What is the purpose use of retention of the same condition test block and the standard culture tes

Test blocks under the same conditions.

It is to determine the actual strength of the on-site components after reaching the age, and the standard maintenance is to determine the ratio strength, and the standard maintenance and the same conditions need to be retained every time (structural load-bearing components).

The standard test block should be placed in a constant temperature and humidity room for maintenance, but the site conditions are not necessarily, and the actual strength of the concrete structure will be greatly different from the standard test block. Therefore, in addition to the standard test block, the same condition test block must be required to evaluate the strength of the concrete structure at this part.

In the national standard 50204 and 107, the sampling frequency of the standard test block is specified in detail, and the test block under the same condition is based on the actual needs of the site (such as the strength of demoulding.

etc.), the same conditions also include the equivalent age of 600 degrees required by the structural entity inspection, and the project transfer is required to have this information, and in the north, the winter is also to be retained under the same conditions, mainly to be familiar with the standards and specifications.

The same condition test block refers to the concrete test block in the same aspects as the maintenance conditions of the concrete after pouring in the construction of the building. That is, the same condition curing: refers to the curing conditions of the concrete test block and the curing conditions of the concrete after pouring, etc., that is, how to maintain the concrete on site, how to maintain the test block

1. Retention site: In Appendix D of the "Concrete Specification", it is clearly stipulated that the retention method and sampling quantity of the curing specimen under the same conditions shall meet the following requirements: "The structural components or structural parts corresponding to the curing specimens under the same conditions shall be jointly selected by the supervision (construction), construction and other parties".

What is the basis for their joint selection? The purpose of curing the specimen under the same condition is to verify the concrete strength of the structural entity test, so the basis for its selection should be subject to the scope of the structural entity test. In the concrete structure sub-division project, it is clearly stipulated that "the important parts involved in the safety of the concrete structure shall be inspected by the structural entity."

The structural physical inspection shall be witnessed by the supervising engineer (the professional and technical person in charge of the project of the construction unit), and shall be organized and implemented by the technical person in charge of the construction project, and the laboratory undertaking the structural physical inspection shall have the corresponding qualifications". The scope of structural entity inspection is limited to the important parts of structural components such as columns, walls, beams and other structural components involved in structural safety, therefore, the non-important parts of structural components such as concrete cushion do not need to be retained for the same condition curing specimens. The author suggests that the design unit should be invited to participate in the supervision (construction) and the construction unit to jointly select the important parts of the structural components.

2. The number of retention stening: Article 3 of the "Code for Acceptance of Construction Quality of Concrete Structure Engineering" (GB50204-2002) stipulates that "the number of retention specimens of the same strength grade and the same condition shall be determined according to the quantity and importance of concrete engineering, and shall not be less than 10 groups and not less than 3 groups". According to the relevant provisions of the "Concrete Strength Inspection and Evaluation Standard" GBJ107, the number of retention specimens of the same strength grade and the same condition shall not be less than 10 groups, so as to constitute the basic conditions for evaluating the strength of concrete by statistical methods.

The number of retention positions is not less than 3 groups, so that it is sufficiently representative to assess the strength of concrete according to non-statistical methods. Instead of "Appendix D, Article 3" of the "Code Appendix D" as some construction personnel understand, "the number of retention specimens of the same strength grade and the same condition should be determined according to the quantity and importance of the concrete project, and should not be less than 10 groups, and not less than 3 groups". Therefore, I only need to do no less than 3 sets of maintenance specimens under the same conditions."

This is wrong, and should be correctly retained according to the quantity and importance of concrete engineering and in combination with the requirements of GBJ107 of the "Concrete Strength Inspection and Evaluation Standard".

Specification for indwelling of concrete specimens under the same conditions:

1. The number of retention specimens of the same strength grade and the same condition should be determined according to the quantity and importance of concrete engineering, and should not be less than 10 groups and not less than 3 groups, of which each floor should not be less than 1 group.

2. The retention of the curing specimens under the same conditions should be evenly distributed in the construction period of the project, and the amount of concrete poured between the two groups of specimens shall not be greater than 1000m.

3. After the mold removal of the curing specimen under the same conditions, it should be placed in an appropriate position close to the corresponding structural component or structural part, and the same maintenance method should be adopted.

Fabrication of mortar test blocks.

1. When making the masonry mortar test block, the bottomless test mold is placed on the ordinary clay brick covered with a layer of wet paper with good water absorption (the water absorption rate of the brick is not less than 10%, and the moisture content is not more than 20%), and the inner wall of the test mold is coated with a thin layer of engine oil or release agent in advance. Wet paper should be fresh. The use surface of bricks is required to be flat, and the four vertical surfaces of bricks are not allowed to be used if they are glued to cement or other cementitious materials.

2. Fill the mortar into the test mold at one time, and insert it 25 times with a tamper evenly from the outside to the inside according to the spiral direction, in order to prevent the low-consistency mortar from leaving holes after insertion, it is allowed to insert the mortar several times along the mold wall with a putty knife, so that the mortar is 6 8mm higher than the top surface of the test mold. When the surface of the mortar begins to appear in a state of pitting (about 15 30min), the raised mortar is cut and smoothed along the top surface of the test mold.

