2017 Volume 71 Issue 1 Pages 674-681
Volcanic silicate powder（VSP）is manufactured through dry gravity classification and pulverization from Ito-Shirasu, one of the biggest pyroclastic flow deposit, which includes crystal mineral, pumice, etc. in natural condition, and its properties are variable in area. But, basic properties of VSP, chemical composition, mineral composition and particle size distribution, are stable over one month manufacturing period, and every random four samples meets the criteria of activity index regulated by JIS A 6207 silica fume for use in concrete. At the experiment, VSP replacement ratio from 10％ to 30％, activity index is almost 100％ in any replacement ratio at the age of 7days, and at the age of 28days, as replacement ratio increase, the value of activity index rises at most 120％. About fluidity, specific surface area will make influence on mortar flow like other mineral admixture from industrial by-products. According to the mechanism of pyroclastic flow deposit, it was indicated that VSP can manufactured from Ito-Shirasu in any area.
