Evaluation of the Characteristics of Silica Fume for a Concrete Admixture

日本使用的硅粉大部分是进口硅粉。由于日本硅粉的产量非常少，因此预计日本硅粉混凝土将是高（或非常高）性能的混凝土。这意味着硅灰混凝土应具有高强度、高耐久性、高和易性等诸多优良性能。因此，有必要了解硅灰的哪些特性关系到混凝土的性能。本研究计划的目的是找出13种二氧化硅烟雾的特性，在日本市场上的1991-1992考虑混凝土外加剂的影响。通过本研究，得出以下结论：1)硅灰的理化性质之间存在一定的相关性，如siO_2与碱含量的相关性。2)硅灰的使用加速了水泥浆体的早期水化。3)硅灰的W/C、含水率和SiO_2含量是影响含硅灰混凝土抗压强度的两个主要因素。但高效减水剂的效果非常强。4)硅灰对碱-硅反应引起的混凝土膨胀的抑制作用可通过硅灰的碱含量来评价。

Most of silica fume used in Japan are imported silica fume.As very small amount of silica fume is produced in Japan, it is expected silica fume concrete to be high (or very high) performance concrete in Japan. It means that silica fume concrete should have many good properties such as high strength, high durability and high workability. So, it is necessary to know which characteristics of silica fume relates to the properties of concrete.The purpose of this research program is to find out the influence of the characteristics of 13 kinds of silica fumes, which were on the market in Japan during 1991-1992, as concrete admixtures considering. Through this study, following conclusions were clarified ;1) There are some correlations among physical and chemical properties of silica fume, such as correlation between siO_2 and alkali content.2) Early hydration of cement paste was accelerated by using silica fume.3) W/C,moisture content and SiO_2 content of silica fume are the two main factors on compressive strength of concrete containing silica fume. But the effect of superplasticizer was very strong.4) Reducing effect of silica fume on the concrete expansion due to A.S.R.(Alkali-Silica Reaction) could be evaluated by alkali content of silica fume.