Concrete Crack and Partial Depth Spall Repair Manual
Contents
1. 25 6 11 Cold Applied Sealant Equipment 25 Chapter 7 Crack Preparation 27 FA IDESCHDUON ais Gia dessine 27 RN 28 Chapter 8 Crack Sealing Procedures 29 8 1 amer es bob s a 29 6 2 Preparatie 29 Chapter 9 Partial Depth Spall Repair 31 9 1 IDESCHIPUON cta ed 31 ORTO ii ot ee 34 9 3 Selecting Repair Materials and Procedure 34 9 4 Removing Old Sealant 34 9 5 BOUNQAMES ctrl die 35 9 6 Concrete Removal 35 9 7 Concrete Soundness 35 E IN rc an eee 35 9 9 SWEEPINg ne 35 9 10 Joint caco o an 36 Bonding Adentiirsississoretier diari dina 36 A A NE Benin Baker 36 9 18 Cl anups is ste es 36 Chapter 10 Spall Repair Materials 37 10 1 comarca anes 37 10 2 Alternative Repair Materials 37 Chapter 11 Spall Repair Equipment 39 A O 39 11 2 Concrete SAW ar 39 11 3 VackhaMmmers ss do manne nd 39 114 39 MD Hand nanas 392. 12 3 5 Sandblasting o bee ee eee ae 12 3 6 Removing Loose Material 12 3 7 VACUUMING 4 48 dances cd ds 12 3 8 Cleanlin SS ss ses Sms ares ren bte tens 12 3 9 Backer isasid esde us ments tepis aan 13 3 10 Foreign Object Damage 13 Chapter 4 Backer and Sealant Materials 15 4 1 DESCIIP ON eae dors 15 4 2 Separating Materials 16 4 3 Fuel and Blast Resistance 16 4 4 Navy Regulations 16 4 5 U S Army and Air Force Regulations 16 Chapter 5 Shape 17 SA DESCIPLION a sr nee ner en 17 5 2 Silicone Sealants 17 Chapter 6 Crack Repair Equipment 21 621 Description daube a 21 6 2 Random Crack Saw 21 6 3 Vertical Spindle 22 6 4 Sandblasting Equipment 22 6 5 Waterblasting Equipment 23 6 5 AOBA EANGE so o eain Sand has 24 6 7 Power Broom ais as 24 6 8 Compressed Air Equipment 24 6 9 Backer Rod Installation Equipment 24 6 10 Hot Applied Sealant Equipment
3. Skokie Illinois 60077 847 966 2272 Phone 847 966 9970 Fax www pavement com
4. Air Entraining Admixtures for Concrete Liquid Membrane Forming Compounds for Curing Concrete Chemical Admixtures for Concrete Epoxy Resin Base Bonding Systems for Concrete Chapter 1 Introduction Table 1 2 American Concrete Institute ACI Publications That Detail Good Practices for Concrete Repair Work ACI 305R 99 Hot Weather Concreting ACI 306R 88 Cold Weather Concreting ACI 308 01 Guide to Curing Concrete ACI 548 1R 97 Guide for the Use of Polymers in Concrete Table 1 3 American Concrete Pavement Association ACPA Publications Pertaining to Joint Crack and Spall Repair That Detail Good Practices for Concrete Repair Work ACPA TB012P Joint and Crack Sealing and Repair for Concrete Pavements ACPA SR903P Stitching Concrete Pavement Cracks and Joints ACPA Guidelines for Partial Depth Spall Repair ACPA 2 Concrete Pavement Restoration Guide Procedures for Preserving Concrete Pavements ACPA 2 Guidelines for Full Depth Repair Table 1 4 Federal Specifications for Sealants 55 5 200 Sealants Joint Two Component Jet Blast Resistant Cold Applied for Portland Cement Concrete Pavement SS S 1614A Sealants Joint Jet Fuel Resistant Hot Applied for Portland Cement Concrete Pavements Chapter 2 Purpose of Crack and Partial Depth Spall Repair CHAPTER 2 PURPOSE OF CRACK SEALING AND PARTIAL DEPTH SPALL REPAIR 2 1 Description The primary purp
5. use wider joints Joint spacing too long use closer joint spacing Incorrect joint configuration sealant installed too thick or too thin use correct depth to width ratio Voids or Bubbles in Cured Sealant 52 High pavement temperature and moisture content when sealed seal during cooler periods and allow concrete to further dry or cure or use non sag type sealant to resist void formation Outgassing of backer material backer may be melting with hot applied sealants use heat resistant backer material and check for proper sealant temperature Backer may be punctured during installation install backer without damaging Top down sealing which can trap air apply sealant from bottom up Air entering the sealant pumping lines tighten all connections or bleed off entrapped air Moisture buildup on backer material due to being installed night before replace backer material Primer not properly cured prior to sealant application Chapter 14 Common Problems and Solutions Sink holes in Sealant Sealant flowing past gaps backer material use larger backer material reapply top off sealant to correct level or use non sag sealant Backer melting when using hot applied sealants use heat resistant backer Cold applied sealants not setting up e Sealant has exceeded its shelf life use fresh sealant e Incorrect proportioning or mixing of two component sealant use correct mix ra
6. 7 Vacuuming Clean the area around the crack with a vacuum sweeper to prevent debris from re entering the crack before sealing Figure 6 5 Compressed air may be required to re clean crack if a power broom is used 3 8 Cleanliness Remember that the cleanliness of both crack faces is extremely important Dirty crack faces are a major cause of loss of adhesion of the sealant and subse quent failure of the crack repair Place the sealant within 24 hours after cleaning If sealant is not placed within 24 hours clean the crack again before sealing If a finger wiped along the crack face picks up dirt or dust the crack face is dirty and must be cleaned Figure 7 3 Wait until the pavement is completely dry before sealing 3 9 Backer Rod Place the backer rod immediately prior to sealing the crack Figure 6 6 Ensure that the backer rod is at least 25 percent larger in diameter than the width of the crack and is placed at the proper depth for the shape factor of the sealant being used Figure 5 1 Seal the crack from the bottom up and from beginning to end in one stroke without interruption when practical Figures 8 1 and 13 5 3 10 Foreign Object Damage After the crack repair operation is complete clean the surrounding pavement and sweep away all potential materials that may cause foreign object damage FOD Clean lubricate and prop erly store all equipment until the next repair operation 13 14 Chapter 4 Backer
7. American Concrete Pavement Associa tion recommends the use of rectangular shaped repairs on all partial depth spalls in concrete pavements regardless of the spall location ACPA also endorses the option of carbide milling to remove spalled areas and create a roughened surface at the patch location as a substitute for removal by chipping 9 1 Description The recommended method for partial depth spall repair is the saw and patch method First the joint or crack sealant adjacent to the spall area must be removed A boundary surrounding the spalled area Figure 9 1 is typically sawed using a concrete saw 3 in min Compressible 75 mm 4 Den 1 For Army 8 Air Force pavements W 8 L gt 6 in 150 mm for Navy pavements W amp L gt 12 in 300 mm 2 For Navy pavements if spall cavity width is less than 2 in 50 mm fill with joint sealant material Figure 9 1 Typical spall repair layout For Army and Air Force pavements the minimum length and width of the rectangular sawcut boundary around a joint spall is 6 in 150 mm and for corner spalls the rectangular sawcut boundaries are a minimum of 6 in 150 mm from the joint corner The minimum depth of the sawcut boundaries is 2 in 50 mm 31 Notes 1 For Navy pavements if spall cavity width is less than 2 in 50 mm fill with joint sealant material 2 For corner spalls in Navy pavements sawcuts must be gt 4 in 100 mm i
8. and Sealant Materials CHAPTER 4 BACKER AND SEALANT MATERIALS 4 1 Description Concrete crack repair sealants are essentially the same as joint sealants and are designed to mitigate two problem areas moisture intrusion into the pavement base and debris retention in the crack opening The influx of moisture through a crack into the pavement base layer can seriously reduce the strength of the base and the ability to sustain a load It can also erode under lying material and cause pumping Debris retention is a particular problem due to thermal movement of the slab at the crack If incompressible material is present in the crack and the slab expands due to thermal changes spalling may result due to the inability of the stress to be relieved through movement of the slab at the crack Backer material is placed in the sawed crack to minimize excess stress on the sealant material from improper shape factors and to prevent three sided adhesion which inhibits the ability of the sealant to expand and compress under thermal stress Typically backer materials are rope shaped and are often referred to as backer rod Figure 4 1 Ensure that the backer material is compatible with the sealant flexible to conform to the shape of the crack path non absorptive to prevent water retention non shrinkable and compressible to allow for easy installation Follow the sealant manufacturer s recommendations on the type of backer rod needed for a partic
