Concrete Roads
and Their Construction

IN OTHER COUNTRIES 111 3 ft. wide on each side composed of the natural earth, gravel or crushed stone. The width was increased to meet local conditions, such as through towns and villages. It was 24 ft. wide for a few miles outside Toronto, and reached a maximum of 50 ft. wide through the town of Oakville. Materials and Method of handling them.—Only tested cement of known quality was used. Before considering any stone for use an inspector visited the quarry, and all details as to the methods of handling, screening, output per day, etc., were recorded. A sample of 100 lb. was carefully selected from different points in the quarry and shipped to the testing laboratory. Here the following tests were made :— (1) Resistance to wear—(2) Resistance to impact—(3) Specific gravity—(4) Absorption—(5) Weight—(6) Granulometric analysis —(7) Voids—(8) Cleanliness. Most of the stone used was limestone or dolomite varying in size from 1J in. down, and had to pass the above tests satis- factorily before being accepted. All sands used were tested for cleanliness, grading and tensile strength, and from the result of those tests certain sands were decided upon to be used. Every car-load of sand or stone was inspected before shipping, and samples were sent in periodically to the laboratory to be tested in order to be sure that they were up to specifications. On these tests, too, was based the exact mixture to be used with a certain aggregate. The mixture adopted was nominally I cement, 1| sand, 3 stone ; but this was checked up by the tests and was varied slightly to suit different aggregates. When there was any change in material the testing engineer gave to the field engineers the correct mixture to be used and the amount of water required for mixing. At convenient points along the road material yards were built alongside the railway, about eight miles apart. New spurs were run into each yard. The cars of material were unloaded by a clamshell bucket into large wooden storage bins with hopper bottoms. The material was then transported to any desired point along the road by means of a narrow-gauge temporary tramway ; the dump cars being loaded automatically from the storage bins,