Kinji Shimada

On the Autoclave-Hardened Bodies Using “SHIRASU”

“SHIRASU” is distributed chiefly in southern Kyushu and consists of volcanic ash, pumice and other materials. SHIRASU and coral limestone were used as raw materials of autoclave-hardened bodies. The press molded and then autoclaved bodies were prepared as follow; mixing ratio of SHIRASU: coral limestone=1:1, 3:1, 6:1, mixing water 15%, press-molding pressure 200kg/cm2, curing pressure 5-15kg/cm2, curing time 4-16hrs. Results are as follows; apparent density 1.81-1.93, bulk density 1.41-1.54, water absorption 21-29%, compressive strength 46-505kg/cm2.The porous lightweight autoclaved bodies were prepared as follow; mixing ratio of SHIRASU: coral limestone=1:1, 2:1, 4:1, mixing water 54-90%, Al powder 0.05-0.75%, curing pressure 10kg/cm2, curing time 10-40hrs. Results are as follow; apparent density 1.05-2.54, bulk density 0.48-0.90, apparent porosity 51-86%, compressive strength 4-85kg/cm2.

Some Properties of Amorphous Silica Connected with Volcanic Actions.

火山作用と関係ある無定形ケイ酸は成囚により物理的,化学的,熱的,X線的性質および赤外吸収に相違が認められる。すなわち,温泉沈殿物である牧園産は外観が生成条件により千差万別で変化に富み,概して水分を多く含み,鉄分多くアルミナ分が少ない。それに対し母岩の変質により生成した別府,沼尻産は均質で鉱量も豊富で,含量水分は比較的少なく,アルミナ分が鉄分より多く含まれている。X線観察では前者は無定形なものが多いのに対して,後者はクリストバラ/トの回折像を認める。熱分析ではいずれも原石ではクリストバライトの存在を認知できないが,900～10000Cに加熱するとクリストバライトのα→ β 転移に起因する吸熱ピークが現われ,アルカリ可溶性分もまたこの温度付近から減少することから,この温度付近で結晶化が促進すると思われる。なお,前者ば加熱温度の上昇と共に収縮するが,後者は2500Cより急激に膨脹して後,加熱温度の上昇と共に微少な膨脹をつづける。比重は前者が後者に比較して小さく,いずれも7000～8000Cで最低の比重を示すがさらに温度が上昇するとふたたび増大し,10000C付近でクリストバライトの比重に近づく。赤外線吸収は温泉作用をうけたと思われる牧園,別府産はシリカゲルと同様に2・7～3・35μ にかけて幅広い吸収が認められ,吸着水分が多量に存在するが,硫化作用により変質したと思われる沼尻産はきわめて微少である。

Fundamental Studies on the White Clays in South Kyushu

White clay resources are very abundant in South Kyushu, though very little have ever been reported on them except the well-known “Ibusuki clay”. The object of this paper is to describe the results of the writers works on the fundamental properties of four kinds of the white clays, namely those produced in Kirishima, Iriki, Okuchi, and Masaki.The clays here selected are all of vast resources and exceptionally poor in iron.Grading analysis, chemical analysis, various thermal tests, X-ray analysis, electron-microscopic survey etc. were conducted on these clays, with the results as follow:(1) It is very likely that the main component mineral of these clays is hydrohalloysite. The mineral composing Masaki, Iriki, and Kirishima clays, all of which are presumed to be of hydrothermal origin, shows a tubular shape under the electron-microscope. On the other hand, the one contained in Okuchi clay, which was derived from tuff through superficical weathering, appers as a rounded granule without any linear outline.(2) Iriki clay is comparatively coarse-grained, while Kirishima and Masaki clays are rather fine-grained. Okuchi clay is so fine-grained that 75% of the component minerals are less than 2μ in diameter.(3) All of the four clays are very high in refractoriness, while the burning colours of Masaki and Iriki clays are snowy white. Thus the two clays are considered to be very suitable for the raw materials of ceramic wares.(4) When burnt up to 1000°C, the coefficients of contractions of Iriki, Okuchi, and Masaki clays were almost similar, about 7.0%, while that of Kirishima clay showed a lower value, 5.6%.