In the process of waterproofing or restoration of anticorrosion coating of the car, a situation often arises when bitumen It is too thick for quality application. This can occur due to prolonged storage, temperature disturbances or the initially high viscosity of a product intended for hot use. Attempting to use such a material without prior preparation will lead to the formation of an uneven layer, air bubbles and, as a result, a decrease in the protective properties of the coating.
The right choice solvent and compliance with the mixing technology are critical stages in the preparation of mastic. Errors at this stage can not only spoil the material, but also create a fire hazard situation or lead to detachment of the waterproofing after a short time. In this article, we will discuss in detail what chemicals are suitable for diluting bitumen, in what proportions they should be used and what safety measures should be followed.
It should be noted that there is no universal answer to the question of “what to dilute” since the choice depends on the type of bitumen, the conditions of application and the required drying speed. Organic solvents Some of them evaporate instantly, others take time to polymerize. Understanding the chemical compatibility of components is the key to a long-term result.
Chemical nature of bitumen and the principle of dilution
Bitumen is a complex mixture of high molecular weight hydrocarbons, resins and asphaltenes. In a solid or viscous state, these components form a dense structure that softens when heated, and dissolves when certain liquids are added. The liquefaction process is based on the introduction of solvent molecules between hydrocarbon chains, which reduces the forces of intermolecular interaction and reduces the strength of the intermolecular interaction. viscosity material.
It is important to understand that bitumen does not dissolve in water and polar liquids. The use of unsuitable substances, such as alcohol or acetone in its pure form, can lead to the curtailment of bitumen or the formation of a heterogeneous emulsion that will lose its hydrophobic properties. Only suitable for work nonpolar organic solventschemically related petroleum hydrocarbons.
The mechanism of action of the solvent also affects the "life" of the finished solution. Fast-evaporating fractions allow you to reduce drying time, but can lead to the formation of crust on the surface when applied with a thick layer. Slow solvents provide deep soaking of the base, but require more time for final drying. The choice depends on the specific task: whether you need to quickly close the layer or provide deep penetration into the pores.
⚠️ Warning: Never try to dilute bitumen with water or water-containing liquids. When heated, such a mixture can boil and splash, causing burns, and after cooling, the material will lose adhesion.
What is happening at the molecular level?
When the solvent is added, a solvation process occurs, where solvent molecules surround bitumen macromolecules, increasing the distance between them and reducing friction, which makes the mass fluid.
The main types of solvents for bitumen mastics
The market offers a wide range of chemical products that can effectively thin bitumen. The choice of a particular type depends on the availability, cost and required characteristics of the finished mixture. The most common and effective are refined products that are chemically compatible with the mastic base.
First on the list is kerosene. It is one of the most popular solvents for bitumen mastics used in construction and auto repair. Kerosene has a moderate evaporation rate, which allows you to work with the solution comfortably, without fear of its instant hardening in an open container. It penetrates well into the structure of bitumen, making it uniform and elastic.
The second common option is Kalosha gasoline (not leaded). It evaporates faster than kerosene, which accelerates the drying process of the coating. However, its use requires more care due to the high fire hazard and toxicity of vapors. Also often used white spirit and solvent, which occupy an intermediate position in terms of evaporation rate and aggressiveness of exposure.
- 🧪 kerosene - optimal balance of drying speed and ease of operation, available in hardware stores.
- ⛽ Kalosha petrol - rapid drying, high penetrating capacity, but increased fire risk.
- 🎨 White Spirit Less toxic than gasoline, dries longer, is suitable for work in enclosed spaces.
- 🏭 Solvent A powerful solvent, often used in industrial mastics, requires careful handling.
When choosing a solvent, it is also worth considering the ambient temperature. In the cold season, the use of rapidly evaporating compounds can lead to clouding of the solution or precipitation. In such cases, heavier fractions such as diesel or special bitumen diluents are preferred.
Mixing technology and necessary proportions
The process of preparing the working solution requires precise compliance with the proportions. Excess solvent will make the coating too liquid, which will lead to the drainage of the material from vertical surfaces and the formation of streams. The disadvantage will not allow you to achieve the necessary viscosity for high-quality application with a brush or sprayer.
The standard ratio for diluting thick bitumen is considered to be a ratio of 1:3 or 1:4, where one part of the solvent falls on three to four parts of bitumen. However, these figures can vary depending on the initial density of the material and the air temperature. For primary primer (priming), the solution is made more liquid, for the main layer - thicker.
The mixing technology should exclude the formation of lumps. It is recommended to add the solvent to bitumen gradually, in small portions, constantly stirring the mixture. If you work with solid bitumen, it is preheated to a temperature of 120-140 ° C, and only then the solvent is introduced, following precautions.
☑️ Mixing algorithm
Therefore, the process should take place in metal or glass containers resistant to aggressive environments. Plastic buckets may deform or react with a solvent.
