CONCRETE SURFACE PREPARATION Fred Goodwin Fellow Scientist BASF Construction Chemicals Beachwood, OH

CONCRETE SURFACE PREPARATIONFred Goodwin

Fellow Scientist

BASF Construction ChemicalsBeachwood, OH

Surface Preparation: The MOST Important Factor for the Success of

Coating and Lining Installations

SSPC Definition: “The method or combination of methods used

•to clean a concrete surface, •remove loose and weak materials & contaminants, •repair the surface, and •roughen the surface to promote adhesion”

•SSPC SP13 “An acceptable prepared concrete surface should:• be free of contaminants,

laitance, loosely adhering concrete, & dust, •provide a sound, uniform substrate •be suitable for the application of the protective

coating or lining system.”

From ICRI 310.2

What are we trying to accomplish?

What problem did we inherit?

What do we have to work around?

What is “unusual” with the material?

What does the “boss” (owner) want??

What is Concrete?

A Picture is Worth a Thousand Words…

Air / Porosity ~1-7%

Water~ 12-16%

Cement ~ 10-15%

Fine Aggregate- Sand ~30-80%

Coarse Aggregate- Stone ~0-50%

1 cubic yard =27 cubic feet=0.765 cubic meter

3 feet

3 feet

3 fe

et

VOLUME %

Proportions

What is Concrete?

Concrete Mix Rules of Thumb• Cement

– as cement content , strength , shrinkage , cost

• Sand– as sand content , workability , finishability , shrinkage

• Stone– as stone content , workability , finishability , shrinkage

• Water or water to cement (w/c) ratio– as water , workability , shrinkage strength , durability

• Air content– as air content , strength , bleed , freeze/thaw resistance

RETARDER

AIR ENTRAINMENT

SHRINKAGE REDUCING

ANTI-BLEED

DEFOAMER

DISPERSANTCORROSION

INHIBITORACCELERATOR

SHRINKAGE COMPENSATION

PLASTICEXPANSION

BINDERCement

MINERAL ADMIXTURES

Concrete Additives & Admixtures

Design & Construction

Kanare, H. Concrete Floors & Moisture, Eng. Bulletin #119 PCA/NRMCA, 2005

Concrete

From SSPC SP13

Plastic Shrinkage

Thermal Properties

Drying Shrinkage

CRACKING

Chloride Ingress

Moisture Ingress

Carbonation Oxygen Diffusion

Contaminant Ingress (oil, acids, nitrates,

etc.)

Reinforcement Corrosion




Freeze/Thaw Deterioration

AARSulfate Attack

Further CRACKING, SPALLING, DELAMINATION, DINTEGRATON

PHASE 1

PHASE 2

PHASE 3

Concrete Cracks!

H2O

Thermal Cracking

Higher Water to Cement Ratios Shrink More

Drying Shrinkage:

ACI 224 R-01

Lower Aggregate Contents Shrink More

Drying Shrinkage:

ACI 224 R-01

At ALL Water to Cement Ratios

Drying Shrinkage:

Thinner sections dry (and shrink) faster%

of

Ult

imat

e S

hri

nk

age

Time (0--------------------------24 Months)

12” Thick Slab

2” Thick Slab

8” Thick Slab

Drying Shrinkage Cracking:

ASTM C1581 Cracking Potential

Inner and Outer Steel

Ring for Mold

Cast Repair Donut

Strip off Outer Steel Ring

Wax Top Surface

Shrinkage HappensCompresses Steel Ring Steel Ring Resists

Specimen Cracks

Steel Ring & Strain Gauges

Reinforcement CorrosionRusting (Oxidation) and deterioration of steel in concrete which results in rust stains and/or disruption of the concrete

What do all of these have in common?

• Natural WATER Sources– Weather– Water Table– Hydrostatic Pressure– Osmosis– Subslab Vapor– Indoor RH– Dew Point

• Artificial WATER Sources– Mix Water– Curing Water– Leakage/Spills– Cleaning– Surface Preparation

Two Types

Construction Methods to Minimize NATURAL Water Ingress


Drying from both sides

No external humidity

Drying from one side

Bottom side moist

Drying of Slabs


Higher W/C dries slower.

