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The existing pavement facilities should be prepared prior to placing the mixture of a wearing course. This preparation should result in the following: • Appropriate, tight, and durable bonding between asphalt course and facilities (e. g., with the use of suitable polymer modified asphalt tapes [Figure 10.7]) • Protection against damage or infiltration of excess […]

The rule for SMA surface preparation is the same that as for other binder courses. The surface of the underlying course should be even, clean, and free from dirt that could disturb the appropriate bonding of the laid-down mixture with the layer underneath. Any soiling of the surface (Figure 10.6) should be removed from the […]

There are additional requirements regarding issues such as wind speed at the laydown site in many national specifications. Let us take the Polish guidelines WT2 2008, for instance, in which the maximum allowable wind speed has been set at 16 m/sec (58 km/hr). The values of wind speed at the construction site are undoubtedly a […]

The limitation of minimum temperatures of SMA laydown has been commonly understood and adopted; however, it is quite a different matter when laying down the SMA mixture on an underlying layer that has an excessive temperature, as in the following examples: • On a recently placed intermediate course that has not yet cooled • While […]

Due to the resistance to compaction provided by the coarse aggregate skeleton, SMA mixtures can cause problems during laydown. Thus in almost all countries that have adopted SMA, some additional requirements on conditions at the work site must be observed, including the appropriate temperature, wind velocity, and the absence of rain. 10.2.1 Minimum Temperature of […]

Special self-propelled hoppers (e. g., MTVs) have been used to avoid segregation dur­ing the discharge of a mixture from the dump truck to the paver hopper and to minimize the risk of placing cool mixture (by remixing). These mobile machines operate between the dump truck and the paver to eliminate any contact between the two. […]

The main objective of transporting a mixture from the asphalt plant to the laydown site is to deliver the mix without changing its properties and in a state that allows for appropriate placement and compaction. Minimizing heat loss and preventing seg­regation of the mixture constituents are two of the most important issues regarding transportation. Requirements […]

Once the SMA has been produced at a hot mix plant, it must be transported to the job site where it will be placed and compacted. This chapter describes issues that need to be considered during this stage of the construction process. 10.1 TRANSPORT OF THE MIXTURE TO A LAYDOWN SITE While it may seem […]

Today almost all asphalt plants are computer controlled. It is worthwhile mentioning the necessity for caution during SMA production. This also applies to these modern asphalt plants. Usually such machines give personnel a feeling of confidence and a sense of complete control over the production process. However, many instances have proved that an excess of […]

Issues concerning procedures for production of bituminous mixtures under EN 13108-21 and specified tolerances are discussed in Chapter 14. 9.5.2 Other Examples of Production Control Some brief examples from around the world include • In some countries, the accuracy of stabilizer dosage is ±10% of its mass as determined in a laboratory formula. • If […]