STUDIES ON AUTOCLAVE TESTS OF VARIOUS CEMENT, Part I

Abstract

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