STATE GEOLOGIST. halal 
and for all ordinary circumstances this is ample if good concrete is used. 
Both natural and Portland cements are used for foundation work, but the 
writer prefers to use Portland cement. Different engineers vary greatly 
in the proportions used. The character of the soil beneath has some 
weight in the choice of the proportions. 
With natural cements these proportions may vary from I cement, 
2 sand and 3 stone, to I cement, 3 sand and 6 stone. When Portland 
cement is used, the limits are from I cement, 2 sand and 5 stone, to I 
cement, 5 sand and Io stone. Under all conditions the writer should 
prefer to use a richer mixture than the last named limit. The concrete 
should be well mixed and compacted, and rather wetter than concrete 
used in walls. 
Some of the later concrete foundations put down in Columbus, Ohio, 
have been of 1 cement, 4 sand and 8 broken stone; these proportions ap- 
pear to make an excellent foundation. 
Figure 57 shows a section of Tenth avenue, Columbus, Ohio, which 
is paved with brick block upon a concrete foundation. This concrete 
foundation costs from 70 to 75 cents per square yard. The labor of 
mixing and laying the concrete cost on an average 15 cents per square 
yard. 
The cost of concrete foundation was carefully kept in Toronto, 
Canada, as follows: 
Cost per cu. yd. 
Cementa ater 24G 1346 Der SDD! eae wees mite ae te ee a $2.15 
IBTHOMEIN, rome eyn SuLMl jee Wil Wels odo ddounobogdauucooo uuu 1.43 
Gravel and sand at $0.80 per cu. yd..... RETA nvaue it aC hatrs aeaenD 0.21 
Wa Orga Catl'd CarPC TOUT ais cistckans es eee te ee ee es ee ater on dee 1.04 
MRO CATA GURY Ce neice ere area or eea a a aU ere a ae aeanENS $4.83 
Or, with concrete six inches deep, 8044 cents per square yard. 
The concrete used in this case was 1 cement, 21%4 sand and 714 stone. 
PAVED STREETS. 
While concrete has not been used extensively as a surface paving ma- 
terial for streets, it has been used quite satisfactorily in some alleys in 
Philadelphia, a couple of streets or courts in Grand Rapids, Mich., and 
on four streets at Bellefontaine, Ohio. The streets in Bellefontaine 
were laid in 1892 and 1893, and are in excellent condition today. The 
concrete was laid upon a well compacted road-bed in two layers, the foun- 
dation layer 4 inches thick, and the surface layer 2 inches thick. In two 
of the streets the foundation concrete was composed of 1 part Portland 
cement to 5 parts coarse gravel, and the surface coat 3 parts'cement to 5 
parts coarse sand. In the other two streets the proportions were: Foun- 
dation, I cement to 4 parts gravel, and surface coat, 1 cement to 1 sand. 
Both top and bottom layers were cut into blocks about 5 or 6 feet square 
and tarred paper used in the joints to give room for expansion. The sur- 
