Asphalt Additives
Pawma Workability-Increasing Additive
Pawma gives asphalt additional workability and allows for application even at low ambient temperatures.
Fields of Application and Use
Pawma is used to increase workability in the production of Bituminous Hot Mixtures (BHM) or Warm Mixture Asphalt (WMA). Various techniques have been developed since the mid-1990s to increase workability in the production of BHM or to reduce the energy consumed by decreasing the mixture and laying temperature.
The following techniques are applied to increase the workability of the Asphalt Mixture:
1) PE waxes, amide waxes or paraffin waxes,
2- Foaming technique and zeolites,
3- Amine-based liquid chemicals.
İstanbul Teknik has developed amine-based chemical Pawma.
Application
PAWMA is used by mixing it with bitumen in advance. The amount of use is between 0.2% and 0.4% of the bitumen weight. This means that approximately 100 to 150 gram Pawma is sufficient for 1 ton asphalt mixture.
The dosage of the additive should be determined on site according to the type of application, whether the asphalt is modified or not, environmental conditions such as ambient temperature and wind. Dosage should be determined on site by producing several batches of PAWMA in different quantities. As each application is different than each other, there is no standard dosage table, and the amount of use should be determined according to the local conditions.
No More Working in Cloud of Smoke.
As the temperature of asphalt mixture is low during the production and spreading phases, the gas release and fume effect is almost negligible in the warm asphalt mixtures prepared by using PAWMA. As the odor and gas releases emitted around are very low, the discomfort to the environment is significantly reduced particularly for urban use. The health of the employees is protected and major contributions are achieved in terms of occupational safety
When it was mandatory to construct a road below 5°C ambient temperature, the aggregate temperature would be increased according to the classical method. If the minimum ambient temperature is below 5°C in the shade, construction is conducted without reducing the aggregate temperature.
PAWMA is produced by using amine compounds just like anti-stripping additives. It positively affects the structure of bitumen and does not impair the chemical and rheological characteristics of bitumen. It increases the stripping resistance and indirect tensile strength of asphalt.
As it does not contain water like in zeolite-based or foaming additives, there is no sensitivity towards water.
One of the most important issues in the application of workability-increasing additives is compression.
Roller operators may apply extra vibration because they will encounter asphalt that behaves more differently than they are familiar with. The planned compression should not be exceeded.
Advantages
It is cost-effective because its amount of use is very low as compared to waxes and zeolites.
Approximate amounts of use for 1 ton asphalt mix:
Pawma
Waxes
Synthetic zeolites
0,1 - 0,15 kg
2,0 - 3,0 kg
2,5 - 3,0 kg
It provides the opportunity to be used even in cold and unsuitable weather conditions. It extends the asphalt road construction season.
As the asphalt mixture remains usable for a long time, it can be transported to longer distances.
It does not have any negative effects on the characteristics of bitumen. It positively improves the characteristics of bitumen and asphalt mixture.
Packaging
It should be stored away from sunlight and moisture. It is supplied in 180 kg barrels.
Technical Specifications
| Pawma | Waxes | Synthetic zeolites |
|---|---|---|
| 0,1 - 0,15 kg | 2,0 - 3,0 kg | 2,5 - 3,0 kg |
Technical Specifications
| Özellikler | Birim | |
|---|---|---|
| Structure | Amidoamine Derivative | |
| Appearance 20 °C | Liquid | |
| Color | Yellow - Orange | |
| Density | 0,93 ± 0,2 | g/cm3 |
| Ph | 7-8 | |
| Flash Point | >150 | °C |
| Viscosity 25 °C | 150 | mPas |
Technical Specifications
| Name of Test | Standard | Unit | Pure Bitumen | Pawma with Pure Bitumen ratio +0,3% | Pawma with Pure Bitumen ratio +0,5% |
|---|---|---|---|---|---|
| Penetration (25 °C, 100 g., 5 s) | TS EN 1426 | dmm | 57,4 | 60 | 57,7 |
| Softening Point | TS EN 1427 | °C | 49,4 | 48,9 | 49,1 |
| Force Measuring Ductility (25 °C, 5 cm/m) | TS EN 13589 | J | 0,05 | 0,04 | 0,02 |
| Flash point | TS EN ISO 2592 | °C | 265 | 260 | 280 |
| Specific Gravity | TS EN 15326 | g/cm3 | 1,040 | 1,035 | 1,038 |
| Brookfield Viscosity (135 °C, 20 rpm) | ASTM D 4402 | cP | 350 | 334 | 312 |
Technical Specifications
| Peeling Strength Test, % | Test Result | Highway Technical Specifications 2013 Limits (Chapter 403-411) | Standard |
|---|---|---|---|
| With Non-Additive AC 50/70 Bitumen | 35-40 | ≥60 | TS EN 12697-11 (EK-A) |
| With AC 50/70 Bitumen and 0,3% Pawma Additive | 95-100 | ≥80 | TS EN 12697-11 (EK-A) |
| With AC 50/70 Bitumen and 0,5% Pawma Additive | 95-100 | ≥80 | TS EN 12697-11 (EK-A) |
Technical Specifications
| Adhesion Test (with Vialit Method) Number of Gravels Dropped, % | Test Result | Highway Technical Specifications 2013 Limits (Chapter 403-411) | Standard |
|---|---|---|---|
| With Non-Additive AC 50/70 Bitumen | 30 | ≤10 | TS EN 12697-11 (EK-B) |
| With AC 50/70 Bitumen and 0,3% Pawma Additive | 8 | ≤5 | TS EN 12697-11 (EK-B) |
| With AC 50/70 Bitumen and 0,5% Pawma Additive | 5 | ≤5 | TS EN 12697-11 (EK-B) |
Technical Specifications
| Name of Test | Dp | Gap Vh | Test Result (kg cm2) | Highway Technical Specifications 2013 Limits |
|---|---|---|---|---|
| Conditional ITS | 2,457 | 3,55 | 8,73 | |
| Unconditional ITS | 2,460 | 3,41 | 10,57 | |
| Tensile Strength Ratio, % | 82,6 | Min. 80 |
Technical Specifications
| Name of Test | Dp | Gap Vh | Test Result (kg cm2) | Highway Technical Specifications 2013 Limits |
|---|---|---|---|---|
| Conditional ITS | 2,470 | 3,04 | 13,08 | |
| Unconditional ITS | 2,469 | 3,04 | 15,09 | |
| Tensile Strength Ratio, % | 86,76 | Min. 80 |
Technical Specifications
| Name of Test | 50 70 Pure Bitumen | Pawma with Pure Bitumen ratio 0,4% | Specifications Standard |
|---|---|---|---|
| Mass Change (%) | 0,23 | 0,10 | TS EN 12607-1 |
| Increase in Softening Point (ºC) | 7,6 | 4,3 | TS EN 1427 |
| Permanent Penetration (%) | 51,0 | 61,7 | TS EN 1426 |
| BBR (Flexural Creep Stiffness) (ºC) S | -12 | -12 | TS EN 14771 |
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