9. contamination before sealant application If vegetation is growing in the cracks remove it and use a water based herbicide to kill the weeds Oil based herbicides can leave a residue that may prevent adhesion of the sealant to the crack face Route or saw the cracks to the proper depth and width according to the shape factor or as designated by the manufacturer s recommendations for the particular sealant being employed Figure 7 1 After completion of the sawing operation sandblast the crack face to remove laitance sawing debris and other foreign material Conduct the sandblasting operation with a multiple pass technique in which one side of the sawed crack face is abraded followed by the other face Figure 7 2 The pavement surface directly adjacent to the sawed crack may also be blasted to remove any debris or material that may cause problems during crack sealing Figure 7 1 A freshly sawed crack 27 Figure 7 2 Sandblasting a joint face 7 2 Cleaning The importance of proper cleaning of the crack faces cannot be overemphasized Surface dust debris and laitance remaining in the sawed crack can prevent adhesion of the crack sealant to the prepared face Figure 7 3 If using a wet saw perform waterblasting immediately after sawing If using a dry saw sandblast the crack Then clean the crack with high pressure air followed by sealing operations Repeat the airblast imme diately prior to placing the sealant in t
10. or crack 9 13 Cleanup After the spall operation is complete clean and sweep the surrounding pavement of all potential materials that may cause FOD In addition clean lubri cate and properly store all equipment until needed 37 38 Chapter 10 Spall Repair Materials CHAPTER 10 SPALL REPAIR MATERIALS 10 1 Specifications The particular repair materials chosen for the repair operation must conform to the appropriate specifications as discussed below For Navy pavements use of asphalt patching materials for temporary spall repair is allowed The Army and Air Force do not allow the use of asphalt patching materials for spall repair The concrete curing compound sealant see the section Crack Sealants backer rod see the section Backer Materials and joint filler must meet ASTM specifications For U S Army Corps of Engineers construction the curing compound must conform to CRD C300 Reference 1 3 13 Joint re forming fillers compressible inserts can be asphalt impregnated fiber board styrofoam sheeting sponge rubber or cork but must conform to ASTM D 1751 or D 1752 and be compressible without excessive change in shape Recommended maximum aggregate size is 3 8 in 10 mm Use Type concrete for the patching material unless other materials are approved by the engineer Use portland cement that conforms to ASTM C 150 Type unless other materials are approved by the engineer Type Il cements a
11. the product etc There are numerous products for concrete repair that address various aspects of the repair project such as high early strengths rapid set times ease of workability low shrinkage and low permeability However since use of rapid setting concretes and polymer concretes may require very different placement and curing procedures be aware of what is required for the repair material before making a decision Use of admixtures in portland cement based rapid setting and polymer concretes must meet appropriate specifications ASTM C 260 and C 494 Table 1 1 If using fast setting polymer concretes or admixtures follow the manufacturer s recommendations on the use and cleanup of these materials to avoid problems Mixing procedures for the polymer concretes vary depending on the material Concrete mixes may harden much faster when tempera tures are above 90 F 32 C Retarding compounds can be added to the mixtures to slow the curing process at pavement temperatures above 90 F 32 C or special mixtures premixed with retarders that extend the setup time are also available Due to the high heat released upon curing of many of the polymer materials only 2 in 50 mm or smaller lifts are suggested Begin cleanup of rapid setting materials soon after placement to prevent these materials from ruining equipment Guidelines for use in placement of polymer concretes are provided in ACI 548 1R Table 1 2 40 Chapter 11 Spa
12. 3 1 and to retain the joint shape If the spall is next to a crack treat the crack as a joint Do not allow spall repairs to bridge cracks or joints The crack must be formed up just as a joint Use a joint re forming medium the same width as the existing joint or crack long enough to cover the spall area and deep enough to extend below the full depth of the spall repair area Figure 13 1 Application of bonding agent to the concrete surface note the joint reforming medium 45 13 3 Bonding Agents Bonding agents can be utilized to improve the bond between the patch and the patch repair materials If required use a light coating of bonding agent when using PCC as the repair material If using a rapid setting or polymer concrete consult the manufacturer s recommendations on the use of bonding agents For PCC repairs the bonding grout used is a mixture of one part portland cement to one part sand with a water to cement ratio less than 0 45 Brush the bonding agent into cracks and crevices to ensure good contact with the repair surface Figure 13 1 Many repair materials are proprietary and may require a proprietary bonding agent When employing these types of material in the repair follow the manufacturer s recom mendations closely Coat or spray the entire surface of the repair area with the bonding agent and place the repair material when the bonding agent has reached a tacky consistency but before it has fu
13. 5 mm max Isolation Joint Chamfer for airfield pavement subjected to heavy load aircraft 18 Chapter 4 Backer and Sealant Materials 1 4 6 mm gt lt Preformed As Required by Neoprene D Manufacturer Compression Seal Joint Preformed Seal Preformed Compression Seal W Sized for Slab and Climate Only for New Pavement Joints Figure 5 1 3 Typical sealant reservoir details and shape factors for joints or cracks 20 Chapter 6 Crack Repair Equipment CHAPTER 6 CRACK REPAIR EQUIPMENT 6 1 Description Inspect all equipment employed in the crack repair operation before during and after the repair project to ensure proper operation of the equipment safety of the personnel involved in the project and poten tial damage to the pavement due to equipment problems Follow proper safety procedures in accordance with OSHA guidelines and common sense practices for the protection of all project personnel Use hand tools for working in areas where machinery is not practical or allowed All sealant equipment must be equipped with nozzles designed to fill the cracks from the bottom up Inspect the equipment daily prior to application of the sealant and during the operation to ensure safe operation and that the sealant is being applied properly If a two component sealant is used the metering ratio must be checked daily Refer to sealant manufacturers recommendations for proper equipment to be us
14. Chapter 12 Spall Repair Preparation 41 121 Description irc entame sie meteo 41 12 2 8388 a io den 41 ARS E arte 42 Chapter 13 Spall Repair Procedures 43 19 1 Deseriplion 453 43 13 2 Joint A8 Tormer 43 119 3 Bonding Agents esac 44 13 4 Mixing and Placing 44 19 5 Consolidation 44 I VER SPA CUMING 52 ara ls ta 46 13 7 Hui oido ara irte 46 13 8 Placing Sealants coccion rra 47 19 9 ClGANUP ide 47 Chapter 14 Common Problems amp Solutions 49 14 1 Joint Crack Sealing amp Resealing 49 14 2 Partial Depth Spall Repair 51 vi Chapter 1 Introduction CHAPTER 1 INTRODUCTION 1 1 Preface This handbook describes methods and procedures for the repair of cracks and spalls in concrete pavements as well as the selection of materials and equipment This handbook is intended for use as a field handbook for airfield concrete pavement repair for all U S Navy Army and Air Force facilities however the tech niques for repair can be used for other concrete pave ments as well References are provided for additional information on pavement repair practices not addressed in this manual Tab
