VITRIFIED BRICK PAVEMENTS FOR COUNTRY ROADS. 17 



be kept moist by gentle sprinkling while this application is being 

 made. The grout should be swept into the joints immediately after 

 it is removed from the boxes and spread upon the pavement. For 

 this purpose a coarse rattan or fiber push broom should be used in the 

 first application and a squeegee in the second application. The 

 squeegee is usually made by clamping a piece of four-ply rubber 

 belting or some other similar material, about 6 by 20 inches in size, 

 between two pieces of board and attaching a suitable handle. The 

 grout in the boxes should be continually stirred until the last of it 

 is removed, otherwise a separation of the sand and cement will almost 

 certainly occur. 



The first application should proceed about 50 feet in advance of the 

 second. Usually both applications are made by the same crew of 

 laborers. They simply turn back after having covered the allowable 

 distance with the first application and, mixing the grout in the same 

 boxes, bring up the second application. The second application of 

 grout should completely fill the joints flush with the top of the brick. 



After the joints are filled as described above and the grout has 

 taken its initial set, the entire surface should be covered to a depth 

 of approximately 1 inch with sand or fine earth. This is done to 

 protect the pavement from the weather and to keep it in a moist 

 condition while the grout is hardening. If necessary, in order to 

 keep the covering moist, it should be occasionally sprinkled for 

 several days after it is spread. 



The covering should be permitted to remain on the surface for 

 at least 10 days, and during this period the pavement should be 

 kept entirely closed to traffic. If the weather is unfavorable, the 

 length of time during which traffic is kept off the road should be 

 increased. 



EXPANSION CUSHIONS. 



It has been customary in the past to provide both longitudinal and 

 transverse bituminous expansion cushions in grout-filled brick pave- 

 ments, but recent practice has demonstrated that the transverse 

 cushions may be advantageously omitted if proper longitudinal 

 cushions are provided. The principal objection to the use of trans- 

 verse expansion cushions is based on the fact that the material com- 

 posing the cushions frequently softens during warm weather and 

 runs out toward the curb, thus leaving the edges of the adjoining 

 brick exposed to destructive impact from the wheels of passing 

 vehicles. Even if the cushion consists of a material which does not 

 run in warm weather, it is necessarily softer than the brick, and the 

 natural result is still the development of unevenness in its immediate 

 vicinity. No such objection can exist concerning longitudinal ex- 

 pansion cushions, however, if they are placed adjacent to the curbs 

 92742°— 15 3 



