An asphalt mixing plant (also known as an asphalt mixing station, intermittent asphalt mixing plant, or hot-mix plant) is a specialized production system whose core task is to precisely heat aggregates and uniformly mix them with asphalt and fillers to produce homogeneous asphalt mixtures for paving. Its role goes far beyond simple mixing. The ultimate success of a paving project—whether it’s a high-traffic highway or an airport runway—directly depends on the quality and consistency of the mixture. Ensuring consistency in each batch is crucial, as any deviation can compromise the durability and performance of the final pavement.

Achieving this high-precision production depends on several key factors of the equipment itself:

Thermal Efficiency

Efficiently removing moisture from the aggregate while heating it to the target temperature of 150-180℃, preventing overheating damage to the aggregate or degradation of asphalt performance;

Precise Weighing and Batching

Each component, including aggregate, asphalt, and filler, must be measured precisely to the gram level;

Efficient Mixing

Ensuring all materials are fully blended to form a homogeneous mixture;

Stable Automated System

A powerful control system capable of perfectly synchronizing every stage of the production process.

Besides the quality of the mixture, the equipment’s operational performance is also crucial to the project timeline and budget. It must continuously provide the required production capacity while ensuring quality, guaranteeing smooth paving operations. Furthermore, its design and the quality of its components are paramount. A reliable asphalt mixing plant can prevent costly downtime due to unexpected malfunctions, saving significant time and money. Therefore, these factors—precision, performance, and reliability—are the most critical considerations when making a purchasing decision.

Modern asphalt mixing plants, thanks to technological upgrades, demonstrate multiple core advantages in engineering applications, making them the preferred equipment for road construction:

High Production Efficiency

Utilizing automated control and optimized production processes, modern asphalt mixing plants can rapidly produce high-quality asphalt mixtures. While ensuring formula accuracy, they efficiently meet project schedule requirements, avoiding construction delays caused by insufficient material supply.

Customizable Mix Formulas

Through advanced control systems, operators can flexibly adjust the proportions of aggregates, asphalt, fillers, and additives, easily switching between different mix formulas to adapt to the diverse needs of various scenarios such as highways, airport runways, parking lots, and rural roads.

Significant Cost-Effectiveness

Supporting on-site production of asphalt mixtures significantly reduces losses and temperature drops during mixture transportation, while eliminating long-distance transportation costs. This ensures that fresh, qualified materials are always available at the construction site, indirectly reducing the overall project cost.

Superior Environmental Performance

Nowadays, mainstream asphalt mixing plants are generally equipped with high-efficiency dust removal systems (such as cyclone + bag filter) and asphalt recycling (RAP) systems. These systems can capture dust generated during the production process, reduce air pollution, and recycle old road materials for reuse, thus practicing the concept of green construction and meeting environmental protection policy requirements.

Asphalt mixing plants can be divided into four main categories based on “mixing method” and “transportation type.” Different types are suitable for different engineering scenarios and each has its core characteristics:

Classification by Mixing Method

Batch Mix Asphalt Plant

This type of plant produces in batches. Each batch of mixture undergoes a complete process of “weighing – mixing – discharging,” with a 40-45 second time interval between batches.

Core Characteristics: Equipped with a mixer, hot aggregates are first screened according to particle size and stored in a hot aggregate bin. Then, they are precisely weighed separately with asphalt and fillers before being added to the mixer for mixing. The mixing accuracy is extremely high, and the formula can be flexibly switched, making it suitable for projects with strict requirements on mixture quality (such as airport runways, urban main roads, and special mixture projects).

Drum Mix Asphalt Plant

Also known as a continuous mixing plant, this type does not require a separate mixer. The heating and mixing of materials are continuously completed within the same rotating drum, ensuring uninterrupted production.

Key Features: Relies on calibrated weighing belts and mass flow meters to control material ratios. It has a simple structure and high production efficiency, but its mixing accuracy is slightly lower than intermittent systems, and its formula adjustment flexibility is poor. It is suitable for projects with a single formula and large-scale continuous production (such as rural roads and auxiliary roads for large-scale infrastructure projects).

Classification by Transportation Type

Mobile Asphalt Mixing Plant

Equipped with a mobile chassis, it adopts a modular design, resulting in low transportation costs, small installation area, and fast setup, requiring no complex foundation engineering.

Key Parameters: Capacity range 60-200t/h, suitable for small to medium-sized projects requiring frequent relocation of construction sites (such as cross-regional road maintenance and rural road construction), enabling rapid response to the production needs of different construction sites.

