Concrete Roads
and Their Construction

44 CONCRETE ROADS Kent On the Main London-Dover Road.—In the autumn and winter of 1914-1915 a trial length of concrete road 300 yds. in length was laid near Gravesend. During the time of its construction the weather conditions were most unfavourable, and as it was on a section of the highway from which the traffic could not easily be diverted, it became necessary to make one-half of the length of the road at a time. The original specification provided that the concrete should be of a 6 : 1 proportion throughout, that is to say, one part of cement to six of aggregate, including sand—certainly not a rich concrete. That portion of the road laid in this manner was, after its completion, tar dressed, probably before the con- crete was properly set. Heavy traffic was put upon it in its early days, and, in consequence, partial disintegration ensued. On the other side, where a bed of 4| in. of 6 to 1 had been put in with a metal mesh reinforcement above it, the authorities consented to a richer concrete being used for the surface, and this consisted of 1| in. of 3 to 1. This road was opened for traffic on March 15, 1915. Nearly six years have elapsed since its construction, and the section last-mentioned, which has never been tar-sprayed or coated with any bituminous material, is still as good as when it was first used, except for a few slight abrasions where the transverse joints were put in. The good condition of this part of the road has on more than one occasion been referred to by Mr. H. T. Chapman, the County Surveyor of Kent. Latest Report.—At the Institute of Municipal and County Engineers in July, 1919, Mr. H. T. Chapman said that the portion which was topped with 3 to 1 concrete was practically as good as when laid, and there were no signs of disintegration or cracks, except at the expansion joints, and we may further add that he is of opinion that the description given above still holds good in 1920. Monmouthshire The Main Road from Newport to Cardiff.—The main Newport to Cardiff road is probably one of the most heavily trafficked roads in South Wales. This road, although specially treated, had never been quite satisfactory, the poor subsoil being to some extent