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The determination of air voids based on compacted Marshall samples has been regarded in the Netherlands as the weakest point of the Dutch method of design. According to many engineers, these samples do not reflect the true arrangement of coarse aggregate particles in real pavement. Under real-world conditions, displacement of grains and their close arrangement […]

Subsequent to the design of the recipe and its approval, it is time for the pro­duction of an SMA mix. Production control using the Dutch method takes into account the same factors that have been used during SMA design (job mix for­mula [JMF]). The properties of some elements are naturally changeable; this particularly applies to […]

Preparation of samples for an SMA recipe is conducted according to the Marshall method, with a compaction effort of 2 x 50 blows, or in a gyratory compactor, where the number of rotations are selected in such a manner that the specimen bulk density is similar to results obtained from the Marshall method. While designing […]

7.4.2.1 SMA Constituents Coarse aggregates of 2/6 mm are not permitted in an SMA mixture with a grada­tion of 0/11 mm just to guarantee a gap gradation. The sand fraction has to consist of a minimum of 50% crushed stone, whereas the content of air voids according to Rigden and the bituminous number* should form […]

A constant, fixed binder content, exclusively dependent on the size of the maximum particle, D, in an aggregate mix is the most unusual feature of the Dutch method. When designing SMA, the binder content for a given gradation should be taken from the regulations; for example, an SMA 0/11 for heavy-duty traffic should have a […]

According to concept of van de Ven et al. (2003), an SMA mixture probably has no real stone skeleton immediately after compaction. A real skeleton in SMA is cre­ated during service under the effects of traffic and climatic loading when sand and filler grains between the coarse aggregates (skeleton) may be crushed or moved. Accordingly, […]

The first step, as in the U. S. method (see Section 7.2), is determining the volume of the skeleton of coarse particles and the voids between them available for the remain­ing SMA elements. Determining the volume occupied by the coarse aggregate skel­eton consists of defining its density and testing the coarse aggregate compaction (namely, the […]

The principles of designing an aggregate mix and then the content of binder are presented in Figure 7.12. It is an illustration of a telescopic[37] method of creating SMA, which involves inserting consecutive elements into free space (air voids) in a compacted component of a larger size. In other words: • A volume of fine […]

There is a widespread belief among many engineers that SMA, due to its peculiar­ity, should be designed by volume. The volume concept also forms the basis of an experimental method of design applied in the Netherlands. To put it concisely, we can repeat what has been explained in the previous chap­ters of this book as […]

The SMA design procedure consists of the following stages: • Selection of the design aggregate mix using an analysis of the impact of the coarse aggregate content on SMA properties • Determination of the optimum design content of the binder for the selected gradation Step by step, the design proceeds as follows (for SMA 0/11). […]