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Pavement

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Appendix E 2.4 Selecting the Proportion of Cutter Oil

Table E 1 is a guide to the concentration of cutter oil that should be added to PMBs. Table E 1 refers to the use of cutter oil in single application seals or the second application of double/double seals. In double/double seal applications, where the second application is applied with little or no trafficking between applications, the proportion of cutter oil in the first application should be reduced to a maximum of 4 parts.

In SAMI applications, where the seal is to be covered with asphalt within a short period (e.g. several days), it is undesirable to add any cutter oil. However, if used, the maximum added should not exceed two parts of cutter oil.

Table E 1: Guide to cutting practice for PMBs

Guide to cutting practice for PMBs (1), (2) (parts by volume of cutter oil to be added to 100 parts of PMB measured at 15 °C (3), (4))
Pavement temperature (°C) (5)Traffic v/l/d* (traffic used to design rates of application)Class of PMB (2, 3)
S10ES15ES20ES35ES45R (6) S15RF
20–25

< 1000
≥ 1000

6
4

6–8
4–6

8
6–8

6
4

10
8

26–32

< 1000
≥ 1000

4
2

4–6
2–4

6
4–6

4
2

6–8
6

33–38

< 1000
≥ 1000

2
2

2–4
2

4
2–4

2
2

6
4–6

39–45

< 1000
≥ 1000

0–2
0–2

2
2

2
2

0–2
0–2

4–6
4

> 45All traffic0–2220–24
  1. In SAMI applications, where the seal is to be covered with asphalt within a short period, it is undesirable to add any cutter oil at all, and the maximum added should not exceed 2 parts of cutter oil.
  2. Proportions of cutter oil refer to use in single/single seals or the second application of double/double seals. In double/double seal applications, where the second application is applied with little or no trafficking between applications, the proportion of cutter oil in the first application should be reduced to 2–4 parts maximum.
  3. Where cutter proportions are added as a percentage of total binder, the proportions shown here as parts per 100 parts of PMB may be taken as a reasonable approximation of percentage by volume.
  4. At high rates of application of PMB, say over 2 L/m², the cutter oil may be reduced by 2 parts.
  5. Pavement temperatures used to determine the proportion of cutter oil should consider the effect of shaded areas of pavement and cooling of pavements at the end of the day.
  6. Pre-blended crumb rubber (R classes) may contain combining/process oils that influence the proportion of cutter oil required. Where appropriate, manufacturer’s guidelines should be followed.

* v/l/d = vehicles per lane per day.

In aggregate retention applications using binders with low levels of polymer, e.g. S10E and S35E, or small proportions of crumb rubber (≤ 10%) the binder should be cut back as per C170 bitumen. A guide to standard cutting practice with C170 bitumen is provided in Sprayed Seal Cutting Practice (Austroads 2010d).

Proprietary blends of PMB should be cut back in accordance with the recommendations of the manufacturer.

Multigrade bitumens may be cut back using the same proportions of cutter oil as that used for C170 bitumen.

Table E 1 is based on the assumptions that good work practices have been adopted and good quality aggregate is adequately precoated.