What are the requirements and time for concrete test block inspection?

Concrete refers to the use of cement as cementitious material, sand and stone as aggregates; It is a cement concrete that is mixed with water (can contain admixtures and admixtures) in a certain proportion and is mixed together. The following is a detailed introduction to the requirements and time for the inspection of concrete test blocks.

Submission requirements. The standard for testing and submitting concrete test blocks is three pieces per group. Regarding the strength test of concrete test blocks, the building materials are determined

The arithmetic mean value of the measured values of the three specimens is used as the compressive strength value of the group of specimens. If the difference between one of the three measured values and the intermediate value exceeds 15% of the intermediate value, the maximum value and the minimum value are rounded together, and the intermediate value is taken as the compressive strength value of the group of specimens; If the difference between the two measured values and the median value is more than 15% of the median value, the test results of the test specimen in this group are invalid.

If the strength of the test block exceeds the standard value by 200%, it is strictly said that the compressive strength value of this group of specimens is invalid.

Time. Generally, the standard maintenance should be sent at 2 days, which can be three days in advance, but not more than 2 days. If it exceeds the number of days, it must be retested, otherwise an expert should be asked to reverse the compressive strength value for 2 days according to the compressive strength value of the overage period.

If the curing under the same conditions is above 600 °, it should generally start to accumulate from the time of pounding the concrete on the same day, and it can be sent when it reaches 600 degrees. The number of days under the same condition cannot be less than 14 days and cannot be greater than 0 days.

Extended Materials. The number of samples taken in batches of the project.

1. For concrete compressive test blocks, every 100 trays and no more than 100 cubic meters of concrete with the same mix ratio shall not be less than 1 time.

2. When the concrete with the same mix ratio is less than 100 trays in each shift, it shall not be less than 1 time.

3. When 1000 cubic meters are poured continuously, the concrete of the same mix ratio shall not be less than 1 time every 200 cubic meters.

4. Each floor, the same mix ratio of concrete not less than 1 time.

5. For every 50 cubic meters of concrete poured into the cast-in-place pile, and the pile less than 50 cubic meters must have 1 group of not less than 1 time.

6. Each mold removal inspection batch concrete.

At least 1 group, diaphragm wall of foundation pit works, every 50 cubic meters or per groove section.

Not less than 1 time. Each layer of the concrete test block of the building ground engineering (inspection batch).

Sampling shall not be less than 1 time for every 1,000 square meters, and 1 additional time shall be taken for every additional 1,000 square meters, and less than 1,000 square meters shall be counted as 1,000 square meters. When the mix ratio is changed, the number of samples is increased accordingly.

For the first time, the concrete mix ratio was used for opening identification.

Below 1000 square meters, a group of 100 square meters is generally raised for 28 days, and a group is raised at a temperature of 600 degrees. Not more than 60 days.

More than 1000 square meters and 200 square meters are raised in a group of standard and a group is raised together.

Impermeability 500 square a group of 6 28 days 60 days.

The demoulding test block is generally needed when the beam plate is needed. At other times, it is basically not, unless the supervisor or Party A proposes that a certain part needs to be removed to do it.

The general standard maintenance of the cubic test block should be sent at 28 days, which can be three days in advance, not more than 28 days, otherwise it will rebound and be counted as an overage period.

If the curing is above 600 degrees under the same conditions, the on-site temperature will begin to accumulate from the time the concrete is pounded on the same day, and it can be sent when it reaches 600 degrees. The number of days under the same condition cannot be less than 14 days and cannot be greater than 90 days.

The number of test blocks under the same conditions shall be in accordance with the provisions of the "Specification": the number of retention test blocks of the same strength grade under the same conditions shall be determined according to the quantity and importance of the concrete project, and shall not be less than 10 groups (statistical method assessment) and should not be less than 3 groups (non-statistical method assessment).

When there is a project of impermeability to prepare for the mountain, the concrete test block should be randomly sampled at the pouring site, and the concrete of the same project with the same mix ratio should not be sampled less than once, and the number of retention groups can be determined according to the actual needs.

The order form indicates the impermeability grade, concrete strength grade, detailed engineering part, test block forming date and inspection date. If 580m of concrete is poured continuously, then fill in 500m, 1 group, 80m, 1 group, a total of 2 groups.

The continuous pouring of waterproof concrete of the same project and the same mix ratio is less than 500m; If 380m of concrete is poured continuously, at least 1 group of impermeability test blocks should be retained. The continuous pouring of waterproof concrete of the same project and the same mix ratio exceeds 500m; If 580m concrete is poured continuously, at least 2 groups of impermeability test blocks should be retained, and if 1400m concrete is poured continuously, at least 3 groups of impermeability test blocks should be retained.

Precautions for concrete test block inspection.

Curing test block under the same conditions: refers to the concrete test block is placed in the concrete structure or component together after demoulding, and the same curing is carried out at the same temperature and humidity environment, and the cumulative curing temperature reaches 600 per dayD plus or minus not more than 20, and the age should be more than 14 days.

In general, the temperature is taken as the average temperature of the day, and 0 is not counted. (There is a new specification that says plus or minus 40, subject to laboratory requirements).

