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