An Integrated Approach to Concrete An Integrated Approach to Concrete

RepairRepair

Concrete Corrosion Basic Concrete Corrosion Basic

MechanismMechanism

Causes: CarbonationCauses: Carbonation

Causes: Lack of CoverCauses: Lack of Cover

Causes: Lack of CoverCauses: Lack of Cover

Causes: Chloride AttackCauses: Chloride Attack

Causes: Freeze Thaw AttackCauses: Freeze Thaw Attack

Causes: Chemical AttackCauses: Chemical Attack

Causes: Construction & DesignCauses: Construction & Design

Concrete in the Marine EnvironmentConcrete in the Marine Environment

�Visual survey

�Delamination (hammer) survey

�Rebound hammer survey

�Potential mapping

�Chloride profile testing

�Reinforcement cover assessment

�Carbonation testing

Investigative TechniquesInvestigative Techniques

�Pre-qualify contractors

�Must have manpower and equipment

�Visit previous works

� Tender to based on recent comprehensive investigation

�Unit rate contract

�Client to have high quality supervision

Contractor SelectionContractor Selection

Repair StagesRepair Stages

�Conventional concrete

�High performance concrete

�Sprayed concrete

�Polymer modified mortars (hand or spray)

� Fluid micro-concrete

�Rapid cure mortar

�Resin mortars

�Composites

Repair OptionsRepair Options

Surface CleaningSurface Cleaning

Surface PreparationSurface Preparation

Steel PreparationSteel Preparation

�Zinc rich coating

� Epoxy coating

�Cement epoxy coating

�Polymer modifed cement slurry

�Zinc anodes

�Surface applied corrosion inhibitor

�Cast in corrosion inhibitor

�Drilled in corrosion inhibitor

Steel Protection OptionsSteel Protection Options

Reinforcement ProtectionReinforcement Protection

�Water

�Non redispersable polymer

� Epoxy

�Polymer modifed cement slurry

Priming OptionsPriming Options

Hand Applied Hand Applied

Cementitious MortarCementitious Mortar

Sprayed ConcreteSprayed Concrete

Form and PourForm and Pour

�Water

�Water & hessian

�Water & hessian sealed with PE sheet

�Curing compound

�Protective coating

Curing OptionsCuring Options

�Silane

�Silane siloxane

�Polymer modified cementitious coating

�Aliphatic acrylic coatings

� Epoxy or PU coatings

Protection OptionsProtection Options

Protection of the RepairProtection of the Repair

� A through investigation is necessary

� Repair as soon as possible after the

investigation

� Select the most appropriate repair technique and materials

� Select a professional contractor with a track record

� Confirm contractor’s track record� Preparation is the key to a good repair� Supervise the works using an experienced consultant

� Install a protection system

SummarySummary