Use of cast asphalt concrete: laying technology, pothole repair

Of course! For the website "All About Concrete," the following is an introduction to the topic "Use of Cast Asphalt Concrete: Laying Technology, Pothole Repair":

A versatile material often used in road construction and maintenance is cast asphalt concrete. It has grown in popularity as a material for pothole repairs and road paving because of its strength and resilience to inclement weather. Cast asphalt concrete, in contrast to conventional asphalt, doesn’t need to be compacted, which makes it a practical choice for tasks requiring quick turnaround times. Because of its special qualities, it is especially helpful in urban settings where maintaining traffic flow is necessary while repairs are being made.

In order to facilitate smooth casting asphalt concrete installation, the material must be heated to a particular temperature. After being poured over a surface that has been prepared, this hot liquid mixture cools to form a thick layer that is waterproof. There are many benefits to this method, such as short setup times and lower labor expenses. It is also perfect for residential areas because there is less noise and disturbance due to the lack of compaction equipment.

One of the most popular uses for cast asphalt concrete is pothole repair. Its capacity to fill irregular shapes and cling to pre-existing road surfaces guarantees a seamless, long-lasting repair. Road maintenance crews can minimize driver inconvenience and lower the possibility of vehicle damage by employing this technique to swiftly fix potholes. Furthermore, cast asphalt concrete’s flexibility lets it expand and contract in response to temperature changes, which stops additional cracking.

Cast asphalt concrete is proving to be a valuable road maintenance solution as demand for it increases. This material presents a dependable and economical choice for both new road construction and infrastructure repair. For engineers and construction experts looking to increase the caliber and lifespan of our roads, understanding its laying technology and repair procedures is crucial.

Concept and features

There are many different types of road surfaces that can be made with cast asphalt concrete, and it offers certain benefits. After cooling, the mixture itself gains a good density without requiring ramming, which expedites and greatly lowers the cost of the laying process. It all comes down to the unique composition.

If maintaining the proper ratios of ingredients is crucial in the manufacturing of regular asphalts, then a binder made of bitumen and mineral additives plays a crucial role in the creation of cast asphalt concrete mixtures. The binder is responsible for the coating’s natural compaction during cooling and for making the laying process simple.

Coatings manufactured from asphalt concrete mixtures have a higher percentage of mineral powder (up to 30%) and bitumen (from 7.5% to 10%) in their binder. The final product will form a dense, non-porous structure thanks to this high concentration.

Types

The composition and adherence to work technology of coatings made from cast asphalt concrete mixtures determine their properties. Prior to applying the material for coating arrangement, it is essential to thoroughly research the various varieties of asphalt concrete and their characteristics.

Standard: An unaltered form of heat-resistant bitumen is added to the mixture.

2) Sulfur asphalt concrete: By lowering the bitumen content, the preparation temperature can be lowered. Modified sulfur and road bitumen function as a binder.

3) Polymer asphalt concrete: a polymer-bitumen mixture is the primary ingredient.

4) Rubber asphalt concrete: By using rubber crumb as a filler, wear resistance is increased, service life is extended, and the amount of crushed stone used in the composition can be decreased.

• 1 – diameter 15 millimeters, the proportion of stone in the composition is 45-55%, asphalt paving is carried out for laying new durable surfaces and restoring old ones.
• 2 – diameter 20 millimeters, in the composition 20-25% of stone, a universal solution for various tasks.
• 3 – diameter up to 40 millimeters, crushed stone in the composition occupies 45-65%, an ideal option for the construction of new durable roads.
• 4 – fractions smaller than 5 millimeters, usually such asphalt concrete is used for the construction of bicycle paths, paths of household territories, sidewalks, indoor screeds, roof waterproofing.
• 5 – grain diameter of 20 millimeters, in the composition of the stone 35-50%, differs in the content of bitumen substance about 22-28%, the mixture is used to perform current repairs of coatings.

