26 BULLETIN 23, TJ. S. DEPARTMENT OF AGRICULTURE. 
the box, which shall be about 6 inches above the pavement. The 
grout shall be constantly stirred hi the boxes until the last of it has 
been removed and applied to the pavement. 
The grout for both applications shall be removed from the boxes 
and spread over the pavement by means of scoop shovels, and shall 
be immediately swept into the joints, with a coarse rattan or fiber 
push broom in the first application and with a squeegee or rubber 
broom in the second application. The pavement shall have been 
thoroughly sprinkled before the first application of grout is made and 
shall be kept moist by means of gentle sprinkling until the grout is 
spread. 
Unless some other arrangement is approved by the engineer, 
both applications of grout shall be made by the same crew of laborers 
and with the same appliances. After the first application has ad- 
vanced about 50 or 60 feet, the second application shall be made. 
When the second application has been finished, the grout shall 
entirely fill the joints and shall appear smooth and flush with the 
surface of the brick. 
After the joints have been filled as above provided and the grout 
has taken its initial set the entire surface of the pavement shall be 
covered with a +-inch layer of sand. This sand layer shall be kept 
moist by sprinkling for at least 3 days and shall remain on the 
pavement for at least 10 days, and during this period the street 
shall be entirely closed to traffic. Any damage resulting from traffic 
or any other disturbing influence which has been prematurely per- 
mitted upon the pavement shall be repaired by the contractor at 
his own expense. 
Expansion cushion.— An expansion cushion of the thickness indi- 
cated on the plans shall be constructed along each curb as follows: 
Suitable provision for the cushions shall be made at the time 
the brick are laid by setting boards of the proper thickness on edge 
in the correct position along the curb. After the brick have been 
laid, rolled, and grouted and -the grout has been permitted to harden, 
the boards shall be removed and the spaces which they occupied shall 
be filled with either coal-tar pitch or blown-oil asphalt. 
If pitch is used, it shall be of such character as to adhere firmly 
to the paving brick and to the curb and shall be sufficiently plastic 
to allow for contraction and expansion in the pavement without 
developing cracks in the joints. It shall contain not less than 25 
per cent and not more than 40 per cent of free carbon and shall 
not contain more than 0.5 per cent of inorganic matter. When 
tested by the cube method, its melting point shall be not less than 
55° C. and not greater than 60° C. 
If oil asphalt is used, it shall be soluble in chemically pure carbon 
disulphide to at least 99 per cent, and when tested by the cube 