15. Concrete Crack and Partial Depth Spall ican Concrete ement Association Reprint from UNIFIED FACILITIES CRITERIA UFC Operation amp Maintenance CONCRETE CRACK AND PARTIAL DEPTH SPALL REPAIR Edited and Annotated by the American Concrete Pavement Association U S ARMY CORPS OF ENGINEERS NAVAL FACILITIES ENGINEERING COMMAND AIR FORCE CIVIL ENGINEER SUPPORT AGENCY APPROVED FOR PUBLIC RELEASE DISTRIBUTION UNLIMITED UFC 3 270 03 May 2004 Any copyrighted material included in this UFC is identified at its point of use Use of the copyrighted material apart from this UFC must have the permission of the copyright holder The format of this document does not conform to UFC 1 300 1 FOREWORD The Unified Facilities Criteria UFC system is prescribed by MIL STD 3007 and provides planning design construction operations and maintenance criteria and applies to all service commands having military construction responsibilities UFC will be used for all service projects and work for other customers where appropriate UFC are living documents and will be periodically reviewed updated and made available to users as part of the Services responsibility for providing technical criteria for military construction Headquarters United States Army Corps of Engineers HQUSACE Naval Facilities Engineering Command NAVFAC and Air Force Civil Engineer Support Agency AFCESA are responsible for administration of the UFC s
16. air A joint re forming medium compressible insert is used to re form the existing joint or crack Ensure that al spall repairs do not bridge a joint or crack without a compressible insert in place Figure 9 3 If required and used correctly bonding agents can help ensure a good bond between the old concrete and the patching material Strictly follow curing procedures for portland cement concrete PCC to prevent shrinkage cracking The ideal curing procedure utilizes moist curing for at least 7 days followed by application of white pigmented membrane forming curing compound or other engineer approved method Applying curing compound immediately after finishing the patch has been shown to work well ACPA NOTE ACPA does not recommend 7 days moist curing unless in a non traffic or low traffic location In traffic areas propose an alternative method meeting the material and traffic requirements 9 1 1 Commence curing immediately after finishing is complete for each repair patch 9 1 2 Apply two layers of completely pre saturated clean burlap conforming to AASHTO M 182 Reference 1 3 12 9 1 3 Re saturate over saturate the burlap after placing and immediately cover with clear or white poly ethylene sheeting at least 100 mm 4 mils in thickness 9 1 4 Cover with plywood at least 1 2 in 13 mm thick or wood form material and weigh down sufficiently to prevent displacement by wind Need for Compressible Insert Point B
17. air Procedures some type of consolidation by tamping or if possible supplemented by vibration Figure 13 2 Vibrators with a small less than 1 in 25 mm head or vibratory screeds are recommended for small repairs Do not use grate tampers After consolidation finish the repair material to match that of the surrounding pavement Figure 13 3 A com pleted patch is shown in Figure 13 4 where the spall repair was conducted on both sides of the expansion joint Note the joint re forming filler separating the spall repair Figure 13 2 Consolidation of the repair material by vibration 2 7 is SUFREA D Figure 13 3 Finishing the patch surface 47 Figure 13 4 Completed partial depth repairs note joint re former as well as heavy coat of curing compound 13 6 Curing Curing of the patching material is very important due to the large surface area to volume ratio of the repair area and because bond strength develops much slower than compressive strength Rapid water loss from the surface due to high temperature low humidity and or windy conditions can result in severe shrinkage cracking on the surface Follow special curing procedures for rapid setting concretes to prevent excessive shrinkage cracking These materials harden rapidly and severe plastic shrinkage cracking may develop on the surface if the materials dry too fast Follow manufacturers recommendations for curing of proprietary concretes For curing s
18. al Remove the concrete inside the boundary to a depth of at least 2 in 50 mm or 1 2 in 13 mm into visually sound concrete whichever is deeper Use a light jackhammer less than 30 Ib 14 kg equipped with a chipping hammer Figure 11 2 scarifier modified carbide milling machine or high pressure water blaster Figure 6 4 If a dowel is exposed during the concrete removal replace it References 1 3 1 1 3 6 or 1 3 9 for details on dowel replacement If more than 90 degrees of the perimeter of reinforcement is exposed ex pose a space at least 1 2 in 13 mm completely around the bar or wire 9 7 Concrete Soundness Check the underlying con crete for soundness and remove any concrete found to be unsound by tapping with a hammer or other metallic object 9 8 Cleaning Clean out the spall recess using sand blasting and compressed air Figure 9 4 Ensure that there is no dust or debris within the spall repair area Figure 9 5 Figure 9 4 Air blasting to remove dust and debris 35 Figure 9 5 Checking for dust amp debris within spall repair area 9 9 Sweeping Sweep the area to prevent debris from re entering the spall repair area 9 10 Joint Re former Install joint re forming medium also called joint filler or compressible insert to provide a rigid boundary along the joint or crack and to retain the shape of the joint This filler must extend the full length of the joint or crack for the ful
19. ck to a depth of 1 8 to 1 4 in 3 to 6 mm below the surface of the pavement for conventional sealant Reference 1 3 3 and 1 4 to 3 8 in 6 to 9 mm for silicone sealant Reference 1 3 4 3 2 Test Section Construct a test section of approxi mately 200 linear feet 61 m of sealed cracks to be approved by the contracting officer before beginning the full crack sealing project Use the same procedures and materials in the test section that will be used in the full 11 project Ensure that crack sawing or routing does not cause spalling Clean the crack faces before placement of any sealant For two component sealants verify the correct mixing ratio to within a specified tolerance according to the manufacturer s specifications for that particular sealant If using hot applied sealants use calibrated thermometers to verify correct application temperatures Ensure that all equipment is in good working condition and operating properly Additional details on joint and crack repair are given in References 1 3 5 through 1 3 8 and in Table 1 3 3 3 Sealant Selection Select the proper sealant material for the area being repaired Chapter 4 Backer and Sealant Materials however ensure that the selected sealant conforms to appropriate specifications and is authorized by the engineer before use Normally it should match adjacent sealants However do not use neoprene compression seals for cracks Time the repair such that prepar
20. cked against the current electronic version prior to use to ensure that they are current FOREWORD BY ACPA This publication is annotated by the American Concrete Pavement Association It is a reprint of a United Facilities Criteria document UFC 3 270 04 and is an ACPA publication 2 The ACPA wishes to thank the Tri Services of the Department of Defense for allowing ACPA to annotate and reprint this document CONTENTS Chapter 1 Introduction 1 Ac AAA 1 1 2 Safety Considerations 1 1 3 R f rences sac cei ra as 1 Table 1 1 American Society for Testing and Materials ASTM 3 Table 1 2 American Concrete Institute ACI 5 Table 1 3 American Concrete Pavement Association 5 Chapter 2 Purpose of Crack and Partial Depth Spall Repair 7 2 1 DESCHPLION socios ee 7 2 2 ODSCHVE zusehen nahe 7 2 3 Airfield Inspections 7 2 4 CrackS era 8 2 5 Pal arar ares 8 2 6 Moderate Severity Spalling 9 Chapter Crack Sealing and Repair 11 3 1 DESCNPLON ss unse 11 3 2 18SE SECHON sac use eerie here 11 3 3 Sealant Selection 11 3 4 Shape Factor and Recess
21. crack tracing saw blades to prepare a sealant reservoir ACPA recommends that water be used only to flush the joint of sawing slurry Waterblasting is not recommended after the joints are sandblasted ACPA cautions personnel on use of hot air lances to dry seal reservoirs Over heating can damage the concrete 3 1 Description The recommended method for preparing cracks with no raveling along the edges is to saw the crack with a small diameter blade or rout it to the proper depth and width for the particular sealant and backer rod Sandblast each face of the sawcut or routed crack The crack faces are then cleaned with high pressure water and or air and the area swept with a vacuum broom to prevent the material from re entering the sawed crack Waterblasting is typically only needed immediately after using a wet saw whereas sandblasting is used after a dry saw Small sections of repair are made at a time to prevent the sawed crack faces from being exposed to the elements for more than 24 hours If the cracks are wet they may be dried with a hot air lance or high pressure air compressor equipped with an operating water and oil separator before placing the sealant and backer rod Use a sealant conforming to the applicable ASTM spec ifications and approved for use at a particular facility by the engineer The sealant is placed in the crack from the bottom up and in one smooth run from the beginning to the end of the crack Fill the cra
