of zero waste. By comparing with three groups of ordinary mix proportion, the performances (e.g., mechanical properties, durability, and brittle property) of the optimized mix proportion were evaluated via multiple mechanical and physical tests. Their air voids' structure was characterized by the BJH method (a method to calculate pore size described by Barrett, Joyner, and Halenda), and the results were combined with the road performances of concrete to analyze the formation mechanism of high durability of optimized fly ash pavement concrete. As for the experimental results for the optimized, its 28 d compressive strength peaked at 50.8 MPa together with corresponding 28 d flexural strength at 8.2 MPa, which indicated a favorable mechanical performance for wide application in pavement construction. Except for the mechanical properties, the better durability indicators obtained after optimization also provided a more compact pore structure for the optimized. The raw materials and construction technology of the two kinds of pavements were compared. Promoting the use of optimized fly ash pavement concrete can break the situation of the asphalt pavement monopolizing heavy-haul highway and greatly reduce the industrial wastes which can be used as raw materials in the production of cement, such as blast furnace slag and fly ash. It was proved that the optimized fly ash concrete pavement can be used to replace the asphalt pavement under the premise of achieving the same working performances.