Stationary Asphalt Mixing Plant

Without a mobile chassis, it adopts a fixed installation design. Its core advantages are high mixing accuracy, stable capacity, and strong durability. It is a classic and mature model.

Key Parameters: Capacity range 60-400t/h, suitable for projects with long-term fixed sites and large-scale production (such as highway construction, urban road network renovation, and large port paving projects). It offers high cost-effectiveness and has the widest range of applications.

A complete asphalt mixing plant consists of several key components working collaboratively, each directly impacting production efficiency and mix quality:

Cold Aggregate Supply System

Comprising a discharge conveyor belt, an aggregate conveyor belt, and multiple cold aggregate bins. Aggregates of different sizes are stored in their corresponding cold aggregate bins. The belt speed is precisely controlled by adjusting the belt speed using an AC drive and frequency converter. The sand bins are equipped with vibrators to prevent material blockage and ensure a stable and continuous cold aggregate supply.

Drying Drum

Driven by four geared motors, the drum rotates at a uniform speed. It is externally wrapped with 50mm thick insulation material and has internal lifting plates (metal plates). Heated by a burner, the lifting plates lift and then drop the aggregate as the drum rotates, achieving uniform heating and moisture removal, providing dry aggregate at the required temperature for subsequent mixing.

Vibrating Screen

Utilizing a 4-layer screen design and working with a vibrator, it separates hot aggregates into different sizes, which are then stored in separate hot aggregate bins, laying the foundation for precise batching. A mixing chamber is located below the screens, where the screened aggregates, after weighing, can be directly fed into the mixing chamber.

Twin-Shaft Mixer

Driven by two independent motors, the twin shafts rotate rapidly, using impellers to rapidly mix aggregates, asphalt, fillers, and additives, ensuring thorough material integration and forming a homogeneous mixture. This component is crucial for ensuring the quality of the mixture; the uniformity of mixing directly affects the pavement strength and durability.

Asphalt Supply System

Includes an insulated asphalt storage tank, heated oil pipes, a circulating pump, and a flow meter. A heat transfer oil heating system maintains the asphalt temperature, ensuring good fluidity. An agitator inside the storage tank prevents asphalt sedimentation, while the circulating pump and flow meter precisely control the asphalt supply, ensuring accurate formula proportions.

Dust Collector

The bag filter is a key environmental protection component. It collects dust generated from the drying drum and mixing cylinder, ensuring emissions meet standards. Modern equipment often also includes a flue gas treatment device.

Control System

As the “brain” of the asphalt mixing plant, the control system integrates and controls the operation of all components, monitors key parameters such as temperature, weighing data, and material flow rate in real time, records production data and issues fault alarms, and ensures smooth production processes and reduces human error through automated synchronization.

Installation Key Points

Site Preparation: Choose a flat, firm site, away from residential areas, ensuring sufficient space for equipment placement and transportation access. Proximity to raw material suppliers such as aggregates and asphalt will reduce logistics costs.

Foundation Construction: Pour the concrete foundation according to the drawings provided by the equipment manufacturer, ensuring the foundation can withstand the weight of the equipment and operational vibrations to prevent later settlement.

Equipment Installation: First install the main unit (drying drum, mixer, hot aggregate silo), then install the cold aggregate supply unit, conveyor belt, asphalt storage tank, dust collector, and other auxiliary equipment in sequence, ensuring all components are securely connected and well-sealed.

Electrical and Piping Connections: Connect wires strictly according to the circuit diagram, checking circuit insulation; connect asphalt, heat transfer oil, and other pipelines, ensuring no leaks and properly insulating the pipelines.

Commissioning Procedure

No-load Commissioning: Without material flow or heating, start the equipment and check the rotation and transmission of each component for normal operation, the sensitivity of the control system, and any abnormal noise.

Cold-state Commissioning: Add aggregate and test the smoothness of the cold aggregate supply, screening, and conveying processes, and verify the accuracy of the weighing system.

Hot-state Commissioning: Start the burner to heat the aggregate and asphalt, mix according to the trial production formula, and check the temperature and uniformity of the mixture to ensure they meet requirements. Adjust the control system parameters to optimal conditions.

Daily Maintenance and Repair

Asphalt mixing plants are large-scale mechanical equipment. Regular maintenance is crucial for ensuring stable operation and extending service life. Core maintenance items are as follows:

Lubrication System Maintenance

Regularly check the oil levels of key components such as the reducer and bearings to ensure adequate lubrication; change the gear oil every 500 working hours (use 220# in summer and 150# in winter); apply high-temperature (≥200℃) grease to the mixer shaft end weekly.

