Concrete Roads
and Their Construction

182 CONCRETE ROADS When a two-course road is being laid the upper course or wear- ing surface shall be spread on the lower course immediately after the latter is deposited and before it has begun to set. 15. Consolidation.—Immediately after being placed in position in a roadway, the concrete shall be struck off to approximate grade and camber and shall then be thoroughly consolidated to eliminate all voids and all surface moisture. This consolidation is to be effected by tamping or punning the surface of the concrete, either mechanically or by hand, or it may be done by rolling. In no event shall any tamping device be used which necessitates a penetration below the concrete surface. 16. Surface.—Failing the use of a mechanical tamper, the wear- ing surface shall be struck off to the finished contour by means of a double template, of which a suitable type is shown in Fig. 126. This template shall be drawn over the concrete with a com- bined longitudinal and transverse motion, so as to produce a surface free from depressions or inequalities of any kind, and this surface shall not afterwards be disturbed by floating off or in any other way. The finished surface shall have a cross fall only sufficient, in the judgment of the engineer or surveyor, to ensure that the surface water will pass off the roadway quickly, and shall not vary more than | in. from true shape. It will be found that, at the most, a cross fall of 1 in 60 will be sufficient. No cessation of work of more than an hour’s duration shall be permitted, except at the end of a completed bay. In cases where it is impossible to divert the traffic and the con- crete has to be laid on one-half of the road at a time, the edge of the concrete in the centre of the road shall be left with a rough verti- cal edge, and immediately before filling in the concrete for the second half this edge shall be thoroughly swept, watered, and painted with.a thin coat of neat cement and water in equal pro- portions. The concrete shall then be applied immediately. 17. Reinforcement.—The concrete may be reinforced with steel reinforcement of a typo approved by the surveyor. When, in the opinion, of the surveyor, reinforcing is necessary, such rein- forcing should be equivalent to 0-05 square inch per foot width of the concrete. In cases where one-half of the roadway is laid at one time, the reinforcement should be carried beyond the centre edge of the concrete first laid so as to provide a positive connection between the two halves.