the best floors start with our finish -...
TRANSCRIPT
The Best Floors Start With Our Finish !
Concrete Floor Contractors Association
Concrete Canada
What is the CFCA ?
• The CFCA is the technical voice of the concrete floor industry.
• CFCA provides design assistance to owners & specifiers.
• CFCA contractor and materials suppliers are concrete floor industry quality leaders.
• The CFCA is a proven pre-qualification tool for specifiers.
Windsor
London
Toronto
Exposed Concrete floors are
THE Sustainable Floor Solution
• Concrete floors are already
part of every building.
• Concrete is both
economical and durable
(low maintenance).
• Good design, materials,
workmanship &
coordination are
necessary.
What makes a good floor ?
The correctly defined & executed combination of
materials & workmanship to meet your clients needs with
sincere consideration for responsible sustainability
(including durability & future maintenance).
“To meet the needs of the present without compromising the ability of
future generations to meet their own needs” USGBC
03345 Specification
• A separate “concrete floor” specification is
necessary which includes all related concrete
floor materials, tolerances and finishes.
• While specifications define the framework for
success – they do not build great floors.
Coordination
• Schedules are short.
• Planning time is almost non existent due to last minute awards of trade work.
• Conditions vary significantly between sites.
• Division of responsibilities create problems.
good materials
+ good workmanship
+ poor coordination
= quality & performance
problems
Concrete
Placing & Finishing
Contractor
Reinforcing
Contractor
Forming
Contractor
Earthworks
Contractor
Concrete Mix
Supply
Sawing Contractor
Material
Suppliers
(multiple)
Caulking
Contractor
Divided responsibilities = opportunities for coordination problems
Your
Floor
Divisions of Responsibility
Curing & Sealing
Contractor
Polishing
Contractor
Concrete Floor
Contractor
Prime
Constructor
• Undivided responsibility
• Single warrantee
• No finger pointing
“Single Source” Scope
For all critical surfaces:
• Architectural finishes
• Rink slabs
• Superflat floors
• Higher quality anything
Reinforcing
Forming
Earthworks
Subcontractor
Jointing
Material
Suppliers
(multiple) Caulking
Curing & Sealing
Polishing
Placing
Finishing Concrete Mix
Putting the pieces together correctly & efficiently
Base elevations
poor workmanship
+ good materials
Why Prequalify ?
good workmanship
+ cheap materials
The selection of good materials
& good trade contractors
is critical for success !!
= quality & performance problems
Two Types of Floor Crews The Cowboys
• Hard working but don’t read
specifications or technical standards.
• Substitute specified materials with
whatever was left over from the last job.
• Only care if they get paid.
• No guarantees – they left town yesterday !
The Professionals
• Are skilled and technically proficient.
• Use specified methods & materials.
• Identify and resolve problems before
they become part of the finished work.
• Stand behind their product with pride.
• Provide a written guarantee.
Quality Materials
• High quality materials are an essential input in high
quality (sustainable) construction.
• Beware “unapproved equal” substitutions.
• All materials are not equal in cost or performance
and requires careful analysis (consultation).
• CFCA members are industry quality leaders.
Pre-Construction Meetings
• To ensure that the Owner’s/specifiers expectations are understood clearly.
• Must be held on site.
• Must include participation by all parties – including the concrete floor contractor.
• Provides an opportunity to express concerns prior to construction.
Review:
• Responsibilities of parties
• building envelope and ambient conditions.
• specified methods & materials.
• Concrete mix
• mock-ups.
• joint details and layout.
• inspection procedures.
• work of other trades.
Coordination Checklist
• There are almost 50
items to review for any
floor installation.
• Divisions of responsibility
increase problems.
• Scopes of work need to
be more inclusive.
Concrete Mix Submissions
• Review all the
ingredients and
proportions carefully.
• The mix needs to be
designed for use as a
floor (not just
compressive strength).
• CSA A23.1 compliant =
maximum 0.55 w/c.
Canadian Construction Association
Must be carefully reviewed in
terms of type and location.
• Construction Joints
• Isolation Joints
• Contraction Joints
• Expansion Joints
(exterior only)
Joint Layout / Shop Drawings
HSS Columns:
Wrap with 6mm foam.
Wide Flange Columns:
Wrap with rigid 12mm asphalt
impregnated fibre board.
