Description and cause analysis of common problems in asphalt mixing plants

The quality of the asphalt mixing plant will be a key factor affecting the quality of the project. After reviewing relevant materials related to the production and construction of asphalt concrete, we summarized some cases of failures in asphalt concrete mixing stations during construction and analyzed the reasons.
1. Unstable output and low production efficiency of asphalt mixing plants
(1) Improper proportioning. The mix ratio of asphalt concrete is divided into target mix ratio and production mix ratio. Among them, the target mix ratio controls the cold material transportation ratio of sand and gravel materials, and the production mix ratio is the mixing ratio of various types of sand and stone materials in the finished asphalt concrete materials specified in the design. The production mix ratio is determined by the laboratory, which directly determines the off-site grading standard of the finished asphalt concrete. The target mix ratio is set to further ensure the production mix ratio, and can be adjusted appropriately during production according to the actual situation. When the target mix ratio or the production mix ratio is not appropriate, the stones stored in each measurement of the asphalt mixing station will be disproportionate, with some overflowing and some other materials, unable to be weighed in time, and the mixing cylinder will be idling, resulting in reduced output.

Asphalt mixing equipment is a large-scale equipment, so you must pay attention to safety when using it to avoid accidents. But to put it simply, if you want to truly use it safely, you must master some basic common sense. The following main things must be kept in mind.

Asphalt damage avoidance mechanism in asphalt mixing plant
1. Asphalt operators should undergo physical examination. Anyone suffering from conjunctivitis, skin disease or allergic reaction to asphalt should not engage in asphalt work.
2. Asphalt operators must apply protective ointment on exposed parts of their skin, and a first aid kit should be provided on the construction site.
3. The factory uniforms and protective equipment of asphalt operators are stored in a centralized manner and are prohibited from being worn home or entering collective dormitories.
4. The transfer of lumpy asphalt should usually be carried out at night and on cloudy days, especially during hot seasons. Small machinery should be used for loading and unloading, and it should not be lifted and transported directly by hand.

The asphalt mixing plant contains multiple different systems with different functions. The drying system is one of them. Its main function is to heat and dry the materials to reach the temperature required for the process. In order to successfully achieve this goal, the drying system must provide a certain amount of heat.

Asphalt (composition: asphaltenes and resin) tanks are divided into: intermittent and continuous functions according to the production process: initial batching of aggregates, heating and drying, screening and measurement; heating and insulation of asphalt (composition: asphaltene and resin) , transportation and measurement; transportation and measurement of filler; uniformly mix the measured aggregate, asphalt (composition: asphaltene and resin), and filler into a finished product of a certain temperature.

Asphalt mixing equipment has a special function, which is that it can perform cyclic heating to make the asphalt product reach the best condition. But how does it achieve this function? Everyone is curious about this.

In order to keep the asphalt mixing plant in a stable operating process, a series of adverse factors related to it must be excluded. What should be paid attention to in this process?
First of all, the selection of the delivery pump in the asphalt mixing plant must meet the requirements of asphalt pouring per unit time during construction, height, and horizontal distance requirements. At the same time, there must be a certain technical and production capacity reserve, and the balanced production capacity is preferably 1.2 to 1.5 times.
Secondly, the movement and hydraulic systems of the asphalt mixing plant must be normal, and there must be no abnormal sound and vibration to avoid large aggregates and lumps inside the equipment, otherwise it is easy to get stuck at the feed inlet of the mixing plant or be blocked due to arching. Another point is that when the asphalt mixing plant is in the same site, it is not suitable to use too many pumps and pumps from multiple manufacturers to avoid affecting its normal operation.

As a special equipment, standardizing the operating procedures of important production tools of asphalt mixing stations, conducting daily maintenance, regular inspections, eliminating hidden dangers, etc. can effectively ensure the safety and stability of the equipment and prevent equipment from malfunctioning due to misoperation. causing equipment damage. Good maintenance operations can also greatly extend the service life of asphalt mixing plants. Therefore, before daily operation, the asphalt mixing plant must be properly maintained to make the asphalt mixing plant operate better and create wealth.

