Ditaike Testing
News
07
2023
-
09
How is witness sampling conducted?
Author:
Witness sampling is one of the supervisory management methods. Witness refers to the activity of on-site supervision by the supervising engineer on the completion of a certain process by the contracting unit. Witness sampling refers to the supervision activity of on-site sampling of materials, semi-finished products, and components related to structural safety used in engineering projects, as well as the inspection of the effectiveness of process activities.
The frequency of witness sampling, if specified by national or local regulatory authorities, shall be in accordance with relevant regulations; If there are clear provisions in the construction contract, the provisions of the construction contract shall be implemented. Implement witness sampling and never replace the self inspection required by the contracting unit when materials and components enter the site. The frequency and quantity of self inspection should be carried out in accordance with relevant specifications.
Number of witness samples
The proportion of witness sampling and sample submission for test blocks, specimens, and materials related to structural safety shall not be less than 30% of the required sampling quantity specified in relevant technical standards.
Scope of witness sampling
According to regulations, the following test blocks, specimens, and materials must undergo witness sampling and inspection:
1. Concrete test blocks for load-bearing structures;
2. Masonry mortar test blocks for load-bearing walls;
3. Steel bars and connecting joint specimens for load-bearing structures;
4. Bricks and small concrete blocks for load-bearing walls;
5. Cement used for mixing concrete and masonry mortar;
6. Admixtures used in concrete for load-bearing structures;
7. Waterproof materials used in underground, roof, and restroom rooms;
8. Materials or specimens used for road subgrade and surface layer;
9. In municipal engineering, materials or components that the owner or supervising unit's project director deems to be closely related to quality;
10. According to national regulations, witness sampling and other test blocks, specimens, and materials that must be submitted for inspection must be implemented.
The "Management Measures for Quality Testing of Construction Projects" (Order No. 57 of the Ministry of Housing and Urban Rural Development of the People's Republic of China) shall come into effect on March 1, 2023. The new regulations particularly emphasize the new requirements for witness sampling: clarifying the uniqueness of witness sampling and testing samples, making the requirements for witness personnel of construction units and supervision units more specific, refining the requirements for testing samples, and clarifying the requirements for witness sampling and submission for inspection.
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2023-09-07
How is witness sampling conducted?
Witness sampling is one of the supervisory management methods. Witness refers to the activity of on-site supervision by the supervising engineer on the completion of a certain process by the contracting unit. Witness sampling refers to the supervision activity of on-site sampling of materials, semi-finished products, and components related to structural safety used in engineering projects, as well as the inspection of the effectiveness of process activities.
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