I. Main factors affecting the production quality of asphalt mixing plants
1. Asphalt concrete mix ratio is incorrect
The mix ratio of asphalt mixture runs through the entire construction process of the road surface, so the scientific ratio of the mix ratio and the production mix ratio can play an important role in the production and construction. The unreasonable production mix ratio of the asphalt mixture will lead to Asphalt concrete is unqualified, which affects the service life of asphalt concrete pavement and the cost control of asphalt concrete pavement.
2. Asphalt concrete discharge temperature is unstable
The “Technical Specifications for Highway Asphalt Pavement” clearly stipulates that for intermittent asphalt mixing stations, the heating temperature of the asphalt should be controlled within the range of 150–170 °C, and the temperature of the aggregate should be higher than the temperature of the asphalt. At -20 ° C, the factory temperature of the mixture is generally 140 to 165 ° C.
If the temperature is not up to standard, the flower will appear, but if the temperature is too high, the asphalt will be burnt, which will seriously affect the quality of paving and rolling.
3, mixing of the mixture
Before mixing, the boiler type and parameters should be strictly checked on the mixing equipment and supporting equipment to ensure that the dynamic appearance is in good working condition.
At the same time, the timing of the metering equipment should be checked to ensure that the amount of asphalt and aggregate in the mixture meet the requirements of the Technical Specifications.
The production equipment of the mixing plant should be placed in a place with convenient transportation conditions, and at the same time, the storage of temporary waterproof equipment, rainproof and fire prevention measures should be done.
After the mixture is evenly mixed, all the mineral particles are required to be bound by the asphalt, and there is no uneven packing, no white matter, no agglomeration or segregation.
In general, the mixing time of the asphalt mixture is 5 to 10 seconds, the wet mixing is more than 45 seconds, and the mixing time of the SMA mixture should be appropriately extended.
It is not possible to reduce the mixing time of the mixture just to increase productivity.
Second, the analysis of common faults in asphalt concrete mixing station
1. Failure analysis of the cold feed device
No matter whether it is stuck in the variable speed belt motor or the cold belt, it will affect the stoppage of the variable speed belt conveyor. If the variable speed belt conveyor circuit fails, it is necessary to check the inverter in detail to see if it can run. Normal, if there is no short circuit, it is necessary to check the conveyor belt to see if it is running off or slipping. If it is a conveyor belt problem, it should be adjusted in time to ensure the normal operation of the function.
2. Analysis of the problem of the mixer
The problem of the mixer is mainly caused by abnormal noise during construction. At this time, we need to first consider whether the motor bracket is unstable due to excessive load of the mixer. In another case, it is necessary to consider whether the bearing with a fixed function may be damaged. This requires the operator to perform all inspections, and to carry out the repair work of the bearing, and timely replace the parts of the mixer that have been seriously damaged to prevent the uneven surface of the mixture.
3. Analysis of the problem of the sensor
There are two situations in which the sensor has a problem. In one case, the blanking value of the silo is inaccurate. In this case, the sensor needs to be viewed. If the sensor fails, it should be replaced in time. In another case, the scale is stuck. As a result of the sensor’s problem, I need to promptly remove the foreign object.
4, the burner can not be normally ignited and burned
The problem that the incinerator cannot be normally ignited and incinerated when the product is heated requires the following methods to be solved by the operator: First, comprehensive inspection of the operating room and each incineration device, such as the belt, power supply, drum, and fan, etc. The power supply is detailed, and then the direction of the fan’s incineration valve is checked to see the condition of the cold damper, the switch status of the fan door, the condition of the drying drum and the internal pressure, whether the meter is already in the manual state, in all indicators In the qualified state, enter the second step of the view: check whether the oil circuit is dredging, whether the burning device is normal, whether the high pressure package is damaged, if it can not solve the problem, it goes to the third process and burns it. The electrode device is taken out to check the cleaning condition, including whether the oil is blocked by the oil and the electrode has a useful distance. If the above observation is normal, then the fuel pump operation status is required. Perform a detailed review and test that the pressure at the pump port is normal.
5. Analysis of abnormal pressure performance
The factors affecting the internal pressure of the blower mainly include two aspects: blower and induced draft fan.
When the blower generates a positive pressure phenomenon in the drum, the induced draft fan will cause a negative pressure in the drum, and the negative pressure generated can not be large, otherwise the dust will fly out from the four sides of the drum to affect the surrounding environment.
When a negative pressure occurs in the drying drum, the worker should perform the following operations: First, in order to determine the performance of the damper, a strict inspection of the air inlet of the induced draft fan is required.
When the damper does not move, it can be set to the manual operation state, and adjust the damper to the hand wheel to check whether it is normal operation, and eliminate the jammed condition. If it can be opened manually, then follow Detailed procedures for the program.
Secondly, under the premise that the damper of the induced draft fan can be used normally, the staff needs to inspect the pulse plate in detail, check whether the line or the electromagnetic switch has any doubt, find the cause of the accident and solve the problem in time.
6, the analysis of the oil-stone ratio is not suitable
The oil-stone ratio refers to the mass ratio of asphalt and sand filled with asphalt, which is an important index for controlling the quality of asphalt concrete.
If the ratio of oil stone is too large, it will cause the pavement paving to be crushed and present a “cake” phenomenon.
However, if the oil-stone ratio is too small, the concrete material will be diverged, resulting in the rolling is not formed. Both of these conditions are serious quality accidents.