Table of compatibility and solvent characteristics
For convenience of selection of the suitable component below is a comparative table of the main characteristics of popular solvents. This data will help you make an informed decision depending on the working conditions and the coverage requirements.
| Solvent | Drying speed | Toxicity | Fire hazard | Recommended application |
|---|---|---|---|---|
| Kalosha petrol | Tall. | Tall. | Critical | Minor repairs, work in the open air |
| kerosene | Medium | Medium | Tall. | Waterproofing of the foundation, anticor car |
| White Spirit | Low. | Low. | Tall. | Interior work, priming |
| Diesel fuel | Very low. | Medium | Medium | Cold weather, deep impregnation |
Analyzing the data of the table, we can conclude that for work indoors or in conditions of poor ventilation, it is better to choose less volatile and toxic options, sacrificing the drying speed. For outdoor work, where speed is important, more aggressive compositions will be suitable.
Security measures and storage conditions
Work with bitumen mastics and organic solvents belongs to the category of high-risk work. Solvent vapors are heavier than air and can accumulate in the lower layers of the room, creating an explosive concentration. In addition, many of these substances have narcotic effects and can cause poisoning when inhaled.
A mandatory requirement is the availability of quality ventilation Or work outdoors. The use of personal protective equipment, such as a carbon filter respirator, protective glasses and gloves made of nitrile or neoprene, is strictly mandatory. Latex gloves can dissolve quickly under the influence of aggressive chemistry.
⚠️ Attention: It is strictly forbidden to smoke or use an open fire within a radius of 50 meters from the site of the work on dilution of bitumen. A spark of static electricity can also cause ignition of vapors.
Store finished solutions and initial components must be in hermetically closed containers, away from heating devices and direct sunlight. The packaging must be labeled to prevent accidental misuse. The remains of dissolved bitumen are not subject to long-term storage, since the solvent gradually evaporates even through a closed lid, changing the properties of the mixture.
Use only a metal tool for stirring. Wooden sticks can contain moisture that will get into bitumen, and plastic can dissolve.
Frequent errors and ways to fix them
Even experienced craftsmen sometimes make mistakes when working with bitumen compounds. One of the most common is the use of excessive amounts of solvent in the hope of making the material more fluid. This leads to the fact that after drying, the thickness of the dry residue is critically small, and the waterproofing film is porous and unstable.
Another mistake is to apply the next layer until the solvent from the previous one has completely evaporated. As a result, bubbles remain inside the coating, which eventually burst or create channels for moisture to penetrate. It is necessary to give each layer an exposure according to the instructions for the used solvent.
If the bitumen is still curled or went flakes after adding a solvent, the situation can be corrected only by filtration and redissolution with heating, but no guarantees of restoration of properties will not give. In such cases, it is cheaper and more reliable to prepare a new portion of mastic.
The golden rule: it is better to add less solvent and then add more than immediately pour out the excess and spoil the bucket of material.
It is also worth mentioning the error associated with the base temperature. Applying diluted bitumen to a cold surface can lead to instant hardening and poor adhesion. The base should be dry and warmed, especially in the cold season.
Restoration of thickened bitumen
If you find that the bitumen in the jar thickened during storage, do not rush to throw it away. In most cases, the material can be restored. To do this, the jar is opened and added fresh solvent (kerosene or white spirit) in an amount of about 10-15% of the volume.
After adding the solvent, the mixture must be thoroughly mixed and left for several hours, or better - for a day, sealed the lid. During this time, the solvent will penetrate the structure of the frozen bitumen and return it to plasticity. If the consistency is still not satisfied, the procedure can be repeated.
However, it is worth considering that reconstituted bitumen may have slightly altered properties compared to fresh material. It is better used for less critical areas, for example, for primary anti-corrosion treatment of hidden cavities or temporary waterproofing.
Can waste oil be used to dilute bitumen?
Use of used motor oil is not recommended. It contains oxidation products, metal shavings and soot, which will worsen the properties of bitumen mastic. In addition, the working may not mix with the bitumen uniformly, forming an emulsion that quickly stratifies.
How long does the diluted bitumen dry?
The drying time depends on the type of solvent, the thickness of the layer and the ambient temperature. When using kerosene or white spirit at a temperature of +20 ° C, surface drying occurs after 12-24 hours. Complete polymerization and evaporation of volatile fractions can take up to 3-5 days.
How to wash the tools after working with bitumen?
To clean tools (hands, spatula, containers) use the same solvent with which the bitumen was diluted. As long as the mastic is not withered, it is easily washed away. If the bitumen is already frozen, the tools will have to be heated or soaked in solvent/diesel for a long time.
Is the smell of bitumen harmful to health?
Yes, bitumen vapors and especially solvents contain volatile organic compounds that can cause headache, nausea, and allergic reactions. Prolonged inhalation of vapors without protection is harmful to the respiratory system and nervous system.