Application of bitumen in road construction
Approximately 80% of the total annual consumption of bitumen, which amounts to 100 million tons worldwide, is utilized in the construction and maintenance of road pavements. The remaining portion of bitumen is employed for various other purposes. The significance of bitumen becomes evident when considering how roads are built.
Modern road construction techniques involve the creation of flexible road layers or courses, which distribute the tensile and compressive stresses caused by traffic evenly across these layers according to their respective strengths. This ensures that neither the road's supporting ground nor its individual layers experience permanent deformation due to concentrated stresses.
Furthermore, road courses must be weather-resistant and durable. Bitumen plays a crucial role in meeting these requirements by binding the particles, sealing the aggregates, and filling the voids between them. The effectiveness of bitumen depends on its general characteristics, the size and number of voids, and the type of bitumen used. By sealing these gaps, bitumen prevents water from penetrating the road and damaging its natural foundation.
The lowest layer of a road is the natural subgrade soil. In the case of a new road, the subgrade is carefully prepared using modern machinery. However, for an existing road, this layer comprises the material left by the traffic. The remaining layers of the road consist of aggregates and bitumen, each serving a specific purpose.
Aggregates refer to hard, non-metallic minerals such as crushed stone, gravel, sand, and gravel. These aggregates must meet engineering specifications regarding their shape, strength, surface properties, and size. The subgrade, which is the first layer constructed by road builders, consists of compacted granular material like rock, gravel, or sand. Its purpose is to contribute to the road's strength and provide a stable working platform for road construction machinery.
Variable design factors
The precise configuration of a road is influenced by several factors, including the anticipated weight and volume of traffic, local weather conditions, and the availability of mineral materials. In many instances, bitumen is the preferred choice due to its waterproof and durable properties, as well as its cost-effectiveness as a readily available adhesive.
For minor roads, bitumen 60 70 may be used solely in the top two layers, typically at a rate of 7 tonnes per kilometer. On the other hand, a highway engineer might opt for three asphalt layers, including binder coats, to capitalize on the superior load-carrying capabilities of asphalt. In such cases, bitumen consumption can amount to 1000 tons per kilometer. The proportion of bitumen in asphalt typically ranges between 4% and 8%.
HOT MIX
The production of asphalt, which involves the mixing of aggregates and bitumen, can occur either at an off-site, purpose-built plant or directly on-site.
In this process, carefully measured quantities of different aggregates, meticulously mixed and graded to meet specific specifications, are heated. They are then combined with a precise amount of dry bitumen within a specialized factory. The resulting hot mixture is transported to the construction site while maintaining a temperature of 160°C.
The aforementioned process, in simple terms, relies on the application of skill and experience alongside computer control systems to execute a series of intricate operations. The aggregates of varying sizes dry, absorb heat, and retain it at different rates. It is crucial to control their temperature to prevent the bitumen from cooling prematurely upon mixing. Aggregate supply is continuously monitored by gauges attached to the bitumen metering pump to ensure a consistent ratio of aggregate to bitumen.
The mixing time should be kept as brief as possible to achieve even distribution of the bitumen as a coating for the aggregate particles. Prolonged mixing can lead to the bitumen film hardening due to exposure to air and oxidation, compromising the durability of the mixture.
Maintaining continuous operation of the system is essential for consistently producing high-quality asphalt mixes. This requires seamless integration of all stages, including drying, screening, mixing, transporting, and loading. Bitumen materials are supplied on a daily basis to fulfill production plans aligned with road construction schedules.
Due to limited bitumen storage capacity, deliveries are made on an as-needed basis, often within a 30-minute window based on the moment the aggregates reach the appropriate temperature for mixing with bitumen. Any delays result in wastage of expensive fuel required to maintain the aggregates at the correct temperature. This level of precision in delivery necessitates a high level of commitment from suppliers in terms of capital equipment, logistics, and technical expertise.
To ensure the continuous operation of bitumen 80/100 and bitumen 60/70, there are several key factors to consider:
- Storage: Adequate storage facilities should be available to accommodate the required quantities of bitumen. The storage tanks should be properly sealed and insulated to prevent heat loss or contamination.
- Heating: Bitumen needs to be heated to an appropriate temperature for effective use. Heating systems, such as heating coils or burners, should be in place to maintain the desired temperature range for the specific grade of bitumen.
- Temperature Control: Continuous monitoring and control of the bitumen temperature are crucial. Temperature sensors and control systems should be utilized to ensure that the bitumen remains within the specified temperature range during storage and transportation.
