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Encouraging results of SMA resistance to deformation are being confirmed both in laboratory tests and on trial sections of pavements in operation. Clearly, in the majority of cases an SMA mixture is actually better than asphalt concrete (AC). Conversely, not every test method confirms that SMA possesses the better charac­teristics. The outcome depends on the […]

Basically, the type of aggregate mix, the type and content of binder, and the amount of air voids (Va), voids in mineral aggregate (VMA), voids filled with binder (VFB) are taken into account when analyzing the resistance to deformation of an asphalt mixture course. The development of rutting is a fairly complex process depending on, […]

Resistance to permanent deformation is the best known and most recognizable fea­ture of courses made from SMA mixtures. This resistance has its origins in the very strong skeleton of coarse particles of an aggregate mix. This issue was already thor­oughly deliberated in Chapters 2, 3, and 6, therefore only some additional informa­tion about testing that […]

Constituent materials, design, production, and placement of a stone matrix asphalt (SMA) mixture were discussed in previous chapters. It would not make sense to spend this much time discussing the mix if SMA courses had not been characterized with many strong points. Conversely, it should be openly admitted that it is not a perfect mixture, […]

It happens occasionally that an additive dosing system does not work correctly. When that happens, there is either too much or too little antistrip additive in the mixture. Its deficiency does not directly affect the quality of the mixture during production or placement. Effects may appear in the form of a lower durability of the […]

Although susceptibility to polishing is not a problem at the construction stage but a result of an earlier decision, greater pavement slipperiness becomes apparent after some time of pavement operation. The source of this problem is at the design stage of an SMA composition. The proper selection of an aggregates for a mixture and the […]

Fat spots in wheel paths appear at the time of SMA pavement trafficking. They are located in the paths of vehicle wheels and can run up to several hundred meters (pos­sibly including the whole SMA wearing course of a road) (Figure 11.34). We have to go back to the chapter on designing an SMA mixture […]

The last problem encountered when spreading SMA (and other asphalt mixtures, too) is unevenness caused by the approach of a paver on mixture residue left over on a bottom layer. Figure 11.33. shows how such residue builds up. Different type of scrapers, sweepers, and other similar inventions fixed to the paver cannot fully protect it […]

Cracking of the mixture under rollers may be observed when there is no bond between an SMA course and the layer under it or when the temperature of the SMA mixture is too high. The temperature of the mixture during compaction is easy to control, therefore it will not be a topic of this section. […]

Transverse (or lateral) porosity can often be seen on pavements made during unfa­vorable weather conditions (in autumn or in winter) or when the mixture has been FIGuRE 11.25 Beginning of a work site—effect shown years later, a consequence of spreading too cool a mixture at the beginning of the work site. (Photo courtesy of Krzysztof […]