水和セメント中に保有する固着水, 半固着水, 自由水等について知るため平衡水分, 乾燥曲線及び灼熱減量等について調べ濕度の變化による之等水分の變動を吟味し次に濕度の變化に基く容積變化について測定した。
之等實驗の結果は次の樣であつた。
(1) 水和セメントは純セメントに對し固着水22%前後半固着水15%以内 (濕度によつて變動する) 及び特に水分の多い條件下 (例へば水中養生の如き) では自由水を含む。
(2) 固着水は所謂化合水又は結晶水と唱へるものであり半固着水はゲル及潜晶質物表面の純吸着水及び之等微粒間隙の極微毛細管内の準吸着水であり自由水は毛細管及び空隙等を充し何等吸着作用を伴はない水であると考へる事が出來る。
(3) 濕度による容積變化は半固着水の量に正比例するものゝ樣である。
その容積變化は濕度1%につき純セメントは50℃空中養生物は初め6ケ月間に於ては100mにつき約27mm位それから1年迄は1.6mm位であり20℃水中養生物は空中養生物より大きく6ケ月位までは5mm前後で空中養生物よりは大きかつた。
モルタルは50℃空中養生物は1年以内では濕度1%の變化について100mにつき0.6mm前後であり20℃水中養生物では6ケ月以内では0.7-0.8mm位でやはり空中養生物の容積變化よりは大きかつた。
コンクリートは2年半位迄は濕度1%の變化について100mにつき大約0.6mm前後でモルタルの場合と大體似てゐる。
しかし之等の値はセメントの種類及び養生法等によつて多少相違するものであることは勿論である。

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As the testing method of soundness of cement is commonly used neat cement or cement paste, e.g., (1) the qualitative test of observation of cracks on pat from neat cement paste curing for 28 days in water or boiling, or (2) the quantitative test of measuring expansion or contraction of neat cement paste of prismatic test piece by the Bauschinger's method or of cylindrical test piece by the LeChatelier's method. These tests are to be commonly carried out under atmospheric pressure, but there are seen some literatures relating to high pressure testing or autoclave test of soundness of cement, and this test was recently seen to be adopted as the standard method by the American Portland Cement Association Fellowship (Cement and Lime Manufacture, 1937, 10, No. 5, 129; R. N. Young, Journ. Amer. Concrete Institute, Vol. 34, Sept. -Oct., 1937; N. C. Rockwood, Rock Products, 1938, 41, No. 1, 85, ect.).
The present author proposed before 10 years the plastic mortar method, as the new cement testing method instead of the present method of dry mortar in the Japanese Portland and blast furnace cements standards (JES 28 and 29), and was studying on this method for various purposes, i.e., (1) Testing of bending strength, (2) Testing of compressive strength, (3) corrosion by salt solution or sea water, (4) Expansion or contraction cured in water or various salt solutions at the room temperature or by boiling, and (5) Soundness test cured under high pressure steam or autoclave test, which results are briefly abstracted from the original Japanese communication, as following:
(1) Cement samples were selected for the purpose of comparison of autoclave test, especially for the studying on the value of autoclave test to discuss the relation between the soundness and chemical compositions of various cements. Two samples of common Portland cement, three of high magnesian Portland cement, two of blast furnace cement, one of high silica mixed Portland cement, and two of high alumina cement first produced in Japan (S. Nagai, Journ. of Japanese Ceram. Assoc., 1938, 46, 123), so that totally ten samples of various kinds of cement were selected.
(2) These cement samples were first compared their chemical compositions and various physical properties, as in the foregoing studies, on variousc ements, e.g., specific gravity, fineness (residue on 4900meshes/cm²-sieve), voids, setting time, etc. The strength tests were also executed in two ways as adopted in the foregoing reports, i.g., (1) by ths dry or non-plastic mortar of 1:3-cement and standards sand in the Japanese engineering standards of Portland and blast furnace cements (JES 28 and 26) and (2) by the wet or plastic mortars of 1:2-or 1:1-cement and fine sand.
(3) Neat cement paste was first tested by the LeChatelier's method but by heating in autoclave, i.e., the increase of opening of calliper was compared by treating in the superheated steam of 153-155°C and about 5kg/cm² steam pressure for two hours. The increase of the calliper opening was not over 3-3.5mm, which is smaller than the limit 5-6mm in the common test under atmospheric pressure by the LeChatelier's method. So that, it is clear that the steam pressure 5kg/cm² of the autoclave test is not sufficient and is necessary to test under higher steam pressure than 10 or 15kg/cm² (and about 182-183°C or 200-202°C), which will be tested and reported in the next report.
(4) Beam test pieces (4×4×16cm) of wet or plastic 1:2-cement and fine sand mortar were treated in the autoclave of superheated steam pressure of 5kg/cm² and about 153-455°C for 2 hours, and measured the expansion of distance between two points on the test beam by the comparator of micrometer type. The results were sufficient to compare the unsoundness or large expansion 10-15mm/10m of high magnesian Portland cement with those (3-5mm/10m) of smaller expansion of other cements.
(5) After

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Quoting many literatures involving origin and occurence of bentonite as well as fuller's earth the author concluded the following theories.
The alteration-reaction of both bentonite and fuller's earth is nothing but that of montmorillonite. The reaction is one of hydrolysis which taking effect on the surface of volcanic glass. It reacts as a colloid chemical reaction and can complete itself as either quicker thermohydration reaction (200 to 300°C?) on the surface or slower deep-bed-weathering one.
When the composition of mother glass is in acidic or neautral the reaction may be said to be normal, i.e., the most wide spread type. The bassaltic nature example seems to be rather rare. It seems to be quite reasonable to think that within a certain limit of the silica content the mother rock results in bentonite of high swelling character but with the excess silica fuller's earth of disintegrating-in-water type. Nevertheless, the small magnesia almost always is accompained.
Natural leaching action can alter a certain non-swelling Ca-bentonite to a swelling type one and at the most to a fuller's earth. The reverse course yet to be traced naturally.

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