ACI Floor Flatness & Levelness (FF/FL Numbers)

Question 1

What do FF and FL numbers measure in concrete slabs?

Accepted Answer

FF measures local surface waviness; FL measures overall slope relative to a horizontal datum

Answer

FF (floor flatness) measures local curvature and waviness of the surface, while FL (floor levelness) measures how level the floor is relative to a horizontal datum.

Question 2

What does a higher FF or FL number indicate about a concrete floor?

Accepted Answer

A flatter and more level floor with smaller deviations

Answer

F-numbers are inversely related to surface deviation; higher numbers indicate smaller deviations and therefore better flatness and levelness.

Question 3

Which ACI document includes F-number tolerances for floor flatness and levelness?

Accepted Answer

ACI 117

Answer

ACI 117, 'Specification for Tolerances for Concrete Construction and Materials,' includes F-number tolerances for floor flatness and levelness.

Question 4

What instrument is most commonly used to measure floor flatness F-numbers per ASTM E1155?

Accepted Answer

Dipstick profiler

Answer

The dipstick profiler is the standard instrument used to measure floor elevation differences for calculating F-numbers per ASTM E1155.

Question 5

What minimum FF number is typically specified for superflat floors used in very narrow aisle (VNA) warehouses?

Accepted Answer

FF 100

Answer

Superflat floors for very narrow aisle (VNA) forklifts typically require FF 100 or higher to ensure safe equipment operation at height.

(ACI) American Concrete Institute Concrete Finisher Practice Test

(ACI) American Concrete Institute Concrete Finisher Practice Test

ACI Floor Flatness & Levelness (FF/FL Numbers)