16 BULLETIN 246, U. S. DEPARTMENT QF AGRICULTURE. 
grades; (3) it does not entirely prevent water from penetrating 
through to the foundation; and (4) it does not bond the individual 
brick together and so enable them to present a concerted resistance 
to traffic. 
The bituminous fillers vary considerably in quality and efficiency, 
but all are more or less unsatisfactory. One of the principal objec- 
tions to their use is based on their tendency to run out of the joints 
into the gutters during warm weather and to crack and spall out 
during cold weather. This tendency can, of course, be partially 
overcome by exercising proper care in selecting the materials. It 
should also be noted in their favor that brick pavements, the joints 
of which have been filled with bituminous preparations, are ordi- 
narily less noisy at first than those in which a Portland cement grout 
filler has been used. The grout filler is unquestionably very much 
superior from a standpoint of durability, however, and the excessive 
noise under traffic which has been frequently observed in connection 
with its use caix be largely eliminated by the use of proper bituminous 
expansion cushions along the curbs. It is, therefore, recommended 
as better adapted for filling the joints in brick pavements than 
any other material which has been commonly used for that purpose. 
When the joints of a brick pavement are properly filled with 
Portland cement grout the individual brick are firmly bonded to- 
gether and the pavement is thereby practically converted into a 
monolith. Moreover, since the material composing the joints scarcely 
wears more rapidly than the brick, the edges of the brick are well 
protected, and the importance of this feature has already been 
pointed out. 
The most satisfactory method yet devised for mixing and applying 
the grout filler may be described as follows : Grout boxes, constructed 
in such manner that when resting on a level platform one corner 
will be lower than the others, should first be provided. A suitable 
design for such boxes is shown in Plate II. The number of boxes 
required depends on the width of the pavement ; ordinarily one box 
to each 10 feet of width will be found sufficient. The grout, which 
should be put on in two applications, is prepared in batches each of 
which consists of a quantity of cement not exceeding one sack, a like 
amount of fine, clean sand, and water. The sand and cement should 
first be thoroughly mixed dry and sufficient water then added to 
produce a liquid mixture. The consistency of the mixture for the 
first application should be approximately the same as that of ordi- 
nary cream, and for the second application it should be somewhat 
thicker. 
The pavement should be cleaned and thoroughly sprinkled as a 
preliminary to making the first application of grout, and it should 