Wear Parts Replacement Management

Inspect the vibrating screen every 3 months; replace it immediately if the hole deformation exceeds 5%. Clean the burner nozzles quarterly; replace them promptly if severely worn. When the mixing blades wear down to 1/3 of their original thickness, replace the entire set of blades to prevent uneven mixing.

Cleaning Procedure

After each workday, remove residual asphalt from the mixer using a specialized cleaning agent. Clean the bag filter cartridges weekly using a backflushing method to ensure dust removal efficiency. After each shift, clean the accumulated material under the aggregate conveyor belt to prevent blockage.

Transmission System Inspection

Check the motor belt tension daily (10-15mm deflection is ideal). Measure the chain elongation monthly; adjust if it exceeds 3%. Replace the coupling buffer pad every 6 months.

Heating System Maintenance

Test the heat transfer oil acidity monthly; replace it if the pH value is below 7. Check the flame sensor sensitivity daily to ensure stable heating. Inspect the drying drum insulation layer annually; replace it entirely if more than 20% is damaged.

Electrical System Maintenance

Tighten high-current contactor terminal connections weekly to prevent poor contact; calibrate temperature and pressure sensors monthly, controlling the error within ±1%; clean PLC control cabinet dust quarterly with anti-static tools to prevent short circuits.

Comprehensive Overhaul

Perform a mid-level overhaul every 2000 operating hours, replacing all seals; conduct a system inspection before each construction season, including steel structure flaw detection; establish a record of critical component replacements, tracking cumulative operating hours to predict replacement times in advance.

Special Precautions

High-voltage circuits, high-altitude operations, and other hazardous maintenance must be performed by certified personnel; equipment modifications must be carried out under the guidance of the manufacturer’s technical personnel to avoid affecting the warranty; it is recommended to introduce a preventive maintenance management system (PMS) for intelligent maintenance reminders.

Choosing the right asphalt mixing plant requires considering various factors, including project requirements, site conditions, and environmental regulations. Key considerations are as follows:

Selection by Project Scale

Small Projects: Select a mobile asphalt mixing plant with a capacity of 60-120 t/h, offering flexibility and convenience.

Medium Projects: Choose either a mobile or small stationary plant with a capacity of 80-200 t/h.

Large Projects: Select a stationary intermittent mixing plant with a capacity of 200-400 t/h, ensuring high precision and high capacity.

Selection by Mobility Needs

For projects requiring frequent site relocation: Select a modularly designed mobile mixing plant for quick installation and disassembly, and low transportation costs.

For projects with long-term fixed locations: Select a stationary mixing plant for structural stability, low maintenance costs, and guaranteed capacity.

Selection by Environmental Requirements

For areas with strict environmental standards (urban core areas, ecological protection zones): Select a mixing plant equipped with a high-efficiency dust collector (bag filter + cyclone filter) and a RAP (Rapid Air Purification) recovery system to reduce dust and pollutant emissions.

Select the appropriate type based on formula requirements

For projects requiring switching between multiple formulas (e.g., simultaneously undertaking highway, parking lot, and sidewalk projects): Choose an intermittent mixing plant, which offers flexible formula adjustments and high precision.

For large-scale production of a single formula (e.g., continuous construction of rural roads): Choose a drum mixing plant, which offers high production efficiency and lower costs.

Core Cost Structure

Equipment Configuration:

Larger models and higher-specification mixing cylinders result in tiered price increases. For the same production capacity, integrated configurations are 15%-30% more expensive than separate configurations, making this a core factor influencing costs.

Drying systems, dust removal levels (national/European standards), and control systems (PLC/intelligent) account for 50-60% of costs.

Production Capacity Specifications: The price difference between 200-type and 400-type equipment can reach 1.5-3 million RMB.

Brand Premium: Imported brands are 30-50% more expensive than domestic brands.

Hidden Cost Items

Environmental Protection Investment: Baghouse dust collectors + activated carbon adsorption require an additional 150,000-300,000 RMB.

Installation and Transportation: Hoisting of large equipment and foundation construction account for approximately 8-12% of the total price.

Energy Consumption Differences: Natural gas burners are 25% more expensive than diesel burners, but long-term fuel costs are 40% lower.

Procurement Tips: Request suppliers to provide a full life-cycle cost analysis, focusing on energy consumption and maintenance cost data.

