When testing SFRM thickness on a beam, ___ thickness measurements are taken at each end of a ___ length.

• A. 6, 6 inch
• B. 8, 18 inch
• C. 12, 24 inch
• D. 9, 12 inch

Answer: (D)

The idea being tested is how field thickness sampling for SFRM is planned to reliably assess a beam section. To get a trustworthy picture of thickness, you take multiple checks over a short, representative length and pay special attention to the ends, where spray patterns and edge effects often create variations.

Taking nine thickness measurements at each end of a 12-inch length gives a solid data set to compute an accurate average and to spot any outliers or edge-related deviations. The two ends are where spray consistency and adhesion can differ from the middle, so sampling there helps ensure the measurement reflects the actual applied thickness for that portion of the beam. The 12-inch length provides a compact, representative segment that balances capturing variation with keeping the sampling practical on site.

If you used too few measurements, you’d risk missing under-thickness zones and misrepresenting the overall thickness. If you sampled over too long a length, local variations could be masked by the broader average. This plan—nine readings at each end of a 12-inch length—gives enough data to verify compliance with the specified thickness and to document consistency across the section.