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CONCRETE APPEARANCECONCRETE APPEARANCEDoes it matter?
Neil CrookThe Concrete Society Advisory Service
1st July 2010
cbdg annual conference– 1st July 2010
Structural or Appearance?
• Structural– Functionality– Structural capacity– Durability
• Appearance– Does it look nice– What will it look like in 20, 50 or 100 yearsy
cbdg annual conference– 1st July 2010
Structural failureStructural failure
cbdg annual conference– 1st July 2010
Visual Concrete
• Planning and assessment• Finishes• Control of blemishes• Weathering, stains & efflorescence
cbdg annual conference– 1st July 2010
Planning and assessment
• Different levels of visuality‘hi h t’– ‘high art’
– Normal (grey/white) exposed but not colouredCoated e g painted– Coated e.g. painted
– Limited visual exposure• Not one size fits all• Not one size fits all• Perfection is not achievable nor should it
be expectedbe expected• Surface never completely uniform
cbdg annual conference– 1st July 2010
Large scale structures
cbdg annual conference– 1st July 2010
Planning and assessment
• SpecificationsBS 8110 Structural use of concrete (withdrawn in 2010)– BS 8110 Structural use of concrete (withdrawn in 2010)
– BS EN 13670 Execution of concrete structures– Highways Agency, Specification for Highway WorksHighways Agency, Specification for Highway Works– National Building Specification– Civil Engineering Specification for the Water Industry– National Structural Concrete Specification for Building
Construction
• ‘Fair faced’ is meaningless• Fair-faced is meaningless• Specification appropriate to the end use
cbdg annual conference– 1st July 2010
Cracking
cbdg annual conference– 1st July 2010
iJoints
cbdg annual conference– 1st July 2010
Rebate feature
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Rebated joints
cbdg annual conference– 1st July 2010
Planning and assessment
• Formwork– Many systems– Many form face materials– All with give a different appearance
cbdg annual conference– 1st July 2010
Formwork typesyp
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Panel System finishes y
cbdg annual conference– 1st July 2010
Planning and assessment
• Form faceSt l GRP Li CPF Ti b– Steel, GRP, Liners, CPF, Timber
• Release agentsOil Ch i l VERA– Oils, Chemical, VERA
• ConcreteC t A t S ifi ti– Cement, Aggregate, Specification
• ConstructionT i l l S W h Pl i– Trial panels, Spacers, Weather, Placing, Vibration, Remedial work
cbdg annual conference– 1st July 2010
Line and block spacers effect of finish
cbdg annual conference– 1st July 2010
Planning and assessment
• Assessment– Age, Lighting, Distance
• Bridges – from carriagewayB ildi• Buildings –– external – 3m– internal – 1minternal 1m
cbdg annual conference– 1st July 2010
Finishes
• Formed and Unformed
cbdg annual conference– 1st July 2010
Board marked
cbdg annual conference– 1st July 2010
Ribbed –hammered,
it bl t dcbdg annual conference– 1st July 2010
grit blasted
Form liners
cbdg annual conference– 1st July 2010
Dream
cbdg annual conference– 1st July 2010
Tamped Brush Turf dragged
TiTine
Textured roller
cbdg annual conference– 1st July 2010 Burlap dragged
Pattern imprintedPattern imprinted
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Exposed and washedExposed and washed aggregate
cbdg annual conference– 1st July 2010
Abrasive blasting
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Di d i dDiamond grind
Diamond groove
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Dry shake and power trowelled
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Polished
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Stained, stencilled and blasted
cbdg annual conference– 1st July 2010
Control of blemishes
• Defects• Blemishes
– Avoidable– Unavoidable
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Natural variation
cbdg annual conference– 1st July 2010
Blow holes
Aggregate bridgingbridging
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Rust staining
cbdg annual conference– 1st July 2010
Water lossLift lines
SScourPoker burns
cbdg annual conference– 1st July 2010
Plastic shrinkage
i dRain damage
cbdg annual conference– 1st July 2010
Frost damage
cbdg annual conference– 1st July 2010
Frost damage
cbdg annual conference– 1st July 2010
R i f t i lReinforcement ripple
Crazing
Delaminationcbdg annual conference– 1st July 2010
Delamination
Weathering, stains & efflorescence
Weathering affects all buildings
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescenceCleaningCleaning
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Orientation
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Surface Permeability
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Surfaces intended to remain dirty – Bold profile
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Details to controlcontrol weathering should be bold not subtle
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Diagonally ribbed surfaces affect the flow of water in ways that are difficult to predict and control
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescenceQuality and detailingdetailing
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Quality and detailing –exposed coarse aggregateexposed coarse aggregate
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Only pyramids will be y pywashed clean on all faces
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Uncontrolled water flowUncontrolled water flow
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Gutters need notGutters need not necessarily be connected to rainwater pipe systems
cbdg annual conference– 1st July 2010
p p y
Weathering, stains & efflorescence
Stains – Bitumen, rust, graffiti, litchen
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Cleaning – water jet, acid grit blastingacid, grit blasting
cbdg annual conference– 1st July 2010
Weathering, stains & efflorescence
Lime bloom, Lime weeping, e weep g,Salt crystallization
cbdg annual conference– 1st July 2010
cbdg annual conference– 1st July 2010
cbdg annual conference– 1st July 2010
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