Concrete Roads
and Their Construction

CHAPTER VI MECHANICAL DEVICES FOR MAKING CONCRETE ROADS The construction of concrete roads in an economical and efficient manner depends, to a very large extent, on the properly co-ordinated use of a number of mechanical devices. It is, of course, possible to make excellent concrete roads without the use of any machinery, but the time required and the cost of such a procedure are excessive. By the use of suitable machinery the drawbacks of hand labour are avoided, the large number of men with wheelbarrows and shovels are unnecessary, and a considerable amount of material as well as time is saved. Consequently, the use of suitable machinery not only reduces the cost of construction, but enables a much larger area of roadway to be laid in a given time. The mechanical devices used for constructing concrete roads may be arranged in five groups :— 1. Appliances used for preparing the road-bed. 2. Appliances used for preparing the concrete. 3. Appliances used in placing the concrete. 4. Appliances used in striking and tamping the concrete. 5. Appliances used in finishing the surface. Appliances used for Preparing the Road-Bed It is essential that the road-bed or foundation shall be properly prepared or the concreted surface will not be durable. Hence great care should be taken to ensure the bed being of the proper width, shape and solidity. This is best secured by digging out the surplus material by mechanical means, giving the bed the cor-' rect curve or camber by means of a grading machine, and rolling or tamping the surface, if necessary, to increase its compactness. Steam-shovels have long been used for quarrying and railway work, but their employment for road-making is comparatively new. They