Concrete Roads
and Their Construction

IN THE UNITED KINGDOM—IRELAND 67 carriage-way of Blackwood Crescent, Edinburgh, 441 feet long and 33 feet wide, was laid in July, 1873. The construction was a 4-inch base of 2-inch broken stone, rolled, and a 5-inch coat of IJ-inch whinstone grouted with 1| parts of fine riddled sea gravel and 1 part Portland cement, well beaten down. No reinforcement was used, and the road has never been surfaced with any other material. I he city road surveyor, Mr. James Sims, reporting on this road on November 16, 1920, states that the surface is still in fair condition and, what is very remarkable, the total cost of main- tenance has been but £40 since the road was laid over forty-seven years ago. Gillespie Crescent, Edinburgh, was laid about the same period and by a somewhat similar method. Ireland Glengormly, Belfast, Antrim.—In August, 1915, a short length of rein- forced concrete road (48 yds.) waslaidinthe Belfast Rural District about four miles oatside the boundary of the borough of Belfast. I his was one of three experimental lengths on a portion of the Antrim main road where maintenance has always proved to be difficult and expensive on account of the boggy nature of the subsoil. I he width of the carriage way is 30 ft., and there is a footpath 6 ft. wide on the north-east side of the road, as well as a grass verge of about the same width on the south west side. Ihe specification adopted for the work was the one used for the Kent experimental length, with the exception that the con- crete, instead of having a uniform thickness of 6 in., was made 7£ in. thick at the middle of the road, reducing to 6 in. at the sides. The road was laid in half widths, and each half width in 10-yd. lengths. After the foundation bed had been prepared a 2-in. layer of concrete was laid, and on this the reinforcement was placed longi- tudinally, with 4-in. overlap where the separate sheets joined. On account of the sheets overlapping, the reinforcement did not come quite to the edge of the 30-ft. width of the concrete, but the width outside the reinforcement was given an exti’a thickness of 3 in. underneath, being 9 in. thick for a width of 12 in. The