SAND-LIME BRICK. 343 
of soluble silica and the hardness of the individual grains, sand- 
lime brick of the best quality can be manufactured from them. 
Both materials are especially suited for the manufacture of tiles 
and ornamental stonework. This is more or less apparent from 
fig. 2, Plate VI, and fig. 1, Plate IV, which are photographs of 3 by 
3 by 2.25-inch sand-lime bricks made from Sisiman and basaltic 
rock, respectively, although these photographs fail to show the 
glossiness of the polished front surfaces. The bricks photo- 
graphed were made from mixtures 22, Table XV, and 23, Table 
XVI, and it should be borne in mind that, in order to obtain a- 
glossy surface and granitic appearance, the stones were not 
ground to the degree of fineness necessary to give a high strength. 
Nevertheless, it is safe to assume that beautiful, polished, dense 
“artificial marbles” can be made with these materials without 
reducing the strength below 4,000 pounds per square inch. 
TABLE XIV.—Available quarry débris. 
Content of silica. 
Rock. Classification. Solubletn Soluble in} 
. sodium Total 
chloric | .arbonate| 2Uartz- | silica. 
Ge) sa (Naz2COs). 
Per cent.| Per cent. | Per cent.|Per cent. 
Sisiman rock A gray andesite which contains no 0.37 23.59 0.00 54.77 
from Mariveles. free silica or quartz. 
Basalt rock from | A dark, dense, basaltic rock which 1.00 21.17 0.00 54. 73 
Talim Island. shows practically no crystalline 
contains no quartz. 
| structure to the unaided eye and 
| 
TABLE XV.—Sand-lime brick made from Sisiman rock quarry débris. 
Degree of pulverization in per cent passing Compressive 
through the standard specified sieves. 4 Molding strength. 
Duration nae 
Mixture of steam | P™ per 
No. Leal square Per 
No. 20. | No. 40. | No. 80. | No. 100. | No. 200, | ™&?™ inch. Total. square 
inch. 
Hours. | Pounds. | Pounds. | Pounds. 
22, 73. 4 48.2 29.4 25.3 16.5 8.0 7, 640 10, 960 2, 740 
22 78.4 48.2 29.4 25.3 16.5 8.0 10, 000 16, 120 4,030 
Molding pres- Density. Absorption after 24 hours in water. 
Mixture | sure in pounds 
No. per square 5 i 
inch. Air dry. Dried at 110°. Air dry. Dried at 110°. 
7.5 
23 10, 000 2.22 2.15 4.4 
