Research On Technique And Performance Of Condensed-Decomposed Silica Fume

China is country with great power for producing ferrosilicon in the world. Ferrosilicon manufacturing enterprises has assembled silica fume collecting dust equipment step by step because the country has reinforced for checking environmental protection in recent years. Therefore, the production of silica fume increases year by year. Silica fume is widely used in different areas as blending material and additives to improve the performance of maerials because of it's excellent function.Whereas, most of the ferrosilicon manufacturing enterprises in our country are concentrated in the provinces where economy comparatively falls behind. These provinces can not consume all the discharged silica fume and want to transport to other areas in order to share resourse. But the accumulate density is too small to transport and store conveniently, then the packing and transporting cost increases. The silica fume in these areas can not be made full use and lead the resource be extravagant for nothing.Although a silica fume condensed technique has been used in the hometown recently, the silica fume is condensed before transporting and applying, so it provides convenience for transporting. But, it also can not completely solve the actual problem until now because the problem of condensed technique, condensed effect and cost of condensed equipments.Based on the condition referred, the author find a new condensed and decomposed technique which is simple and convenient. The condensed costs is low and this technique can make the volume density of silica fume up to 1000kg/m3. The condensed effect is improved, so it practically solves the problem for storing and transporting of silica fume. In order to confirm the serviceability of the method, the author has systemly studied and analysed three aspects for condensed and decomposed technique such as the influence of performance, the influence of condensed silica fume performance and the application of condensed silica fume in high strength concrete. The author takes concrete as medium in the process of studying and add silica fume to concrete, then characterized the influence of silica fume by the influence of the performance of concrete.As the result of studying: (1) The condensed technique can make the volume density of silica fume to 1010kg/m3 through machinery compression method and water infusion method, the latter method is not only simple but also serviceability, it can disperse condensed silica fume. (2) The condensed and decomposed silica fume only lead a trend to descend for slump loss ratio of concrete, reduce the setting time of concrete and bleeding capacity of concrete, it nearly has no influence for compressive strength, splitting strength, anti-sulfate corrodes and the anti-permeability function of concrete. So we can regards as the technique of condensed and decomposed has small influence to the performance of silica fume. (3)The condensed and decomposed silica fume is added to concrete after separately store one month, two months, three months and one day, two days, three days. It only has influence for slump loss ratio, setting time, bleeding capacity,anti-permeability function and anti-sulfate corrodes of concrete, it nearly has no influence for compressive strength and splitting strength. And these influence all have advantage to the late performance of silica fume concrete .So we can regards as the storing time of condensed and decomposed silica fume has small influence to the performance of silica fume. (4) The author use condensed silica fume researched by theirselves to make C70 concrete. The compressive strength of 28 days can reach to 83.1MPa through experiments, it approaches to the compressive strength of original silica fume concrete. Therefore, we can regard condensed silica fume not only can make high strength concrete, but also has same heighten effect as the original silica fume.