7, analysis of the screen problem
The problem of the screen is mainly the appearance of the screen hole, which will cause the aggregate of the previous gear to enter the silo of the next gear, and the sampling of the mixture is extracted and screened, if the oil stone of the mixture is relatively large. The oil cake phenomenon occurs after paving and rolling the road surface.
Therefore, if every time or an abnormality occurs in the extraction of the screening data, it is necessary to think about the screening of the screen.
Third, the maintenance of asphalt concrete mixing station
1. Maintenance of the tank
Mixing tanks are important equipment for concrete mixing stations and are the most abrasive.
Generally, the mixing station liner, mixing arm, blade and shaker door seal should be adjusted and replaced in time according to the wear condition, and after each concrete is mixed, the tank must be flushed in time, and the mixing station should be The concrete remaining in the tank and the concrete attached to the material door are thoroughly washed to avoid solidification of the concrete inside the tank.
Also check the flexibility of the opening and closing of the door to avoid the door jam.
The maintenance of the tank must be disconnected from the power supply, and a special person should be sent to take care of it. Before each lift, it must be ensured that there is no foreign matter in the tank, and the host is stopped.
2, the travel limiter maintenance
The limiter of the concrete mixing station includes the upper limit position, the lower limit position, the limit limit and the circuit breaker.
In the work, the sensitivity and reliability of each limit switch should be carefully checked. The contents of the inspection mainly include whether the control circuit components, connectors and wiring are good, and the line is normal. This affects the safe operation of the mixing station. Far-reaching.
Fourth, asphalt mixture mixing quality control measures
1. The position of coarse aggregate in asphalt concrete is very important. Generally speaking, the particle size of the mineral is 2.
The gravel of 36 to 25 mm is consistently referred to as coarse ore.
Its main application is used in the surface layer of concrete to strengthen the particle material and increase the frictional force to reduce the influence of displacement. This requires that in the field of chemical properties, the coarse aggregate mechanical structure can be matched with its needs to reach the technology. The need, and has specific physical properties, such as high temperature physical manifestation, density of material and influence factors of strength, etc. After the coarse aggregate is broken, the appearance should adhere to the rough state, and the character of the test body should be a square with significant angularity. The content of the needle-like particles should be kept at a lower state, and the friction inside is relatively strong.
And the particle size is about 0.
075 to 2.
The broken rock in the 36mm section is collectively referred to as fine aggregate, which mainly includes mineral ore and mineral powder. These two fine aggregates are very strict in cleaning requirements. It is not allowed to attach or stick any harmful substances. The interlocking force between each other also compresses the gap between the aggregate and the aggregate to enhance the stability of the material.
2. When mixing the mixture, strictly carry out the mixing according to the specified construction temperature of the asphalt mixture. Before the mixture is stirred and opened, increase the temperature by 10 °C to 20 °C on the basis of this temperature. The quality of the material is very favorable. Another method is to properly reduce the amount of aggregate entering the drying cylinder, increase the temperature of the flame, and ensure that the heating temperature of the coarse aggregate and the asphalt is slightly higher than the specified when the stirring is started. The numerical value can effectively avoid the situation that the first tray of the asphalt concrete mixture does not present waste.
3. Before the construction work is carried out, the grading review of the aggregate particles should be done first. This review process is very important and directly affects the construction quality of the project.
Under normal circumstances, there is often a big difference between the actual ratio and the target ratio. In order to better match the actual ratio with the target ratio, the hopper’s motor rotation speed and loading flow rate should be adjusted. To better ensure consistency, so as to better achieve the matching effect.
4. At the same time, the screening capacity of the screen affects the setting of the half and floor production to a certain extent. In the case of less experience, if you want to do the screening of the screen, you must set different production speeds. to fulfill.
In order to ensure the normal operation of geotextile production, it is necessary to ensure that the distribution of mineral materials does not have too much error. The proportion of mineral materials should be calculated according to the expected output before construction. The production parameters should be balanced with the set parameters. So that it does not change during the construction process.
5. On the basis of ensuring the normal use of asphalt mixture, it is necessary to set the specific aggregate and the actual use of the ore powder, and at the same time appropriately reduce the amount of mineral powder used; secondly, it should be noted that it cannot be used in the process of mixing construction. Change the size of the damper, and assign professional staff to conduct regular inspections to ensure that the thickness of the asphalt film is suitable for construction requirements, and prevent the mixture from appearing white color to improve the quality of construction.
6. The mixing time of the mixture and the mixing temperature should be strictly controlled.
The uniformity of the asphalt mixture has a very close relationship with the length of the mixing time. The two are proportional to each other, that is, the longer the time, the more uniform, but if the control is not good, the asphalt will age and the mixture will be aged. Quality has a bad influence.
Therefore, the temperature should be scientifically controlled during mixing. The mixing time of each batch of batch mixing equipment should be controlled between 45-50 seconds, and the dry mixing time should be longer than 5-10 seconds to mix. The mixing of the materials is uniform.
In short, as a mixing station staff in the context of the new era, we must fully realize the importance of strengthening the quality of the asphalt mixing plant equipment and its maintenance. Only by controlling the quality of the asphalt mixing station can we ensure the asphalt mixing. The quality of the station production can produce more high-quality and efficient asphalt mixture, laying a solid foundation for the improvement of engineering quality.