22. earing Popout and Breakage Closure Debonding Expansion m 4a Expansion Figure 9 3 Point bearing occurs when partial depth patch bridges joint or crack without compressible insert 33 9 1 5 Extend all covering materials burlap plastic and wood at least 6 in 150 mm beyond every edge of the patch 9 1 6 At least once every 24 hours remove the plywood and plastic re saturate the burlap and immedi ately replace the plastic and plywood 9 1 7 When moist curing operations are complete remove the plastic sheet and the plywood Between 3 and 7 hours later remove the burlap and immediately apply a uniform coat of white pigmented curing compound to the repair area Use curing compound conforming to CRD C300 Reference 1 3 13 and apply at a coverage rate of 200 ft2 gal 4 9 m2 L 9 1 8 Protect the patches from traffic for the following 7 days or until they have developed sufficient strength 11 proprietary concrete patching materials are to be used in the repair be sure to follow the manufacturer s recom mendations for bonding agents mixing placement and curing After the spall area has been filled and the material cured seal the joint or crack 9 2 Test Area Before beginning a full scale patching operation conduct a test area of spall repair This ensures familiarity with equipment and materials and any potential problems with techniques etc before beginning the full scale repair ope
23. ed 6 2 Random Crack Saw Sawing is the preferred method for preparing cracks for sealing This device is essentially a concrete saw but has a smaller rear mounted blade approximately 7 in 175 mm in diameter Figure 6 1 These saws are generally self propelled machines with caster wheels that allow more freedom of movement than an ordinary concrete saw for following the path of cracks Use diamond blades manufactured for tracing cracks which are wide enough to cut each edge of the crack and will not warp during operation Figure 6 1 Random crack saw 21 6 3 Vertical Spindle Router Cracks may be routed out if a saw is not available The vertical spindle router has a vertically mounted router bit and is constructed such that the device can caster and easily follow the contours of a crack Figure 6 2 The bit must be the proper size for the sealant reservoir and be belt driven for safety considera tions arising from jamming of the bit ifthe router is forced along the crack Use proper size bits that yield the proper shape for the sealant reservoir and do not cause spalling or raveling along the crack path This type of equipment is not recommended by ACPA Figure 6 2 Router used to shape sealant reservoir for cracks 6 4 Sandblasting Equipment Light sandblasting is used to clean joint or crack faces prior to sealing Figure 6 3 The necessary sandblasting equipment includes an air compressor air hose and a 1 4
24. ed Sealant Equipment The necessary equipment for application of cold applied sealants depends on whether the sealant is a single component or a two component mix and whether the material is hand mixed or machine mixed Two component machine mixers consist of an extrusion pump air compressor and the associated hoses to dispense the components through separate nozzles and mixed in a 50 50 ratio with 25 less than 5 error just prior to discharge from the nozzle Hand mixing equipment for two component sealants is generally a slow speed electric drill with a paddle mixer or an air powered mixer Mix single component sealants to overcome any segregation before they are applied to the pavement Small hand held caulking guns can also be employed for small jobs Contact the sealant manufac turer for recommendations on equipment ACPA NOTE Hand mixing of two component sealants is not recommended due to the potential for inconsistency and resulting variable performance of the sealant material 26 Chapter 7 Crack Preparation CHAPTER 7 CRACK PREPARATION 7 1 Description One essential element of the crack sealing operation is proper preparation of the crack and the crack face If the prepared cracks are dirty or contain excess moisture the sealant will not adhere to the surface and eventually will separate from the crack wall Schedule the crack sealing operation such that the prepared cracks are sealed as soon as possible to prevent
25. ed cracks are not exposed for more than 24 hours before sealing If the cracks get wet or are cleaned with high pressure waterblasting continue the sealing operation only when the cracks are completely dry The cracks may be dried with a heat lance as long as proper precautions are followed to prevent heat damage to the concrete 3 4 Shape Factor and Recess Saw or rout Figures 6 1 and 6 2 the crack to the proper width and depth to reach the desired shape factor and recess Chapter 5 Shape Factors recommended by the manufacturer of the sealant to be used For silicone sealants use of a backer rod in lieu of separating tape is recommended Chapter 4 Backer and Sealant Materials Small cracks may be sawed by hand 3 5 Sandblasting Clean the crack faces by light sand blasting using the multiple pass technique Figures 6 3 and 7 3 While standing to one side of the crack pass the wand along the crack face at an angle to allow a strong blast on one crack face then step to the other side of the crack and reverse direction Direct the nozzle to the location where the sealant will bond to the concrete and not above or below this region 3 6 Removing Loose Material Blow debris out of the crack using compressed air then clean the crack with high pressure water not recommended by ACPA Figure 12 Chapter 3 Crack Sealing and Repair 6 4 Ensure that there is no loose material in the bottom of the crack 3
26. evices along with the oil coated pressure hoses and install in line oil and water traps to provide a clean air source for the airblasting operation 6 9 Backer Rod Installation Equipment There are different types of equipment available for installing backer rod either custom made by contractors or produced by 24 Chapter 6 Crack Repair Equipment Figure 6 6 Installation of backer rod manufacturers These devices place the rod at a consis tent depth without undue stretching or tearing of the backer materials Figure 6 6 6 10 Hot Applied Sealant Equipment Hot applied sealant equipment must be capable of holding a sufficient amount of sealant and be able to heat the material to the proper controlled application temperature usually be tween 325 163 C and 410 F 210 C without over heating Installation hoses should be insulated to maintain the proper temperature as the sealant enters the reservoir The equipment necessary for application of room temperature solid sealants consist of a double wall type kettle that is heated by a fluid between the walls of the chamber and a mechanical agitator to prevent localized overheating at the walls Calibrated thermometers must be easily visible to allow constant monitoring of the sealant temperature to prevent the possibility of over heating The sealant must be circulated through the delivery hose and back to the heating chamber when not being applied 6 11 Cold Appli
27. he sawed reservoir if the sealant is not placed within a few hours of the cleaning Use a power broom or hand broom to remove sand and dust and prevent it from re entering the crack References 1 3 7 and 1 3 8 ACPA NOTE ACPA does not recommend high pressure waterblasting after sandblasting Figure 7 3 Dust and debris in a joint or crack will prevent proper adhesion 28 Chapter 8 Crack Sealing Procedures CHAPTER 8 CRACK SEALING PROCEDURES 8 1 Description Conduct the crack sealing operation only when pavement temperatures are above 40 F 4 C and rising Monitor application temperatures for hot applied crack sealants constantly to ensure that they are in the correct range 8 2 Preparation Ensure that crack faces are clean and free of moisture If moisture is present hot air lance or compressed air can be used to dry the crack face before sealing Insert the backer rod into the crack immediately prior to sealing Fill the crack from the bottom up to prevent air from becoming trapped under the sealant and cause bubbling Fill the crack from beginning to end in one smooth oper ation whenever practical Figure 8 1 For jet fuel resistant hot applied sealants at the end of a day s work remove and discard the sealant remaining in the pot Do not reheat and re use Figure 8 1 Sealing a crack 29 30 Chapter 9 Partial Depth Spall Repair CHAPTER 9 PARTIAL DEPTH SPALL REPAIR ACPA NOTE The
