16 BULLETIN 246, U. S. DEPARTMENT OF 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 can 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 



