Finished Concrete Floor Flatness

This was measured by laying a 10 foot straightedge on the finished floor and measuring the greatest gap below the straightedge.

Finished concrete floor flatness.

Specifically joints and cracks curl making the floor less flat with the passage of time. Aci 117 begins by defining what the tolerances mean in terms of such things as bowing deviation flatness and levelness and provides drawings to help explain these terms. Both numbers are dimensionless and the higher the number the more accurate the floor construction. History of concrete floor flatness and floor levelness traditionally concrete floors were specified to have a deviation of less than 1 8 over 10 feet.

Due to concrete shrinkage and slab curling ff fl numbers diminish with time. The ffnumber relates to the rate of change of the elevation of a concrete floor over a 12 interval. Floor flatness f f controls the bumpiness of the floor surface and is primarily affected by the finishing operations after screeding including restraightening and power floating. This method worked quite well for decades.

Tom klemens the dipstick tool is the typical measurement taken for flatness the morning after concrete is placed. The fallacy of the straightedge method was the location of the measurement. Floor flatness levelness one of the things that distinguishes a high tolerance floor is its f number requirement. The higher the f number the flatter or more level the floor.

Ff flatness is most affected by the finishing operation. Material tolerances are in section 2 including the location tolerance for reinforcing bars which varies depending on the thickness of the concrete member. F numbers were developed in the 1980s to provide a systematic quantitative way to indicate the flatness and levelness of a concrete floor. For the concrete contractor flatness is specified as an ff number and levelness as an fl number.

Fl levelness is most affected by forming and strike off. Rejecting floors based on one sample measurement line concrete international jul pp. Concrete floor slab flatness and levelness traditionally allowable tolerances of concrete floor slabs were determined by checking the slab surface with a 10 foot straightedge. Aci staff 2008 concrete q a.

Floor flatness and levelness testing the complete. American concrete institute aci 301 16 specifications for structural concrete.