If bottom of slab is wet, harder to dry.

4” Slabs to MVTR = 3 Lb/1000 sq. ft.

• Erosion

• Impact

• Pulverization

• Pressure

• Solvation

• Reaction

• Expansive Pressure

Surface Preparation MethodMechanics of Removal

ICRI 0310.2 Guideline for Selecting and Specifying

Concrete Surface Preparation

for Sealers, Coatings, and Polymer Overlays

Mechanics of Removal

Objectives–Not Damage Structure

–Not Damage Reinforcing Steel

–Not Damage Surface To Be Coated

–Achieve Satisfactory Surface

Mechanics of Removal

– Mechanism of Method– Limits of Method– Surface Texture & Pattern– CSP Profiles– Problems & Issues with Method– Prepared Surface Result – Speed of Surface Preparation Range– How to QC Surface

ICRI 0310.2 Guideline for Selecting and Specifying

Concrete Surface Preparation

for Sealers, Coatings, and Polymer Overlays

Surface Preparation Methods

• Detergent Scrubbing• Low Pressure H2O• Acid Etching• Grinding• Sand/Abrasive Blasting• Shot Blasting• Scarifying• Needle Scaling• Hydrodemolition/High/Ultrahigh H2O Pressure• Scabbling• Liquid Surface Etchant• Flame Blasting• RotoMilling

From ICRI 310.2



From ICRI 03732Surface Preparation Methods

Removal Methods

• Detergent Scrubbing– Method: Solvation, Reaction

– Limits: Soluble/Emulsifiable Contaminants

– Surface Texture: No Improvement

– Profile: ICRI CSP 1

– Problems: Solution Disposal

– Result: Wet Substrate

– Production: 50-5000 sq m/hr (Mop→Large Riding Scrubber)

– QC: Compare to Hand Scrubbed, Water Beading, Slip Tester

• Low Pressure Water Cleaning– Method: Solvation, Erosion– Limits: Soluble/Emulsifiable Contaminants and Loose

Debris– Surface Texture: No Sound Concrete Removal, No

Profile– Profile: ICRI CSP 1– Problems: Water & Loose Debris Disposal, Noise, Mist– Result: Wet Substrate– Production: 25-200 sq m/hr (hand held→quality of

cleaning)– QC: Water beading, no loose material


Surface Preparation Methods• Acid Etching

– Method: Reaction, Solvation– Materials: Muriatic (HCl), Sulfamic, Phosphoric, Citric– Limits: <10 mils Coatings– Surface Texture: Clean, Light Profile– Profile: ICRI CSP 1-3– Problems: Corrosive Solution, Rinse Water, Neutralization

Concrete >6 weeks old, Vacuum Removal– Result: Wet Substrate– Production: 150-750 sq m/hr

(hand scrubbing, vacuuming-medium scrubber)– QC: Sandpaper type surface, pH

Grinding– Method: Erosion– Limits: Coatings <6 mils,

Not for Sealers or Rubbery/Thermoplastic Coatings– Surface Texture: Smooth, Dusty– Profile: ICRI CSP 1-3– Problems: Dusty, Noisy, Pattern & Edge Problems,

Media Replacement Cost– Result: Leaves Dry, Dusty Substrate, – Production: 2-75 sq m/hr (hand held-walk behind)– QC: Visual Profile, Dust?


Abrasive (Sand) Blasting– Method: Pulverization, Erosion– Limits: Resilient Coatings, Dusty Or Wet/Vacuum (expensive)– Versatile: Sealers to 5mm Toppings– Surface Texture: Dry, Dusty Substrate, Media & Debris

Disposal,

Profile: ICRI CSP 2-4– Problems: Compressed Air, Dust Control, Large Volume of

Media– Result: Dry Dusty Surface– Production: 100-600 sq m/hr (soft concrete/equipment)– QC: Visual Profile, Dust & Contaminant Removal Verification


Shot Blasting– Method: Pulverization, Impact, Erosion 1-5 mm removal – Limits: Resilient Coatings, Sticky, Metallic, Saturants – Surface Texture: Striping, Pebbled, Sl. Exposed Aggregate– Profile: ICRI CSP 2-8– Requirements: Magnetic Broom,

