Recent developments in asphalt techniques for hydraulic applications in the Netherlands

Since 1945 and particularly after the flood in 1953 new means were developed to accelerate the construction of hydraulic engineering projects in the Netherlands. This development was initially related to paving sand dikes with durable materials. The available knowledge of the mechanical properties of asphaltic mixtures and the experience with asphalt paving technology proved to be very useful for this purpose. It enabled the application of local minerals bound with asphalt, instead of the classical stone materials and tough clay which are not always available in sufficient quantities and are difficult to handle with mechanical equipment. The success of the first projects promoted application of asphaltic mixtes in a much wider field such as the construction of large harbour dams. The paper also describes construction practices involving mixing, handling and placing of mixtures of various compositions and properties for different types of construction. In several cases the mixtures have to be applied under unusual circumstances, generally at a high rate, and always in an economical way. The most interesting asphaltic materials to be considered are: 1 . Lean sand asphalt 2. Sand-mastic asphalt 3. Normal dense asphaltic concrete k. Stone asphalt ("Bitumarin concrete")Deltawerke