﻿26 BULLETIN 23, U. S. DEPARTMENT OF AGRICULTURE. 



the box, which shall be about 6 inches above the pavement. The 

 grout shall be constantly stirred in 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 payement 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 



