1, the workability of concrete mixture can meet the construction needs.
2. The concrete strength can meet the design requirements.
3, concrete should have good durability.
4. Under the condition of meeting the above requirements, try to reduce the cost and increase the income.
Extended data:
Trial mixing, adjustment and determination of self-compacting concrete mixture ratio shall meet the following requirements:
1. The raw materials actually used in the project should be used in the trial mix of concrete, and the minimum mixing amount of each plate of concrete should not be less than 25L.
2, try to match, should first try to mix, first check the mixture self-compacting performance must control index, then check the optional index of mixture self-compacting performance. When the self-compacting performance of the mixture obtained by trial mixing fails to meet the requirements, the volume fraction of cementing material, admixture or sand should be adjusted under the principle of constant water-binder ratio and reasonable dosage of cementing material and admixture until the requirements are met.
3. The concrete strength test should adopt at least three different mix proportions. When different mixture ratios are adopted, one of them shall be the benchmark mixture ratio determined in the second paragraph of Article 5.2.2 of this Regulation, and the water-binder ratio of the other two mixture ratios shall be increased and decreased by 0.02 respectively compared with the benchmark mixture ratio; The water consumption is the same as the benchmark mixture ratio, and the volume fraction of sand can be increased or decreased by 65438 0% respectively.
4. When making concrete strength specimens, it should be verified whether the self-compacting performance of the mixture meets the design requirements, and the result represents the performance index of the concrete mixture with corresponding mixture ratio.
5. During the concrete strength test, at least one set of specimens shall be made for each mixture ratio. When the standard curing reaches the age of 28d or the design requirements, pressure test shall be conducted, and several groups of specimens can be made at the same time.
According to the standard of Test Method for Early Estimation of Concrete Strength (JGJ/T 15), the early estimation of concrete strength is used to adjust the mix proportion, but it should finally meet the strength requirements of standard curing for 28d or design specified age. If there are durability requirements, the corresponding durability indicators should also be tested.
6, should adjust the benchmark mixture ratio according to the test results.
7. For projects with special application conditions, it is appropriate to adopt the determined mixture ratio to carry out simulation tests to test whether the designed mixture ratio meets the engineering application conditions.
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