2. Material quality assurance documents (such as certificate of conformity, quality certificate, etc.) are generally provided by material suppliers.

3. Materials that must be inspected shall be reported to the material inspection report before use. This means that the materials entering the site should be sampled and tested in accordance with relevant regulations or called retest, and even witness sampling is needed.

4. Finally, attach a declaration form for the entry and use of materials, and submit it to the construction unit or supervision unit for inspection.

Extended data:

Procedures and methods for quality inspection of building materials

1, determine the test items.

There are many kinds of building materials used in the construction site, which need to be tested when entering the site. The materials to be tested shall comply with the provisions of the national, industrial and local construction authorities (or relevant departments). For example, cement for concrete needs to be tested in batches for its stability, strength, setting time and fineness.

2, sampling samples

Sampling should be representative. Generally, a specified number of samples are randomly selected from different parts of a batch of materials (the number of different materials in each batch is different) (steel is intercepted from the specified parts), that is, not only the number of samples should be correct.

Sampling locations and methods should also be carried out in accordance with regulations. The number of samples is related to the accuracy of the test results. Too few samples and the deviation of sampling position and method will increase the test error and even get the opposite result. However, in actual detection, sampling is often not representative, the number of samples is not enough, and the sampling method is incorrect.

3. Ambient temperature and humidity

Temperature and humidity have great influence on the performance of some building materials. Therefore, the material maintenance and environmental conditions during testing are clearly defined in the standard. Only by strictly observing these regulations can the test results be comparable. Waterproof materials such as elastomer modified asphalt waterproofing membrane are sensitive to environmental temperature, and the room temperature should be controlled at 23℃ 2℃ during tensile test.

If nine groups of specimens are made of elastomer modified asphalt waterproofing membrane (SAS) samples from the same parent material for tensile (longitudinal) test, the nine groups of specimens can be divided into three groups on average, and then a tensile test with a temperature difference level is carried out at 50℃.

Among them, 1 large group of specimens were tested at 23℃ required by the standard, and the other two groups of specimens were tested at 28℃ and 18℃ respectively. After the test, the average tensile strength of three groups of specimens in each large group was calculated respectively. It is found that the average tensile strength of the three groups of specimens tested at 28℃ is higher than that of the three groups of specimens tested at 23℃ standard temperature.

However, the average tensile strength of the three groups of specimens tested in l8 environment is 3.5% higher than that of the three groups of specimens tested in 23℃ standard temperature environment. The test can reflect the influence of environmental temperature and humidity on the material test to a certain extent, so it is required that the temperature and humidity must be controlled within the specified range during the test.

4. Test error

Test methods should be carried out in strict accordance with the standards. However, it is incorrect for some testers to only test the necking of the specimen without breaking it when doing the tensile test of steel bars, which will inevitably lead to the error of the test results, but this is not a test error, but a human error.

If the steel bar is not broken, the elongation measured after the break is lower than the specified elongation of the specimen, which is contrary to the standard. This is not allowed (the welded steel bar can stop after the specimen shrinks, because it does not need to measure the elongation). Test requirements must be accurate to reduce errors.

5. Data processing

For various reasons, sometimes the test data results of the same group of specimens are discrete. In order to make the test results accurate, the standard requires that the test result data of some materials be selected. For example, in the flexural strength test of cement mortar, if one of the three strength values exceeds the average value of soil 106, this value should be excluded and the average value of the other two strength measurements should be taken as the flexural strength result.

If two measured values exceed +/- 106 of the average value, the remaining measured values shall be taken as the bending strength result. If all three measured values exceed 106 of the average, they should be re-inspected.

There are different methods to calculate the average strength of concrete and mortar compressive specimens. It should be noted that you can't simply add up the data. The correction method of calculated data shall be implemented according to GB/T8 170, and the mantissa shall be rounded to the nearest single or even number, and the number of data bits shall be reserved according to the standard.

Sometimes the test results are higher or lower than expected, the data in the same group of specimens are very different, or the performance indexes of the same specimen are contradictory, which needs to be paid attention to, find out the reasons, and conduct re-inspection and re-inspection in time.

References:

Baidu encyclopedia-material test