28. in 6 mm diameter venturi type nozzle The compressor must be capable of delivering 150 ft8 minute 4 25 m3 minute at 90 psi 620 kPa and be equipped with operating in line traps to keep the air hoses and the sandblasted surface free of oil and water This device must be capable of removing all sawed slurry dirt and old sealant that may be present in cracks that are being resealed Ceramic and tungsten carbide nozzles are available for sandblasting but the tungsten nozzles last longer A guide that keeps the nozzle consistently close to the pavement surface and at an effective angle to the crack face pro motes consistency to the sandblasting technique and 22 Chapter 6 Crack Repair Equipment Figure 6 3 Sand blasting reduces operator fatigue Ensure that the nozzle has an adjustable guide that will hold the nozzle aligned with the crack approximately 1 in 25 mm above the pavement surface Make safety a primary concern Sandblasting operators are required to follow OSHA guidelines A helmet with a separate air source and air purification equipment reduces the possibility of inhalation of silica dust Protective clothing may also be required 6 5 Waterblasting Equipment Waterblasting is another technique for cleaning crack faces lt is sometimes em ployed as an alternative to sandblasting due to local air reg ulations or where the sand and debris might create additional problems Waterblasting equipment consists
29. ir Force Base Florida 1 3 5 Unified Facilities Guide Specification 1997 Field Molded Sealants for Sealing Joints in Rigid Pave ments UFGS 02760A 1 3 6 Headquarters Departments of the Army and Air Force 1989 Repair of Rigid Pavements Using Epoxy Resin Grouts Mortars and Concrete TM 5 822 9 AFM 88 6 Chapter 10 Washington DC 1 3 7 Evans L D and Romine A R 1993 Mate rials and Procedures for the Rapid Repair of Joint Seals in Concrete Pavements SHRP H 349 Strategic Highway Research Program Transportation Research Board Washington DC 1 3 8 Unified Facilities Criteria 2003 O amp M Con crete Repair UFC 3 270 04 ACPA JPOO2P 1 3 9 Unified Facilities Guide Specification Sept 1999 Patching of Rigid Pavement Partial Depth UFGS 02983N 1 3 10 Unified Facilities Guide Specification Aug 1997 Patching of Rigid Pavements UFGS 02980A 1 3 11 Evans L D et al 1993 Materials and Procedures for Rapid Repair of Partial Depth Spalls in Concrete Pavements SHRP H 349 Strategic Highway Research Program Transportation Research Board Washington DC 1 3 12 American Association of State Highway and Transportation Officials AASHTO 1991 Burlap Cloth Made From Jute or Kenaf AASHTO M 182 Washington DC 1 3 13 U S Army Corps of Engineers Waterways Experiment Station 1990 Specification for Membrane Forming Compounds for Curing C
30. l depth of the spall repair area and extend below the bottom of the patch to prevent patching material from flowing into the joint crack space 9 11 Bonding Agent If required apply bonding agent to the spall repair surface Figure 13 1 Always ensure that the spall repair is clean before adding bonding agent or repair material If the spall repair area is large and the repair material is cementitious cement based be sure to place the bonding grout rapidly so that areas do not begin to dry prior to filling the area with repair material Place the spall repair material Figure 13 2 finish the surface Figure 13 3 and follow the curing procedure recom mended by the manufacturer of the repair material or refer to the guidelines outlined in Chapter 13 Spall Repair Procedures 9 12 Sawing Where the spalled area abuts a joint use a compressible insert or other joint re forming medium to prevent bond at the joint face After the curing is com plete saw a reservoir for the joint sealant with a small diameter saw blade to the dimensions required for other joints or as required to be routed for cracks Sandblast each face of the fresh sawcut wash with high pressure water airblast and sweep the area Place the proper width backer rod at the required depth for the sealant Place the 36 Chapter 9 Partial Depth Spall Repair sealant from the bottom up and in one smooth operation from the beginning to the end of the joint
31. l powered or pneu matic paddle wheel mixer for smaller operations 11 5 Hand Tools Hand tools such as shovels trowels tampers and screeds must be available 41 Figure 11 2 Using a jackhammer to remove damaged concrete 42 Chapter 12 Spall Repair Preparation CHAPTER 12 SPALL REPAIR PREPARATION 12 1 Description As with most concrete repairs an essential element of the spall repair operation is the proper preparation of the spalled area If the prepared spalls are dirty or contain excess moisture the repair material will not completely adhere to the surface Schedule the spall repair operation such that the prepared areas are filled as soon as possible to prevent contami nation of the surface The importance of proper cleaning of the repair area cannot be overemphasized After completion of the sawing and removal of the concrete clean the recess by sandblasting airblasting and or waterblasting to remove concrete chips laitance sawing debris and other foreign material from the recess The area must then be thor oughly swept using a vacuum broom if available to prevent debris from re entering the spall repair area 12 2 Boundaries To begin the saw and patch proce dures mark the boundaries of the area to make the sawcuts easier and decide which repair material s are to be employed in the patching effort Remove the joint or crack sealant a few inches on either side of the spall Make the sawcu
32. les 1 1 1 2 and 1 3 list applicable American Society of Testing and Materials ASTM speci fications American Concrete Institute ACI publications and American Concrete Pavement Association ACPA publications 1 2 Safety Considerations lt is the responsibility of supervisory personnel to ensure worker safety by informing the workers of any potential hazardous prac tices Follow the applicable Occupational Safety and Health Administration OSHA guidelines at all times for hazardous practices such as sandblasting joints and cracks airblasting for cleaning cracks and working with chemicals Workers are required to be informed of all hazardous materials and practices that may involve exposure to toxic materials in the workplace Material Safety Data Sheets must be available to all workers at the work site 1 3 References 1 3 1 Department of the Navy Naval Facilities En gineering Command 1994 Concrete Pavement Repair Manual MIL HDBK 1102 7 2 Norfolk Virginia 1 3 2 Headquarters Departments of the Army and Air Force 1989 Procedures for U S Army and U S Air Force Airfield Pavement Condition Surveys TM 5 826 6 AFM 93 5 Washington DC 1 3 3 Unified Facilities Guide Specification Sept 1999 Resealing of Joints in Rigid Pavement UFGS 02982N 1 3 4 Air Force Civil Engineer Support Agency 1996 Silicone Joint Sealants for Pavements Engineering Technical Letter ETL 96 4 Tyndall A
33. ll Repair Equipment CHAPTER 11 SPALL REPAIR EQUIPMENT 11 1 Description Much of the equipment necessary for spall repair has been previously described under Crack Preparation However additional equipment such as concrete saws jackhammers mixers small spud vibrators tampers and hand tools may also be necessary 11 2 Concrete Saws A conventional concrete saw is similar to a random crack saw but generally is less maneuverable and has a larger blade Figure 11 1 Concrete saws are employed extensively for re facing joints for joint sealing projects but are often used for large patching operations or full depth repair Use small diameter blades of 6 to 10 in 170 to 250 mm to minimize the size of the runout kerfs when sawing out the spalled area Larger blades may be necessary for re facing joints or cracks Small patches can be sawed with a random crack or a hand held saw 11 3 Jackhammers The jackhammer needed for large patching operations may be 30 Ib 13 6 kg model Figure 11 2 for smaller jobs 10 to 15 4 6 to 6 8 kg model is sufficient Use a chipping hammer at an angle of between 45 and 90 degrees relative to the pavement surface Take special care to not damage the layer of concrete under the spall repair area or cause microcracking around the crack 11 4 Mixers Drum or mortar mixers are usually employed for most patching operations Buckets may be used with a hand held electric dril
