Document ID: chunk:federal_register_of_legislation:F2021C00509:front:0:p49
Version: federal_register_of_legislation:F2021C00509
Segment Type: other
Provision Reference: 
Character Range: 141489–144754

and of a material with a high resistance to crushing;
         The chippings used in the mix shall be washed;
         No extra chippings shall be added onto the surface;
         The binder hardness expressed as PEN value shall be 40-60, 60-80 or even 80-100 depending on the climatic conditions of the country. The rule is that as hard a binder as possible shall be used, provided this is consistent with common practice;
         The temperature of the mix before rolling shall be chosen so as to achieve by subsequent rolling the required voids content. In order to increase the probability of satisfying the specifications of paragraphs 2.1. to 2.4. above, the compactness shall be studied not only by an appropriate choice of mixing temperature, but also by an appropriate number of passings and by the choice of compacting vehicle.

Table 1: Design guidelines

                                                                           Target values             Tolerances
By total                                                                   By mass of the aggregate
mass of mix
Mass of stones, square mesh sieve (SM) >2mm Mass of sand 0.063 < SM <2mm   47.6%  50.5%              +/- 5
Mass of filler SM < 0.063mm                                                38.0%  40.2%              +/- 5
Mass of binder (bitumen)                                                   8.8%  9.3%                +/- 2
Max. chipping size                                                         5.8%  N.A.                +/- 0.5
Binder hardness                                                            8mm                       6.3-10
Polished stone value (PSV)                                                 (see para. 3.2.2. (f))
Compactness, relative to Marshall compactness                              > 50
                                                                           98%

4. Test method

4.1. Measurement of the residual voids content

           For the purpose of this measurement, cores have to be taken from the track in at least four different positions which are equally distributed in the test area between lines AA and BB (see Figure 1). In order to avoid inhomogeneity and unevenness in the wheel tracks, cores should not be taken in wheel tracks themselves, but close to them. Two cores (minimum) should be taken close to the wheel tracks and one core (minimum) should be taken approximately midway between the wheel tracks and each microphone location.
           If there is a suspicion that the condition of homogeneity is not met (see para. 2.4.), cores shall be taken from more locations within the test area. The residual voids content has to be determined for each core, then the average value from all cores shall be calculated and compared with the requirement of paragraph 2.1. In addition, no single core shall have a voids value which is higher than 10%. The test surface constructor is reminded of the problem which may arise when the test area is heated by pipes or electrical wires and cores must be taken from this area. Such installations must be carefully planned with respect to future core drilling locations. It is recommended to leave a few locations of size approximately 200 x 300 mm where there are no wires/pipes