Pce very flat burnished floor practice
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Leading Practical Concrete Technology
PURPOSE OF THIS DOCUMENT
• To provide the simple and clear information to contractors about the best
practice on Very Flat Burnished Floor construction (ACI 117, ACI 302)
2
DEFINITIONS
Term and dispute
Do you mean superflat?
OR just a flat floor?
I want to do a
superflat floor…
I can do a
superflat floor…
But your floor is not
flat enough…
The spec says 3mm gap under
3m straightedge…
Straightedge?
FM2?
3
DEFINITIONS
• What is flatness and levelness
•
Flatness relates to the
bumpiness of the floor.
Levelness relates to the
tilt or slope of the floor.
4
DEFINITIONS
• What is flatness and levelness
5
DEFINITIONS
• Bad Levelling
6
DEFINITIONS
• Bad Finishing
7
DEFINITIONS
• Random Traffic
8
DEFINITIONS
• Defined Traffic
9
DEFINITIONS
• Very Flat Floor:
Random traffic floor measured in accordance with ASTM 1155
Floor surface classification
Specified overall flatness
SOFF
Specified overall flatness
SOFL
Conventional
20
15
Moderately flat
25
20
Flat
35
25
Very flat
45
35
Super flat
60
40
10
DEFINITION
• Burnished Floor:
- With no need for added materials such as chemical or shake-on hardeners.
- Mirror-like finish and be free of defects, including delamination.
- Process of smoothing and hardening the floor surface by purely mechanical
means, using floats and power trowels
- Burnishing hardens the surface of a concrete floor by relying on concrete’s
inherent properties.
11
DEFINITION
12
TYPICAL STEPS
• Formwork set-up.
• Reinforcement installation.
• Concrete control.
• Concrete placing and compaction.
• Concrete raking & screeding.
• Finishing.
• Floor levelness and flatness check by Dipstick.
13
FORMWORK SET-UP
• The formwork is set up so the trowelling machines can overlap
the edges. This requires the top edge of the formwork to be
made of a thin steel shim (fix the thin steel shim as the top
edge of the formwork).
• For slabs on ground
14
FORMWORK SET-UP
• For slabs on pile or suspended slabs
15
FORMWORK SET-UP
16
REINFORCEMENT INSTALLATION
• For Very Flat floor construction, Ride-on Somero laser screed and Allen
troweling machines are specified to improve the levelness & flatness as
well as increase the construction productivity. The followings are
requirements on reinforcement for using the laser screed and trowelling
machines:
17
CONCRETE
• Air Content < 2.5%
• Bleeding between 1-3%
• Cement content in the range 325-400 kg/m3
• Maximum content of fly ash is 25% and dependant on weather conditions.
• Slump on site nominal 100 or 120mm
• The supply of concrete in the project will be such that:
Slumps are consistent
Setting time is consistent, such that the trowelling process can be
conducted evenly and methodically in a regular pattern
Bleeding is uniform and early
18
CONCRETE
19
CONCRETE
20
CONCRETE PLACING & COMPACTION
• Pump line set up.
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CONCRETE PLACING & COMPACTION
• Pump line set up.
22
CONCRETE PLACING & COMPACTION
23
CONCRETE PLACING & COMPACTION
24
CONCRETE PLACING & COMPACTION
•
Vibrator must be inserted immediately after placing
25
