Cold asphalt concrete: technology, advantages

Though it may sound like something from a science fiction film, cold asphalt concrete is a useful and cutting-edge material used in road building and maintenance. Cold asphalt is very versatile and simple to work with because it can be used directly from the bag or container, unlike traditional asphalt, which needs to be heated before application. Because of this special feature, it’s perfect for small maintenance jobs and quick fixes that don’t call for complicated setups or large machinery.

Convenience is one of the main advantages of cold asphalt concrete. It can be used in a greater variety of environments and weather conditions because it doesn’t require heating. This implies that repairs can be performed even in colder climates or at distant job locations where it would be impractical to set up a hot asphalt plant. Faster project turnaround times and cheaper labor costs are further benefits of the ease of application.

The long-term durability of cold asphalt is another benefit. After application, it creates a solid bond with the current surface and withstands traffic well. When it comes to fixing potholes and restoring road surfaces that are subjected to continuous wear and tear, this durability is especially helpful. Cold asphalt is a dependable option for both short-term and long-term repairs due to its resilience.

All things considered, cold asphalt concrete is revolutionary in the field of road upkeep. It is a useful tool for maintaining the condition of our roads because of its flexibility, durability, and ease of use, which all provide substantial advantages. Because of its efficiency and effectiveness, cold asphalt is a viable option for both small repairs and larger road projects.

General information

The composition of cold asphalt concrete mix varies from hot asphalt due to the inclusion of either medium-thickening (SG) or slow-thickening (MG) road bitumen. The primary binder, petroleum bitumen, makes up 4-6% of the mixture. The bitumen used has to match grades MG70/30 and SG 70/130 in terms of viscosity.

The method and intended shelf life are taken into consideration when choosing the class and viscosity of material for cold mix preparation:

• in a warehouse in packaged form (plastic bags, etc.);
• in piles – in bulk;
• permissible storage temperature;
• quality of mineral components.

The presence of a thin oil-bitumen film on the mineral grains accounts for finished asphalt’s long-term ability to stay loose. This film also makes the structural bonds in cold asphalt concrete so weak that even small forces can cause them to collapse.

This feature allows ready-made mixtures to be easily laid in a thin layer for installing or repairing road surfaces, and it also keeps them in a technically suitable condition for an extended period of time. The range of shelf life is 8 to 12 months.

The following elements are included in the composition of cold asphalt concrete in addition to the binder:

• coarse-grained crushed stone from hard rocks, strength 60–80 MPa, grain size — 5–20 mm (up to 50%);
• sand from crushing screenings;
• mineral powder (up to 20%);
• modifying additives (2–3%).

Thanks to its cutting-edge technology and useful advantages, cold asphalt concrete is completely changing the road construction industry. Cold asphalt is a more adaptable and environmentally friendly alternative to traditional hot asphalt because it can be mixed and applied without heating. This method minimizes the impact on the environment, lowers energy costs, and streamlines the paving process. Road construction and maintenance are finding that cold asphalt is a game-changer due to its advantages, which include ease of use in a variety of weather conditions and quick repairs.

Calculation of concrete composition

The usage of the aforementioned grades of bitumen, which demand a higher quantity of these components during the structure formation phase of cold mixtures, accounts for the comparatively low content of crushed stone and the increased volume of mineral powder.

Hints: The conditions for the formation of road surfaces deteriorate with an increase in grain size (>20 mm) and an increase in crushed stone content (>50%).

Classification of cold compositions

To achieve a contemporary, high-quality road surface, careful attention must be paid to the standards and guidelines that have been established for specific asphalt concrete grades. Each type of asphalt has unique qualities that show up in the conditions of mixture preparation and application, according to this documentation.

Premature wear and coating destruction will result from breaking the suggested technologies given for a particular type of concrete.

Depending on the structural makeup of the mixtures, GOST cold asphalt concrete offers the following varieties of asphalt:

1. By crushed stone content:

• cold asphalt concrete type Bx – amount of crushed stone 40%-50%;
• type Bx – crushed stone 30%-40%.

1. By type and content of sand used:

• Gx – sand content 30% and below:
• Dx – sand volume 30-70%.

