SAND-LIME BRICK. 337 
true when the molding pressure is low. The color of the product 
is darker and less pleasing, but the bricks made took a fairly good 
polish, due largely to the presence in quantity of large grains of 
andesite and basalt rock, as is shown by the granularimetric 
analysis of mixture 6. Fig. 1, Plate V, is a photograph of a 3 by 
3 by 2.25-inch brick made from mixture 6. The front surface 
had been polished. Fig. 6, Plate VII, is a photograph of a brick 
made from mixture 7 and shows the perfect soundness after the 
brick had been subjected to the fire test. 
The Pasig sand used in the above experiments contained very 
little iron, and, thus far, the surface of the bricks has not shown 
signs of rust stains. Sand from some parts of the Mariquina 
River contains large quantities of iron, and the use of such 
material should be avoided. 
The granularimetric analyses of mixtures 6, 7, and 8 show 
a graduated increase in the degree of pulverization and a 
corresponding increase in strength. A comparison of the gran- 
ularimetric analysis of the sand as used in mixture 8 with 
that of the sand as it is received shows that considerable grind- 
ing is necessary in order to obtain great strength. However, 
we have a large quantity of very fine beach sand near at hand, 
and grinding expenses can be reduced to a low figure by mixing 
this with coarser available siliceous materials.” The lower 
initial cost of beach sand would also make the production more 
economical. The results given in Table IX for an equal mixture 
of Pasig and beach sand were obtained without grinding any 
of the siliceous materials. A still better product would have 
been obtained had the beach sand been ground a little before 
mixing. 
TABLE IX.—Sand-lime bricks made with equal parts of Pasig and beach 
sand.* 
Granularimetric composition of mixed sands in F Compressive | 
Mi per cent passing through the specified sieves. |Duration| Molding strength. 
iis of steam | Pressure 
No. iret: square Per 
No. 20. | No. 40. | No. 80. |No. 100. ]No. 200.} ™™* | inch. | Total. panaie 
‘ inch. 
Hours. | Pounds. | Pounds. | Pounds. 
9 99.8 75.7 64.8 27.2 3.2 8.0 7, 640 10, 720 2, 680 
4) 99.8 75.7 54.8 27.2 3.2 8.0 10, 000 18, 760 8, 440 
a Plate VII, fig. 2, shows the perfect soundness of one of these bricks after it had been 
subjected to the fire test. 
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