SawcutSawcut
Wind Columns:
Isolate columns which do not align
with sawcut layout using sonotube.
GiffelsStandard
Perimeter Column Isolation Joint Details
Asphalt coating on
base plate, anchor bolts & column below
finished floor.
6mm Foam Isolation Joint
(Typical)
Infill ONLY after adjacent sawcuts
have cracked.
6mm foam
typical
Columns require careful isolation from a
concrete floor in order to avoid cracking
caused by restraint.
Similarly, other through-slab vertical elements also require isolation from the
concrete to avoid problems related to
the drying shrinkage of the concrete.
These details should be submitted for approval by the Concrete Floor Contractor
for each project.
Mock-ups
• Are co$tly and must be
specified.
• Must be representative
of the final product (not
too small – or too
perfect).
• Samples are required to
meet expectations.
MUST be mandatory for all exposed/architectural work
Inspection
• INSPECTION IS CRITICAL TO SUCCESS !!!
• Inspectors are part of the quality team.
• Full time inspection on pour days is an investment in quality – not an optional expense.
• Inspect and record the quantity and source of all materials being.
• Site inspection letters can be requested from major materials suppliers.
• Inspection stops mistakes, last minute substitutions and ensures value for your money !
! If you don’t check it – you may not get it !
Inspection Items
• Obtain a list of materials to be used at the P/C meeting.
• Inspect and verify the quantity and product names of all materials being used on site.
• Inspect the elevation of the granular base.
• Check the air content of all concrete.
• Ensure that inspectors are instructed to advise of any deficiencies immediately when they are observed.
!
Inspection catches mistakes,
stops cheaters and ensures value
CSA A23.1-2009
Our national mandatory concrete standard.
• Granular base elevation tolerances (±10mm).
• Slab thickness tolerances (> T - 10mm overall and > T -
20mm or R&R).
• Designing for curling.
• Vapour retarders.
• Concrete mix (maximum 0.55 w/c for floors).
• Concrete batching, handling and testing information.
• Floor surface tolerances (FF20/FL15 etc.).
• Bonded toppings.
Concrete Mixes
• Cement & concrete constituents are changing rapidly to reduce the carbon footprint.
• The need to manage concrete materials is essential - these new materials require careful design, ordering and handling for success.
There is no such thing as “normal” concrete anymore
Concrete Mixes for Floors
• Compressive strength has little
relationship to finishability, wear
resistance, drying time, moisture
permeability and drying shrinkage
curling and cracking.
• CSA A23.1-2009 mandates a maximum 0.55 water:cement ratio (minimum paste quality).
Drying Time for Applied Finishes
• A 25 MPa “compressive strength” mix is a ± 0.67 w/c (160/240).
• A CSA “standard” residential concrete floor mix is a 0.65 w/c.
• A CSA “standard” ICI concrete floor mix is a 0.55 w/c.
• Drying time for a 100mm SOG to reach 3lb/000sf/24hrs:
– 0.4 w/c: 2 months
– 0.5 w/c: 6 months
– 0.6 w/c: 1 year
• Thickness factor (based on 0.5w/c):
– 100mm to 150 mm: 2 times longer
Calcium
Chloride Test
RH Sensors
Tramex
Moisture
Metre %
SCM’s
• Pozzolans versus hydraulic cements.
• Slag cement: ground steel slag by-
product (hydraulic).
• Flyash: from coal burning powerplants
(quality varies): 2 types !
– Type C (hydraulic)
– Type F (pozzolanic)
• Silica Fume: from silicon metals
manufacturing in electric furnaces
(pozzolan).
• GUL Cement: Inter-ground limestone dust
(pozzolan).
(Cement Replacing / Extending Materials)
Slag
Flyash
Silica Fume
Portland Cement
SCM % for Floors
• Cement contents for floors are relatively low - hydraulic
cements are necessary !
• Without requiring the use of chemicals & water fog
spraying.
– Summer: FA[h]/15 + S/25 ≤ 1.00
– Winter: FA[h]/10 + S/10 ≤ 1.00
* Using Type C hydraulic [h] flyash
• CAUTION: New “GUL” cement adds up to 15% cement
replacement automatically (+ SCM’s ??).
Plastic Protection
• “GREEN” & other high-tech
concrete mixes have new
set & plastic properties (low
bleed rates).