Demoulding test block: placed at the same component of the pouring structure, cured together, generally sent for inspection in 7 (general template) 14 (tall template) days, at least before the same conditions. It is used to estimate the strength of the pouring part.

Concrete and mortar test blocks must be identified with labels, which should indicate the name of the project, the name of the sample, the representative part, the maintenance conditions, the date of production, and the name of the sampler.

For the production mode of small batch of sporadic concrete, its quantity is limited, and it does not have the conditions to evaluate the concrete strength according to the statistical method, and the concrete strength can be assessed by non-statistical methods; When evaluating the strength of concrete by this method, the number of specimen groups n 9 forms an inspection batch, and its strength should meet the requirements of the following formula at the same time:

mfcu≥,k。

fcu,min≥,k。

According to the requirements of the specification, the number of your specimens should be left in is:

1. Wall: 3 groups of C35 standard maintenance specimens, C35

1 group of 600 degree maintenance specimens under the same conditions.

2. a plate; C30 standard curing specimen 3 groups, C30

1 group of 600-degree maintenance specimens under the same conditions, 1 group of C30 demoulding specimens.

Looking at the concrete strength of your wall panel, it can be estimated that your project should be a high-rise building, so one part of the maintenance specimen under the same conditions can meet the requirements.

Project name, strength grade, pouring date, curing conditions (standard or similar).

Date, number, pouring site.

Concrete and mortar test blocks must be identified with labels, and the labels should indicate the name of the project, the name of the sample, the representative part of the cultivation, the maintenance conditions, the date of production, and the name of the sampler.

For the production of small batches of sporadic concrete.

Its quantity is limited, and it does not have the condition of evaluating the strength of the soil in the concrete mass by statistical methods, and the concrete strength can be evaluated by non-statistical methods; When the concrete strength is evaluated by this method, the number of specimen groups n 9 forms an inspection batch.

Its strength should meet the requirements of the following formula:

mfcu≥,k。

fcu,min≥,k。

Quantity specification as well as sample time regulations.

1. Specific requirements for inspection:

1. The standard for testing and inspection of concrete test blocks is three pieces per group.

Regarding the strength testing of concrete test blocks, the "Building Materials" stipulates that the arithmetic average of the measured values of the three specimens shall be used as the compressive strength value of the group of specimens. If the difference between one of the three measured values and the intermediate value exceeds 15% of the intermediate value, the maximum value and the minimum value are rounded together, and the intermediate value is taken as the compressive strength value of the group of specimens; If the difference between the two measured values and the median value is more than 15% of the median value, the test results of the test specimen in this group are invalid.

The strength of the test block exceeds the standard value by 200%, strictly speaking, the compressive strength value of this group of specimens is invalid, and our local requirement is that it must be measured with a rebound tester on site.

2. There are also strict requirements for the inspection time.

Generally, standard maintenance should be sent at 28 days, which can be three days in advance and cannot exceed 28 days. More than 7 days must be carried out on-site rebound test, otherwise experts should be asked to reverse the compressive strength value of 28 days according to the compressive strength value of the overage period. If the curing under the same conditions is above 600 °, it should generally start to accumulate the on-site temperature from the time of pounding the concrete on the same day, and it can be sent when it reaches 600 degrees.

The number of days under the same condition cannot be less than 14 days and cannot be greater than 90 days.

2. The number of batch samples of the project:

1.Concrete compressive test block is mixed with 100 trays and no more than 100m3 of concrete with the same mix ratio, not less than 1 time.

2.When the concrete with the same mix ratio is less than 100 trays in each working shift, not less than 1 time.

3.When a continuous pouring of 1000m3, the same mix ratio of concrete every 200m3, not less than 1 time.

4.Concrete of each floor and the same mix ratio shall not be less than 1 time.

5.For every 50m3 of concrete poured into cast-in-place piles, piles less than 50m3 must have 1 group for each pile, not less than 1 time.

6.Each demoulding inspection batch concrete, at least 1 group.

7.The underground diaphragm wall of foundation pit engineering shall not be less than 1 time every 50m3 or each groove section.

8.Each layer of concrete test block of building ground engineering (inspection batch) shall not be less than 1 time per 1000m2 of sampling, and 1 time shall be added for every additional 1000m2, and less than 1000m2 shall be counted as 1000m2. When the mix ratio is changed, the number of samples is increased accordingly.

The general standard maintenance should be sent at 28 days, three days in advance, not more than 28 days, otherwise it will rebound, and the maintenance of the same conditions during the overage period is above 600 °, generally from the day when the mixed round of cherry blossom concrete rana bush begins, the on-site temperature begins to accumulate, reaching 600 degrees can be sent.

First, the concrete test block is submitted for inspection, and the same condition maintenance and standard maintenance must be submitted for inspection.

Second, it is divided according to the pouring time and sent for inspection. Standard maintenance is submitted for inspection within 28 days; The equivalent curing period under the same conditions can be taken according to the average daily temperature when the cumulative amount reaches 600 °C d, and the age period of 0 °C and below is not included; The equivalent curing age should not be less than 14 days and should not be greater than 60 days; Others are sent for inspection as needed.

3. The standard maintenance of the mortar test block will be sent for inspection within 28 days.