Hålrumshalt hos asfaltborrkärnor: utvärdering av provningsmetoder för bestämning av skrymdensitet

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Henrik Broms

pavements. It is usually calculated by means of the bulk density and the maximum density of the core. In this project the following four methods for determination of the bulk density have been studied:

  • Water method –Saturated surface dry specimen
  • Paraffin sealing method
  • Caliper method
  • Vacuum sealing method

The Swedish Transport Administration applies today the first three methods for determination of bulk density. The fourth method, the vacuum sealing method, has only been used on a small scale in Sweden. The paraffin method is used as the reference method for all asphalt types except porous asphalt, but the application and removal of the paraffin layer is complicated. The water method is easier to perform, but coarser void structure of the specimen increases the risk of underestimation of the void content. The caliper method has lower precision and is used only for porous asphalt. The vacuum sealing method can be used for all asphalt types and thus replace all of the other methods. This report compares the water method with the paraffin method in order to clarify its applicability. The vacuum sealing method is also compared with the paraffin method and the caliper method. The project included more than 70 cores from five different asphalt paving objects with the Swedish mixture types ABT16 (dense asphalt concrete), ABS16 (stone mastic asphalt) and ABb22 (asphalt concrete - binder course). The void contents according to the paraffin method where below 10 per cent for most of the specimens, but for 16 specimens (ABT16) the void contents were in the range of 11 to 15 per cent.

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