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BULLETIN 23, U. S. DEPARTMENT OF AGRICULTURE. 



been found to give good results, are contained in the section entitled 

 "Typical specifications." (Cf. p. 21 et seq.) 



Expansion cushions should be provided for at the tune the brick are 

 laid, by placing a board of the required thickness on edge adjacent 

 to each curb, as shown in figure 3. Small iron wedges, such as are 

 shown in this figure, may be inserted between the curb and the board 

 at the time the board is set. These wedges may be readily loosened 

 and removed after the bricks have been laid and grouted, and may 

 consequently be made to facilitate the removal of the board. 

 - The proper thickness for expansion cushions is a matter concerning 

 which, much difference of opinion exists among highway engineers. 

 Some engineers advocate a minimum thickness of 1 inch, while 

 others claim to have secured their best results by using expansion 

 cushions having a minimum thickness as low as three-eighths inch 

 for very narrow pavements. It is generally agreed, however, that the 

 thickness of the cushion should vary with the width of the pavement. 

 The following suggestions for proportioning the cushion are offered 

 as being fairly representative of the best practice. 



Table 1. — Ratio of thickness of cushions to width of roadway. 



Width of roadway 

 (feet). 



Thick- 

 ness of 

 cushion 

 (inches). 





2 

 f 



1 

 11- 



20 to 30 



30 to 40 



Over 40 





Plates III to VII, and Plate VIII, figure 1, show the various steps 

 in the construction of a brick pavement. Plate VIII, figure 2, and 

 Plate IX, figure 1, show the finished pavement as it should appear, 

 and Plate IX, figure 2, shows the advantage possessed by grout-filled 

 joints over joints filled with a soft material. 



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 materials 

 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 influence on the 

 cost of the pavement. The following statements regarding cost, 

 then, must be considered as representing average conditions, and 



