edoc.pub_icri-310-2r-2013.pdf

TECHNICALTECHNICAL

GUIDELINESGUIDELINES

Prepared Prepared by by the the International International Concrete Concrete Repair Repair Institute Institute October October 20132013

Guideline No. 310.2R–2013Guideline No. 310.2R–2013 Copyright ©2013 International Concrete Repair InstituteCopyright ©2013 International Concrete Repair Institute

Selecting and Specifying ConcreteSelecting and Specifying Concrete Surface Preparation for Sealers,Surface Preparation for Sealers, Coatings, Polymer Overlays, andCoatings, Polymer Overlays, and Concrete Repair Concrete Repair

Copyright © 2013 Copyright © 2013 International Concrete Repair InstituteInternational Concrete Repair Institute

All rights reserved.All rights reserved.

International Concrete Repair InstituteInternational Concrete Repair Institute

10600 West Higgins Road, Suite 607, Rosemont, IL 6001810600 West Higgins Road, Suite 607, Rosemont, IL 60018

Phone: 847-Phone: 847-827-0830 827-0830 Fax: 847-Fax: 847-827-0832827-0832

E-mail: info@icri.orgE-mail: info@icri.org

Web: www.icri.orgWeb: www.icri.org

Guideline No. 310.2R-2013Guideline No. 310.2R-2013

Selecting andSelecting and

Specifying ConcreteSpecifying Concrete

Surface PreparationSurface Preparation for Sealers, Coatings,for Sealers, Coatings, Polymer Overlays, andPolymer Overlays, and

Concrete RepairConcrete Repair

TECHNICALTECHNICAL

Prepared Prepared by by the the International International Concrete Concrete Repair Repair Institute Institute October October 20132013

Copyright © 2013 Copyright © 2013 International Concrete Repair InstituteInternational Concrete Repair Institute

All rights reserved.All rights reserved.

International Concrete Repair InstituteInternational Concrete Repair Institute

10600 West Higgins Road, Suite 607, Rosemont, IL 6001810600 West Higgins Road, Suite 607, Rosemont, IL 60018

Phone: 847-Phone: 847-827-0830 827-0830 Fax: 847-Fax: 847-827-0832827-0832

E-mail: info@icri.orgE-mail: info@icri.org

Web: www.icri.orgWeb: www.icri.org

Guideline No. 310.2R-2013Guideline No. 310.2R-2013

Selecting andSelecting and

Specifying ConcreteSpecifying Concrete

Surface PreparationSurface Preparation for Sealers, Coatings,for Sealers, Coatings, Polymer Overlays, andPolymer Overlays, and

Concrete RepairConcrete Repair

TECHNICALTECHNICAL

Prepared Prepared by by the the International International Concrete Concrete Repair Repair Institute Institute October October 20132013

SELECTING AND SPECIFYING SELECTING AND SPECIFYING CONCRETE SURFACE PREPARACONCRETE SURFACE PREPARATION FOR TION FOR SEALERS, COATINGS, POLSEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE YMER OVERLAYS, AND CONCRETE REPAIRREPAIR310.2R-2013310.2R-2013

About ICRI GuidelinesAbout ICRI Guidelines The International Concrete Repair Institute (ICRI) wasThe International Concrete Repair Institute (ICRI) was founded to founded to improve the durability improve the durability of concrete repairof concrete repair and enhance its value and enhance its value for structure owners. The iden-for structure owners. The iden-tication, development, and promotion of the mosttication, development, and promotion of the most promising promising methods methods and matand materials erials are are primary primary vehiclesvehicles for for acceacceleralerating ting advancadvances es in in reprepair air techtechnologynology. . WWorkiorkingng through a variety of forums, ICRI members have thethrough a variety of forums, ICRI members have the opportunity to address these issues opportunity to address these issues and to and to directlydirectly contribute to improving the practice of concrete repair.contribute to improving the practice of concrete repair.

A A principaprincipal l component component of of this this effort effort is is to to make make carefcarefullyully selected selected informinformation ation on on importimportant ant repair repair subjecsubjectsts readily accessible to decision makers. During the pastreadily accessible to decision makers. During the past several decades, much has been reporte several decades, much has been reported in the liter-d in the liter-ature on concrete repair methods and materiaature on concrete repair methods and materials as theyls as they have been developed and rened. Nevertheless, it hashave been developed and rened. Nevertheless, it has been difcult to nd been difcult to nd critically recritically reviewed information onviewed information on the state of the art condensed into easy-to-use formats.the state of the art condensed into easy-to-use formats.

TTo that end, o that end, ICRI guidelines are prepared by sanctionedICRI guidelines are prepared by sanctioned task groups and approved by the ICRI Technicaltask groups and approved by the ICRI Technical

Activities Committee. Activities Committee. Each Each guideline is guideline is designed designed toto address a specic area of practice recognized as essenaddress a specic area of practice recognized as essen--tial to the achievement of durable repairs. All ICRItial to the achievement of durable repairs. All ICRI guideline documents guideline documents are subject are subject to continual to continual reviewreview by the membership and may by the membership and may be revised as approved bybe revised as approved by the Technical Activities Committee.the Technical Activities Committee.

