ACI Concrete Field Testing Technician - Grade I Practice Exam

The specified number of roddings for each layer of concrete in the context of density testing, such as when using a concrete slump cone or a similar apparatus, is 25. This number is established to ensure that the concrete is adequately consolidated, which is crucial for achieving accurate and repeatable test results. Proper consolidation helps eliminate air pockets that can lead to inaccurate density measurements, allowing for a reliable assessment of the concrete's workability and strength characteristics.

Using 25 roddings per layer, applied uniformly and intentionally, contributes to achieving a consistent mix and enhances the integrity of the concrete sample being tested. This number is based on established testing standards and practices reinforced by materials and procedures outlined by organizations like ACI. The choices reflecting fewer or more than 25 would not adhere to these standard practices and may yield less reliable testing outcomes.