22 BULLETIX 373, U. S. DEPAETMEXT OF AGEICE'LTE'EE. 



through poorh' grouted joints, or otherwise. Also, -srhen 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 gi^out. The only warrant for this apprehension at present, 

 however, is in theory and not in fact. 



(2) ^"Mienever 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 widel}' 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 jpi'ices 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 

 subgi"ade 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 gradmg 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- 