34. lly dried To prevent the bonding agent from entering any small openings where the joint re forming medium meets the bottom of the spall recess a small bead of caulk may be placed against the interface 13 4 Mixing and Placing The mixing and placing of spall repair materials often varies considerably due to the widely different materials that can be used It is good practice to place the repair material at pavement temper atures above 55 F 13 C and below 90 F 32 C If water is required add the correct amount of clean fresh water and thoroughly mix Hand mixing almost always requires more time than drum or mortar mixers When hand mixing there is also a tendency to add more water than required to ease the mixing effort Strictly follow the manufacturer s recommendations for mixing and curing of materials to ensure a quality patching job For more details on placing concrete in hot and cold weather refer to ACI 305R and 306R Table 1 2 Do not place repair materials at temperatures less than 40 F 4 C and for temperatures less than 55 F 13 C only with special insulation and longer cure times In summer it is best to place repair materials in the morning when pavement temperatures are lower In winter afternoons are best 13 5 Consolidation After placement thoroughly consolidate the repair material to remove entrapped air Cementitious and polymer concrete materials require 46 Chapter 13 Spall Rep
35. luid spillage may occur or in an area subjected to high temperature from jet blast or exhaust from auxiliary power units Use a repair material that conforms to ASTM and or federal specifications designated for joint and crack sealants for use in these areas as listed in Table 1 1 under Joint and Crack Repair and Table 1 4 4 4 Navy Regulations Naval regulations require that all materials used on U S Navy facilities conform to UFGS 02982N Reference 1 3 3 The Navy recommends use of silicone sealants on all Naval facilities and as an alter native to materials meeting ASTM D 5893 if approved by the engineer Silicone sealants may be used in place of preformed neoprene sealants for new joints if cost is a major factor References 1 3 3 and 1 3 4 4 5 U S Army and Air Force Regulations Sealants used on U S Army and Air Force pavements must con form to the ASTM specifications listed in Table 1 1 under Joint and Crack Repair Preformed neoprene com pression seals are common on Air Force pavements 16 Chapter 5 Shape Factors CHAPTER 5 SHAPE FACTORS ACPA NOTE ACPA does not recommend the use of crack routers due to the chipping and micro cracking damage this equipment causes to the concrete ACPA recom mends small diameter crack tracing saw blades to prepare a sealant reservoir 5 1 Description For proper crack sealing route or saw the crack to a designated width and depth for the particular type
36. lying concrete or loose material present This can be easily accomplished with a steel rod a short length of chain or a ball peen hammer A hollow or dull thud indicates a crack or loose material beneath the sounding device If unsound concrete is located remove it to a depth of at least 1 2 in 13 mm into sound concrete Conduct a thorough cleaning of the repair area to remove debris by compressed air and high pressure water Use a power broom vacuum sweeper or at least a thorough hand broom sweeping of the area to prevent debris from re entering the repair zone 44 Chapter 13 Spall Repair Procedures CHAPTER 13 SPALL REPAIR PROCEDURES 13 1 Description The repair process begins after the final cleaning of the area The area must be dry and free of dust oil dirt etc A good repair begins with a clean surface Since the volume of most spall repairs is usually small use a small drum or mortar mixer for mixing the repair material Some repair materials come premixed and others allow the mix to be extended by adding aggregate maximum recommended size is 3 8 in or 10 mm Consolidate the material through tamping supplemented when possible by vibration and work the surface to match the surrounding finish as closely as possible 13 2 Joint Re former If the spalled area is adjacent to a joint or a crack use a joint re forming medium compressible insert to prevent the repair material from fouling the joint Figure 1
37. ments Lubricant for Installation of Preformed Compression Seals on Concrete Pavements Joint Sealant Hot Applied Elastomeric Type for Portland Cement Concrete Pavements Joint Sealant Hot Applied Elastomeric Jet Fuel Resistant Type for Portland Cement Concrete Pavements Cold Applied Single Component Chemically Curing Silicone Joint Sealant for Portland Cement Concrete Pavements Joint and Crack Sealants Hot Applied for Concrete and Asphalt Pavements Table 1 1 American Society for Testing and Materials ASTM Specifications for Sealants Joint Fillers Patching Materials etc Continued Spall Repair ASTM C 31 2000 ASTM C 33 2002 ASTM C 39 2001 ASTM 94 2000 ASTM C 131 2001 ASTM C 136 2001 ASTM C 143 2000 ASTM C 150 2002 ASTM 171 1997 ASTM C 173 2001 ASTM C 231 1997 ASTM C 260 2001 ASTM C 309 1998 ASTM C 494 1999 ASTM C 881 2002 Making and Curing Concrete Test Specimens in the Field Concrete Aggregates Compressive Strength of Cylindrical Concrete Specimens Ready Mixed Concrete Resistance to Degradation of Small Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine Sieve Analysis of Fine and Coarse Aggregates Slump of Hydraulic Cement Concrete Portland Cement Sheet Materials for Curing Concrete Air Content of Freshly Mixed Concrete by the Volumetric Method Air Content of Freshly Mixed Concrete by the Pressure Method
38. n length and gt 12 in from the joint for rectangular spalls W 8 L gt 12 in 300 mm Figure 9 2 Corner spall repair for Navy pavements For Navy pavements the minimum length and width of the rectangular sawcut boundary around a joint spall is 12 in 300 mm For corner spalls the sawcuts are a min imum of 12 in 300 mm from the joint corner and extend a minimum of 4 in 100 mm perpendicular to the joint A third cut is then made between the two 4 in 100 mm cuts to form a pentagon with the joint corners and saw cuts comprising the five sides Figure 9 2 The minimum depth of the sawcut boundaries is 2 in 50 mm A light jackhammer less than 30 Ib 14 kg equipped with a chipping hammer scarifier or high pressure water blaster is then used to remove the concrete within the boundary to a depth of at least 2 in 50 mm or to 1 2 in 13 mm below the surface of visually sound concrete whichever is deeper If a dowel is exposed during the concrete removal it must be removed if within the upper one third of the slab Procedures for dowel replacement will not be covered here but may be found in References 1 3 1 1 3 6 and 1 3 8 lf more than 90 degrees of the perimeter of reinforcement is exposed a space must be exposed completely around the bar or wire and at least 1 2 in 13 mm below it to allow for complete consoli dation of patch material around the reinforcing steel 32 Chapter 9 Partial Depth Spall Rep
39. ncrete not cured sufficiently too much moisture in concrete allow concrete to further cure and dry out before sealing Sealant picks up or pulls out when opened to traffic Opened to traffic too soon after application delay opening High ambient temperature seal in cooler tempera tures Excessive sealant application apply flush with surface or with specified recess Sealant too soft for climate use stiffer sealant Use a detackifier or blotter to reduce initial tack Overheated or underheated sealant install at correct temperature verify temperature gauges on melter Sealant contaminated with solvent or heat transfer oil from tank leak Joint faces contaminated with old incompatible seal ant may also cause bleeding re clean joint to re move old sealant Preformed sealant installed too high in joint use required recess Preformed sealant was stretched during installation 51 Sealant Gelling in Melter Overheated sealant check melter temperature gauges Sealant reheated too many times use fresh sealant Using sealant with short pot life use sealant with longer pot life Sealant Cracking or Debonding in Winter Sealant too stiff use softer grade Poor cleaning during installation improve cleaning Sealing during extreme hot summer temperatures when joints at their narrowest avoid sealing during extremely hot temperatures Joint too narrow for the movement experienced
