42 BULLETIN 1017, ij. s. depaiitme:n't of agriculture. 



grade so that there will be no segregated material in the surface of 

 the pavement. Exceptionally wet batches should be shoveled from 

 the subgrade and wasted on the shoulders. 



FINISHING THE SURFACE. 



After the concrete has been spread approximately to the required 

 cross-section, the finishing operations are begun. These operations 

 consist of striking-off and tamping the concrete, and finishing the 

 surface. Two methods may be employed, viz, hand finishing and 

 machine finishing. In hand finishing, each operation must be per- 

 formed separately, while in machine finishing all operations can be 

 performed simultaneously. Machine finishing is greatly to be pre- 

 ferred. 



Hand finishing. — The concrete is first struck off with a strike board 

 having from one-fourth to one-half inch more crown than the fin- 

 ished crown of the pavement. This allows for a slight amount of 

 settlement when the concrete is compacted. The striking off is ac- 

 complished by advancing the strike board with a combined longi- 

 tudinal and crosswise motion, A slight surplus of concrete should 

 always- be maintained ahead of the strike board. The tamping 

 should be done by means of short, quick, up-and-down strokes of 

 the tamper, which should have the same crown as the finished road. 

 The best results are obtained by pivoting one end of the tamper on 

 the side forms and advancing the other from 2 to 3 feet, at the same 

 time tamping the area over which the tamper is advanced. This 

 operation is then repeated by pivoting the tamper on the opposite 

 form and advancing the end which was first pivoted. As soon as 

 possible after the concrete has been tamped it should be rolled with 

 a roller having a smooth, even surface and weighing approximately 

 three- fourths of a pound per incli of length. The roller should pre- 

 ferably be 10 inches in diameter, and 6 feet in length and a long 

 handle or ropes may be provided with which to operate it from the 

 sides of the pavement. The purpose of rolling is to eliminate slight 

 inequalities in the surface and remove the surplus water. After the 

 pavement has been rolled the final finish is obtained by means of a 

 belt. A 10 or 12 inch canvass or rubber belt is generally used for 

 this purpose. The belt should be at least 2 feet longer than the 

 width of the pavement and should be provided with wooden handles 

 at each end. The first application of the belt should consist of long 

 strokes with only a slight longitudinal advance at each stroke. A 

 greater longitudinal advance and somewhat shorter stroke should be 

 used for the second belting. The final belting should not be done 

 until after the water glaze or sheen on the surface disappears. It 

 should consist of a rapid longitudinal advance with as short a stroke 



