Finishing Concrete

WHAT IS FINISHING Finishing is
screeding, floating or trowelling the
concrete surface to densify and further
compact the surface of concrete, as
well as giving it the look you want.
Finishing takes place in two stages:
INITIAL and
FINAL finishing.
INITIAL FINISHING Concrete is first screeded to the level of the formwork, then
bullfloated and left to set.
In some cases screeding leaves a good enough finish, especially if floor coverings are to
be used over the concrete.
Water then appears on the surface of the concrete.
This water is called bleed water.
No final finishing can begin until the bleed
water has dried up. Mixing bleed water with the
surface paste will weaken it, possibly resulting
in a dusty surface.
Excess bleed water can be removed by dragging
an ordinary garden hose across the surface of the
concrete.
Never try to dry up the bleed water using stone dust or cement as this will weaken the
concrete surface in the long run.
Once the bleed water dries up and concrete can support a person’s weight, with only a
slight marking to the surface, the final finishing can begin.




FLOATING There may be two stages in floating:
The BULLFLOAT, which is part of the initial float.
The POWER or HAND FLOAT which is part of the final float.
Floating helps compact and level the surface and close minor cracks.
See CHAPTER 16 Cracking in Concrete
Floating can be done by hand or with a power float.
Power floating leaves a better finish than hand floating.
FINAL FINISHING This involves floating, trowelling, edging, jointing or patterning the
concrete. Special finishes such as brooming, colouring or patterned finishes can be
applied to the surface.
See CHAPTER 13 Surface Finishes on Concrete
Trowelling Trowelling leaves a dense, hard, smooth
and durable surface.
The surface should be trowelled TWICE. A well
trowelled surface will be very smooth and can be
slippery when wet. Trowelling can be done by hand or
power trowel.
Edging and Grooving All the edges of a slab should be
finished with a special edging tool. This gives a neater and
stronger edge, less prone to chipping. Joints should
be planned before placing and are usually formed
into the concrete during finishing.
See CHAPTER 11 Joints in Concrete
Once any surface has been finished it MUST be cured.
See CHAPTER 10 Curing Concrete