Asphalt is commonly used in our modern urban life, especially in the process of urban highway construction. As an important road surface paving material, the demand for its use is relatively high. Only by using better relevant material performance characteristics can the overall effect be well helped.
Asphalt mixing plants are equipment products that need to be involved in the production and use of such products. With its own excellent performance, it has been better expanded in the promotion of the existing market use scope. The coordination of external use factors is also a key part, and the relationship between various factors must be handled well.

At present, the assembly and installation technology of large-scale asphalt concrete mixing equipment in high-grade highway construction is gradually improving. In order to improve work efficiency, it is necessary to analyze the pretreatment agent for the selection and matching of large-scale mixing equipment and auxiliary equipment, and clarify the installation and commissioning of asphalt stations. With the continuous change of highway construction methods, it is necessary to adopt production equipment according to the requirements of the development of the times. Intermittent asphalt mixing equipment is a widely used road construction equipment with the characteristics of simple operation and high work efficiency. Relevant staff are required to master the installation, construction and management methods of mixing equipment.

Judging from the situation of highways in our country, asphalt pavement is the most used, which is one of the reasons why asphalt mixing plants have developed so rapidly. Under the situation of rapid economic development, the quality problems of asphalt pavement are gradually increasing, which puts forward higher and higher requirements for the quality of asphalt. It is understood that the primary factor that affects the quality of asphalt is the ratio of raw materials. This is also covered in the introduction of asphalt mixing stations. You can discuss it together.
In order to obtain high-quality asphalt products, in addition to the asphalt mixing equipment meeting the requirements, selecting the appropriate asphalt mixture gradation type is also a top priority. According to my country’s current regulations, the maximum particle size of the asphalt mixture in the upper layer of the highway should not exceed half of the layer thickness; while the maximum particle size of the aggregate in the middle surface layer of asphalt mixture should not exceed two-thirds of the layer thickness; and the asphalt layer should not exceed half of the layer thickness. The maximum nominal aggregate size of the pavement structural layer mixture should not exceed one-third of the layer thickness.
Based on this analysis, if an asphalt surface layer with a certain thickness is selected according to the above specifications, the particle size of the asphalt mixture aggregates will generally be larger, which will inevitably bring insurmountable construction difficulties to the construction of asphalt concrete pavement. After investigation, testing, analysis, and comparison, it can be seen that the lower layer has a wider choice, so the AG-201 gradation type can be used; while the selection of the upper layer mixture type is more difficult, and it is necessary to achieve a reasonable choice of this mix ratio. , on the one hand, we must examine as many aggregate resources as possible, and on the other hand, we must also consider the model of the mixing equipment.
In order to ensure the quality of the project, strict selection and inspection of engineering materials must be carried out. Therefore, the selection and determination of raw materials should be based on the requirements for pavement structure and use quality, combined with the supply of floor materials, and inspection in accordance with the requirements of relevant test procedures, and then Select the best materials so that all technical indicators of the materials meet the specified technical requirements.

In fact, asphalt mixing stations are not uncommon in our daily lives. They are mainly a unit of equipment specially designed to mix asphalt. What we really don’t understand is the gas system of the asphalt mixing station. Only correct maintenance And operation can bring out the best production effect. So what are the faults in the gas circuit of asphalt mixing station?
The following three points are the more common gas path failures of asphalt mixing stations:

Modified Bitumen

Asphalt mixing plant refers to a complete set of equipment used for batch production of asphalt concrete. Its main function is to produce asphalt mixture, colored asphalt mixture, etc., and has been widely used in road construction. However, during the production process of asphalt mixture, pollutants such as noise, dust, and asphalt smoke will be produced, seriously polluting the environment and threatening the health of workers. Therefore, under the current background of building a resource-saving and environment-friendly society in our country, it is very important to save energy and reduce consumption during the use of asphalt mixing plants. The following article mainly starts from the three factors that affect the asphalt mixing plant, and explores the energy saving and consumption reduction measures of the asphalt mixing plant, aiming to reduce the cost of asphalt production and improve the efficiency of the asphalt plant.