Technical characteristics and properties

Cast asphalt concrete is a material that can be used indoors and outdoors for a variety of road surface arrangements and repairs. The primary distinction between this type of asphalt and regular asphalt is the technology used to lay it. All mixture manipulations are done at a high temperature (+1,220-250C): the mixture is prepared first, then delivered in kochers while being continuously stirred to prevent it from cooling, and finally laid.

The mixture self-compacts during cooling because of the addition of a special binder and large amounts of mineral powders (up to 11% of bitumen and up to 25% of mineral components, respectively). This eliminates the need to invest money and time in a specialized tool, the compaction itself. Low porosity and high density are achieved in the road layer made of cast asphalt concrete, which also exhibits exceptional plasticity.

• Small porosity – in the range of 20-22% by volume (residual porosity is 2%)
• Water saturation is 1% for asphalt types 1 and 2, 5.7% and 0.5% for the rest, which makes it possible to talk about high-quality protection from moisture of the lower layers of asphalt. Also, thanks to this characteristic, the material is completely frost-resistant
• Compressive strength – 0.7 for type 4, 1 for all the others
• Density and weight – can be different, depending on the volume of crushed stone in the composition, the indicator fluctuates in the range from 1.5 to 2.2 tons per 1 cubic meter
• Durability of cast asphalt concrete – serves much longer than conventional, which is due to the peculiarities of the production of cast mixtures and laying technology
• Minimum deformation – at an operating temperature of up to + 40C, the indentation depth is 1-10 millimeters
• High level of adhesion to the lower layers – due to the fact that cast asphalt concrete is laid with increasing temperature and better adheres (almost "sinters") to waterproofing, lower layers
• Complete absence of corrosion, resistance to salts

Application area

It is recommended to use cast asphalt concrete in a range of construction and repair applications. The material’s excellent performance characteristics allow for a significant expansion of its scope of application.

• In the construction of roads, bridges of various configurations, tunnels, and other objects.
• Type 1-2 material is relevant for the lower and upper layers of pavements with loads of more than 3000 vehicles per day – usually these are airfields, popular highways, high-speed sections of roads, etc.d. (although asphalt concrete can be used in the arrangement of coatings with lower loads, but in this case the high price will not be economically justified)
• Mixtures of types 2-4 are used for the arrangement of all layers of paths for bicycles and pedestrians, sidewalks
• Asphalt concrete types 1-2 and 5 are relevant in the construction of tunnels, bridges, various repair work
• For roofing, floors, waterproofing layers, which is due to the excellent waterproofing properties of asphalt concrete
• The material can be used wherever it is necessary to ensure an increased level of adhesion of vehicle tires to the asphalt surface (dangerous sections of roads where accidents often occur during snowfalls, rains), since asphalt concrete has increased roughness

Material production

The material is made in unique circumstances, at high temperatures, and with strict adherence to the ratios of the constituent parts as well as the production technology. We are able to guarantee the essential operational qualities and characteristics because of these two factors—the right composition and a high temperature.

Composition

Cast asphalt concrete is made of a slightly different mixture of ingredients than regular asphalt concrete. GOST is required.

• Bitumen – usually take grades BND 40/60 or 40/90, often with polymer additives (styrene-butadiene-styrene, for example), especially when it comes to arranging coatings with increased loads.
• Crushed stone – material from metamorphic and igneous rocks with a maximum content of lamellar grains of 20%
• Mineral powder – selected according to GOST R 52129-2003
• Sand – crushed or natural, used in small quantities in the upper layers
• Modifying additives – various types of dephlegmators, pigments, etc..

Preparation

Production of mold asphalt concrete is limited to high temperatures because it is made from a unique, highly viscous bitumen. Enough heat should be applied, but not too much, to prevent the components’ properties from changing.

• Heating bitumen to + 160-180C
• Heating mineral components up to +190-240С
• Mixing the components and releasing the mixture at a temperature of +200-220C, but if activated mineral powder is added to the composition, then the temperature of the mixture can be lowered to +170-190C, which is more preferable from a technology point of view

Cast asphalt concrete is made using a unique process that makes on-site preparation impossible. As a result, factories order and deliver the solution in specialized vehicles to the site. Stirring the mixture during transportation is necessary because it can stratify and behave similarly to a suspension.

