1.
Through comparison of several projects, we found that the actual volume of columns, beams and slabs was little different from the settlement in the drawings, while the difference between the foundation, roads and other parts was large.
In case of any error between the actual amount and the drawing after pouring, the construction unit shall bear the responsibility, which has nothing to do with the concrete company.
What is the concrete unit weight of each strength grade? When the concrete mixer truck enters the construction site, the construction unit should organize personnel to weigh it, or conduct spot check.
2.
1.
It is better to select the same clinker.
As a kind of semi-finished product, the strength commercial concrete is sold to the construction unit and transformed into qualified products through the standardized operation of the construction unit.
The construction party does not recognize the quantity exceeding the quantity calculated on the drawings and does not sign a bill.
The construction party always thinks that the difference between the quantity calculated according to the drawings and the actual supply quantity is that the concrete enterprise is cutting corners and shifting the responsibility to the concrete enterprise.
The causes (1) are related to the structural design and stress load, such as exceeding the design load range, structural settlement difference, insufficient member section size, insufficient reinforcement amount, unreasonable reinforcement arrangement, etc; (2) Related to use and environmental conditions, such as environmental temperature, humidity change, reinforcement corrosion, impact, vibration, etc; (3) Related to raw materials and mix proportion: such as high cement consumption, high hydration heat, admixture problems (such as calcium content of fly ash), improper mix proportion of concrete, etc; (4) Related to construction: such as poor water adding and tamping on site, excessive slump, aggregate sinking and bleeding, concrete surface strength is too low, and the next process is started, maintenance measures are improper or maintenance is not timely.
Cracked commercial concrete has more cracks than the original on-site self mixed concrete, because the original self mixed concrete does not add admixtures and admixtures, the coarse aggregate size is large, the slump is small, and the cracks are relatively small.
After the cooperation between the volume concrete enterprise and the construction unit, the volume problem is often disputed in the supply.
Preventive measures (1) Cement.
2.
If the strength is found to be unqualified or the test block is found to be unqualified in the inspection on the acceptance site, the construction unit will often shift the responsibility to the concrete enterprise, from reducing the concrete volume to bringing a lawsuit.
1.
Preventive measures In order to avoid such disputes, we suggest that the concrete unit weight should be agreed upon when the contract is signed.
Many construction units unilaterally believe that the strength must be guaranteed when purchasing commercial concrete, while ignoring the premise that the construction unit should use commercial concrete according to the correct requirements.
When the spot check process finds that the deviation value is lower than the agreed value, the supplied batch of concrete should be signed for the minimum quantity.
2.2 In terms of concrete raw materials and mix proportion (1) the mix proportion design must be reasonable; 2.3 Construction: (1) Formwork support shall be firm; (2) The concrete mixer truck shall not stay at the construction site for too long to avoid adding water at will; (3) Concrete vibration shall be dense; Color difference We must control the concrete with color difference requirements, such as fair faced concrete, exposed wallboard, column, etc.
Reasons: (1) The mix proportion design is unreasonable, and the commercial concrete is really weak; (2) The control of concrete raw materials and processes is unstable, and the quality of commercial concrete fluctuates greatly; (3) Add water randomly on site, change the water cement ratio, and affect the strength; (4) The vibration is not dense (5) The curing is not in place; (6) The specimen is poorly formed and not cured as required.
2.
The construction unit always thinks that the color difference is caused by the color difference of the raw materials of the concrete company, so it always puts the responsibility on the concrete company when the color difference problem occurs.
With the continuous popularization of commercial concrete, the contradiction between the project department and the mixing plant has also been pushed to the forefront of the storm.
If there is no objection to the quantity during the spot check, the delivery note shall be signed for confirmation.
1.
It is required to determine the manufacturer, strength grade and batch number.
Causes: (1) The color difference of raw materials of concrete is large and unstable; (2) The slump of concrete is unstable; (3) Reasons for construction operation; (4) Reasons for the template; (5) Reasons for on-site curing.
2.
Preventive Measures 2.1 The design of measures adopts the “principle of dense distribution of fine bars”, with local reinforcement, such as the role of mid span, slab column junction, post cast strip, settlement strip and reinforcement strip.
Portland cement is preferred.
Do not give up effective curing due to trouble or increased costs, which will lead to potential quality problems of concrete; (4) On site test block fabrication The concrete company sends technicians to cooperate with the site documenter to make the test block according to the Sampling System and maintain it in time to ensure that the strength of the concrete test block is uniform and qualified.
Preventive measures (1) The quality of incoming raw materials shall be well controlled, and unqualified raw materials shall be resolutely rejected to ensure that the quality of raw materials is qualified and stable; The laboratory shall strengthen the certification of the trial mix of the mix proportion, and adjust the mix proportion in time with the change of seasons to ensure the surplus ratio of strength; (2) Strengthen the technical communication with the person in charge of the construction and the on-site supervisors, and provide the commercial concrete operation instructions to eliminate illegal operations, standardize the construction, and ensure the project quality; (3) The curing of concrete after pouring shall be effectively communicated with the construction unit and implemented according to the specifications.
What are the contradictions between the construction site and the mixing plant? Here are some common problems with the mixing plant and their solutions, to provide some solutions for friends engaged in construction.
Causes (1) Measurement problems of concrete enterprises; (2) Waste of concrete enterprises in the unloading process (unloading to the ground, reversing the mixer truck, etc.); (3) Drivers steal concrete; (4) Move the construction site to other parts for pouring; (5) The pouring thickness is not well controlled, and it is too thick; (6) There is a large margin in the pump truck pipe; (7) The concrete mixer truck will drive away before unloading.
For this reason, after the commercial concrete cracks appear, the construction unit will shift the responsibility to the concrete company.
(2) Coarse aggregate (crushed stone)..