Producers of this GuidelineProducers of this Guideline

ICRI Committee 310, Surface PreparationICRI Committee 310, Surface Preparation Andrew S. Fulkerson, Chair Andrew S. Fulkerson, Chair

Patrick Winkler, SecretaryPatrick Winkler, Secretary**

Randal M. BeardRandal M. Beard

Don CapleDon Caple

Fred GoodwinFred Goodwin

David G. KarinsDavid G. Karins

Kenneth M. LozenKenneth M. Lozen

Kevin A. MicholsKevin A. Michols

Beth NewboldBeth Newbold

Jeffery SmithJeffery Smith

**Subcommittee ChairSubcommittee Chair

TTechnical Activities echnical Activities CommitteeCommittee Kevin A. Michols, Chair Kevin A. Michols, Chair

James E. McDonald, SecretaryJames E. McDonald, Secretary

Frank ApicellaFrank Apicella

Jorge CostaJorge Costa

Andrew S. FulkersonAndrew S. Fulkerson

Fred GoodwinFred Goodwin

Gabriel A. JimenezGabriel A. Jimenez

Ralph C. JonesRalph C. Jones

Peter R. Kolf Peter R. Kolf

David Rodler David Rodler

Lee SizemoreLee Sizemore

Aamer SyedAamer Syed

David WhitmoreDavid Whitmore

SynopsisSynopsis Proper surface preparation is a key element inProper surface preparation is a key element in determining the success of a determining the success of a concrete restorationconcrete restoration project. Improper surface project. Improper surface preparation may leadpreparation may lead to the failure of the protective system or repairto the failure of the protective system or repair material, resulting in further repairs, addedmaterial, resulting in further repairs, added expense, and loss of use, and may ultimatelyexpense, and loss of use, and may ultimately compromise the integrity of the compromise the integrity of the structure.structure.

Surface preparation is the process by which aSurface preparation is the process by which a sound, clean, and suitably roughened surface issound, clean, and suitably roughened surface is produced produced on a on a concrete concrete substrate. substrate. Surface Surface prepa-prepa-ration includes the removal of ration includes the removal of laitance, dirt, oil,laitance, dirt, oil, films, paint, coatings, sound and unsound con-films, paint, coatings, sound and unsound con-crete, and other materials that will crete, and other materials that will interfere withinterfere with the adhesion or penetration of a sealer, coating,the adhesion or penetration of a sealer, coating, poly polymer mer overoverlay, lay, or or reparepair ir matematerialrial. . SurfSurfaceace preparation will preparation will open open the the pore pore structure of structure of thethe concrete substrate and establish profiles suitableconcrete substrate and establish profiles suitable for the application of the specified protectivefor the application of the specified protective system or repair material.system or repair material.

KeywordsKeywords Abrasive blasting; acid etching; detergent scrub-Abrasive blasting; acid etching; detergent scrub-bin bing; g; grigrindinnding; g; hanhandhedheld ld conconcretcrete e brebreakeakers;rs;

high- and ultra-high-pressure water jetting; low-high- and ultra-high-pressure water jetting; low-pressure water cleaning; microcracking; pressure water cleaning; microcracking; needleneedle scaling; rotomilling; scabbling; scarifying;scaling; rotomilling; scabbling; scarifying;

shotblasting; surface preparation; surface profile;shotblasting; surface preparation; surface profile;

surface retarders.surface retarders.

This document is intended as This document is intended as a voluntary guideline for the owner, design professional, anda voluntary guideline for the owner, design professional, and concrete repair contractorconcrete repair contractor. It is . It is not intended to not intended to relieve the professional engineer or designerrelieve the professional engineer or designer of any responsibility for the specication of concrete repair methods, materials, or practices.of any responsibility for the specication of concrete repair methods, materials, or practices.

While we believe the information contained herein represents the proper means to achieveWhile we believe the information contained herein represents the proper means to achieve quality results, the International Concrete Repair Institute must disclaim any liability orquality results, the International Concrete Repair Institute must disclaim any liability or responsiresponsi bility to thos bility to those who may choose e who may choose to rely on all to rely on all or any part of tor any part of this guideline.his guideline.

310.2R-2013310.2R-2013SELECTING AND SPECIFYING SELECTING AND SPECIFYING CONCRETE SURFACE PREPARACONCRETE SURFACE PREPARATION FOR TION FOR SEALERS, COATINGS, POLSEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE YMER OVERLAYS, AND CONCRETE REPAIRREPAIR

ContentsContents

1.0 Introduction1.0 Introduction ........................................................................................................................................................................................................................................................1

1.1 Surface 1.1 Surface Preparation Preparation ..................................................................................................................................................................................................................1

1.2 1.2 Guideline Guideline TTools ools

2.0 Definitions2.0 Definitions

3.0 3.0 Selecting Selecting Surface Surface Preparation Preparation Method(s)Method(s)

3.1 Project 3.1 Project Evaluation Evaluation

3.2 3.2 Evaluate Evaluate Surface Surface Preparation Preparation Method(s) Method(s)

3.3 3.3 Select Select and and Specify Specify Surface Surface Preparation Preparation Method(s) Method(s)

3.4 Quality 3.4 Quality Control Control

4.0 4.0 Mechanics Mechanics of of Concrete Concrete RemovalRemoval

4.1 4.1 IntroductionIntroduction

4.2 4.2 Cleaning...............Cleaning

4.3 4.3 Acid Acid Etching Etching and and Surface Surface Retarder Retarder

4.4 4.4 Abrasion Abrasion ....................................................................................................................................................................................................................................................3

4.5 4.5 High-Pressure High-Pressure Water Water Erosion Erosion

4.6 Im4.6 Impact pact

4.7 Pulve4.7 Pulverization rization

5.0 5.0 Microcracking Microcracking (Bruising)(Bruising) ..............................................................................................................................................................................................................4

5.1 5.1 Effect Effect on on Bond Bond Strength Strength

5.2 5.2 Risk Risk of of Introducing Introducing Microcracking Microcracking .......................................................................................................................................................................4

