Recommended Procedures for Concrete Inspection
The following procedures have been found worthwhile, to enhance the probability of carrying out the intent of the designs and specifications on a large variety of projects. This results in a completed facility that will properly ensure the purpose for which it is intended, at minimum maintenance cost.
- The purpose of inspection is to assure that good practices are followed in constructing the project in accordance with the design and specifications and not to establish these practices. Any needed change in plans or specifications should be brought to the attention of the architect or engineer so that the designer will have an opportunity to make the final decisions in so far as the changes affect his design. Inspection does not relieve the contractor of his responsibility to do the work properly in accordance with the contract documents. Inspection personnel should co-operate with the contractor, but must refrain from running the job for the contractor, as this is not part of the inspection function and may result in undesirable claims in case of later trouble.
- Since the architect or engineer has the final responsibility for inspection in this recommended practice, he should insist that the owner should give him the authority to go with this responsibility. He should then plan inspection commensurate with the character, magnitude and importance of the job, and advice the owner of the approximate cost necessary to execute the inspection properly.
- Proper inspection provides for continual inspection during the placing of concrete and its finishing, and includes preparations prior to the start of concreting such as proper formwork, placing or reinforcing etc, as well as proper protection and curing of the finished concrete. on large projects, or where special concrete with strength, density or texture is desired, continuous inspection of batching and mixing operations should be provided.
- The architect or engineer should see to it that qualified and dedicated inspectors are on the job, as this is vital to effective inspection. Where such inspectors are not available or where there are special requirements in the designs and specifications, training should be carried out to qualify such inspectors.
- A meeting between the architect or engineer, the contractor, and the inspection personnel just before construction is started is a must. At such a meeting questions can be answered and procedures reviewed, so that everyone knows ahead of time what is expected and how it is to be carried out. This advance understanding will minimize future arguments, and will give the inspector status and knowledge of the backing he can expect as well as confidence that he will receive it.
- The following constitute a partial list of inspection functions that could be covered:
- Inspection and approval of batching and mixing facilities
- Control of proportioning of concrete mixes
- Inspection, testing and approval of materials
- Inspection of forms, reinforcing steel, shoring, bracing, embedded items, joints, etc
- Inspection of concrete handling, placing equipments, such as buckets, chutes, hoppers, vibrators, pumps, etc.
- Inspection of concrete handling, placing, consolidation, finishing, curing, protection, and repair patching
- Inspection at the plant of precast items, including prestressed work for strength, dimensions and special properties
- Inspection of stripping, form removal and shoring
- Preparation and testing of concrete strength specimens
- Daily reports on all these items
- The number of inspectors to carry out such a programme will vary from job to job depending on the size, importance, the contractor’s set-up etc and must be planned by the architect or engineer for each individual case.
- Unless otherwise provided in the specifications, concrete inspected in accordance with the provisions of this recommended practice should have the averages of all sets of three consecutive strength test results equal or exceed the requires strength and no individual strength test result fall below the required strength by more than 500 psi (as per ACI 318-71).