Document ID: chunk:federal_register_of_legislation:F2021C00509:reg:6:p2
Version: federal_register_of_legislation:F2021C00509
Segment Type: reg
Provision Reference: reg 6 (pt 2/10)
Character Range: 202955–205911

the required physical characteristics as well as the test methods for these characteristics.

2. Required characteristics of the surface

          A surface is considered to conform to this standard provided that the texture and voids content or sound absorption coefficient have been measured and found to fulfil [all] the requirements of paragraphs 2.1. to 2.4. below and provided that the design requirements (para. 3.2. ) have been met.

2.1. Residual voids content

          The residual voids content, Vc, of the test track paving mixture shall not exceed 8%. For the measurement procedure, see paragraph 4.1.

2.2. Sound absorption coefficient

          If the surface fails to conform to the residual voids content requirement, the surface is acceptable only if its sound absorption coefficient, alpha , < 0.10. For the measurement procedure, see paragraph 4.2. The requirement of paragraphs 2.1. and 2.2. is met also if only sound absorption has been measured and found to be alpha < 0.10.
          Note: The most relevant characteristic is the sound absorption, although the residual voids content is more familiar among road constructors. However, sound absorption needs to be measured only if the surface fails to conform to the voids requirement. This is because the latter is connected with relatively large uncertainties in terms of both measurements and relevance and some surfaces may therefore be rejected erroneously when the voids measurement only is used as a basis.

2.3. Texture depth

          The texture depth (TD) measured according to the volumetric method (see para. 4.3. below) shall be:
          TD > 0.4 mm

2.4. Homogeneity of the surface

          Every practical effort shall be taken to ensure that the surface is made to be as homogeneous as possible within the test area. This includes the texture and voids content, but it should also be observed that if the rolling process results in more effective rolling at some places than others, the texture may be different and unevenness causing bumps may also occur.

2.5. Period of testing

          In order to check whether the surface continues to conform to the texture and voids content or sound absorption requirements stipulated in this standard, periodic testing of the surface shall be done at the following intervals:

           (a)     For residual voids content or sound absorption:
            when the surface is new;
            if the surface meets the requirements when new, no further periodical testing is required. If it does not meet the requirement when it is new, it may do later because surfaces tend to become clogged and compacted with time.
           (b)     For texture depth (TD) :
            when the surface is new;
            when the noise testing starts (NB: not before four weeks after laying) ;
            then every 12 months.

          3. Test surface design

          3.1. Area

          When designing the test track