Hot Rolled Asphalt and Asphalt Concrete (Macadam) - Ministry of ...

Specification 12 Hot Rolled Asphalt and Macadam for Airfields 6 Design and Composition of Pervious Macadam
TABLE 6.1 PERVIOUS MACADAM GRADING
LIMITS
Sieve (mm) Mass passing (%)
40
31.5
20
14
100
90 – 100
10 – 30
4 – 6
6.4.2 Fine aggregate shall not be added.
6.4.3 The mixture shall contain by mass of the
total mixture either:
• 2 % of hydrated lime;
• 4 % of Ordinary Portland Cement, by mass of
the total aggregates; or
• Up to 1.5 % of Stearine Amine or other approved
wetting agent by mass of the total binder content
so long as it can be demonstrated to the
approval of the Project manager that no
drainage of the binder from the aggregate takes
place during transport to the point of placing.
(NOTE 1. Project Manager to delete final option when
not required for specific job specifications; advice given in
Clause Z.9 of Appendix Z.)
(NOTE 2. The Contractor shall state which filler
aggregate option he chooses.)
6.4.4 Depending on the application, the binder
selected shall be either:
• 160/220 paving grade bitumen; or
• 160/220 paving grade with an approved
modifier.
Pervious Macadam using unmodified 160/220
paving grade bitumen shall only be used for small
works and for remedial works to French drain
toppings with the approval of the Project Manager.
(NOTE. Pervious Macadam using 160/220 paving grade
bitumen and a modifier will have a higher binder content
than unmodified Pervious Macadam, and is expected to
have improved durability; it should be used for new
works.)
6.5 MIXING, DELIVERY AND
COMPACTION TEMPERATURES
6.5.1 Pervious Macadams shall be mixed and
delivered within the material temperature limits
given in Clause 5.12 of BS EN 13108-7.
6.5.2 Pervious Macadams shall be laid and
compacted within the material temperature limits
given in Table 6.2.
TABLE 6.2 PERVIOUS MACADAM
TEMPERATURES
Paving Grade of Min. Temperature (°C)
Bitumen Paver-out * Compaction ‡
160/220 85 65
160/220 plus natural
rubber
85 65
160/220 plus other
modifier
† †
† In accordance with the Supplier’s
recommendation.
* Recommended values that are required in order
to achieve the maximum available compaction
time. They are useful for monitoring purposes to
ensure that adequate compaction time is
available.
‡ These values are the mid-layer temperatures at
which completion of compaction should have
been achieved.
6.5.3 The Contractor shall check the temperature
of the delivered load and the load in the hopper
according to the method in BS EN 12697-13 at the
following intervals:
• whilst discharging from the delivery lorry; and
• at any time the Project Manager or his
representative directs.
6.5.4 The rolling procedure shall have been
completed before the surfacing temperature has
fallen to the minimum compaction temperature.
18 July 2010