Appendix F 4.2 Allowances Applied to Basic Binder Application Rate
The following allowances need to be considered to complete the design. Allowances are determined to the nearest 0.1 L/m2 and are cumulative. They must be added to or subtracted from the basic binder application Rate, Bb (L/m²), to determine the design binder application rate, Bd (L/m2).
Surface texture allowance (As)
Surface texture allowance for existing seals
Table 6.3 provides a guide to binder application rate allowances for different sizes of aggregate for a seal over various existing seal sizes and textures.
Table F 3: Surface texture allowance for existing surfacing, As (L/m2)
| Existing surface | Aggregate size of proposed seal | Measured texture depth (mm) | Surface texture allowance (L/m2) |
|---|---|---|---|
| 14, 16 or 20 mm seal | 5 or 7 mm | 0 to 0.3 | Note 1 |
| 0.4 to 0.6 | Note 2 | ||
| 0.7 to 0.9 | +0.1 | ||
| 1.0 to 1.3 | +0.2 | ||
| 1.4 to 1.9 | +0.3 | ||
| 2.0 to 2.9 | +0.4 | ||
| > 2.9 | +0.5 | ||
| 10 mm | 0 to 0.3 | –0.1 | |
| 0.4 to 0.5 | 0 | ||
| 0.6 to 0.7 | +0.1 | ||
| 0.8 to 0.9 | +0.2 | ||
| 1.0 to 1.3 | +0.3 | ||
| 1.4 to 1.8 | +0.4 | ||
| > 1.8 | Note 3 | ||
| 14 mm | 0 to 0.3 | –0.1 | |
| 0.4 to 0.5 | 0 | ||
| 0.5 to 0.6 | +0.1 | ||
| 0.6 to 0.7 | +0.2 | ||
| 0.8 to 0.9 | +0.3 | ||
| 1.0 to 1.3 | +0.4 | ||
| 1.4 to 1.8 | +0.5 | ||
| > 1.8 | Note 3 | ||
| 10 mm seal | 5 or 7 mm | 0 to 0.3 | Note 1 |
| 0.4 to 0.9 | +0.1 | ||
| 1.0 to 1.4 | +0.2 | ||
| 1.5 to 2.0 | +0.3 | ||
| 2.1 to 2.7 | +0.4 | ||
| > 2.7 | +0.5 | ||
| 10 mm | 0 to 0.3 | Note 1 | |
| 0.4 to 0.7 | +0.1 | ||
| 0.8 to 1.1 | +0.2 | ||
| 1.2 to 1.7 | +0.3 | ||
| > 1.7 | Note 3 | ||
| 14 mm | 0 to 0.2 | Note 1 | |
| 0.3 to 0.6 | +0.1 | ||
| 0.7 to 0.9 | +0.2 | ||
| 1.0 to 1.2 | +0.3 | ||
| 1.3 to 1.7 | +0.4 | ||
| > 1.7 | Note 3 | ||
| 5 or 7 mm seal | 5 or 7 mm | 0 to 0.3 | Note 1 |
| 0.4 to 0.9 | +0.1 | ||
| 1.0 to 1.5 | +0.2 | ||
| 1.6 to 2.2 | +0.3 | ||
| 2.3 to 3.2 | +0.4 | ||
| > 3.2 | +0.5 | ||
| 10 mm | 0 to 0.3 | Note 1 | |
| 0.4 to 0.7 | +0.1 | ||
| 0.8 to 1.1 | +0.2 | ||
| 1.2 to 1.8 | +0.3 | ||
| > 1.8 | Note 3 | ||
| 14 mm | 0 to 0.2 | Note 1 | |
| 0.3 to 0.6 | +0.1 | ||
| 0.7 to 0.9 | +0.2 | ||
| 1.0 to 1.4 | +0.3 | ||
| 1.5 to 2.0 | +0.4 | ||
| > 2.0 | +0.5 | ||
| Asphalt/microsurfacing | All | 0 to 0.1 | 0 |
| 0.2 to 0.4 | +0.1 | ||
| 0.5 to 0.8 | +0.2 | ||
| 0.9 to 1.4 | +0.3 | ||
| > 1.4 | +0.4 |
Notes:
- Embedment considerations dominant.
- Specialised treatments necessary.
- This treatment might not be advisable depending on the shape and interlock of aggregates so alternative treatments (surface enrichment, small size seal or others) should be considered.
- For application of aggregate sizes greater than 14 mm, adopt allowances applicable to 14 mm aggregate.
Texture allowance for microsurfacing
For microsurfacing, a typical allowance is between +0.0 to +0.3 L/m2.
Texture allowance for concrete surfaces
The concrete must be primed and, in order to get a satisfactory seal over a well-primed concrete surface, the allowance should be +0.2 to +0.4 L/m2, even on smooth surfaces, to compensate for the lack of aggregate embedment and interlock into the texture of the concrete surface. For broom dragged or tyned surfaces, the allowance can be as high as +0.4 to +0.5 L/m2.
Texture allowance for timber surfaces
Timber may be untreated, primed, coated or impregnated. Similar to concrete, and as a guide, an allowance of between +0.2 to +0.4 L/m2 may be appropriate.
Texture allowance for primes or initial seals
Texture allowance for these seals includes:
- initial seals – a texture allowance is determined similar to existing sealed surfaces
- primes – some pavement materials present a coarse textured surface and it may be possible to measure surface texture. If not, and based on experience, the texture allowance is generally in the order of +0.0 to +0.3 L/m2..
Texture allowance for regulation or patched areas
Variations in texture as well as curing of patching materials should be considered.