6.0 6.0 Concrete Concrete Surface Surface Profiles Profiles (CSPs)(CSPs)

7.0 7.0 Method Method SelectorSelector

7.1 7.1 CSP CSP and and Protective Protective Systems Systems

7.2 7.2 CSP CSP and and Preparation Preparation Methods Methods

8.0 8.0 Method Method SummariesSummaries

8.1 Abrasive 8.1 Abrasive Blasting Blasting

8.2 8.2 Acid Acid Etching Etching

8.3 8.3 Handheld Handheld Concrete Concrete Breakers Breakers

8.4 Detergent 8.4 Detergent Scrubbing Scrubbing

8.5 Grinding 8.5 Grinding

8.6 8.6 High- High- and and Ultra-High-Pressure Ultra-High-Pressure Water Water Jetting Jetting

8.7 8.7 Low-Pressure Low-Pressure Water Water Cleaning Cleaning

8.8 Rotomilling 8.8 Rotomilling

8.9 8.9 Needle Needle Scaling Scaling

8.10 8.10 Scabbling Scabbling

8.11 8.11 Scarifying Scarifying

8.12 8.12 Shotblasting Shotblasting

8.13 8.13 Surface Surface Retarders Retarders

9.0 References9.0 References

9.1 9.1 Referenced Standards Referenced Standards and Reports and Reports

9.2 9.2 Cited Cited References References

Appendix A: S Appendix A: Surface Preparation Selection urface Preparation Selection

Appendix B: Appendix B: TeTesting .................sting

Appendix C: Safety Appendix C: Safety

SELECTING AND SPECIFYING SELECTING AND SPECIFYING CONCRETE SURFACE PREPARACONCRETE SURFACE PREPARATION FOR TION FOR SEALERS, COATINGS, POLSEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE YMER OVERLAYS, AND CONCRETE REPAIRREPAIR310.2R-2013310.2R-2013

310.2R-2013 - 1SELECTING AND SPECIFYING CONCRETE SURFACE PREPARATION FOR SEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE REPAIR

1.0 Introduction

1.1 Surface Preparation

This guide provides owners, designers, speciers, contractors, and manufacturers with the tools needed to select and specify the methods for pre-paring concrete surfaces prior to the application of a protective system or repair material. Surface preparation is the process by which a sound, clean, and suitably roughened surface is produced on a concrete substrate. Surface preparation includes the removal of laitance, dirt, oil, lms, paint, coat-ings, sound and unsound concrete, and other materials that will interfere with the adhesion or penetration of a sealer, coating, polymer overlay, or repair material. Proper surface preparation will open the pore structure of the concrete substrate and establish proles suitable for the application of the specied protective system or repair material.

Proper surface preparation is a key element in determining the success of a concrete restoration project. Improper surface preparation may lead to the failure of the protective system or repair mat-erial, resulting in further repairs, added expense, and loss of use, and may ultimately compromise the integrity of the structure. The existing conditions of the concrete and the type of protective system or repair material to be applied should be considered in determining the surface preparation method(s).

The designer, specier, contractor, and manufac-turer should all participate in the selection of the surface preparation method(s). Detailed attention to proper surface preparation will help ensure the long-term success of the restoration project.

1.2 Guideline Tools

The following tools are contained within the guideline to assist the user in the selection and/ or specication of the proper surface preparation method(s):

• Method Selector (Section 7.0): Identifies methods capable of producing the concrete surface prole(s) (CSP[s]) typically recom-mended for the protective system or repair material.

• Method Summaries (Section 8.0): Discusses the capabilities, limitations, operating require-ments, and environmental factors for each method.

• CSP Chips (Section 6.0): Provides replicas of surface preparation profiles produced by methods described in the guide and visual standards for specication, execution, and verication of surface proles.

• Method Selection Checklists (Appendix A):

Provides checklists to help ensure that critical information is identied, organized, and con-sidered in the development of criteria for the selection of a surface preparation method(s).

• Testing (Appendix B): Discusses various test methods that may be used to specify and evaluate the quality of the surface preparation.

• Safety (Appendix C): Provides links to specic safety information.

2.0 Definitions

Denitions for terms used in this guideline may be found in ICRI Concrete Repair Terminology

(http://www.icri.org/GENERAL/repairtermi-nology.aspx).

3.0 Selecting Surface

Preparation Method(s)

3.1 Project Evaluation

Concrete surface conditions, material require-ments, and job-site conditions will vary consider-ably for each project. Most projects will have unique conditions and requirements that must be evaluated to determine which surface preparation method(s) is/are suitable for the project and which will ensure the long-term success of the protective system and/or repair material. More than one method may be capable of producing the desired results. Appendix A provides a more complete list of items to be considered and can be used as a checklist in evaluating a project. The checklist will help ensure that the various conditions affecting the surface preparation have been considered.

3.1.1 Substrate condition

The condition of the substrate, including the pres-ence of unsound concrete, bond-inhibiting mate-rials, substrate deterioration, cracking, and surface contaminants, need to be evaluated to determine the nature and degree of preparation required. The surface preparation method must provide a clean, sound substrate with a surface prole appropriate for the specic material installation.

3.1.2 Material requirements

Surface preparation requirements may vary with the material selected. The manufacturer of the system may have specic requirements for sur -face preparation, including the surface prole and moisture sensitivity, and should be consulted.

Proper surface preparation could impact the

2 - 310.2R-2013 SELECTING AND SPECIFYING CONCRETE SURFACE PREPARATION FOR SEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE REPAIR manufacturer’s warranty. The properties and appli-cation requirements of the selected protective system or repair material must be determined prior to the selection of a surface preparation method.