3. After the test block is made, it should be stopped for one day and night (24 2h) in the temperature environment of 20 5, and when the temperature is low, the time can be appropriately extended, but it should not exceed two days and nights, and then the numbering is dismantled. After the mold is removed, it should be cured to 28d under standard curing conditions, and then the pressure test should be carried out.

Test blocks under the same conditions.

After the mold is removed, it is placed in the construction site for self-return to He Ran for maintenance, and the standard maintenance room is placed after the standard maintenance of the test block after the mold is removed, and the mold removal test block is naturally cured. The number of standard and indwelling test blocks under the same conditions is based on the principle of not less than one group for each part, not less than one group per 100m, and not less than one group for each strength level. The mold removal test block is according to the supervision requirements.

The beam slab is impermeable concrete, so a group of impermeable test blocks must be retained, that is, 175*185*150 cylinders.

According to the amount of concrete, the standard maintenance test block is indulging, a group of 100 square meters within 1000 square meters, and a group of less than 100 square meters is also a group, more than 1000 square meters, and a group of 200 square meters.

There is no specific requirement for the same condition test block specification, if the site requires each layer to be retained, then about a group is left in each layer every 500 squares, and the test block of the mold removal is left in the number of groups according to the need, if the mold is removed in a hurry, then several groups are left in place, and pressed once after a period of time until the mold removal strength is reached.

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Differences: 1. Different definitions:

The standard culture test block is the test block that is maintained in the standard culture room. The specification stipulates that the specimen shall be maintained for 28 days in the standard maintenance room with a humidity of more than 90% in (20 3).

The isotrophic test block refers to the specimen sampled and made at the concrete pouring site, and cured according to the curing conditions of the on-site structural entity (that is, placed near the component for curing), and the compressive strength of the test block under this condition.

The values are more reflective of the concrete strength of the structural entity. The cumulative curing temperature is generally from the beginning of the curing, to the average outdoor temperature every day to accumulate to 600 degrees after the pressure test begins, but when the construction site.

When the temperature of the area is special, it should also be ensured that the curing time should not be lower than 14d and not higher than 60d.

2. The objects are different:

For concrete inspection batches.

At least one group of each inspection batch should be retained;

For the intensity level, the number of retention positions for each intensity level is determined according to the needs, and it is generally best to have the same number as the standard retention level.

3. Different roles:

For acceptance, after all the test block results come out, they must be evaluated, and the evaluation results must be qualified, otherwise the structure will be tested;

Sampling re-inspection, generally used for structural measurement, homotrophic qualified, in the structure testing can do a few points less (that is, less rebound, even without structural testing).

4. Sampling method.

And the proportions are different:

Each inspection batch is generally to be retained, the site is stirred and mixed, the same strength grade, the same mix ratio, the same production process of each concrete sampling unit (that is, when the following conditions are met, a group should be retained) should meet the following requirements:

a. Make 100 trays per mix, but not more than 100m3.

b. According to each workbench shift.

c. Each floor is coarsely poured.

d. When the amount of continuous pouring concrete is greater than 1000m3, it is calculated every 200m3. If the commercial concrete is used: the concrete used for delivery inspection is 100m3, and the concrete mixed in a workbench shift is less than 100m3 according to each workbench shift.

When the amount of continuous ** concrete is greater than 1000m3, it is calculated every 200m3.

According to the same strength level of retention, the same strength of the same condition of curing specimens, the number of retention should be determined according to the amount and importance of concrete engineering, should not be less than 10 groups, and should not be less than 3 groups, important parts (beams, plates and columns in the main body) such as generally can be retained as standard maintenance.

5. Maintenance is different

The maintenance environment of the concrete standard culture test block is (20 3), the humidity is more than 90%, and the standard maintenance room is generally built on the construction site, or sent to the standard maintenance room of the laboratory immediately after the mold is removed.

Test blocks under the same conditions.

It must be placed near the representative area for protection.

6. The conditions for inspection are different

The age of the standard culture test block is 28 days, and the age cannot be exceeded.

The age of the homotrophic test block is generally 14-60 days, that is, the equivalent maintenance age can be taken according to the daily average temperature when the cumulative age reaches 600 ° day by day, and the age period of 0 °C and below is not counted; The equivalent maintenance period should not be less than 14 days and should not be greater than 60 days.

Hello dear! We'll be happy to answer for you. How many groups of test blocks should be retained under the same conditionsA:

The structural component or structural part corresponding to the ridge slip with the condition maintenance specimen should be jointly selected by the supervision (construction), construction and other parties; For each concrete strength grade in the collapse process of the concrete structure worker, the same condition should be retained for curing specimens; The number of retention specimens of the same strength grade under the same conditions should be determined according to the importance of the concrete engineering quantity, and should not be less than 10 groups and should not be less than 3 groups; After the mold removal of the curing specimen under the same conditions, it should be placed in an appropriate position close to the corresponding structural component or structural part, and the same curing method should be adopted. Under the same conditions, the curing specimen should be witnessed and sampled by all parties at the concrete pouring mold site. The number of retention specimens under the same conditions of the same strength grade should not be less than 10 groups, so as to constitute the evaluation of concrete strength by statistical methods.