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The application of gradation limits has become the most commonly used method for designing SMA mix composition. This method involves gradation analyses of all the constituent aggregates, including the filler, followed by balancing the proportions of all the aggregates in such a way that the ultimate gradation curve is situated between the adopted gradation limits. […]

The 30-20-10 rule suggests that proper stone-to-stone contact is created if the per­centages of aggregate passing sieves of 0.075 mm, 2.36 mm, and 4.75 mm equal 10%, 20%, and 30%, respectively, which should provide for the appropriate discontinuity in the gradation. After comparing this rule with the data of Table 6.4, one can see that […]

The requirements for gradation of SMA mixtures have been provided in the European standard PN-EN 13108-5 (see Chapter 14). This standard does not set out the crite­ria and conditions for selecting the particular gradation of a mixture. Establishing these criteria remains the responsibility of each CEN-member state. In Figures 14.2 through 14.5, examples of gradation […]

Coarse-graded mixtures make stronger skeletons. That is why the majority of requirements for SMA contain a noticeable tendency toward increasing the maxi­mum particle size in a mixture in conjunction with an increase in the traffic loading. When selecting a mixture, both the strengths and weaknesses of an accepted solutionshould be considered; mixtures with larger maximum […]

In bituminous mixtures, the adopted rule used to be that the thickness of a course should not be less than 3.5 times the nominal maximum aggregate size (NMAS) in a given mixture. However, due to problems with compaction, usually 3.5-4.0 times the NMAS in a mixture is normally suggested as the appropriate thickness of an […]

No matter the method applied when designing the SMA composition, the first step that must be taken is establishing the maximum particle size in the aggregate mix. The following factors should be taken into account when considering this issue: [23] 6.1.1 In Which Course? Due to the outstanding performance of SMAs in surface courses, they […]

Stone matrix asphalt (SMA) mixtures and courses made from them have many strengths. Naturally, these mixtures must be well-designed, but that attribute has various shades of meaning. A review of publications on this subject has not revealed a method that is clearly “the best.” There is as wide a variety of design methods as there […]

Slags of different sorts may be used in SMA mixtures, providing they meet suit­able requirements. For example, in Europe these can be determined in the National Application Documents for the EN 13043 standard; examples were presented in Table 5.2 (for more information, see Chapter 14). When considering the possibility of using slag in an asphalt […]

Generally, most regulations do not recommend using reclaimed asphalt or simply do not allow recycling old asphalt layers into SMA. However, some good test results do exist for SMA mixtures with reclaimed asphalt (Perez et al., 2004). The requirements for reclaimed asphalt to be used for SMA according to the EN 13108-5 standard are discussed […]

The requirements for cellulose fibers according to PANK 2000 have been divided into obligatory and recommended ones as follows: • Obligatory requirements • Water content according to PANK 3103: < 8.0% (m/m), • Instantaneous heat resistance (mass loss) according to PANK 3104: < 7.0% (m/m) • Recommended values for bulk fibers • Bulk density according […]