Equipment Types and Customization Needs

Mobile asphalt mixing plants, due to their relocation capabilities, have a production capacity approximately 30% higher than stationary plants of the same capacity. Adding additional features such as environmental dust removal, intelligent central control, and flue gas treatment, or customizing site layouts, will increase costs further.

Production Quality Issues

Aggregate Segregation: Optimize the layout of the cold aggregate bin, install anti-segregation baffles, and control the discharge height.

Asphalt Content Fluctuations: Calibrate the asphalt scale daily, check the nozzle atomization effect, and set temperature compensation parameters.

Mixing Cylinder: Material adherence and coking on the inner wall of the mixing cylinder are time-consuming to clean and affect the uniformity of the mixture.

Burner: Burner flameout and unstable fuel supply affect the mixing temperature and delay construction progress.

High-Incidence Equipment Failures

Drying Cylinder Ignition Failure: Clean the ignition electrodes, check the gas pressure, and optimize the air-fuel ratio setting.

Abnormal Pressure Difference in Bag Filter: Establish a pulse cleaning cycle schedule and use waterproof membrane filter bags.

Environmental Management Challenges

Excessive Dust: Install atomizing sprays in the cold aggregate area and adopt a double-layer sealing structure at the discharge port.

Blue Smoke Issue: Adjust the negative pressure value of the drying cylinder (-50~-80Pa) and install a flue gas recirculation device.

Operational Management Pain Points

Project Size and Equipment Capacity: Poor flexibility in capacity adjustment; using large stations for small projects leads to resource waste.

Component Wear and Tear: Frequent replacement of wear parts; some parts have poor compatibility and long procurement cycles.

Capacity Not Meeting Targets: Establish a preventative maintenance calendar, focusing on the maintenance of vibrating screen bearings and hot material elevators.

Mix Ratio Control Issues: Implement three-level inspection of incoming raw materials and install an online moisture content monitoring system.

Upgrade Recommendation: Invest in an IoT monitoring system, which can reduce unexpected downtime by 40% and material waste by 3-5%.

The core difference lies in the product and process. An asphalt mixing plant produces asphalt mixtures for road paving. Its main raw materials are aggregates and asphalt (a petroleum derivative), and the production process requires heating. A concrete mixing plant produces concrete for building structures. Its main raw materials are aggregates, cement, and water, and it is usually mixed at room temperature without heating.

The core difference lies in the production method and precision: asphalt batch mix plants produce in batches, with each batch of materials weighed and mixed separately. This allows for flexible formulations and high precision, making it suitable for demanding projects. Drum-type asphalt plants produce continuously, with material heating and mixing occurring simultaneously. This results in high efficiency and low cost, but formulation adjustments are inconvenient, and precision is slightly lower. This type is suitable for large-scale projects with a single formulation.

They are suitable for small to medium-sized projects that require frequent site relocation, such as cross-regional road maintenance, rural road construction, and short-term construction projects. Their modular design facilitates transportation and rapid installation, allowing for flexible responses to the production needs of different sites.

The core maintenance cycles include: changing gear oil every 500 hours, inspecting the vibrating screen every 3 months, performing a mid-level overhaul every 2000 hours, and conducting a comprehensive system overhaul annually. Daily routines include cleaning the mixer daily, checking belt tension, lubricating the shaft ends weekly, and cleaning the dust collector weekly.

The key lies in “precision” and “uniformity.” Precision: This refers to the absolute accuracy of the proportions of aggregates, asphalt, and fillers, and the precise temperature control. Uniformity: This means that all materials must be thoroughly and uniformly mixed within the mixing drum. This depends on the accuracy of the mixing plant’s metering system, temperature control system, and the design and power of the mixing drum.

The appropriate capacity should be determined based on a comprehensive assessment of construction progress, paving speed, transportation cycle, and project scale: Small projects (daily paving volume < 1000 tons) can choose a capacity of 60-120 t/h; medium-sized projects (daily paving volume 1000-3000 tons) can choose a capacity of 120-200 t/h; large projects (daily paving volume > 3000 tons) require a capacity of 200-400 t/h, while reserving a buffer capacity to cope with peak demand.

The most easily overlooked aspects are the accessibility and quality of after-sales service, as well as the energy consumption and lifespan of wear parts. Don’t just look at price and capacity; examine whether the supplier has a local service team and sufficient spare parts inventory. At the same time, compare the fuel consumption rates of different models and the design life and replacement costs of key wear parts (such as mixing blades and screens), as these directly affect long-term operational efficiency.