1. By residual porosity:

• highly porous (12-18%);
• porous (5-12%);
• dense (1-5%).

The mixtures are categorized into grades shown in the table below based on the attributes and specific filler properties that have been presented.

Application

Cold mixes are mostly utilized for the construction of the upper layers of category III and IV road surfaces as well as for the quick repair of damaged asphalt sections with a defect area of up to 1 m2.

• construction of local roads with a capacity of up to 2000 cars per day;
• installation of sidewalks and bicycle paths;
• pedestrian paths on personal plots;
• improvement of courtyard areas;
• roadways of overpasses, bridges, etc.d.;
• patching of road surfaces (see. photo).

The primary characteristic of this material is its ability to be used in temperatures ranging from +5 to – 5 °C and in any type of weather, including rain and snow.

Advantages and disadvantages

Cold mixes harden as a result of the evaporation of hydrocarbon compounds that arise during the chemical reaction of modifying additives and bitumen binder, in contrast to standard hot asphalt concretes, which gain strength due to coating cooling.

By considering this characteristic, the following benefits can be attained:

1. Possibility of repairing coatings in winter.
2. Carrying out pothole repairs without the use of special equipment and road equipment.
3. Opening of traffic immediately after completion of road works.
4. Availability of material. Cold mixtures are packaged in plastic containers or polyethylene bags of 25–50 kg, which is very beneficial when carrying out minor repairs.
5. Shelf life of the material is up to 10–12 months.

• Strength and water resistance are 2–3 times lower than that of hot water;
• Low resistance to shear loads (rutting, waves, etc.);
• The average price is higher than that of similar standard mixtures.

Preparation of mixtures

The same techniques used to calculate the composition of hot asphalt concrete mixtures are also applied to cold asphalt concrete. One feature is to raise the caking values in situations where The volume of petroleum bitumen decreases by 10-15% over extended storage.

There are two methods used in batch concrete mixing units to produce cold asphalt:

1. With heating of mineral components to 80-110°C.
2. Without heating – using bitumen emulsions with modifying additives.

The following steps are taken in order to prepare the asphalt concrete mixture, including heating and drying the component parts beforehand:

1. Cold mineral fillers, via a conveyor, enter the drying drum.
2. There they are dried, heated to operating temperature (110°C) and fed to the dosing device.
3. From the dosing device, after weighing, they enter the mixer.
4. Next, the mineral powder heated to a certain temperature is introduced into the dry mortar mixture.
5. All components are mixed and hot bitumen is added.
6. Last of all, modifying additives are introduced, extending the shelf life of the finished material.
7. Then the finished asphalt (temperature 95-105°C) is taken to a prepared site and mixed using a front loader, which ensures rapid cooling of the mixture to the recommended values ​​(25°C).
8. Next, the resulting loose cold mixture is packed into bags or put into a dump for long-term storage.

• cold sand and crushed stone are dosed and added to the mixer;
• then a mineral additive is added;
• everything is thoroughly mixed and cold modified bitumen emulsion is added;
• within 15-20 minutes, mix and load into a waste heap or pack into prepared containers.

A practical and adaptable solution for a range of paving requirements is cold asphalt concrete. It is revolutionary in the field of road building and maintenance because it can be used without the need for heating. This technology is more environmentally friendly since it streamlines the application process and uses less energy during production.

The simplicity of use of cold asphalt concrete is one of its main benefits. You can handle repairs and new projects more flexibly because it can be used in colder weather and doesn’t require specialized equipment for heating. When it comes to small-scale projects or urgent repairs, where efficiency and speed are crucial, this can be especially helpful.

Furthermore, cold asphalt concrete provides exceptional weather resistance and durability. It offers a sturdy surface that can withstand daily use’s demands and holds up well to traffic and weather. Because of its versatility, it’s a sensible option for both urban and rural environments, extending the lifespan of roads and pathways.

To sum up, cold asphalt concrete is a major development in the field of paving technology. Its benefits for the environment, durability, and ease of application make it a worthwhile choice for contemporary building and maintenance projects. Whether you’re planning a new development or handling a fast fix, cold asphalt concrete is an intelligent and effective option.

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