3.1.3 Job-site requirements

Noise, vibration, dust, and water may be generated by various preparation methods. The need for uninterrupted use of the structure, concerns about the operating environment, or the potential for property damage may limit the choices. Mechanical ventilation, available power sources, the size of door openings, and minimum clearance may also affect surface preparation decisions. The surface preparation may also release hazardous contami-nants (for example, asbestos from old ooring mastic). Any condition that may affect the method of surface preparation should be considered.

3.2 Evaluate Surface

Preparation Method(s) Selecting the method(s) that will provide a clean, sound substrate and optimize the success of the material installation requires knowledge of the available options. The surface prole achieved following the surface preparation is often the primary requirement in specifying the preparation method(s). The method selector chart may be used to make a preliminary identication of the methods capable of producing the required CSP.

Each of the methods capable of meeting the

CSP requirement can be compared in the method summaries section, which provides data on the capabilities, limitations, operating requirements, and environmental considerations for each sur-face preparation method.

3.3 Select and Specify Surface

Preparation Method(s) The nal selection is based on the relationship between substrate conditions, material require-ments, and job-site conditions. The specication may include a CSP range as well as other criteria, such as bond strength. These requirements should be clearly dened in the specication, along with the test method(s) that will be used to evaluate the completed surface preparation. The test pro-cedures described in Appendix B may be used in preparing the specications to ensure that the desired results are achieved.

3.4 Quality Control

The CSP chips (CSP 1-10) provide benchmark proles to aid in achieving the desired result.The prepared surface should be compared to the CSP chips specied for the project. Tests, such as the tensile bond test, may be performed to verify that all deteriorated or damaged concrete has been removed. Other specied tests should be per -formed prior to installing the protective system or repair material. The cost of providing addi-tional surface preparation will be signicantly less than the cost of correcting a failure of the installed system or repair. Appendix B describes various tests that may be used to evaluate the prepared concrete surface. SSPC-SP 13/NACE

No. 6, ASTM D5295, ASTM E1857, and ASTM

F2471 provide additional considerations for sur-face preparation and quality control.

4.0 Mechanics of

Concrete Removal

4.1 Introduction

In addition to project-specic requirements, the selection of a surface preparation method should ensure that:

• The surface is not damaged;

• The reinforcing steel is not damaged, nor its bond with the concrete compromised; and

• Vibration, impact, or construction loads do not weaken the concrete.

This section describes the mechanics used by the various surface preparation methods to remove deteriorated concrete and contaminates from the surface. This information will help users determine the potential of each preparation method to achieve the desired results and also assess the potential for damage to the substrate that may be caused by the individual methods.

4.2 Cleaning

Cleaning does not noticeably alter the prole of concrete surfaces. Cleaning and detergent scrub-bing are accomplished through one or a com-bination of the following: the surfactant effect of detergents, the solvent effect of water, the shearing force of brushes, and the force of low-velocity water. Applicable methods: low-pressure water cleaning and detergent scrubbing.

4.3 Acid Etching and

Surface Retarder Acid etching chemically dissolves calcium hydroxide and calcium silicate, which make up the hydrated solids in cement paste. The dissolu-tion of these materials at the surface causes a

310.2R-2013 -3SELECTING AND SPECIFYING CONCRETE SURFACE PREPARATION FOR SEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE REPAIR slight loss of cement paste and produces a very light prole on the exposed surface. Surface retarders slow the hydration of cement, allowing low-pressure water cleaning to remove the retarded layer, creating an exposed aggregate surface. Applicable methods: acid etching and surface retarders.

4.4 Abrasion

Abrasive force applied through grinding with stones, abrasive discs, or blocks with embedded diamonds wears away the cement paste, nes, and coarse aggregate at a uniform rate to pro-duce a nearly at surface having little or no pro-le (Fig. 4.1). Applicable methods: grinding.

4.5 High-Pressure Water Erosion

Erosion causes the ushing away or progressive disintegration of concrete surfaces. A stream of water projected onto the surface under high pres-sure will result in the gradual erosion of the sur-face. The impact of the water and the water velocity combine to wear away the cement paste.

As exposure to water jetting increases, so will the prole as the softer paste and embedded nes erode, leaving behind “islands” of the harder coarse aggregate. Under prolonged exposure to water jetting, the coarse aggregate will be undercut and washed away (Fig. 4.2). Applicable methods:

high- and ultra-high-pressure water jetting.

4.6 Impact

Several preparation methods strike the surface repeatedly with hardened points to produce momentary mechanical loads that exceed the strength of the concrete, causing it to fracture.

The force of the impact pulverizes and fractures the cement paste and aggregate at and adjacent to the point of contact (Fig. 4.3 and 4.4). Some of the cracks and loosened aggregate may remain, leaving a “bruised” layer at the surface. Appli-cable methods: scarifying, scabbling, rotomilling, needle scaling, and handheld concrete breakers.

4.7 Pulverization

The cutting effect is derived from the collision of small particles traveling at a high velocity against the concrete surface (Fig. 4.5). Because the mass of the particles is comparatively small, their impact is not known to produce bruising. Hard, sharp-edged media and high pressure can produce fast cutting rates. As with water jetting, the cement paste is usually reduced at a faster rate than the coarse aggregate. This difference in removal rate has the effect of exposing and under-

Fig. 4.1: Grinding

Fig. 4.3: Scarifying, scabbling, rotomilling, needle scaling

Fig. 4.5: Abrasive blasting, shotblasting cutting the coarse aggregate to produce a surface that will become highly proled as exposure time is increased. Applicable methods: steel shot-blasting and abrasive blasting.

