BRICK EOADS. 13 
concrete composed of 1 part of Portland cement, 3 parts of sand, and 
from 5 to 7 parts of broken stone or screened gravel. 
The sand should be clean and well graded in size, and the stone or 
gravel should conform to the usual requirements for coarse aggregate 
to be used in concrete construction. 
Brick pavements have in some cases been constructed with the sub- 
grade as a foundation, and where the materials composing the 
subgrade possess considerable supporting power under all weather 
conditions to which the road is subjected, this method may prove 
fairly satisfactory. Perhaps the most notable examples of brick roads 
constructed in this way are to be found in the peninsular section of 
Florida, where the soil is composed essentially of sand and where 
there is no danger of upheaval due to frost action. At best, this 
method of construction could hardly prove satisfactory for any ordi- 
nary soil conditions above the thirty-fifth parallel of latitude, and even 
beloAv that latitude it should necessarily be confined to localities 
where the soil is composed of sand, gravel, or some other material 
. Joints filled with Portland cement grout. 
^^^^gri^^— A^ Slope 1 : 12. 
Crown J to I. 
Slope of shoulders at least I tol2. 
Fig. 4. — Typical section for a brick road. 
which does not lose its stability when wet. Sand is the only material 
of this kind which is at all widely distributed. The precautions most 
necesary to observe in preparing sand foundations may be briefly 
described as follows: 
(1) The road should be so graded and drained as absolutely to 
prevent the foundation from becoming saturated with either storm or 
ground water after the brick are laid. 
(2) The entire roadway should be thoroughly saturated with water 
while it is being compacted, and a roller weighing not less than 10 
tons should be used for compacting. Dry sand can not usually be 
compacted by rolling. 
(3) Adequate stone or concrete curbs should always be provided. 
At present wooden boards are being used in lieu of curbs for many 
of the Florida roads, and in some cases this substitution can perhaps 
be justified by the immediate necessity for improving a large mileage 
of roads without suddenly increasing taxation to an unwarranted 
burden. On the other hand it seems very doubtful if any community 