• More mixes must now be
protected immediately after
concrete placement.
• Concrete mixes can be
designed to reduce or
eliminate this need.
Concrete Slump
• The slump at the point of deposit should be a minimum 100 mm for consolidation and screeding (+ H&S).
• Concrete for floors should be plasticized to reduce shrinkage (with water reduction).
• All fibre reinforced concrete require plasticizers to over-come mechanical slump loss.
Air Entrainment
• Protects the paste from deterioration in
freeze/thaw cycles.
• Is not required for interior freezers or rink
slabs.
• Must not be machine trowel finished.
• Must be measured at the point of deposit.
• Air contents should be checked for non-air
entrained concrete too.
• Is not compatible with the application of dry
shake-on surface hardeners.
Granular Bases
• Elevations “shall” be within
±10 mm.
• “The concrete floor
contractor shall not be
responsible for any liability
associated with slab
thickness reductions as
caused by incorrect
granular base elevations or
changes in slab thickness
caused by soft spots (eg:
rutting). “
Major Problem
Poor QC
Slab Thickness
• Acceptable if the average thickness is not more than
10 mm less than the specified thickness.
• No individual measurement is more than 20 mm less
than the specified thickness.
• “Should” be taken within 7 days of each floor
placement to avoid compounding of any problems (ACI
117 = “shall”).
Vapour Barriers Retarders
• To reduce future delaminations of non-breathing finishes due to vapour movement.
• Located directly under the concrete slab.
– Will increase shrinkage.
– Will reduce drying time for applied finishes.
• Changes to the concrete required (less water without loss in workability).
• Maintain restraining reinforcing.
• Review schedule of applied finishes at the pre-construction meeting.
• Follow manufacturer’s instructions !!!
Floor Reinforcing
• Unreinforced designs must reinforce joints.
• Micro synthetic fibres for plastic shrinkage.
• Normal Gauge wire mesh is impractical to
install at a fixed elevation.
• Macro synthetic fibres for light traffic &
loading.
• Steel fibre reinforcing for light to heavy traffic
and loading.
• Rebar heavy loads and jointless floors.
• Post tensioned designs uncommon.
Steel is the best thing that ever happened to concrete !
Sustainability: Design for long term performance
Curling
• Curling occurs at all floor joints through differential drying shrinkage between the top and bottom of a slab.
• Costly to repair for applied finishes – can ruin an exposed architectural finish.
• Restrain curling with reinforcing !
CSA: “Owners shall specify low-shrinkage concrete mixes, appropriate
curing, or suitable reinforcing, or a combination of these, as necessary
to minimize curling to suit their intended usage”.
Sawcuts
Differential Joint Movement Uneven joints are a common exterior failure
Dowel between pours reinforce across joints
• Unreinforced concrete is problematic.
• Micro synthetic fibres DO NOT reinforce
hardened concrete against joint movement.
• Performance must be considered in design
for all exposed concrete work.
Steel Fibre Reinforcing
• Practical & economical.
• Turns brittle concrete into a ductile material.
• Can restrain curling forces effectively.
• Will not interfere with wire guidance systems.
• Some fibres are ULC rated for slabs on deck.
• Is durable in exterior applications.
• Can spot rust in corrosive environments.
Steel Fibres
• All fibres are not equal in
performance – do not substitute
alternatives without a design
review !
• Steel fibres must be supplied
with a “certificate of
conformance” and “test reports”
as per ASTM A820.
Various Fibres
Every Fibre Type is Unique
• Each floor loading condition is designed using a single fibre type resulting in a specific dosage rate for that particular fibre’s performance.
• 20 kgs SFR ≠ 3 kgs marco synthetic fibre.
Drawn
Wire
Mill
Cut
is NOT
equal to
is NOT
equal to
Macro
Synthetic
Marginal Cost Analysis
• For any given set of loading
conditions there is an optimal
design.
• Plotted combinations of
concrete strength, slab
thickness, fibre type and fibre
dosage by cost.
• Best result:
Thinnest floor with 30MPa,
premium $ fibre @ 30 kgs/m3.
Surface Durability
• The surface of plain concrete is weaker than the bottom of a slab.
• Wear resistance is significantly increased by hardening the surface of the slab with hard aggregates.
• Good quality curing is essential to achieving superior surface durability (often not done).