Fig. 4.2: High- and ultra-high-pressure water jetting

Fig. 4.4: Handheld concrete breaker

4 - 310.2R-2013 SELECTING AND SPECIFYING CONCRETE SURFACE PREPARATION FOR SEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE REPAIR

Fig. 5.1.a: Microcracking of the concrete

Fig. 5.1.b: Microcracking

Fig. 5.1.c: Microcracking under LMC overlay

5.0 Microcracking

(Bruising)

5.1 Effect on Bond Strength

Fig. 5.2: Potential risk of microcracking during surface preparation weakened plane (Fig. 5.1a to 5.1c). It is generally accepted that the extent of the damage increases with the weight and power of the equipment used.

However, the use of sharp, ne-toothed cutters contacting the surface at a shallow angle may reduce or prevent the development of bruising.

The relative risk of introducing bruising or micro-cracking into the substrate is indicated for each method in Section 5.2. Surfaces prepared using impact methods should be tested using a tensile pulloff test to conrm that the prepared surface does not contain microcracks that may compro-mise the installation of a repair material or protec-tive system (refer to Appendix B).

5.2 Risk of Introducing

Microcracking Figure 5.2 identies the potential risk of intro -ducing microcracking when performing surface preparation using the method listed.

Surface preparation using methods resulting in a high probability of microcracking, including handheld concrete breakers, rotomilling, and scab-bling, generally require further surface preparation to remove the microcracks. Surface preparation using methods resulting in a moderate probability of microcracks, including needle scaling and scar-iers, may require further surface preparation, and the surface should be evaluated to determine if the preparation created microcracks. All surfaces should be tested, regardless of preparation method, to ensure adequate concrete strength and a properly prepared surface (refer to Appendix B).

Abrasive blasting

Acid etching

Handheld concrete breakers

Detergent scrubbing

Grinding

High- and ultra-high-pressure water jetting

Low-pressure water cleaning

Rotomilling

Needle scaling

Scabbling

Scarifying

Shotblasting

Surface retarders

Several of the preparation methods described may locally damage the prepared substrate. Field studies have shown that bond strengths of surfaces prepared using high-impact mechanical methods are frequently lower compared to surfaces pre-pared using nonimpact methods. This reduction in bond strength is caused by the fracturing of the cement paste and loosening of the aggregate without fully separating from the surface. This creates a weakened or “bruised” surface layer of interconnecting microcracks typically extending to a depth of 1/8 to 3/8 in. (3 to 10 mm). Micro-scopic examination usually indicates that cracks initiate at the surface at approximately a 45-degree angle and propagate horizontally to produce a

310.2R-2013 - 5SELECTING AND SPECIFYING CONCRETE SURFACE PREPARATION FOR SEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE REPAIR

6.0 Concrete Surface

Profiles (CSPs) Several of the methods summarized are capable of producing a range of proles on concrete surfaces. Communication of project objectives and requirements may be improved by using

CSPs to dene the desired surface prole (ampli-tude or roughness).

ICRI has identied 10 distinct proles pro-duced by the surface preparation methods described in this guideline. As a set, these proles replicate degrees of roughness considered to be suitable for the application of one or more of the sealer, coating, polymer overlay systems, and/or concrete repair materials. Each prole carries a

CSP number ranging from CSP 1 (nearly at) through CSP 10 (very rough; amplitude greater than 1/4 in. [6 mm]). The prole characteristics for each preparation method are identied by

CSP number in the “Profile” section of the method summaries. Molded replicas* of these

Caution! The texture and appearance of the prole obtained will vary depending on the concrete strength, the size and type of aggregate, and the nish of the concrete surface. On sound substrates, the range of variation can be sufciently controlled to resemble the referenced CSP standard. As the depth of removal increases, the prole of the prepared substrate will be increasingly dominated by the type and size of the coarse aggregate.

Fig. 6.1: CSP 1 (acid-etched)

Fig. 6.2: CSP 2 (grinding)

Fig. 6.3: CSP 3 (light shotblast)

Fig. 6.4: CSP 4 (light scarification)

Fig. 6.5: CSP 5 (medium shotblast)

Fig. 6.6: CSP 6 (medium scarification)

Fig. 6.7: CSP 7 (heavy abrasive blast)

Fig. 6.8: CSP 8 (scabbled)

Fig. 6.9: CSP 9 (heavy scarification— rotomilled)

Fig. 6.10: CSP 10 (handheld concrete breaker followed by abrasive blasting) proles provide clear visual standards for pur -poses of specication, execution, and verica-tion. These benchmark proles may be referenced in specications, material data sheets, applica-tion guidelines, and contract documents to effectively communicate the required surface prole. It is probable that more than one prole will produce acceptable results, and a range of suitable proles should be specied.

The concrete surfaces shown in Fig. 6.1 to

6.10 were produced using a variety of prepara-tion methods. Although each numbered CSP replica bears the characteristic pattern and tex-ture of the specic preparation method used, each replica is representative of the prole height

(amplitude) obtained with all methods identied with the same CSP number.

* Molded replicas are available with this guideline by contacting ICRI at the number listed on the back cover of this document or on ICRI’s website at http://www.

icri.org/bookstore/bkstr.asp.

6 - 310.2R-2013 SELECTING AND SPECIFYING CONCRETE SURFACE PREPARATION FOR SEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE REPAIR

Figures 6.11 and 6.12 provide a guide to the general appearance of a CSP 10. After prepar-ation is complete, the aggregate should appear clean and crisp and protrude above the paste line a minimum of 1/4 in. (6 mm).