Electric/Propane/Diesel/Gasoline– Problems: Noisy, Striping Pattern, Edge Effects,

Maintenance, Powder Disposal, Vacuum, Shot Size & Usage– Result: Leaves Dry, Non-dusty Substrate, – Production: 14-420 sq m/hr (equipment, profile)– QC: Visual Profile, Contaminant Removal Verification


Scarifying– Method: Impact 1-20 mm Removal– Limits: Not for <15 mil coatings, Elastomeric, Only Horiz.– Surface Texture: Striated Pattern, Multiple Passes– Profile: ICRI CSP4-9– Requirements: Power, Spare Parts, Vacuum Cleaner– Problems: Bruising, Dusty, Maintenance, Edge Effects,

Noisy,

Debris Removal, Vibration– Result: Dry Substrate, 0.1-1cm/pass, Dust + Granular Debris– Production: 2-75 sq m/hr (hand held-walk behind)– QC: Visual Profile, Contaminant Removal, Bruising

Verification


Bruising Induced Bond Failure

• Needle Scaling – Method: Impact, 1/2-2mm Removal, Edge Detailing, Vertical, Horizontal, Overhead– Limits: For <15 mil coatings, Elastomeric

Bruising?, Brittle Removal– Surface Texture: Striated Pattern, Multiple Passes– Profile: ICRI CSP 4-9– Requirements: Compressed Air, Vacuum, Replacement

Rods– Problems: Dusty, Maintenance, Vibration– Result: Leaves Dry Substrate, Dust + Granular Debris– Production: 1-5 sq m/hr (hand held)– QC: Visual Profile, Contaminant Removal, Bruising?


• High & Ultra High Pressure Water Jetting, Hydrodemolition– Method: Erosion, Expansive Pressure,

10-150 mm Removal, Horizontal & Vertical, Robots– Limits: Water Disposal, Mist, Noise, Removal Based on

Soundness – Surface Texture: Variable Depending on Substrate,

Equipment– Profile: ICRI CSP 6-9– Requirements: Water, Debris Collection, Special Equipment – Problems: Maintenance, Messy, Vibration,

High Pressure, Runoff Protection, Mist, Spray– Result: Leaves Wet Substrate, Runoff, Debris– Production: 12-28 sq m/hr, Variable on Equipment & Substrate– QC: Visual Profile, Water Beading, Contaminant Removal


Nozzle Rotation

0 – 1,800 rpmAdjustable in field

Angled Nozzle 0 – 30 degreesChangeable in field

High Pressure Water - 15,000 - 40,000-psi, Water Jet Velocity - up to 1,500 mph (Rampart uses 35,000psi)

Stand OffEquipment setting

Flow Rate - 7 – 100 gpmControlled by size and number of parallel pumps

Hydrodemolition

Scabbling (Bush Hammer)– Method: Impact, 2-20 mm Horizontal, Light Duty Vertical– Limits: Frequent Bruising, Not for Elastomeric or Gummy – Surface Texture: Irregular Pattern w/Fractured Aggregate– Profile: ICRI CSP 7-9– Requirements: Air or Hydraulic Powered, Low Maintenance– Problems: Dusty, Noisy, Moderate to Severe Vibration,

Sweeping & Vacuuming – Result: Dry/Dusty/Fractured Substrate, Debris <12mm– Production: 2-9 sq m/hr (hand held-walk behind)– QC: Visual Profile, Contaminant Removal

Bruising (Eliminate w/Sand-, Steel-, or H2O-Blast)


Flame Blasting– Method: Expansive Pressure, Reaction,

2-12 mm Horizontal, Vertical, & Overhead, Portable, Good for Coatings, Elastomeric, Saturants, Gummy

– Limits: H2O Presaturate, Open Flame, Toxic Fumes, Hot Flying Chips– Surface Texture: Dust Free, Irregular Chipped Surface, No Pattern– Profile: ICRI CSP >8– Requirements: Ventilation, Oxygen/Acetylene, Special Equipment– Problems: Hot Flying Debris, Fumes, Bruising?– Result: Dry Chipped Surface with Hot Charred Debris

