Which statement is true about the slump test procedure?

Which statement is true about the slump test procedure?

• A. Rodding per layer is 25 strokes.
• B. Rodding per layer is 20 strokes.
• C. The mold is rotated during lifting.
• D. The slump measurement is from top to bottom of mold.

Answer: (A)

In slump testing, you fill the cone in three layers and compact each layer with 25 strokes of a rod. This fixed per-layer stroke count standardizes how the concrete is worked, so readings are reproducible regardless of who conducts the test. After filling and rodding, you lift the mold straight up—no twisting or rotation—to prevent adding any extra motion that could affect the reading. The slump is then read as the vertical distance the concrete surface drops from the top of the mold when the cone is removed; equivalently, it’s the difference between the cone’s original height and the final height of the settled concrete. The other statements don’t fit because 25 strokes per layer is the standard, the mold isn’t rotated, and the measurement isn’t taken from top to bottom of the mold but from the mold’s top height to the settled surface.

In slump testing, you fill the cone in three layers and compact each layer with 25 strokes of a rod. This fixed per-layer stroke count standardizes how the concrete is worked, so readings are reproducible regardless of who conducts the test. After filling and rodding, you lift the mold straight up—no twisting or rotation—to prevent adding any extra motion that could affect the reading. The slump is then read as the vertical distance the concrete surface drops from the top of the mold when the cone is removed; equivalently, it’s the difference between the cone’s original height and the final height of the settled concrete. The other statements don’t fit because 25 strokes per layer is the standard, the mold isn’t rotated, and the measurement isn’t taken from top to bottom of the mold but from the mold’s top height to the settled surface.