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Quality assurance system of concrete mixing plant

Author: admin Release time: June 20, 2017 Number of visits:

1. Organizational assurance

Establish and improve the post responsibility system of concrete mixing plant, clarify the responsibilities and work contents of each post responsible person, and formulate corresponding reward and punishment methods. The quality group regularly organizes and holds the mixing plant engineering regular meeting, analyzes the concrete quality, discovers the problem, takes the corrective measure, rewards the good and punishes the bad, promotes the concrete quality improvement.

2. Technical guarantee

We should insist on the regular education of common problems of mixing quality, and make unremitting efforts in quality and technology education. According to the characteristics of project progress, process transformation and environment change, timely organize construction personnel to seriously study professional knowledge. For example, different winter and summer seasons, the technical department formulated detailed winter concrete mixing technical assurance measures to meet the low and high temperature of high performance concrete.

3. Ideological guarantee

The quality team has been making unremitting efforts to do a good job of ideological education for workers in the mixing plant for a long time, so as to grasp the ideological trends of the staff at any time, mobilize the enthusiasm of the work, and improve the sense of responsibility, so as to ensure the concrete quality from all aspects.

4. Material assurance

Strictly implement the raw material inspection system and the concrete incoming inspection system to ensure that the raw materials used meet the requirements of concrete construction.

5. Detection

Establish self inspection and sampling inspection system. After the concrete is discharged, self inspection is carried out at random, and the concrete specimen is made, and the standard curing is sent to the laboratory for test and detection.

6. Mixing quality control measures

(1) Before mixing concrete, the moisture content of coarse and fine aggregates should be strictly controlled and measured, and the moisture content changes of coarse and fine aggregates caused by weather changes should be accurately measured. According to the actual measurement, the amount of various materials required for each concrete plate is calculated. The amount of water, cement, fly ash and admixture should be accurate to ± 1%, and the amount of coarse and fine aggregate should be accurate to ± 2% (by mass).

(2) Before concrete mixing, the batching system of the concrete mixing station should be checked to ensure that the batching can be carried out in strict accordance with the construction batching list. The type and grade of cement used for mixing concrete, the concrete mix proportion and the quantity of each component material of each concrete plate shall be indicated in text form beside the console.

(3) Before mixing one plate of concrete each time, the mixer should be started to run empty. After the operation is normal, the mixer should be added with 10% more cement, water and fine aggregate or reduced by 10% coarse aggregate according to the mix proportion, so as to make the surplus mortar cover the inner wall of drum and mixing blades, so as to prevent the mixing of one plate of concrete The mortar in the material is less.

(4) When the concrete mixer starts mixing each time, the workability and other indicators of the pan and the third pan concrete should be inspected. If the concrete does not meet the requirements, the situation should be analyzed and treated immediately until the mixture meets the requirements, and then the production can be sustainable.

(5) During the mixing process, the slump and air content test and temperature inspection shall be carried out for the concrete according to the specified frequency. The testing personnel of the mixing station shall inspect the mixing site at least once per shift. The test results shall meet the requirements of the concrete workability in the table, and records shall be made.

(6) The relevant staff of mixing station should actively cooperate with the tester.

7. Process quality control

(1) The quality control of raw materials entering the site should be operated in accordance with the specific operating procedures and specifications of the laboratory, and the quality of materials should be strictly controlled to ensure the quality of concrete.

(2) Raw materials should be classified and stacked to avoid mixing. On the material warehouse, there should be obvious identification plate, indicating the origin, quantity, specification and inspection of materials.

(3) When the raw materials are transported from the material stacking site to the material bin of the mixer, fixed loaders and drivers should be used. Attention should be paid to avoid waste caused by the scattering of materials. The materials scattered on the road should be cleaned by special personnel. Materials shall be transported to the designated material warehouse.

(4) The mix proportion of concrete shall be proportioned in strict accordance with the "mix proportion notice" and input into the control computer in the operation room of the concrete mixing station to mix the raw material proportion of concrete.

(5) The control room of mixing plant shall be manned by operators, and other non operators shall not enter without permission. The operator should be trained strictly and work with certificate, understand the working principle and basic performance of concrete mixer, be able to operate the machine skillfully and be able to handle simple faults.

(6) The performance indexes of the mixed concrete should meet the design and specification requirements, otherwise it can not be put out of the site. The laboratory shall take samples at the mixing plant and construction site for inspection, so as to fully ensure the quality of concrete.

(7) In the transportation of concrete, the driver should ensure that the concrete tank is in the state of low-speed mixing, and determine the pouring speed according to the concrete situation after it is transported to the site.

8. Winter construction scheme

When the day and night average temperature of the construction site (the average value of higher and lower temperature or the average value of outdoor temperature at 6:00, 14:00 and 21:00 local time) is lower than 5 ℃ for 3 consecutive days or the lower temperature is lower than - 3 ℃, winter construction measures shall be taken for concrete construction.

Quality assurance measures for winter concrete construction:

(1) The water cement ratio should be smaller. The strength of concrete should be improved when it is mixed with one grade of antifreeze.

(2) Water and aggregate shall be mixed according to thermal calculation and actual trial mixing to determine the heating temperature meeting the needs of concrete pouring.

First of all, water should be heated (heating method), the heating temperature should not be higher than 80 ℃. When the aggregate is not heated, the water can be heated to above 80 ℃, but the aggregate and heated water should be put in first, and then the cement should be put into the mixture. When the heating water can not meet the requirements, the aggregate can be evenly heated (furnace), and the heating temperature should not be higher than 60 ℃. When the slump of the mixed concrete decreases or rapid setting occurs, the heating temperature of the mixture should be readjusted. The mixing time of concrete should be 50% longer than that of normal temperature construction.

(3) The aggregate shall not be mixed with ice, snow, frozen block and minerals easy to be cracked.

(4) Before mixing concrete and after stopping mixing, the drum of mixer shall be washed with hot water.

(5) The concrete truck is wrapped with cotton felt. The transportation time should be shortened as much as possible.

(6) Warm shed method shall be adopted for curing concrete, and the temperature at the bottom of the shed shall not be lower than 5 ℃, and the concrete surface shall be kept moist; when coal is used for heating, the flue gas shall be discharged out of the shed.

(7) Stones should be covered with colored strip cloth to prevent rain and snow, and sand should be covered with sheds for heat preservation.