Presented by: Peter Emmons, Achieving Durability in Concrete Repairs Presented by: Peter Emmons,

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

Photo Courtesy of Tnemec 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

Photo Courtesy of Tnemec 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 Surface 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