Total Utilization of Pyroclastic Flow Deposits as Construction Materials through Dry Gravity Classification and Pulverization
Pyroclastic flow deposits called Ito-Shirasu which erupted out in 29,000 years ago covers an area of about 3,427 km2, and it forms extensive pyroclastic plateaus with a layer about 10 meters to 200 meters thick in the southern regions of Kyushu, Japan.The amount of sediments of Ito-Shirasu is estimated to have a volume of 75 billion m3.It includes a crystal mineral and an amorphous silicate and so on, therefore it has the properties of both a fine aggregate and a supplementary cementitious material(SCM) owing to its pozzolanic reaction.However, the basic properties as a fine aggregate is undesirable;low fluidity by high fineness and angular particles, low density (2.1 lg/cm3), high water absorption (4.9%).Furthermore, properties as a SCM is unacceptable;low early strength by low reactivity.This paper reports the results of investigations to utilize pyroclastic flow deposits as construction materials by focusing on the differences of physical properties between the components.It is shown in this study that dry gravity classification by gravity separator combined with winnowing sorter is effective for dividing into high-purity volcanic glass, crystal mineral, pumice, and clay fraction.Through the method, the density of classified crystal mineral increased up to 2.65g/cm3, and the water absorption decrease down to 1.52%.Additionally, glass content of classified volcanic glass increased up to about 90%, when that of raw material is about 60%.Tests were conducted on concrete mixture.The concrete using classified crystal mineral as fine aggregate showed better fluidity compared to the reference concrete with crushed sand.And pulverized separated volcanic glass exhibited high performance as a SCM equivalent to that of silica fume from the early age.
Natural pozzolan dry gravity classification supplementary cementitious materials
A.Tomoyose T.Noguchi K.Sodeyama K.Higashi
the University of Tokyo, Tokyo, Japan Kagoshima prefectural institute of industrial technology, Kagoshima, Japan Principle Co., Ltd., Kagoshima, Japan
国际会议
福州
英文
475-481
2018-11-04（万方平台首次上网日期，不代表论文的发表时间）