- Transportation: Bitumen may need to be transported from storage tanks to the application site. Insulated tanker trucks or specialized containers should be used to maintain the desired temperature during transportation.
- Mixing and Application: Depending on the specific requirements of the project, the bitumen will need to be mixed with aggregates or other materials to produce asphalt or other bituminous products. Proper mixing equipment and techniques should be employed to achieve the desired consistency and quality.
- Quality Control: Regular testing and quality control measures should be implemented to ensure that the bitumen meets the required specifications and performance standards. This may involve laboratory testing of samples and adherence to industry standards.
- Maintenance: Regular maintenance of equipment, such as heating systems, storage tanks, and transportation vehicles, is essential to prevent breakdowns and ensure continuous operation.
By effectively managing these factors, the continuous operation of bitumen 80/100 and bitumen 60/70 can be maintained, enabling smooth and efficient use in various construction and industrial applications.
Application of bitumen in asphalt
Asphalt mixtures encompass various types, commonly referred to as compacted asphalt or asphalt concrete. These mixtures consist of a dense and well-ordered combination of coarse and fine aggregates, mineral fillers, and bitumen, with precise control over their composition.
Hot Rolled Asphalt
This type involves the application of a sand-based, high-viscosity bitumen material with around 30% selected stone content. It is rolled onto the surface, incorporating larger stones.
Stone Mastic Asphalt
Stone Mastic Asphalt utilizes a mix with larger stones that form a load-bearing matrix, providing exceptional resistance to deformation, particularly at the interface with the filler mastic bitumen.
Graded Open Asphalt
Graded Open Asphalt is a blend of graded aggregate and bitumen designed to create an open-textured surface with air voids. This allows for efficient water drainage through the finished asphalt layer, and it is also referred to as porous asphalt or drainage asphalt.
Tack Coat
A thin layer of emulsified or sprayed bitumen that acts as a bonding agent between two layers of road. The current practice favors the use of bitumen emulsion for this application instead of cutting.
Sprayed Sealing
Also known as surface dressing or chip seals, this process involves spraying a bituminous coating onto a track or granular surface. The sprayed sealing can be done using bitumen emulsion, cutback bitumen, or asphalt-grade bitumen. Aggregates are then applied in one or two layers.
These remedial methods are employed to renovate and waterproof existing roads requiring maintenance or to establish asphalt pavements without boundaries in new construction. One example of a remedial method is fog sealing, which applies a layer of bitumen emulsion to an existing surface to seal cracks or replenish worn bitumen as part of a maintenance approach.
Bitumen Slurry Seal
A significant surface maintenance repair method that involves applying a mixture of fine aggregate, filler, and emulsified bitumen to partially correct the road surface and restore its structural integrity. This method offers the advantage of quick application and relatively low cost, often carried out using a truck mix plant.
Application of bitumen in road reconstruction
Road recycling techniques aim to recover materials used in road construction, resulting in reduced material and energy demand. The process involves crushing and reprocessing road surface layers with varying proportions of fresh aggregate, new bitumen or bitumen emulsion, and, if necessary, recycled materials. This process can be carried out on-site simultaneously or by transporting the reclaimed material to the site for mixing.
Industrial applications of bitumen
While industrial applications account for less than 20% of global bitumen consumption, they are crucial for manufacturers and engineers who rely on its unique properties as a cost-effective adhesive and protective material. In many regions, bitumen is extensively used to waterproof roofs of houses.
Typically, it is applied in the form of strips that are first impregnated with bitumen and then covered on both sides with harder bitumen and a layer of mineral grains. Another construction method involves using sheets of saturated bitumen material on flat roofs, with layers of bitumen positioned below, between, and above them. Bitumen is also utilized in anti-slip and floor tiles.
Additionally, other materials such as felt and paper are impregnated with bitumen to enhance their insulation capabilities. Industrial-grade bitumen finds its way into a wide range of products, including paper packaging, printing inks, floor coverings, soundproofing felts for automotive applications, underlay compounds, electrical insulation compounds, and battery boxes. These are just a few examples of the numerous industrial and household products that may contain bitumen.
ATDM CO is a reputable manufacturer and exporter specializing in Bitumen 60/70 and Bitumen 80/100. We offer a diverse range of quality grades available in drums, bags, and bulk quantities. Our product portfolio consists of three distinct types: premium, second, and third, each tailored to meet specific customer preferences and volume requirements. We take pride in providing a comprehensive selection of options to cater to a wide range of customer needs. Our products are manufactured with utmost care and adhere to stringent quality standards, ensuring reliable performance and customer satisfaction.