40. of a trailer mounted water tank pumps high pressure hoses an auxiliary water supply a wand with a safety cutoff if the operator should lose control and a proper size nozzle for the crack width Figure 6 4 After waterblasting is com pleted dry the entire crack prior to sealant installation Figure 6 4 High pressure water cleaning 23 ACPA NOTE Waterblasting is not necessary when sand blasting is employed 6 6 Hot Air Lance If waterblasting is used to clean crack faces a hot air lance is sometimes employed to dry the crack or joint immediately prior to sealing The operator must take special precaution not to overheat the pavement which may cause cracks and chalking of the concrete surface Do not use direct flame devices Use strict safety precautions to reduce operator hazard such as protective clothing as well as eye and ear protection ACPA NOTE Hot air lances are not recommended by ACPA 6 7 Power Broom Ensure that a vacuum type power broom is present to remove debris from the pavement surface and reduce the potential for FOD Figure 6 5 Figure 6 5 Power broom 6 8 Compressed Air Equipment Compressed air is em ployed for the final cleaning phase of the project The air source must produce sufficient pressure 90 psi 0 63 MPa min and contain no oil that may foul the surface prior to sealing Some compressors have in line sources for the constant lubrication of air tools Remove these d
41. of sealant employed in the crack repair The dimensions of a typical crack reservoir Figure 5 1 are defined by a shape factor S D W that is the ratio of the depth of the sealant D to its width W Shape factors generally range from 0 5 to 2 0 however these dimen sions may be particular for the type of sealant employed in the repair operation and a recommended value will be supplied by the sealant manufacturer 5 2 Silicone Sealants Silicone sealants require a shape of approximately 0 5 Reference 1 3 3 For example if the width W of the sawed crack is 1 2 in 13 mm the depth of the sawed crack T must be 1 25 in 30 mm to accommodate a backer rod of 5 8 in 16 mm The top of the backer rod will be 1 2 in 13 mm below the pave ment surface This allows for a depth D of 1 4 to 3 8 in 6 to 9 mm of silicone sealant on top of the crown of the backer rod to keep the sealant at 1 8 to 1 4 in 3to 6 mm below the pavement surface 17 1 4 6 mm Sealant W recess typ Material A 1 32 mm A minimum Backer Rod Joint or Crack Field Poured Sealant Hot Poured Sealant D W 1 typical Silicone Sealant D W 0 5 typical Two Component Material Cold Poured D W 0 5 typical 1 4 6 mm 1 4 6 Chamfer or Radius Recess Typ a y Sealant Material 1 25 mm Bond Breaker Non Extruding Pre Molded Compressible Material gt 1 2
42. oncrete CRD C 300 90 Handbook for Concrete and Cement Vicksburg MS Chapter 1 Introduction Table 1 1 American Society for Testing and Materials ASTM Specifications for Sealants Joint Fillers Patching Materials etc Joint and Crack Repair ASTM C 603 1997 ASTM C 639 2001 ASTM C 661 1998 ASTM C 679 1997 ASTM C 719 1998 ASTM 792 1998 ASTM C 793 2002 ASTM D 412 1998 ASTM D 1751 1999 ASTM D 1752 1996 ASTM D 2628 1998 ASTM D 2835 1998 ASTM D 3406 2000 ASTM D 3569 2000 ASTM D 5893 1996 ASTM D 6690 2001 Extrusion Rate and Application Life of Elastomeric Sealants Rheological Flow Properties of Elastomeric Sealants Indentation Hardness of Elastomeric Type Sealants by Means of a Durometer Tack Free Time of Elastomeric Sealants Adhesion and Cohesion of Elastomeric Joint Sealants under Cyclic Movement Effects of Heat Aging on Weight Loss Cracking and Chalking of Elastomeric Joint Sealants Effects of Accelerated Weathering on Elastomeric Joint Sealants Vulcanized Rubber and Thermoplastic Rubbers and Thermoplastic Elastomers Tension Preformed Expansion Joint Filler for Concrete Paving and Structural Construction Nonextruding and Resilient Bituminous Types Preformed Sponge Rubber and Cork Expansion Joint Fillers for Concrete Paving and Structural Construction Preformed Polychloroprene Elastomeric Joint Seals for Concrete Pave
43. ose of sealing joints and cracks and repairing spalls in portland cement concrete pavements on airfields is to reduce the costs associated with foreign object damage FOD and to pro long the service life of the pavement reducing the life cycle costs for the pavement structure A considerable investment has been made in the construction of a con crete surface and the vehicles that use these surfaces therefore costs decrease dramatically for every additional year of pavement use that does not cause vehicle damage or require repeated patching or full slab replacement Routine periodic inspections and rapid repair of pavement problems are essential for reducing life cycle costs References 1 3 1 and 1 3 2 A properly constructed and maintained concrete pavement can last for many years 2 2 Objective The objective of joint crack sealing and spall repair is to reduce FOD and to minimize moisture or incompressible material rocks sand other pieces of concrete etc entering into the crack or joint Unsealed joints and cracks will allow moisture to penetrate under the slab causing an increase in the moisture content in the base and or subbase As thermal cycling occurs and the joint or crack expands and contracts incompressible material such as rocks chunks of concrete sand or ice in the crack may cause stress to build in the slab Such stress can result in more spalling or cracking and further damage to the slab thereby increasing the
44. potential for FOD 2 3 Airfield Inspections For airfields conduct inspec tions of the pavement surfaces receiving traffic at least monthly to locate spalls or cracks that may cause FOD Otherwise conduct routine field evaluations at least bian nually once during the summer and once during the winter Seasonal checks allow for evaluation of the material during the two extremes of ambient conditions Locate and inspect all cracks and spalls If concrete has begun to break away from the crack or spalled area repair the damaged area 2 4 Cracks Cracks less than 3 16 in 5 mm wide and without any surface spalling do not require repair or sealing Seal all cracks between 3 16 in 5 mm and 2 in 50 mm wide Cracks larger than 2 in 50 mm require full depth patching Use of a backer rod is recommended for all crack sealing unless irregular crack dimensions preclude its use If spalling is present adjacent to a crack of any width repair the damaged area by treating the crack the same as a joint The sealed crack protects the repaired area from damage that might result from movement of the slab along the crack faces 2 5 Spalls Spalling is generally caused by incom pressible materials in the joints and cracks that prevent the necessary movement of the slab due to thermal fluc tuations thereby causing breaks in the concrete adjacent to the joint or crack Figure 2 1 Minor spalls may also be caused by snowplows overwo
45. ration Additional information on spall repair is available in References 1 3 9 through 1 3 11 All applicable ASTM test methods are listed in Table 1 1 and information on joint crack and spall repair from the Amer ican Concrete Pavement Association is listed in Table 1 3 9 3 Selecting Repair Materials and Procedure Select the spall repair materials and the spall repair procedure saw and patch is recommended however carbide milling has worked for highway projects in Minnesota and Wisconsin The recommended patch materials are discussed in Chapter 10 however use of these materials concrete joint sealer joint filler etc must meet specifi cations and or be authorized by the engineer As with any repair operation the cleanliness of the area to be patched is one of the most important factors in a long lasting patch Take extra care to ensure the repair area is clean before repair Schedule the repair procedures such that the prepared spall recess is not exposed to the elements for more than 24 hours without additional cleaning 34 Chapter 9 Partial Depth Spall Repair 9 4 Removing Old Sealant Remove any sealant present in the joint or crack adjacent to the spall as discussed in Chapters 3 and 6 9 5 Boundaries Cut along the marked boundary around the area to a depth of at least 2 in 50 mm using a concrete or a hand saw Figure 11 1 Size the spall repair area as described in Chapter 12 9 6 Concrete Remov
46. re generally not necessary for repair projects Type 111 cements can be employed when the repaired area has be opened to traffic within 1 to 3 days after placement of the PCC Typical concrete mixtures for partial depth Spall repairs have a range of 0 to 1 2 in 0 to 13 mm of slump and a thoroughly tamped or consolidated in place specimen should meet a minimum compressive strength of 5 000 psi 35 MPa at 28 days of age On U S Navy facilities the materials chosen must meet all of the specifications outlined in UFGS 02983N Reference 1 3 9 and UFGS 02982N Reference 1 3 3 For U S Army and Air Force facilities refer to UFGS 02980A Reference 1 3 10 and UFGS 02760A Reference 1 3 5 For U S Air Force pavement repair also see Reference 1 3 6 For filling popouts use a sand cement mortar of one part cement to two parts sand Ensure that the water to cement ratio does not exceed 0 40 by weight 10 2 Alternative Repair Materials Spall repair mate rials can be classified into three broad categories cemen 39 titious polymeric and bituminous Only the cementitious or polymeric materials are approved for use on airfields Do not use bituminous materials for spall repair material on Army and Air Force airfields due to the potential for FOD Typical concerns for selection of a spall repair material are cost physical properties curing time how soon can the section be opened to traffic material availability familiarity with