7.0 Method Selector

7.1 CSP and Protective Systems

The type of protective system or repair material to be applied will impact the type of surface preparation selected. Penetrating sealers will have little or no effect on the appearance of the prepared surface. Any surface defects, contami-nants, or profile resulting from the surface preparation will be visible. Thin lms may be formulated to achieve high hiding power; how-ever, even relatively minor surface imperfections and proles produced by surface preparation equipment will be visible. High-build materials will have both high hiding power and some ability to ll irregularities and level the prepared surfaces. A smooth nish over higher proles may be achieved by increasing the thickness of the applied coating system. Manufacturers of these materials often have minimum thickness requirements, which can be affected by the sur-face profile. A surface profile greater than specied by the manufacturer may result in an increase in the cost of the system. Overlays and repair materials are generally installed such that the depth of the material covers the amplitude of the surface prole.

Possible surface profiles to be used with various protective systems are given in Table 7.1.

Consult the manufacturer to determine the rec-ommended surface prole.

7.2 CSP and

Preparation Methods An approximate range of surface profiles obtained using various preparation methods is shown in Table 7.2.

Fig. 6.11: CSP 10—Surface prepared using handheld concrete breaker followed by abrasive blasting

Fig. 6.12: CSP 10—Surface prepared using high-pressure water jetting

310.2R-2013 -7SELECTING AND SPECIFYING CONCRETE SURFACE PREPARATION FOR SEALERS, COATINGS, POLYMER OVERLAYS, AND CONCRETE REPAIR

Table 7.1: Protective Systems

Material to be applied

Concrete Surface Profile

CSP 1 CSP 2 CSP 3 CSP 4 CSP 5 CSP 6 CSP 7 CSP 8 CSP 9 CSP 10

Sealers, 0 to 3 mils (0 to 0.075 mm)

Thin films, 4 to 10 mils (0.01 to 0.025 mm)

High-build coatings, 10 to 40 mils (0.025 to 1.0 mm)

Self-leveling toppings, 50 mils to 1/8 in. (1.2 to 3 mm)

Polymer overlays, 1/8 to 1/4 in. (3 to 6 mm)

Concrete overlays and repair materials, >1/4 in. (>6 mm)

Table 7.2: Preparation Methods

Surface preparation method

Concrete Surface Profile

CSP 1 CSP 2 CSP 3 CSP 4 CSP 5 CSP 6 CSP 7 CSP 8 CSP 9 CSP 10

Detergent scrubbing

Low-pressure water cleaning

Grinding

Acid etching

Needle scaling

Abrasive blasting

Shotblasting

High- and ultra-high-pressure water jetting

Scarifying

Surface retarder (1)

Rotomilling

Scabbling

Handheld concrete breaker

(1) Only suitable for freshly placed cementitious materials

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8.0 Method Summaries

8.1.3 Profile

CSP 2-7—Abrasive blasting should not introduce any noticeable pattern. The prole achieved is dependent on the duration of exposure to the blast stream and the size and cutting efciency of blast media.

8.1.4 Accessibility

The small size and portability of the hose and blast nozzle provide virtually unrestricted access to all surfaces, including edges, corners, and recessed spaces.

8.1.5 Limitations

Abrasive blast is not recommended for the following:

• Removal of resilient coatings, uncured coatings or adhesives, and tar-based materials;

• When occupied space, goods, or equipment cannot be adequately protected from dust inltration; and

• Removal of signicant quantities of concrete.

8.1.6 Environmental factors

Dry abrasive blasting will produce airborne dust con-taining silica and particles of any material being removed.

8.1.1 Summary

Abrasive blasting is used to clean and prole concrete surfaces (Fig. 8.1.a). The process can provide a light, clean prole, often referred to as a “brush blast,” or it can be used to achieve a moderate prole. It may also be used to remove surface contaminants and thin, brittle coatings or adhesive lms (Fig. 8.1.b) from surfaces and corrosion products from reinforcing steel (Fig.

8.1.c). This method may be used on horizontal, vertical, and overhead surfaces and is suitable for both interior and exterior applications. Both vacuum recovery and wet abrasive blasting equipment are sometimes used to reduce environmental contamination from the abrasive blasting technique. Abrasive blasting is often used to mitigate microcracking caused by other surface prepa-ration methods.

8.1.2 Removal

This method uses a compressed air stream with an abrasive media to clean concrete and steel surfaces.

Removal is accomplished by the eroding effect of the blast media impacting the surface at high velocity.

Fig. 8.1.a: Column

Fig. 8.1.b: Floor

Fig. 8.1.c: Reinforcement cleaning

Fig. 8.1.d: Protective equipment

8.1 Abrasive Blasting

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Any special requirements for containment and disposal will depend on the specic contaminants or materials being removed. Blast media substitutes such as sodium bicarbonate are sometimes used to reduce the dust hazard or volume of debris. Water may be injected into the blast stream to reduce dust. Vacuum recovery systems may also be used with abrasive blast units to reduce dust and cleanup. Noise levels are likely to exceed 85 dB.

8.1.7 Execution

The blast media stream is directed at the surface using a controlled sweeping motion. The required duration of exposure to the blast stream will depend on the strength of the substrate, air pressure, air volume, blast media type, and degree of cleaning or proling required. Special provisions are often needed to protect people, property, and the environment from dust and airborne debris. Blast curtains and containment areas may be used to isolate the blast process.

8.1.8 Equipment

• Blast nozzle and hose;

• Air compressor of sufcient capacity;

• Blast media hopper (meters the media into the air stream passing through the hose and nozzle);

• Moisture and oil separators to ensure clean, dry air supply; and

• Protective equipment, including an air-supplied hood

(Fig. 8.1.d).

