Concrete Roads
and Their Construction

SUGGESTIONS FOR FORM OF SPECIFICATION 179 low result as to indicate a faulty specimen shall be eliminated in arriving at the average of the results for any test. 4. Water—The water shall be fresh and clean, and shall be taken from a public drinking water supply or from other source of known purity. 5. Reinforcement.—All metal for reinforcement shall be free from oil, paint, excessive rust, or coatings of any character which will tend to destroy the bond with the concrete. The metal shall develop an ultimate tensile strength of not less than 60,000 lbs. per sq. in., and withstand bending when cold 180 degrees around one diameter and straighten without fracture. 6. Joint Filler.—Joint filler must be an elastic waterproof material, which will not lose these properties under extremes of weather conditions. Preparation of the Existing Surface 7. Foundation.—The preparation of the foundation will necessarily vary with local conditions, and must be determined by the sur- veyor in charge of the work. Any necessary embankments or fills shall be executed to the satisfaction of the surveyor, and shall be thoroughly consolidated, so that there is no possibility of settle- ment at any point. Any soft or weak places must be excavated and filled up with hard stone or other suitable material, so as to obtain, solidity equal to the remainder of the surface. The sur- face shall be finally rolled to the required contour with a roller of not less than 10 tons in weight. It should be noted that the use of concrete for the road cannot be assumed to do away with the necessity for a good and even foundation over the whole surface. The surface thus prepared shall be regular and may be flat, or with a slight cross fall as may be specified by the survoyor. When the road is not supported by kerbing on either side, a channel may be dug, longitudinally, immediately inside the edge of the prepared base, so that the concrete when placed has a cross section at this point as shown in Fig. 125. Immediately before the concrete is placed, all foreign matter shall be removed from the prepared surface, which shall then be thoroughly watered. 8. Drainage.—Where local conditions require, a suitable drainage system shall be provided to the satisfaction of the surveyor.