Concrete Roads
and Their Construction

CHAPTER VIII SUGGESTIONS FOR A FORM OF SPECIFICATION FOR CONCRETE ROADS In submitting the following suggestions, it must be clearly under- stood that they are put forward more in the light of a useful guide when, drawing up a specification for making concrete roads, than laying down any hard and fast formula. There will always be found, from time to time, certain conditions in road construction requiring special treatment, and undoubtedly these are matters which will naturally engage the close attention of the road engineer, surveyor or contractor in charge of the work. It may be stated, however, that the suggestions set out have been compiled after much study and observation of concrete road work in this country, and in addition, valuable aid has been rendered by those who have had considerable experience in the most modern and successful methods of concrete road-making in America. These notes are, therefore, presented in the full belief that they will be found reliable and instructive in framing the definite principles of a specification. Materials 1. Cement.—The cement shall be supplied by a British manufacturer of repute, and shall comply with the requirements of the British Standard Specification for cement in force for the time being. It shall be of the “ slow-setting ” quality as defined in that specification. Conditions as to testing, delivery and storage shall be agreed between the vendor and purchaser. 2. Aggregates.—Great care shall be taken in the selection of the aggregates. The actual materials to be used must depend upon local circumstances, subject to the following limitations :—• No natural deposits of sand and gravel shall be used without washing, screening, and grading to comply with the conditions hereinafter laid down. If crushed stone is used it shall be screened, graded, and, if 177 N