Determining the material is a necessary stage in the design process of asphalt mixing equipment, and it is also one of the most critical links, because the material will be directly related to the use effect and service life of the entire equipment. Generally, when we determine the machine material, we usually base it on the characteristics of the working medium, and the same is certainly true for asphalt mixing equipment.

[1]. Composition of intermittent asphalt mixing plant
The intermittent asphalt mixing plant mainly consists of cold material silo, cold material distribution system, cold material conveying system, combustion and drying system, ventilation and dust removal system, hot material elevator, vibrating screen, hot material silo, powder conveying system and asphalt conveying system. System, metering system, mixing cylinder, control system, finished material transportation and storage system, asphalt heating and insulation system, etc.
2. Discussing the phenomenon of warehouse cascading in asphalt concrete mixing plants
2.1 First, let’s introduce the structure and principle of vibrating screen. The main components include: RetentionRubber, SupportTube, vibrating screen drive system and supporting electrical components
The working principle is introduced as follows: hot aggregate is sent to the vibrating screen through the hot aggregate elevator, and the hot aggregate is vibrated and screened by the vibrating screen. Stones of different specifications enter their corresponding hot aggregate bins through the screen and cannot pass through the geotechnical work. The super-sized particles from the cloth screen enter the overflow bin and are sent out.

Oscillating screen. It can screen the heated aggregate according to the design. It requires fully enclosed, double oscillating motor replacement (replacing one substance for another (mostly the strong one takes the place of the weak)) eccentric shaft oscillation, each The layer screen is easy to install quickly. The service life of the drying roller and the power part is not less than 6000h. The roller can fully use heat, the material curtain flows evenly, and the inclination is required to be adjustable.

Asphalt mixing stations are constructed according to a certain process, which can not only ensure the construction quality, but also ensure that the asphalt mixing station is not damaged. Although construction details are critical, the key skills of asphalt mixing station construction must be mastered.
Before the construction of the asphalt mixing plant, the top surface of the asphalt mixing station construction range should be removed, and the site elevation should be kept dry and flat to meet the design requirements. If the surface is too soft, the foundation should be reinforced to prevent the construction machinery from losing stability and ensure that the pile frame is vertical.
Then the on-site construction machinery should be inspected to ensure that the machinery is intact and assembled and tested under the premise of meeting the requirements. To ensure the verticality of the asphalt mixing plant, the deviation of the gantry guide and the mixing shaft from the verticality of the ground shall not exceed 1.0%. Asphalt mixer manufacturer.

Safety is the key point for any piece of equipment, and asphalt mixers are of course no exception. What I want to share with you is the knowledge in this area, that is, the safe operation specifications of asphalt mixers. You might as well pay attention to it.
In order to prevent the asphalt mixer from moving during work, the equipment should be placed in a flat position as much as possible, and at the same time, use square wood to pad the front and rear axles so that the tires are elevated. At the same time, the asphalt mixer must be provided with secondary leakage protection, and it can only be started after the inspection, trial operation and other aspects are qualified.

There is also a reversing valve in the asphalt mixing plant, which generally does not cause problems, so I have not understood its solutions in detail before. But in actual use, we encountered this kind of failure. How should we deal with it?
The failure of the reversing valve of the asphalt mixing station is not complicated, that is, the reversing is not timely, gas leakage, electromagnetic pilot valve failure, etc. The corresponding causes and solutions are of course different. For the reversing valve to not change direction in time, it is generally caused by poor lubrication, the spring is stuck or damaged, oil dirt or impurities get stuck in the sliding part, etc. For this, it is necessary to check the status of the lubricator and the quality of the lubricating oil. Viscosity, if necessary, the lubricant or other parts can be replaced.
After long-term use, the reversing valve is prone to wear of the valve core sealing ring, damage to the valve stem and valve seat, resulting in gas leakage in the valve. At this time, the sealing ring, valve stem and valve seat should be replaced, or the reversing valve should be replaced directly. In order to reduce the failure rate of asphalt mixers, maintenance must be strengthened on a daily basis.

