Drying Shrinkage And Carbonation Of Pavement Concrete With Nano-Particles

With the development of national economy in Mainland China, the heavier vehicles and traffic flow have arisen in highway transportation. For a long time, asphalt pavement is the main type of high-grade highway. However, the quantity and quality of asphalt are so poor. Concrete pavement has good mechanical performance and durability, and thus is widely used in high-grade highway. The construction of concrete pavement will produce significant economic and social benefits.Due to the small dimension, nano-materials have many unique physical and chemical properties, and become the focus of material science field. High performance concrete is the main field of materials in civil engineering in21century, and nano-materials break a new path for improving the performance of conventional concrete. At present, the application of nano-materials in civil engineering attracts more and more attentions.In this thesis, based on the unique characteristics of nano-materials, the pavement concrete with nano-SiO2and nano-TiO2is prepared to obtain good mechanical performance and durability. The relative performances of concrete with polypropylene fibers and concrete with both nano-particles and polypropylene fibers are also studied and compared to concrete with nano-particles. The main contents are listed as follows.Firstly, the preparation methods of concretes with nano-particles, polypropylene fibers, both nano-particles and polypropylene fibers are investigated. And then, the mix proportions of various concretes are determined based on that of plain pavement concrete.Secondly, the mechanical property, drying shrinkage and carbonation of various concretes are experimentally studied and compared. The regularity of strength, drying shrinkage rate and carbonation depth of pavement concrete with the change of variety and amount of nano-particles is analyzed. And the action mechanism of nano-particles in mechanical property, drying shrinkage and carbonation of pavement concrete is discussed.Finally, the relationship between flexural strength and compressive strength and that between drying shrinkage rate and strength and test age are analyzed. The prediction model of carbonation depth of pavement concrete with nano-particles is established.