Asphalt Additives
NovaPrene Polymer Bitumen Additive
The most commonly used additive in bitumen modification is styrene butadiene block copolymers (SB-BK). These elastomeric additives, some of which are also known as SBS, significantly improve the properties of bitumen when they are added to bitumen. As a result, the performance of the asphalt mixture roads constructed by using polymer modified bitumen (PmB) made based on this method against the following factors have been excellently improved in the course of time:
- wheel marks (permanent deformation),
- thermal cracking,
- fatigue cracking,
- their anti-aging performance has improved tremendously.
Fields of Application and Use
It is a high performance PmB additive that consists of two components as liquid NovaPrene-P and solid NovaPrene-S. It is designed to be used together.
NovaPrene-P Liquid Component:
It contains polyphosphoric acid. It is a high saturation polymer mixture that has inorganic structure.
NovaPrene-S Solid Component:
It is an elastomeric-based polymer modified bitumen additive made by the combination of different polymers from the Styrene Butadiene Block Copolymer (SB-BK) family. NovaPrene-S is a molecular weight SB block copolymer with high diblock, triblock mixture.
When NovaPrene-P is added into bitumen, it forms ionic bonds by reacting with asphaltenes, which exist in bitumen in clusters and do not contribute to the formation of the continuous polymer phase. As a result of the breaking of the hydrogen bonds, asphaltenes transform from a large structure into smaller molecules, and their molecular weights decrease.
The molecular weight of asphaltenes is very high as compared to other components of bitumen. Asphaltenes exist in tightly-clustered structures called micelles. As asphaltenes are packed in micelle structure through very strong bonds, the modifying additives or polymers may not affect this structure.
NovaPrene-P breaks the large asphaltene structure through the points where the bonds are weak, reduces the asphaltene molecular weight, disperses them in the maltene phase and helps with the formation of a continuous phase.
In this way, the NovaPrene-S polymer can also affect the areas where it could not reach before, making it easier to form a continuous phase in maltene. The amount of polymer required is reduced.
As a result of the change in the particle structure and morphology of bitumen, the effect of the maltene phase in the bitumen increases. This creates a more suitable environment for the formation of the continuous polymer phase. It is sufficient to add NovaPrene-P at 0.3 - 0.5% by weight to hot bitumen and mix it for 30 minutes.
In this way, the first step of a mechanism that can ensure the formation of a continuous phase by using less amount of NovaPrene-S to bitumen is started.
Styrene Butadiene Block Copolymer (SB-BK)
SB-BK is an elastomeric, high molecular weight, synthetic rubbers with hard polystyrene blocks at its ends where these polymers are bonded to each other through flexible polybutadiene bridges.
The most commonly used polymer in the asphalt sector is SBS (styrene-butadiene-styrene). When polystyrene is heated above the glass transition temperature of 90 ºC, the molecule softens and becomes fluid. In this way, it becomes easier to mix with bitumen. When it is cooled below 90 ºC, polybutadiene blocks lock the polystyrene blocks, and a physical cross-bonding occurs.
This bonding is very rigid due to its polystyrene structure, but it is also flexible due to its polybutadiene bridges. This physical locking that occurs as a result of cooling restores to its original form above 90 ºC, and the workability is achieved.
Bitumen Modification with NovaPrene
When SB-BK is added into bitumen, it interacts with the malten phase in bitumen, and expands up to 10 times of its volume. In this way, it increases the performance of bitumen by forming a three-dimensional network structure. The change of pure bitumen characteristics is only possible when a continuous polymer phase is formed.
The formation of continuous polymer phase occurs with the typical S curve. The continuous polymer phase is formed when the amount of SB-BK added is only used with a certain amount or reaches a certain ratio. Starting from that moment, a sudden increase occurs in the softening point of the polymer modified bitumen.
The ratios of malten and asphaltene in bitumen determine the time that the continuous polymer phase will occur when a particular amount or ratio of SB-BK is used. The SB-BKs expand in the malten phase in bitumen and may not interact with asphaltene, which exists in bitumen in the form of micellar structure.
To obtain a continuous polymer phase in bitumen with high asphaltene ratio; a higher amount of SB-BK is required when compared with bitumen that has a high malten phase.
When the PmB that has been made by using SB-BK is cooled, resistance increases as a result of the above-mentioned physical cross binding. Thermal and fatigue resistance and aging resistance of the PmB asphalt mixtures that are made based on this method increase extraordinarily.
The most remarkable characteristics of the NovaPrene system is that it aims to ensure 25% saving on the ratio of use of the standard polymer that should be added into bitumen. Of course, the criteria that will determine the final ratio of use are the type of bitumen to be used and the PG performance degree to be achieved.
Bitumen Structure
Bitumen is a complex structure that consists of the following components.
Advantages
High storage stability
Lower investment costs
Increased resistance to wheel marks, fatigue cracking, thermal cracking and peeling.
Ensures the production of PmB faster and with high capacity thanks to lower energy consumption
Saving on the amount of polymer to be used.
As a result of use of a lower amount of polymer, an asphalt mixture with lower viscosity is obtained. Ensuring easier workability particularly in Stone Mastic Asphalt (SMA) applications.
Improved performance against aging (oxidation).
Application
Styrene Butadiene Block Copolymers (SB-BK) are an elastomeric, high molecular weight, synthetic rubbers with hard polystyrene blocks at its ends where these polymers are bonded to each other through flexible polybutadiene bridges.
The most commonly used SBS (styrene-butadiene-styrene) in the asphalt sector is SB-BK polymer. As opposed to the known SBSs, NovaPrene-S in the form of fine powder can easily dissolve and disperse in bitumen. It is recommended to mix for 2-4 hours in the bitumen tank so that the modification can occur completely.
Bitumen with Hipren-P is heated to a temperature range of 170-180 ºC. NovaPrene-S is added into the tank. The mixture is mixed with a standard mixer for 2-4 hours in the bitumen tank.
We propose an efficient and cost-effective PmB solution by using NovaPrene-S at 2.5-3.5% ratio in 0.4% NovaPrene-P bitumen based on the suitable formulation works according to the bitumen type used and the level of performance required to be achieved.
Packaging
It should be kept in its sealed packaging protected from moisture. Do not expose it to sunlight.
NovaPrene S: in 500 kg big bag packaging
NovaPrene SK: in 500 kg big bag packaging
NovaPrene P: in 1500 kg IBC tank
Technical Specifications
Technical Specifications
| Specification | Unit | Typical Value | Test Method |
|---|---|---|---|
| Molecular Structure | Polymer | ||
| Active Agent | Inorganic Acid | ||
| Physical appearance | Clear Liquid | ||
| Color | 21 | ||
| Specific gravity | g/cm3 | 1,95 | ASTM D 792 |
| Viscosity (@ 25 ºC) | cP | 2800 | ASTM D 4402 |
| Evaporation | ºC | >300 | ASTM D 5668 |
| Active agent | % | 100 |
Technical Specifications
| Specification | Unit | Typical Value | Test Method |
|---|---|---|---|
| Molecular Structure | SB kopolimer | ||
| Physical appearance | Fine Powder | ||
| Styrene content | % | 28 | |
| Butadiene content | % | 72 | |
| Specific gravity | g/cm3 | 0,94 | ASTM D 792 |
| Volatile substance (@ 25 ºC) | % | 0,21 | ASTM D 5668 |
| Ash content | % | 5,0 | ASTM D 5667 |
| Molecular weight | Dalton x 1000 | 250-400 | ASTM D 5296 |
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