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Presented by: Peter Emmons,
Achieving Durability in Concrete Repairs
Learning Outcomes• At the end of this webinar, you will be
able to:– Recognize when a repair method needs
to be defined on a concrete substrate– Describe proper repair methods– Describe types of repair materials
available
Introduction• This webinar focuses on concrete
conditions that require removing some or all of the concrete before standard surface preparation for coating application.
Method of Repair• When the selecting the method and
equipment for repair you should consider:– The size of the area to be repaired– Is there cracking– Is there exposed reinforcing steel (rebar)– Location of the floor (indoor/outdoor)– The ambient conditions– The specified ICRI Concrete Surface Profile
(CSP)– The coating or coating system that will be
applied over the repair areas
Repair Conditions• Before a successful repair project can
begin, several key issues need to be addressed:– Determine the cause of concrete
deterioration or damage– Determine the most suitable repair
method, equipment and materials– Determine if there is an industry standard
to follow (SSPC, ICRI, ASTM, ACI)– Determine if the project should involve a
structural engineer and/or architect
Method of Crack Repair• Cause of cracking must be
determined before a crack repair method can be selected– Is there a likelihood of further
movement?
Settlement Cracking• Cracks resulting from settlement of
the structure with a low likelihood of further movement can be repaired by epoxy pressure injection
Dynamic Cracks• Cracks that will continually move due
to:– Thermal expansion– Thermal contraction– Absence of adequate expansion joints
Damage Due to Thermal Property Changes
Expansion Joint
Cracks Causing Water Intrusion
• The sources of water intrusion vary– Water may be coming through
• Cracks in the• Concrete structure• Between concrete and piping through the
concrete structure• Through honeycombs in the concrete• Through control or expansion joints
Water Intrusion
Photo Courtesy of Tnemec
Reinforcement Repair• The most frequent cause of damage
to reinforcing steel is corrosion
Spalling• Spalling of reinforced concrete is
commonly associated with corrosion of the rebar
• The increase of volume due to the corrosion product causes the outer layers of the concrete to detach
Reinforcement Repair• Proper steps to prepare the
reinforcement will help insure that the repair method is a long-term, rather than temporary, solution– Remove concrete surrounding steel– Clean the reinforced steel by wire
brushing– Repair of reinforcement
• Replace the reinforcement• Supplement the reinforcement• Coat the reinforcement
Deteriorated Concrete• A repair or rehabilitation project will
usually involve removal of deteriorated, damaged or defective concrete
Methods to Remove Deteriorated Concrete
• Classification of concrete removal methods are:– Blasting – Cutting– Impacting– Milling– Hydrodemolition– Prospecting– Abrading
Surface Preparation
• One of the most important steps in the repair of a concrete floor is the preparation of the surface to be repaired
ICRI Guideline No. 310.2
• ICRI Guideline No. 310.2, Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings and Polymer Overlays provides designers, specifiers, contractors and manufacturers with the tools needed to select and specify the methods for preparing concrete surfaces prior to the application of sealer, coating and polymer overlay systems
ICRI Guideline 310.2
ICRI Guideline 310.2
• Photo Courtesy of Tnemec
Surface Preparation Methods
• Chemical cleaning• Acid etching• Mechanical
preparation• Abrasive
preparation
Material Selection• Things to consider when selecting which
repair material to use are:– Coefficient of thermal expansion– Shrinkage– Permeability– Modulus of elasticity– Chemical properties– Electrical properties– Color properties
Selecting the Repair Product
• Repair systems include:– Cast-in-place
concrete– Pre-placed aggregate
concrete– Troweling and dry
packing– Injection grouting– Cement grouting– Chemical grouting
Bonding Methods• Repair materials may require a
separate bonding agent• Application must be done with care in
order to avoid premature cure creating a bond breaker with the new repair material– Cement based– Epoxy and latex based
Surface Treatments• The objective is to limit corrosion by
establishing conditions that reduce the free water in the concrete while preventing further moisture or chloride intrusion
Surface Treatments• Generically classified as:
– Sealers– Coatings
• Membranes
– Overlays
Sealers• Penetrating
– After application material penetrates within the substrate of the concrete
• Surface– Thin film that lays on the surface of the
concrete
Penetrating Sealers• Such products include, but are not
limited to:– Boiled linseed oil– Silanes– Siloxanes– Epoxies– Methacrylates
Surface Sealers• Such products include, but are not
limited to:– Epoxies– Polyurethanes– Methyl methacrylates– Moisture-cured urethanes– Acrylics
Coatings• Materials with a DFT greater than 10
mils and less than 30 mils
Coatings• Such products include, but are not
limited to:– Acrylics– Styrene-butadienes– Polyvinyl acetates– Chlorinated rubbers– Urethanes– Polyesters– Epoxies
Membranes• Materials with a DFT greater than 30
mils and less than 250 mils
Membranes• Such products include, but are not limited
to:– Urethanes– Acrylics– Epoxies– Neoprenes– Cement– Polymer concrete– Methyl methacrylates– Asphaltic products
Overlays• Materials with a DFT greater than
250 mils
Overlays• Such products include, but are not
limited to:– Polymer concrete– Concrete– Epoxies– Methyl methacrylates– Polymer modified concrete
Summary• This webinar has outlined important
components of repairing concrete, resources for concrete repair and examples of how to successfully repair concrete. Proper identification of the cause of damage to concrete as well as the selection of appropriate repair methods and materials is important not only to successful patching but also to successful surface preparation and coating application