Pumices have been used for several purposes. In Hokuriku District, however, no pumice product has been reported before it was found near Kanazawa recently. The authors carried out an experimental investigation on the properties of this pumice in order to find the possible uses. The experiment consisted of three series. The first was the tests of pumice itself. The results were obtained on sieve analysis, soundness by use of sodium sulfate, chemical quantitave analysis, X-ray analysis, heat difference analysis, weight change in heat, heat expansion, heat conduction, specific gravity, water absorption rate and compressive strength. The second was the experiments of pumice mortal. The pumice mortal showed the following values, comparing with the sand mortal, 70% in weight, twice in water absorption, 3-4 times in water permeation, about a half in compressive strength, tensile strength and Young's modulus, and 1.6〜2 times in drying shrinkage in length. In concrete block, when the sand aggregate was replaced by the pumice, the compressive strength was lowered to 50% but the weight decreased by 45% and the heat conduction was reduced by half. The third was the tests of pumice tile. Ten groops of pumice tile spesimen, having different mixing proportion of pumice and clay, were made. And each group had four different heat treatments within the range of 1230〜1300℃. It was found that the mixing of pumice and clay in 6 : 4 and 1240℃ heat treatment was the best combination among them and the weight of the tille, thus obtained, was 80% comparing with the clay tile and the water absorption was only a half of that of clay tile.
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