22 BULLETIN 3T3, U. S. DEPARTMENT OF AGRICULTURE. 
through poorly grouted joints, or otherwise. Also, when a sand 
bedding is used, the joints between the brick are nearly always 
partially filled by sand being pushed up into them when the brick 
are rolled, and the effectiveness of the grout may be thereby greatly 
reduced. 
(3) If the pavement continues to act as a monolith, the pressure 
on the subgrade, due to concentrated loads on the surface, will 
be much better distributed for the same depth of brick and base 
than if the two were separated and able to act independently. 
The two principal objections to this type which suggest themselves 
at present are : 
(1) The difference in the coefficients of expansion of brick and 
concrete may eventually cause a separation of the two materials, 
and as there is no adjustable bedding between them, any relative 
movement might result in shattering the bond between the brick and 
the grout. The only warrant for this apprehension at present, 
however, is in theory and not in fact. 
(2) "Whenever it becomes necessary to renew or repair the surface 
of the pavement, it will probably be necessary to renew the base 
also. 
Until sufficient time has elapsed to show how this new type of 
pavement will be affected by changing temperatures and increasing 
age, no specific recommendations can be made concerning its adop- 
tion. But the indications are certainly sufficiently promising to 
warrant a careful watch being kept on these pavements and to en- 
courage the undertaking of further experiments. 
COST OF BRICK PAVEMENTS. 
The cost of brick pavements varies widely and is affected by so 
many influences that it is difficult to attempt to derive a general 
expression showing the relation between probable cost and local con- 
ditions. The prices of brick, as also the prices of the various mate- 
rials entering into the foundation, vary greatly according to the 
locality and the freight rate. The cost and efficiency of labor is also 
far from being constant. Furthermore, the material composing the 
subgrade and the method of preparing it may exert a marked influ- 
ence on the cost of the pavement. The following statements regarding 
cost, then, must be considered as representing average conditions, and 
care must be exercised in applying them to special cases. They are 
intended as a guide in preparing estimates of probable cost. 
The grading is usually paid for by the cubic yard, and the cost, of 
course, varies with the character of the soil and the necessary amount 
of excavation. In light, easily loosened soils, grading may usually 
be done at from 25 to 40 cents per cubic yard. In hard earth con- 
