What is the typical field procedure for slump testing the delivered concrete?

What is the typical field procedure for slump testing the delivered concrete?

• A. Collect a sample, fill the slump cone in lifts, compact each layer, strike off the top, lift the cone and measure the slump.
• B. Collect a sample, strike off the top before filling the slump cone, then compact each layer and measure.
• C. Fill the slump cone with concrete, compact each layer, then collect a sample and measure the slump.
• D. Collect a sample, fill the slump cone in lifts, compact only the bottom layer, strike off the top, and measure slump.

Answer: (A)

Measuring slump focuses on assessing the workability of the fresh concrete by how much it settles when confined in the slump cone. Start with a representative sample and place the cone on a rigid, level base. Fill it in three roughly equal lifts, compacting each layer with the standard tamping rod (about 25 strokes) to remove large air voids and ensure uniform density. After the last layer is compacted, strike off the top with a straightedge so the surface is level with the top edge of the cone. Immediately lift the cone straight up and measure the vertical difference between the top of the cone and the new surface of the concrete. That difference is the slump. Compacting all layers is essential for consistent results; striking off before filling, or compacting only the bottom layer, would lead to inaccurate measurements.

Measuring slump focuses on assessing the workability of the fresh concrete by how much it settles when confined in the slump cone. Start with a representative sample and place the cone on a rigid, level base. Fill it in three roughly equal lifts, compacting each layer with the standard tamping rod (about 25 strokes) to remove large air voids and ensure uniform density. After the last layer is compacted, strike off the top with a straightedge so the surface is level with the top edge of the cone. Immediately lift the cone straight up and measure the vertical difference between the top of the cone and the new surface of the concrete. That difference is the slump. Compacting all layers is essential for consistent results; striking off before filling, or compacting only the bottom layer, would lead to inaccurate measurements.