The Road Studies With The Pulverized Coal Ash High Performance Concretes

In this dissertation, a great deal of experiments are used to test the effect of fly ash on the compatibility between cement and WRA (water reducing admixture), on flowability of binding materials and on mortar strength. The results indicate that fly ash works well in improving the compatibility between cement and WRA, and in controlling slump loss.The result shows that 56d flexural-tensile strength of the concrete is always higher than 28d strength when the total dosage of cement and fly ash is in the common range of 360-500kg/m~2, which indicates that fly ash is quite available to improving the concrete late strength. Therefore, high performance flyash concrete takes on a higher the late flexural-tensile strength, which improves the flexural-tensile strength and anti-fracture roughness of the cement concrete pavement, enhances resisting adverse effect from nonuniform settlement of the road foundation, and meets the requirements of the pavement performance.The flyash concrete which mixed with more quantity of high quality fly ash takes on good resistance to alternate freezing and thawing, to chloride penetrating, to carbonizing, and to attacking by sulphate, chlorate and magnesia. Therefore, fly ash helps well to improving the concrete comprehensive durability, which is very important to concrete pavement performance.According to 28d cement concrete wear-resistance, the maximums quantity of 20% fly ash is mixed in cement concrete pavement. If exceeding it, the wear-resistance will be reduced.The action principle of fly ash in high performance concrete is different with the principle in ordinary concrete. In high performance concrete, fly ash could reduce early concrete calefactivity and shrinkage, which is good for concrete to shape into good structure, to reduce the microcrack occurrence, and to improve the concrete volume stability, permeability resistance, freeze-thaw resistance and erosion resistance, etc.High performance flyash concrete is a main breakthrough of traditional concrete technology. It is environmental friendly and a new "green concrete". It will bring outstanding technical economic profits and social benefits, while used in highway construction.