ACI Concrete Field Testing Technician - Grade I Practice Exam

When rodding the final layer of a concrete sample, how deep should the rod penetrate the previous layer?

1. 15 mm

2. 25 mm

3. 35 mm

4. 50 mm

The correct answer is: 25 mm

When preparing a concrete sample for testing, particularly during the consolidation process with a rod, it is essential to ensure that the rod penetrates the previous layer to achieve proper consolidation and layering. The correct depth for the rod to penetrate the previous layer is specified as 25 mm. This depth strikes a balance that allows for effective bonding between the layers, ensuring that the sample reaches the necessary density and homogeneity for accurate testing results. Penetrating a depth of 25 mm adequately disrupts the previous layer, helping to eliminate air pockets and ensuring the layers are well-integrated. Consistently applying this standard will help maintain uniformity in sample preparation, which is critical for reliable concrete testing. In contrast, other suggested depths may be insufficient or excessive, potentially affecting the sample integrity and testing outcomes.