Research On Self-compacting And Micro-expansive High Performance Concrete

With the improving of the complexity of structure and the advancing of constructing technology, Self-Compacting Concrete have been widely used in constructing engineering. But some problems with Self-Compacting Concrete such as high slump loss and the difficulty of harmonizing the cohesiveness and the flowability should be solved. The theory of concrete mix design should also be perfected. In accordance with these problems , this thesis carry out such research works as follows to deal with them .On the basis of experiments, a new technique route of preparing micro-expansive agent have been presented, and a new type of mineral admixture composed of fluorite-gypsum, fly-ash and functional component X been explored. This kind of mineral admixture is denominated as H mineral admixture. And the relationship between the component of H mineral admixture and its' performance or its' impact on mortar and concrete was studied. The results show that H mineral admixture possesses expansion function and it can improve the durability and workability of concrete. Because of its' lingering micro-bubble producing mechanism, it can control the slump loss of concrete effectively and enhance the frost-resistance ability significantly. And it has several expansion sources, so it can produce biggish initial expansion and stable upper expansion. There is almost no alkali in the raw material of H mineral admixture, and the possibility of alkali-aggregate reaction in concrete can be reduced. Moreover, the main components of H mineral admixture is procured from industry waste, and its' production procedure is simple, so its' production cost is very low.The most tightness pile up theory and rheology is successfully applied in the designation of self-compacting concrete, and the factors such as sand rate, aggregate grading,paste content and mineral admixtures are been studied. Under the guidance of mix design theory and on the basis of mass experiments, C20-C80 high performance self-compacting concrete is been produced. The results of research work show that the values of sand rate, aggregate grading, paste content and mineral admixtures control the degree of tightness pile up and the workability of fresh concrete, furthermore, they determined the mechanics performance and the durability of self-compacting concrete. The adding of mineral admixtures and high performance water reducer is the key factor of preparing self-compacting concrete, especially high strength and extra strength self-compacting concrete. Mineral admixtures have unsuperseded advantages in improving the workability and durability of self-compacting concrete.The reasons of tendency of cracking in self-compacting concrete and the influence factors have been studied, and the new type of mineral admixture has been used in high performance self-compacting concrete, and its defects such as high slump -losing and shrinking or cracking is successfully prevented. The research work about durability of high-performance self-compacting micro-expansive concrete show that the micro-expansive function and micro-bubble producing function of mineral admixture H can improve the impermeability, frost-resistance ability and sulfate eroding resistance ability etc of self-compacting concrete.