1. Rebar raw materials: According to GB50204-2015 "Code for Acceptance of Construction Quality of Concrete Structural Engineering": inspection and acceptance are carried out in batches, and the weight of each batch is not more than 60t. Each batch should be composed of steel bars from the same factory, the same furnace number, the same grade, the same specification, the same production process, and the same entry time. The quantity and method of sampling shall comply with specified requirements.

2. Rebar welding parts: According to Chapter 5 of JGJ18-2012 "Reinforcement Bar Welding and Acceptance Regulations": Quality Inspection and Acceptance.

Flash butt welding, arc welding, electroslag pressure welding, air pressure welding, embedded parts T-type joints: every 300 joints of the same type (same steel bar level, same joint type, same diameter steel bar) are one A batch of less than 300 joints shall also be calculated as a batch. (For stirrup flash butt welding, 600 pieces are considered as one batch, and less than 600 pieces are also calculated as one batch).

3. Mechanical connectors for steel bars: According to Article 7.0.5 of JGJ107-2016 "Regulations for Mechanical Connection of Steel Bars": On-site inspection of joints shall be carried out according to the acceptance batch. Joints of the same grade, form, and specifications using the same batch of materials under the same construction conditions shall be accepted and inspected in an acceptance batch of 500 pieces. If there are less than 500 joints, an acceptance batch shall be made.

Extended information

After the steel bars enter the site, the on-site supervision should check the factory certificate, specifications, models, quantities, etc. The construction unit is also required to carry out sampling re-inspection in a timely manner in accordance with the requirements stipulated in the specifications. After passing the re-inspection and approved by the resident supervisor, it can be used in the project. Steel bar welding, including arc welding, flash butt welding, electroslag pressure welding, straight rib mechanical connection, and tapered rib mechanical connection, must be witnessed and sampled for inspection.

1. The witness laboratory must pass the metrology (CMA) and quality (CMC) certification of the provincial (or above) technical supervision bureau, and have a Grade B certificate issued by the provincial (or above) quality supervision department. Laboratories with test and testing qualification certificates (including Class B) and above.

2. The witness must hold a test and testing qualification certificate, and the witness is responsible for the representativeness and authenticity of the witness sample.

3. The sample or its packaging should be marked and sealed. The label and seal should indicate the sample name, sample quantity, project name, sampling location, sampling date, and be signed by the sampler and witness.

4. The laboratory responsible for witness testing can only conduct the test after checking and confirming that the witness mark and seal on the sample are correct. Otherwise, the test shall be rejected.

5. The witness test report must be signed and stamped by the witness, and must be stamped with the special seal of "Witness the Test".

Baidu Encyclopedia - Witness Sampling

Baidu Encyclopedia - Construction Project Supervision Witness Sampling Submission System