Concrete Cleanliness Inspections - Laitance

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Concrete Cleanliness Inspections –
Extent of Paint Removal
• For repaints, verify
adequacy of paint removal
• Definitions for the amount
of paint or stain allowed to
remain on the surface do
not exist (nothing available
like the blast cleaning
standards that define
specific percentages or
amounts)
Concrete Cleanliness Inspections –
Soundness of Remaining Paint
• Extent/quality of
feathering required
• Test the integrity of
the coating that
remains after cleaning
• Although not a
standard for concrete
cleaning, consider dull
putty knife test
Concrete Cleanliness Inspections –
Roughness
• Verify acceptable
degree of substrate
roughness – need to
coordinate with
Owner’s expectations
• Standards showing
varying degrees of
roughness for given
methods of
preparation do not
exist
Concrete Cleanliness Inspections –
Acid Etching
• Confirm the thoroughness
and degree of etching when
using acid on floors
• Typical comparison is
medium grit sandpaper finish
and measuring pH
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Response to Industry Needs for
Concrete Inspection Standards
• A newly formed SSPC Commercial Coating
Committee will be developing guides and
standards to address the preceding concerns,
and other concrete inspection issues
• Committee meetings will be held on Feb 1,
during the SSPC 2012 conference in Tampa
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Inspect Concrete/Brick
Moisture Content
• The surface should be examined
for unacceptable levels of moisture
prior to painting. Sources of
moisture include pressure washing,
and external sources such as leaks
and ground water
• Test with moisture meters and
plastic sheet, ASTM D4263
• The SSPC committee will be
developing a guidance document to
address test instruments, test
locations, test frequency, and
interpretation of results
• Moisture testing is the subject of a
webinar in March 2012
Moisture Testing - Identifies
Potential Problems before Painting
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Inspect for Removal of
Gloss and Chalk
• When overcoating, inspect the
existing coating for chalk.
Cleanliness can be tested by
rubbing a clean black fabric (wool
felt) across the surface and
comparing the appearance of the
residue with an ASTM rating scale
(ASTM D4214)
• Shiny surfaces should be inspected
for removal of gloss to assure
proper adhesion of the subsequent
coats. There are no standards for
the assessment, but the surface
should be viewed from different
angles to determine if shiny areas
remain
Summary - Surface Preparation
Inspections of Metal and Concrete
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Standards are available for nearly
all types of cleaning and inspection
of metal substrates
Limited standards are available for
cleaning and inspection of
cementitious surfaces, but SSPC is
addressing it.
Visual cleanliness inspections
involve 100% of the surface
Frequency of surface profile
measurements (metal surfaces) is
being established by SSPC
Moisture detection of concrete is
critical and standards are being
developed by SSPC to address it
For overcoating, gloss and chalk
must be removed
Monitor Ambient Conditions
Poor Conditions can Impact Quality
• Temperature, Relative Humidity, Dew Point/Surface Temp
Relationship are critical for proper coating performance
• Must be carefully monitored
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