Concrete Roads
and Their Construction

IN THE UNITED KINGDOM—METROPOLITAN 9 It was not proposed to surface the road with tar, but to test it, at any rate for some months, as an unsurfaced concrete road. An experiment was, however, being made in material in the fol- lowing way with a view to ascertaining which treatment produced the best results in point of wearing quality. The length of the road was, for this experiment, divided into four sections, in each of which a different treatment has been adopted for the wearing coat, thus Section 1 . Wearing coat plain 3 : 1 concrete. Section 2 . Same as section 1, but sprinkled with powdered carborundum. Section 3 . Plain 3 : 1 concrete with a different brand of cement. Section 4 . Same as No. 3, but sprinkled with carborundum. The carborundum was laid to prevent horses from slipping. It was, of course, applied while the concrete was wet, and was not tamped, but allowed to sink in by its own. weight. After the concrete had set sufficiently hard the surface was covered with damp sand to a depth of 2 in. or 3 in., and the traffic was kept off the road for a month. The cost of this road was 17s. per super, yard, but now that the men have experience in this form of work it is expected that the next concrete road will be laid at a cost of from 10s. to 12s. per yard. The road has been open to traffic for eighteen months, and w'th the exception of two or three small surface cracks and a pot-hole at one of the joints, the road is in a good condition. In a report, dated July, 28, 1920, the Borough Surveyor states that this road was tar-sprayed for the first time on May 10, 1920. “It was treated with a very thin coat of tar and covered with fine sand. The present condition is good.” Latest Report.—The Borough Surveyor, Mr. H. Morley Lawson, in his report in November, 1920. on the present condition of the road, attributes the pot-hole, mentioned above, to careless floating after the surface screed was removed ; this conclusion was arrived at from the fact that all the other joints are perfect and show little deterioration. The cost of repairing this pot-hole will be small. As before stated, the road takes all the heavy traffic going to and from the Supply Reserve Depot, which is ever increasing, and on account of the narrow width o£ the road the test to which it will be submitted is severe.