Dry Shake Hardeners
• Mineral or metallic aggregates applied to the surface of freshly placed concrete.
• Applied at 3, 5 or 7 kgs/m2.
• Rates above 5kg/m2 may be impossible to install without utilizing special application techniques, specially designed concrete mixes and having suitable ambient conditions.
• 7 kg/m2 is the specified rate for pigmented hardeners.
Application Rates
60 lbs / 100 sf
[3.0 kgs/m2]
100 lbs / 100 sf
[5.0 kgs/m2]
Or
66lbs Agg. &
33lbs Cement
150 lbs / 100 sf
[7.0 kgs/m2]
Common Practice
5kgs/m2 is an ideal and practical application rate
Ideal
Relative Abrasion Resistance
0
50
100
150
200
250
300
350
400
450
500
Plain - Uncured
Plain - Cured
Hard Troweled
Liquid Hardened
NM Traprock
NM Silica
NM Emery
Metallic
The Concrete Floor Revolution
Light Reflective Floors
• Originally developed for
aircraft hangers to improve
light levels.
• Can reduce energy costs by
increasing light spacing –
reusing light.
• Increased surface wear
resistance.
• 7 kgs/m2 application rate.
Stencil Artistry
Polished Concrete
• High shine, low maintenance
finish.
• Concrete can be plain,
stained/dyed or pigmented.
• Eliminates an applied finish
and associated future
maintenance costs.
• Must be liquid silicate
densified to reduce porosity.
• Various aggregate
exposures.
Specification Bulletin
• Aggregate exposure:
– Class A, B or C
• Gloss level:
– Level 1, 2 or 3
Floor Tolerances
• Tolerances are poorly understood by many (& are not always measured).
• Can be based upon data taken from existing facilities.
• Tolerance losses caused by curling must be calculated into the design - consider applied finishes carefully.
• Each environment must be reviewed carefully (check lift truck data).
Shall be measured within 72 hours of floor casting !!!
1/8” in 10’ Tolerances
FF62
FF27 FF22
FF37
Straightedge tolerances are meaningless
Flatness & Levelness
Floor Levelness – (FL) Defines conformity to a
horizontal plane measured over 10’ (screeding
methods).
Floor Flatness – (FF) Defines a floors curvature over a
2’ length (finishing methods).
Bumpy Level Floor Bumpy Tilted Floor
-1500
-1000
-500
0
500
1000
1500
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221 231 241
Inc
he
s x
10
00
Half-Feet
Run 2 Profile
-1000
-500
0
500
1000
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221 231 241
Inc
he
s x
10
00
Half-Feet
Run 1 Profile
Examples
FF15/FL11*
-1000
-500
0
500
1000
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221 231 241
Inc
he
s x
10
00
Half-Feet
Run 17 Profile
FF48/FL35**
FF68/FL19*
-1000
-500
0
500
1000
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221 231 241
Inc
he
s x
10
00
Half-Feet
Run 5 Profile
FF91/FL70**
* Hand Screed
** Laser Screed
Elevation change
+/- 6mm
+/- 15mm
-70mm
+/- 3mm
Sloping Floor
Elevated Slabs
• Deflection levelness is a function camber and
dead load - not finishing techniques.
• Flatness significantly affects the appearance of
applied finishes.
• FF30 is the highest F Number that can be
achieved (specify FF25).
• Straightedge tolerances measure deflection &
camber and not flatness.
Superflat Floors
• Required for AGV defined-traffic floors and narrow-aisle high-rack warehouses and other special applications.
• Require the use of the “Fmin” system (NOT FF/FL).
• Placed in long strips without sawcuts (to avoid tolerance losses due to curling).
• Require reinforcing against longitudinal shrinkage and surface hardening without the use of aggregate hardeners.
FF30
FF117
Construction Joints
• Joints must be doweled with smooth bars /plates that are de-bonded and aligned to permit horizontal movement.
• Do not use deformed rebar.
• Do not use keyways.
Formed keyways
do not work
Contraction Joints
• Must be cut in a timely
manner and at a
sufficient depth to work.
• Maximum 4.5m spacing
at approx. 25 times the
slab thickness.
• Should be located at all
sources of stress
including: bollards,
columns, corners,
thickenings, pits, etc.
• Sawcuts may be added
over supporting
members in exposed
slabs on deck to
minimize cracking.