8.1.9 Materials

The most common abrasive blast materials are silica sand and slag. There are a wide variety of blast materials avail-able to meet different needs. These materials are consumed in the blast operation and are generally not recycled.

8.1.10 Employee skill level

Medium skill level is required. Special training in safe operation and environmental hazards is required for crew members. A two-person crew per blast unit is required.

One crew member will operate the blast nozzle while the other supports the operation by monitoring the blast operation and maintaining the blast media hopper, com-pressor, and hoses.

8.1.11 Setup and downtime

Time required for mobilization, setup, and maintenance of blast equipment and compressor will take several hours.

Signicant time may be needed to set up dust protection around the work area.

8.1.12 Cleanup

Dust, ne particles of concrete or other pulverized mate-rials, and blast media are generated by the dry abrasive blast process. The area will require sweeping and/or vacuuming to collect the debris. Dust will accumulate on all unprotected surfaces and will require cleaning. Recu-perative or wet abrasive blasting may substantially reduce the volume of dust generated.

8.1.13 Production rates

Productivity is highly variable and is dependent on the strength of the concrete, surface contaminants, accessi-bil ity, capacity of blast media hopper, compressor capacity, and type of blast media used. Production rate estimates range from 1000 to 6000 ft2 (100 to 600 m2) per

8-hour shift per unit.

8.1.14 Quality control

Various test techniques are described in Appendix B. The practitioner is encouraged to specify the appropriate test to verify that the desired surface preparation results have been achieved. At a minimum, verify that the CSP required by the specications has been achieved. Visual inspection should show no dirt, laitance, or debris on the surface.

The prepared surface should be free of bond-inhibiting materials. A bond test may be required to demonstrate adequate bond strength. Beads of water may indicate a surface contaminant that could require further surface preparation to achieve a clean surface. ASTM D4259 provides additional considerations for surface preparation and quality control using this method.

8.1.15 Safety hazard

Abrasive blasting will cause the release of dust containing silica. Minimum recommended personal protective equip-ment (PPE) is as follows:

• Eye protection—Hood incorporating eye and face protection;

• Respiratory protection—Air-supplied hood;

• Hearing protection—Earplugs and/or earmuffs;

• Protective clothing;

• Automatic shutoff for the blast nozzle; and

• Leather or specialty gloves while operating handheld equipment.

Consult the material and equipment manufacturer’s current recommended safety procedure. Consult ICRI

Technical Guideline No. 120.1 (Sections 2.0 through 7.0) for guidelines and recommendations for safety in the concrete repair industry. Refer to Appendix C for addi-tional information on safety issues related to concrete surface preparation.

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8.2 Acid Etching

8.2.1 Summary

Acid etching is designed to remove cement paste from the surface and surface pores of concrete (Fig. 8.2.a).

8.2.2 Removal

The acid in the etching solution attacks the calcium hydroxide (Ca(OH) ) and calcium silicate hydrate (CSH) in the cement paste, causing rapid deterioration at the surface. The concentration and volume of solution applied are controlled to limit the depth of chemical attack. The typical depth of removal is 0.004 to 0.010 in. (0.1 to

0.25 mm). Etching will remove the cement paste and slightly prole the surface by exposing ne silica aggregate.

8.2.3 Profile

CSP 1-3—Etching should not introduce any noticeable pattern effect on sound concrete surfaces. The surface should feel like ne sandpaper with no residue or grit. The surface should have a dull, even appearance. If the surface is still smooth or glossy, repeat procedure.

8.2.4 Accessibility

The equipment used for this method is portable and maneuverable. Access may be restricted by the presence of nonportable machinery or equipment subject to damage from corrosive mist or splash.

8.2.5 Limitations

• Caution must be exercised to avoid excessive absorp-tion of acid by the concrete. Absorption may result in the introduction of contaminants such as chlorides (in the case of muriatic/hydrochloric acid);

• The surface may require neutralization following acid etching. All traces of the acid must be removed. Incom-plete removal or neutralization of the acid may leave bond-inhibiting contaminants on the surface;

• Solution is highly corrosive. Electronic equipment, machines, and other metal components should be protected or removed;

• Thorough removal of etching debris requires large quantities of rinse water, mechanical scrubbing, and vacuum removal;

• Hydrochloric acid may not be used on metallic hard-ened surfaces;

• A signicant amount of oils, grease, and other surface deposits must be removed prior to etching;

• Not recommended for use on green concretes;

• The etching process will saturate the substrate. When used in preparation for moisture-sensitive materials, time restrictions may not allow for sufcient drying; and

• Environmental considerations may require full contain-ment and recovery of spent acid and rinse water.

Fig. 8.2.a: Etched and clean surface Fig. 8.2.c: Spreading acid

Fig. 8.2.b: Acid applied to concrete Fig. 8.2.d: Rinsing to remove acid

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8.2.6 Environmental factors

Applied as an acid wash, the mixture may corrode metals on contact. Debris produced by acid etching will contain particles of the material or contaminants being removed.

Any special requirements for containment and disposal will depend on the specic materials or contaminant being removed. Spent acid and rinse water must be disposed of as required by local regulations or project restrictions. The acid solution may release toxic vapors.

