Investigation Of Refinement Means For Microstructure Of Hypereutectic Al-Fe Casting Alloys

The fact that high strength and high performance fly ash concrete plays an important role in improving the workability and durability of concrete, lowering its heat of hydration makes fly ash concrete be more and more extensively applied in civil construction, Therefore, the researches regarding the mechanical properties of fly ash concrete under the conditions of freezing and thawing, particularly mechanical properties of reinforced fly ash concrete component are of important economic and engineering significance.In order to study the mechanical properties of fly ash concrete under the freeze-thaw conditions, the paper firstly researched the resistance of freeze-thaw and corrosion and compressive strength development law of three concrete cubes with their size 100mm x 100mm×100mm and different content of fly ash. The experimental results showed that mixing suitable amount of fly ash into concrete could improve resistance of freeze-thaw and corrosion while it reduced the early strength of concrete. However, an appropriate amount of fly ash could enhance strength development in post period.Followed was another freeze-thaw cycle and bending pressure test on four reinforced concrete cubes with their size 1000mm x 120mm x 150mm and different contents of fly ash . Then the cracking conditions and bearing capacity of reinforced fly ash concretes component respectively affected by none pre-stressed action, pre-stressed action, a double factor of pre-stressed action and freeze-thaw cycles were observed and comparatively analyzed.Finally, test results showed that the load-bearing capacity, anti-cracking and anti-deformation properties of the concrete specimens under the dual roles of freeze-thaw and pre-stressed action had declined in different extents compared with those not affected by pre-stress and pre-stress only. Simultaneously, the decline was inversely proportional to the content of gradeⅡfly ash.This study showed that the pre-stress action and the dual roles of pre-stress and freeze-thaw cycle significantly had a negative impact on the performance of concrete and simultaneously found that mixing a certain amount of fly ash couldn't apparently affect its compressive strength and bearing capacity, but significantly improved its anti-cracking, anti-frost and ductility. These illustrate that mixing appropriate amount of fly ash into concrete is simple and effective method to improve the properties of concrete.