BEICK EOADS. 15 



Tlie proper thickness for the bedding depends, of course, upon the 

 extent of the inequalities in the brick and the foundation. In the 

 past, 2 inches has been the most usual thickness, but as the accuracy 

 secured in constructing the base has increased, and as the size of 

 paving brick has become more nearly uniform, the necessary tliick- 

 ness for the bedding has naturally diminished. At present a thick- 

 ness of 1^ inches is considered conservatiTe where the bedding con- 

 sists of sand alone, but where dry mortar is employed the inequalities 

 should be so reduced that a thickness of 1 inch will be sufficient, 

 because it is cheajDer to make the surface of the base uniform than 

 to supply the additional dry mortar which would otherwise be 

 required. 



Sand bedding should consist of moderately clean sand and be free 

 from pebbles. If dirt or vegetable matter is present, it will soon be 

 leached out and cause unerenness to develop in the pavement, while 

 pebbles prevent the brick from securing a uniform bearing and ulti- 

 mately produce the same result. It is also unportant that the sand 

 should be dry when spread, especially if it is fine, because a compara- 

 tively small amount of moisture increases the volmne of fine sand 

 considerably, and moisture when present is not, as a rule, uniformly 

 distributed. Even if it were uniformly distributed at the start, some 

 spots would dry out more rapidly than others while the spreading 

 was under way, and a lack of uniformity would thus be produced in 

 the bedding. 



In forming the bedding the sand is uniformly spread over the base 

 to a depth slightly in excess of that desired, and is then smoothed ofl' 

 by drawing over it a template shaped to conform with the cross sec- 

 tion of the finished pavement. The length of the template is ordi- 

 narily made equal to the width of the pavement where this is less 

 than about 25 feet, and equal to half the width for wider pavements. 

 Tunber guides may be laid in the same direction as the pavement for 

 the template to slide on, or the curbs may be made to serve as guides 

 where this is convenient. 



After the bedding material is spread and uniformly "struck ofi'" 

 with the tem^Dlate to a depth slightly in excess of that required, it 

 should be thoroughly compacted by rolling with a hand roller weigh- 

 ing from 300 to 100 pomids, and any depressions which form should 

 be corrected. This is necessary in order to secure uniform density 

 and to prevent unequal settlement of the surface. 



If a dry mortar bedding is to be employed, the sand used should be 

 clean and the manner of spreading and compacting the bedding 

 should be practically the same as for sand alone. The proportion in 

 which the sand and cement should be mixed is a subject regarding 

 which there is more or less uncertaint}' at present. One part of 