8.2.7 Execution

1. Dilute acid mixture according to oor type, strength of concentrate, and manufacturer’s recommendations.

Dense or chemically hardened oors may require higher concentrations and/or multiple passes;

2. Thoroughly wet concrete surfaces to minimize absorption of the acid solution into the concrete surface. Standing water must be removed prior to application of acid;

3. Apply mixed solution uniformly (Fig. 8.2.b);

4. Agitate acid solution with stiff bristle broom or power brush for 5 to 10 minutes (Fig. 8.2.c). Do not allow sur-face to dry;

5. Vacuum residue;

6. Thoroughly scrub with an alkaline detergent and then vacuum the residue. Repeat as necessary to completely remove etching debris;

7. Rinse with clean water (Fig. 8.2.d), scrub, and vacuum dry; and

8. Verify that all acid etching material has been removed by checking the pH of the rinse water (refer to Appendix B.4).

8.2.8 Equipment

• Container to mix etching solution;

• Applicator: Low-pressure sprayer, plastic sprinkling can, or mop;

• Floor scrubber or disc machine equipped with an abrasive bristle brush;

• Power washer or hose to apply rinse water; and

• Vacuum system or scrubber for recovery.

The use of automatic scrubbing equipment to apply acid etching solution is not generally recommended. However, this equipment is often used to recover etching solution after it has been diluted with rinse water. Consult the equipment manufacturer to determine suitability.

8.2.9 Materials

• Acid etch solution. Typical solutions include muriatic

(hydrochloric), sulfamic, phosphoric, and citric acids.

Always add acid to water—never add water to acid;

• Alkaline detergent for cleanup scrub;

• Water source; and

• Plastic sheeting to protect materials and equipment.

8.2.10 Labor

Medium to above-medium skill level is required to safely handle and mix hazardous materials and operate equipment.

8.2.11 Setup and downtime

Minimal time is required to mix etching solution. Filling and emptying scrubber and wet-vacuum tanks should take

10 to 20 minutes. Additional time may be required to protect material and equipment in the work area.

8.2.12 Production rates

The rates shown as follows are approximate. Actual rates will vary with the method used, density of surface, dilution ratio, and size of machines.

• Manual application with wet/dry vacuum recovery:

1600 ft2/h (150 m2/h); and

• Medium scrubber: 8000 ft2/h (740 m2/h).

8.2.13 Quality control

Various test techniques are described in Appendix B. The practitioner is encouraged to specify the appropriate test to verify that the desired surface preparation results have been achieved. At a minimum, verify that the CSP required by the specications has been achieved. Visual inspection should show no dirt, laitance, or debris on the surface.

The prepared surface should be free of bond-inhibiting materials. A bond test may be required to demonstrate adequate bond strength. Beads of water may indicate a surface contaminant that could require further surface preparation to achieve a clean surface. Testing (such as pH testing) should verify that all acid materials have been removed by checking the pH of the rinse water before and after rinsing. ASTM D4260 provides additional consid-erations for surface preparation and quality control using this method.

8.2.14 Safety hazards

Acid etching involves the use of dangerous chemicals that will cause serious injury if exposed to any part of the body. Always add acid to water, as some acids may react violently if water is added to the acid. The acid may also produce dangerous vapors, which may damage the respi-ratory system. Operators must be trained in the proper use and handling of the acid materials. Minimum recom-mended PPE is as follows:

• Eye protection—Anti-fog goggles meeting ANSI requirements for high impact and face shield;

• Acid- and alkaline-resistant gloves, boots, aprons, and clothing;

• Respiratory protection using respirators equipped with acid-gases canister; and

• Hearing protection may be required if powered scrub-bers are used.

Consult the material and equipment manufacturer’s current recommended safety procedure. Consult ICRI

Guideline No. 120.1 (Sections 2.0 through 7.0) for guide-lines and recommendations for safety in the concrete repair industry. Refer to Appendix C for additional information on safety issues related to concrete surface preparation.

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8.3 Handheld Concrete Breakers

8.3.1 Summary

Handheld concrete breakers are typically classied by their weight. Larger handheld concrete breakers (jackhammers) in the 30 lb (14 kg) class and larger (Fig. 8.3.a) are typically used on horizontal surfaces, while smaller breakers (chipping hammers) weighing 20 lb (9 kg) or less (Fig. 8.3.b) may be used on horizontal, vertical, and overhead surfaces to remove concrete to a predetermined depth (SHRP-S-336). A typical application for a chipping hammer is the removal of deterio-rated and/or chloride-contaminated concrete from around reinforcing steel. Handheld concrete breakers may also be used as an initial step in preparation for overlays. This method is suitable for use in interior and exterior applications.

8.3.2 Removal

Removal is accomplished by the impact of the tool (point or chisel) on the surface. The tools may be pneumatic, electric, or hydraulic. The impact of the tool on the surface will fracture and split the concrete. This will also result in microcracks in the remaining substrate, which will affect the bond of the repair material (Fig. 8.3.c). Surfaces prepared using chipping hammers and handheld concrete breakers will require further preparation (sandblasting, waterblasting, or shotblasting) to remove microcracks in the substrate

(Fig. 8.3.d and 8.3.e). The use of heavier handheld concrete breakers will result in deeper microcracking.

8.3.3 Profile

CSP 7-10—Handheld concrete breakers will produce a very irregular surface dominated by fractured coarse aggre-gate. They will cause microcracks in the substrate and the points and chisel will leave marks on the concrete surface.

Fig. 8.3.a: Jackhammer

Fig. 8.3.b: Chipping hammer with chisel and point tools

Fig. 8.3.c: Chisel tool

Fig. 8.3.d: Chipped surface using handheld concrete breaker before additional surface preparation

8.3.4 Accessibility

Most surfaces are accessible to chipping hammers, while handheld concrete breakers are used on horizontal surfaces.

8.3.5 Limitations

• Handheld concrete breakers will induce microcracking, requiring further surface preparation;

Fig. 8.3.e: Chipped surface followed by abrasive blasting to remove fractured substrate

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• The use of…