When we operate the asphalt mixing station, we should heat the equipment half an hour in advance, and the clear tank should be heated for at least two hours; and manually operate each part of the equipment to ensure that it is in good operation. status; it is also necessary to conduct relevant inspections on the valves and manually collect and return oil to ensure that the equipment can operate normally.
Several requirements for safe operation of asphalt mixing plants:

When inspecting the asphalt mixing plant, it was found that the asphalt in the pipeline solidified because the temperature of the asphalt transportation pipeline did not meet the requirements. Analysis believes that the reasons for this result are that the high-level oil tank of the heat transfer oil is too low, resulting in poor circulation of the heat transfer oil; the second is that the inner tube of the double-layer pipe is eccentric; the third is that the heat transfer oil pipeline is too long; and the fourth is that the heat transfer oil pipeline is not insulated measure.

Due to raw materials or usage, asphalt mixing plants will be subject to a certain degree of wear or other failures during daily use. If they are not controlled or repaired in time, the problem will be further exacerbated. For asphalt mixing plants, what are the ways to prevent wear and failure?
If the asphalt mixing plant is not treated in time after being worn, it may corrode once it is in contact with air, rainwater, etc. for a long time. If the parts of the asphalt mixing plant are severely corroded, the service life and normal operation of the entire equipment will be affected.

The first step in establishing an asphalt mixing station is to determine the host machine and feed batching system. Generally, the configuration is based on the project’s construction period, total amount of concrete, daily concrete consumption and other indicators. The basic principle is to meet the daily concrete consumption. Under normal circumstances, a project can only have one asphalt mixing station, or separate mixing stations can be set up according to zones, or a large mixing station can be set up together with an appropriate number of concrete transport trucks, all of which depend on the actual situation.

The HMA-B series forced asphalt mixing plant can produce reliable quality asphalt in various proportions. The product technology is mature, the operation is stable, the specifications are complete, the efficiency is high, the output is large, and the finished asphalt quality is good. It is suitable for various sizes and This type of road construction project has more obvious advantages in larger-scale road construction projects and high-grade highway construction projects.

As an important production equipment in construction, asphalt mixing plant has high production investment. Therefore, production is very important during use, but daily maintenance is also very important. In addition to regular maintenance, routine maintenance is also essential. The editor of Asphalt Mixing Plant shares some key points of daily maintenance and scheduled maintenance;

In today’s road construction, the use of a large number of road construction machinery represents the entry into the era of highway mechanization. For users, the goal is to use road construction machinery reasonably and tap its potential as much as possible. However, road construction machinery requires various accessories to work together. Now let’s take the asphalt mixing plant as an example to see what commonly used accessories and equipment are available.
Asphalt mixing plant equipment is a relatively complex system, which includes many equipment, mainly nine parts, namely: bag dust removal, finished material temporary storage warehouse, grading machine, fast heating asphalt tank, asphalt barrel removal machine, asphalt recycled material crushing and screening system, coal block crusher, coal mill and dust removal equipment, etc.

Due to certain restrictions on the current development status and conditions, the profits of the domestic asphalt pavement construction industry are getting lower and lower. Therefore, in the process of using asphalt mixing plants for production, on the one hand, the quality of the products and customer requirements must be ensured. , on the other hand, it is necessary to reduce production costs. Therefore, cost management is very important, and refined management should be implemented in this regard.
First, for device management. Since equipment is the foundation and key of production, in the cost management of asphalt mixing stations, the management of equipment plays an important role in reducing costs. Only by managing the equipment well can the normal working status be ensured, which provides the necessary guarantee for the smooth progress of the project. In fact, in today’s highway projects, equipment costs account for a large part of the cost and profit. The huge profits after the construction of a highway will be greatly affected by the management of materials and equipment.