Remove by Sweeping or Air– Production: 5-55 sq m/hr (hand held-walk behind)– QC: Visual Profile, Eliminate Bruising (Sand Blast Follow up)

Contaminant Removal

OX

YG

EN

AC

ET

YL

EN

E

• RotoMilling

– Method: Impact, Horizontal 4-100mm depth, – Limits: Bruising, Edge & Corner Effects, Straight Path,

Clearance, Overlapping Passes, Large Volume Debris– Surface Texture: Deep Profile, Striated or Grooved Pattern,

Fractured Aggregate– ICRI CSP: 9– Requirements: Support of Heavy Equipment, Special Equipment– Problems: Bruising, Clearance, Heavy, Large Areas, Dust, Noise,

Vibration, Removal of Large Volume of Debris– Result: Very Rough, Chipped Surface, Grooves– Production: 9-1400 sq m/hr (size of machine)– QC: Visual Profile, Contaminant Removal,

Eliminate Bruising (Sand, Steel, or H2O Blast Follow up)

• Liquid Surface Etchant– Method: Reaction – Limits: Fresh Concrete Only, Timing, Debris

Removal, Wet&Green Substrate

– Surface Texture: Deep to Shallow Profile, No Pattern, Exposed Aggregate

– ICRI CSP: 3-9– Requirements: Apply During Concrete

Placement, Poly Film Cure, Water Blast Off– Problems: Removal of Large Volume of

Debris, Timing, Wet & Green Substrate, Return for

Removal– Result: Controlled depth of etch by:

• Etchant type, • Cure rate, • Timing or Removal

– Production: 5-100 sq m/hr – QC: Visual Profile, Debris Removal,

(H2O Blast Follow up)

Performance tests for concrete following surface preparation from SSPC SP 13.

?

ICRI 210.3ASTM C1583

Bond Test

Concrete

ToppingCompound

Bond/Tensile Adhesion/Bruising Test

Adhesive

Failure ?Adhesive

Failure ?

Repair Bond Failure

Overlay Tensile

Failure

?Bruising

?

Substrate Failure

Appearance

Water Beading

Water Wetting

pH of Wash Water

pH of Surface

Phenolphthalein in ~70% Alcohol

Compressive Strength

Things to Know:

Cylinders vs Cubes

Cored/Cut vs. Cast

Break ~15% to 20% lower

Defects Increase Variance & Decrease Strength

Hard to Cheat

Wet Burlap Poly Film Curing Compound

Curing

Curing Induced Strength Variations

TESTING Water Vapor PermeabilityGeneral

Guidance

ASTM E 1907

ACI 302.2 R-06

ASTM F 1869

ASTM F 2170

ASTM D 4263

Substrate Conditions

Orientation

Horizontal

Vertical

Overhead

On Grade

Suspended

Vapor Barrier Present

No Vapor Barrier

Over Granular Fill

Under Granular Fill

Moisture

From Concrete Placement (Fresh / Green Concrete)

From Cleaning / Process

From Surface Preparation

From Hydrostatic PressurePositive Hydrostatic

Negative Hydrostatic

From SubstrateMoisture Vapor Emission

Drainage

Contamination

Form Release

Curing Compound / Existing Membrane

Oil

CarbonationEarly / Dusting / Laitence

Late

Chlorides

Other Chemicals

Exposure

Interior

Exterior

Temperature

Elevated

Freezing

Ambient

Differential

Concrete Quality

Finish

Formed

Wood Float

Metal Trowel

Power Trowel

Broom Finish

Sacking

Stoning

Block

Shotcrete

Porosity

Strength

Extent of CrackingDynamic

Static

Chemical ContainmentPrimary

Secondary

Substrate

Conditions


Orientation

Horizontal

Vertical

Overhead

On Grade

Suspended


No Vapor Barrier

Over Granular Fill

Under Granular Fill

Moisture







Drainage

Contamination

Form Release


Oil


Late

Chlorides

Other Chemicals

Exposure

Interior

Exterior

Temperature

Elevated

Freezing

Ambient

Differential

Concrete Quality

Finish

Formed

Wood Float

Metal Trowel

Power Trowel

Broom Finish

Sacking

Stoning

Block

Shotcrete

Porosity

Strength


Static


Secondary

Surface Preparation Mechanism

Cleaning

Erosion

Impact

Pulverization

Chemical Reaction

Expansive Pressure

low pressure water

detergent scrubbing

Grinding

Surface Retarder Application

Acid Etchning

Priming?

