STUDIES ON AUTOCLAVE TESTS OF VARIOUS CEMENTS, II

Abstract

The author, in continuing the previous study (This Journal, 1938, Vol. 38, No. 584, p. 397-p. 403), studied further on the autoclave test for soundness and expansion or contraction of cement or cement-sand mortar. This testing method was applied on various kinds of Portland cement and mixed Portland cement for various purposes, i.e., (1) Testing expansion or contraction, (2) Bending strength, and (3) Compressive strength from the same test pieces by using 4×4×16cm prismatic test pieces of plastic mortar, which results are briefly abstracted from the original Japanese communication, as following:(1) Cement samples were selected for studying on the value of autoclave test, especially for testing on the relation between the soundness and chemical compositions of various cements. Three samples of common Portland cement, three of low-heat or modified Portland cement, three of high iron oxide Portland cement, one of blast furnace cement, and five of high silica mixed Portland cement, so that totally fifteen samples of various kinds of cement were selected for the present study.(2) These cement samples were first compared their chemical compsiotions and various physical properties. The strength tests were also carried out in two ways, (1) the dry or non-plastic mortar of 1:3-cement and standard sand for Portland and blast furnace cements (JES 28 and 29) of Japanese Engineering Standards, and (2) the wet or plastic mortar of 1:2-or 1:1-cement and fine sand.(3) Beam test pieces (4×4×16cm) ot wet of plastic 1:2-cement and fine sand mortar were treated, after seven days common water curing, in hot water under steam pressure (5kg/cm2 and about 152-153°C or 30kg/cm2 and about 227-228°C) in autoclave for two hours, and measured the expansion or contraction after cooling in water of room temperature and atmosperi pressure. The results were sufficient to make clear the differences between various cements, especially the unsoundness of high iron oxide containing special Portlant and soundness of high silica containing mixed Portland cement by mixing about 30% of proper admixture containing large amount of soluble silica.(4) After this measurement of expansion, the beam test pieces were tested on their bending strength or modulus of rupture and then compressive strength, and these results were compared with those obtained in the above section (2) by the common curing in water of room temperature and atmospheric pressure. These comparisons are useful to discuss various mixed Portland cements being better than special Portland cements of high iron oxide or silica content.(5) Neat cement paste was tested by the LeChatelier's calliper method curing in autoclave as above mentioned and the increase of opening of calliper was compared to discuss various samples of mixed Portland cement being better than simple Portland cements containing large amount of iron oxide or silica.