When should the contractor’s certified concrete technician perform a slump test?

The correct procedure for conducting a slump test is to perform it before any concrete is placed. This ensures that the concrete mix meets the required workability specifications as determined by the project’s needs. By conducting the slump test prior to pouring, the contractor's certified concrete technician can assess the consistency and flow of the mix. This is crucial for preventing issues that might arise from an improper mix, which could affect the quality and durability of the concrete.

Other scenarios for testing, such as conducting the test after pouring or every hour during the process, are not standard practices. Testing after pouring might not provide useful information for adjustments to the mix, and while periodic tests during pouring can be beneficial, they are typically not required at such frequent intervals as every hour without specific guidelines. Acceptance tests are often conducted but are generally not the only reason for performing a slump test. The proactive approach of testing before placement is vital for quality assurance in concrete work.