Bush Hammers

Scabblers

Scarifiers

Abrasive Blasting

Shotblasting

Hydrodemolition

Flame Scarification

Emulsification

Needle Scaling

Coating Requirements

Moisture

Tensile Strength

Profile

pHSurface Cleanliness (Dust)

Sealers 0-3 mils/ 0-75 microns CSP 1-2 1/2Thin Film Coatings 4-10 mils / 100-250 microns CSP 1-3High Build Coatings 10 mils - 40 mils 250 - 1000 microns CSP 2-5Self Leveling 50 mils - 1/8" 1250 microns - 3 mm CSP 3-6Polymer Overlays 1/8 - 1/4" 3 - 6 mm CSP 4-9Toppings >1/4" >6mm CSP 4-9

Wet Substrate OKDry Substrate NeededMoisture Vapor Emission Problems

Application Conditions

Time

Temperature

Utility Supply

Environmental Impact

Physical Constraints

DurationWorking Window

AmbientConditionedElectricityWaterVentilationCompressed AirLight

NoiseVibrationFumesDebris DisposalHazardous WasteSurrounding Area

HeightWeightAccessWidth/Turning RadiusArea

Owner Requirements

Abrasion ResistanceChemical ResistanceAestheticsThickness ToleranceSlip ResistanceTime ConstraintsEnvironmental ImpactCost

BASF Construction Chemicals

Fred Goodwin Fellow Scientist

?

BRUISING

Surface Preparation Selection

Coating Requirements

Application Conditions

Owner Requirements


Moisture

Orientation

Horizontal

Vertical

Overhead

On Grade

Suspended


No Vapor Barrier

Over Granular Fill

Under Granular Fill

Moisture







Drainage

Contamination

Form Release


Oil


Late

Chlorides

Other Chemicals

Exposure

Interior

Exterior

Temperature

Elevated

Freezing

Ambient

Differential

Tensile Strength

Profile

pH

Surface Cleanliness (Dust)

Sealers 0-3 mils/ 0-75 microns CSP 1-2 1/2

Thin Film Coatings 4-10 mils / 100-250 microns CSP 1-3

High Build Coatings 10 mils - 40 mils 250 - 1000 microns CSP 2-5

Self Leveling 50 mils - 1/8" 1250 microns - 3 mm CSP 3-6

Polymer Overlays 1/8 - 1/4" 3 - 6 mm CSP 4-9

Toppings >1/4" >6mm CSP 4-9

Surface Preparation Mechanism

Cleaning

Erosion

Impact

Pulverization

Chemical Reaction

Expansive Pressure

low pressure water

detergent scrubbing

Grinding

Surface Retarder Application

Acid Etchning

Priming?

Bush Hammers

Scabblers

Scarifiers

Abrasive Blasting

Shotblasting

Hydrodemolition

Flame Scarification

Emulsification

Needle Scaling

Time

Temperature

Utility Supply


Physical Constraints

Duration

Working Window

Ambient

Conditioned

Electricity

Water

Ventilation

Compressed Air

Light

Noise

Vibration

Fumes

Debris Disposal

Hazardous Waste

Surrounding Area

Height

Weight

Access

Width/Turning Radius

Area

Wet Substrate OK

Dry Substrate Needed

Moisture Vapor Emission Problems

Abrasion Resistance

Chemical Resistance

Aesthetics

Thickness Tolerance

Slip Resistance

Time Constraints


Cost

Concrete Quality

Finish

Formed

Wood Float

Metal Trowel

Power Trowel

Broom Finish

Sacking

Stoning

Block

Shotcrete

Porosity

Strength


Static


Secondary

Documents

CONCRETE SURFACE PREPARATION Fred Goodwin Fellow Scientist BASF Construction Chemicals Beachwood, OH