CAUTION: lightly / un-
reinforced concrete cracks easily !
Cracks
Many causes:
• High shrinkage concrete.
• Contraction joint spacing too far apart, too late or not deep enough.
• Points of restrain not isolated with cuts.
• Conduits cast into the slab.
• Contraction joints held together by bonded or deformed steel reinforcing.
• Granular base settlement.
• Concrete over-loaded / under designed.
Soffcut Sawcuts
• A specialized dry process.
• Cuts directly behind the finishing
operation before shrinkage starts.
• A 38mm deep cut can create a
crack in up to 300mm of concrete.
• Soffcut joints are shallow and less
expensive to fill full depth.
Joint Filler Details
Epoxy or
Urethane Sealants Epoxy
Fillers Polyurea
Fillers
Cannot displace
vertically
FOOT TRAFFIC
ONLY FORKLIFT TRAFFIC FORKLIFT TRAFFIC
** Soffcut joints require less filler materials = lower cost
**
May displace
vertically
Joint Fillers
• Floor joints subjected to hard wheel traffic should be protected from deterioration by filling full depth with a semi-rigid (min. Shore “A” of 80) load bearing filler after a minimum 120 days of drying.
• Joints subject to foot / light traffic may be sealed 1/2” deep with a more flexible sealant on a backer rod after 60 days of air drying.
• Use hot rubberized asphalt
filler for exterior joint filling
due to excessive thermal
movement.
• Fill freezer joints at operating
temperatures (do not pre-fill).
These joints are 4m apart.
Filler Timing
• Leave joints unfilled and
fill after a minimum 120
days of air drying at 20°C.
• “The requirement to
replace joint
sealants/fillers which de-
bond as a result of early
filling is not a
workmanship or material
deficiency.“
Curing & Sealing Membranes
• Are relatively soft – not
durable.
• Are only meant to retain
moisture to help cement
hydrate (harden).
• Should not be used with
penetrating or applied
finishes.
Liquid Hardeners
• Inexpensive.
• React chemically with the
CaOH over several months.
• Do not wear off with traffic =
maintenance free.
• Are not curing agents.
Before After
Application
• Spray versus flood coating.
• Applied at the time of
finishing.
• Applied after 3 days of wet
curing, wash & dry.
• Applied after 28 days of air
drying.
• Applied to old surfaces.
Concrete mixes with pozzolans also react with CaOH
Green Concerns
• “Green-washing” is a major problem (eg: coal
byproduct = green cement replacement / bleached
recycled paper / deleting reinforcing).
• Green changes are occurring VERY quickly.
• Properties of GREEN concrete are significantly
different than “normal concrete”.
• There is no measurement of actual performance (eg:
durability, repairs and maintenance).
• LEED is also creating some issues.
LEED Cement Issue
• Reductions in portland cement are rewarded.
• However - large increases in alternative cements
change the behavior of concrete (set, bleed rate,
finishing and shrinkage).
• 25 MPa x 10 factor = 250 kgs/m3 Cement
• 160w/250c = ±0.65 w/c (porous, high shrinkage & low
wear).
Compressive strength is NOT the
most critical concrete mix factor for floors
REMEMBER:
Drying to 3lbs/000sf/hr:
0.4 w/c: 2 months
0.5 w/c: 6 months
0.6 w/c: > 1 year Source: ACI 302
On the Web @ concretefloors.ca
Summary
• Exposed concrete floors are a very sensible and
sustainable solution.
• Specify fully inclusive scopes of work including concrete
supply & polishing for high quality results.
• Use pre-construction meetings to manage coordination
and expectation problems.
• Inspect everything to ensure value.
• Prequalify CFCA industry leaders in your specifications
for the best results.
Other References
• CSA A23.1 Concrete Materials and Methods of Concrete Construction.
• American Concrete Institute
– ACI 117 Tolerances for Concrete Construction
– ACI 302 Guide to Concrete Floors
– ACI 360 Guide to Design of Slabs on Ground
• Portland Cement Association *
• Concrete Floor Contractors Association website.
Contact Information
Concrete Floor Contractors Association
RPO DUNDAS NEYAGAWA, PO Box 30021, Oakville, ON, L6H 7L8
Tel: (905) 582-9825
Fax: (416) 981-3913
E-mail: [email protected]
Website: www.concretefloors.ca
Windsor
London
Toronto