The steps involved in making cast asphalt concrete are as follows: ingredients are delivered to bunkers, mixed, dried, and heated to the proper temperature in a special drum. The heating of the bitumen and its transfer to the mixer happen in two stages: dry mixing is done first, followed by the addition of bitumen. Special boilers are used for transportation, where mixing occurs continuously.

Laying

After being filled with the heated, dense mixture, a unique asphalt paver applies a layer that ranges in thickness from 3 to 7.5 centimeters. The surface is carefully cleaned before laying starts, and support bars are put in place to stop the mixture from spreading. The bars are removed when the mixture temperature falls to +70C. There is no coverage of the roads.

However, the black crushed stone is added to the layer if more surface roughness is required. The lightest rollers should be these.

Cost and popular manufacturers

Compared to hot or cold concrete, cast asphalt concrete is more costly. The characteristics of production and laying technology are to blame for this. 10% of the total weight of asphalt is produced in Russia as cast asphalt concrete. However, the share rises with time.

• Surgutneftegaz – produces and sells oil, as a by -product is produced by cast asphalt concrete (but large volumes)
• OJSC "Asphalt concrete Plant No. 1" (St. Petersburg)-market leader, specializes in the manufacture of all types of material
• State Unitary Enterprise "Bashkiravtodor" – the company builds and repairs road surfaces, produces and sells all materials (including cast asphalt concrete)
• JSC Asphalt Concrete Plant No. 4 (Moscow) – produces all types of asphalt concrete, including cast asphalt
• JSC "Sverlovskavtodor" – the company owns 45 plants producing all types of asphalt concrete and performing all work

The type, brand, and production location of the material can all affect the cost of cast asphalt concrete. The mean value is 5940-8800 rubles/m3, or 3700-4200 rubles/t.

With its special blend of flexibility and durability, cast asphalt concrete is a useful option for paving and repairing roads. It is perfect for urban roads and highways because of its resistance to heavy traffic loads and changing weather conditions. Cast asphalt, in contrast to regular concrete, is applied while still molten, enabling quick installation and a smooth finish. This lessens the need for ongoing maintenance and minimizes traffic interruptions.

Cast asphalt is laid by heating it to a high temperature and then distributing it uniformly over the surface that has been prepped. By using this method, a thick, waterproof layer that sticks well to the base and surface layers is guaranteed. To guarantee the right thickness and compaction, skilled laborers use specialized equipment, creating a smooth, long-lasting road surface. Compared to other materials, roads can be reopened to traffic considerably sooner thanks to cast asphalt’s short cooling time.

Because of cast asphalt’s strong bonding properties and flexibility, it is particularly effective for pothole repair. Cast asphalt, when properly applied, fills and seals potholes, stopping water intrusion and additional deterioration. This prolongs the life of the road while also restoring its surface. Pothole frequency and severity can be greatly decreased with routine maintenance using cast asphalt, making roads safer and more dependable.

All things considered, cast asphalt concrete is a useful instrument in contemporary road building and upkeep. Many infrastructure projects choose to use it because of its efficiency in application and ability to adapt to different conditions. Municipalities and road authorities can lower maintenance costs, improve road quality, and increase safety for all users of the road by investing in this technology. Using cast asphalt as a standard procedure can help create resilient and sustainable road networks.

Cast asphalt concrete is an effective material for road construction and maintenance due to its durability and flexibility, making it ideal for both new pavement installations and quick pothole repairs. This versatile material is created by heating asphalt and mixing it with aggregates, resulting in a pliable mixture that can be easily applied without the need for extensive compaction. Its unique properties allow for seamless integration with existing road surfaces, reducing the time and effort required for repairs. Cast asphalt concrete provides a long-lasting solution for pothole repair, withstanding heavy traffic and harsh weather conditions while minimizing future maintenance needs. By streamlining the laying technology and repair process, cast asphalt concrete helps improve road safety and prolong the lifespan of transportation infrastructure.

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