47. rking of the plastic con crete or popouts To repair a spalled area remove incom pressible materials from the joint or crack patch the spalled area and replace the sealant Additional repairs of previous spall repairs due to failure of the material or poor repair practices are also common If the spall depth is greater than 1 3 the slab depth full depth patching is needed Full depth patching will not be covered in this manual but is addressed in Reference 1 3 8 or ACPA 002 Cracking of slabs can be due to load related failure or environmental stress on the slab Figure 2 1 Incompressibles causing spalling in joint or crack Chapter 2 Purpose of Crack and Partial Depth Spall Repair 2 6 Moderate to Severe Spalling An example of moderate to severe spalling is shown in Figure 2 2 Spalls are present along the face of the joint Missing chunks of concrete are visible with the potential for more pieces to become dislodged and cause FOD Repair all spalled areas that have loose concrete to reduce FOD potential er i 7 LE gt a Por 2 a AE ii Figure 2 2 Moderate to severe spalling along joint 10 Chapter 3 Crack Sealing and Repair CHAPTER 3 CRACK SEALING amp REPAIR ACPA NOTE ACPA does not recommend the use of crack routers due to the chipping and micro cracking damage this equipment causes to the concrete ACPA recom mends small diameter
48. t is being replaced For pavements on Naval facilities the sealant must conform to UFGS 02982N Reference 1 3 3 however silicone sealants may be used in lieu of materials called for in ETL 94 9 Reference 1 3 4 13 8 Placing Sealant Placement of the sealant is similar to that of crack sealants in that the sealant is being placed from the bottom up and in a smooth stroke from the beginning to the end of the joint or crack if practical Figure 13 5 For details on sealing of joints refer to the section on crack sealing as this is analogous to sealing joints In addition procedures for sealing joints are given in References 1 3 4 through 1 3 7 and in Table 1 3 13 9 Cleanup After the repair is complete clean all equipment lubricate if necessary and properly store until needed for the next repair operation Figure 13 5 Resealing joints after partial depth repairs complete 49 50 Chapter 14 Common Problems and Solutions CHAPTER 14 COMMON PROBLEMS amp SOLUTIONS 14 1 Joint Crack Sealing amp Resealing Sealant not adhering to joint crack Joint not clean enough re clean Wet joint surfaces allow to dry Low sealant application temperature hot applied sealants heat to correct temperature or verify temperature gauges Cold ambient temperature allow temperature to rise Insufficient recess for cold applied sealants traffic pulling sealant out use correct recess for joint width Co
49. tandard concrete materials cover the patched area with two layers of presaturated burlap which is then covered with clean polyethylene sheeting The burlap and sheeting is then covered with weighted plywood or form board Extend all cover layers at least 6 in 150 mm beyond the outline of the patch Cover the fresh patching material as soon as possible after finishing the surface 13 7 Resealing After the patch has cured the final repair step is to replace the sealant to maintain the existing joint or crack Do not begin joint or crack resealing preparation and installation until the concrete curing is complete The joint sealing operation is anal ogous to crack sealing The joint or crack adjacent to the spall is sawed out to the same width as the existing joint or crack using a concrete saw router or hand saw 48 Chapter 13 Spall Repair Procedures Remove the joint filler compressible insert by hand or by sawing Ensure that joint preparation conforms to the specifica tions outlined in Chapter 7 The sides of the sawcuts are then sandblasted and airblasted with compressed air to prepare a good surface for sealant adhesion Sweep the area surrounding the repair with a vacuum broom to remove debris etc After cleaning the area install backer rod in the joint or crack recess For U S Army and Air Force facilities the sealant employed must conform to the ASTM specifications for the particular location in which the sealan
50. tios and mixing systems 14 2 Partial Depth Spall Repair More deterioration below pavement surface than evi dent above Extend limits of repair area into sound concrete e f deterioration extends below one third of the pavement thickness do a full depth repair Dowel bar or reinforcing steel is exposed during con crete removal e f steel including dowel bars is in the upper third of slab remove the steel to the edges of the patch and continue e f unsound concrete extends to mid depth of the slab do a full depth repair Patch material flows into joint or crack e Place a bead of caulk along bottom of joint or crack before placing joint insert e Ensure joint insert extends far enough into the adjacent joint crack and below the patch Ensure insert is correctly sized for joint crack width Patch cracking or debonding e Check that joint insert is being used properly e Ensure that the insert is correctly sized for the joint crack width and that it has been inserted correctly e Check that patch area was cleaned immediately prior to grouting concrete placement 53 54 Check that air blowing equipment is not releasing oil in the compressed air Check that grout material has not dried out before concrete placement Check that patch material is not susceptible to shrinkage Ensure that curing compound has been applied adequately 2004 American Concrete Pavement Association 5420 Old Orchard Road Suite A100
51. ts at least 2 in 50 mm deep and 2 to 3 in 50 to 80 mm outside the boundary of the spall Figure 11 1 For joint and crack spalls in Army Air Force and Navy pavements and corner spalls in Army and Air Force pave ments make sawcuts straight and at right angles to each other with the cuts forming a rectangle with the joint or crack as one side For corner spalls in Navy pavements make the initial cuts at least 4 in 100 mm long and per pendicular to the joint with the final cut joining the initial cuts to form a pentagon at the slab corner Figure 9 2 A small jackhammer may then be used to remove the concrete to a depth of at least 2 in 50 mm from the sur face or 1 2 in 13 mm into visually sound concrete which ever is deeper within the cut area by starting in the center of the spall and working toward the cuts Figure 11 2 If both sides of the joint or crack are spalled repair the spall on each side while maintaining the joint or crack An example is shown in Figure 12 1 The joint re forming filler is placed in the joint or crack and the spalls on each side are repaired independently See References 1 3 7 43 Figure 12 1 A partial depth repair spanning both sides of the joint through 1 3 9 and 1 3 12 for additional details on joint sealant removal and repair 12 3 Soundness After the concrete in the area has been removed test the repair area for soundness to ensure that there are no cracks in the under
52. ular sealant Figure 4 1 Installation of backer rod into joint 15 Typical backer materials are polychloroprene polysty rene polyurethane and polyethylene closed cell foams Do not use paper rope or cord Ensure that the melting temperature of the backer material is at least 25 F 14 C higher than the sealant application temperature to prevent damage during sealant placement Ensure that the uncompressed backer rod has a diameter at least 25 larger than the sealant reservoir so that it remains in position during the sealing operation The use of backer rod is recommended prior to sealant placement in repairing cracks 4 2 Separating Materials Separating tape may be employed when the sealant reservoir dimensions corre spond to the proper shape factor and the use of backer material would lead to an incorrect shape factor for that sealant material Separating materials are usually a thin adhesive tape or a flexible plastic strip employed to pre vent three sided adhesion of the sealant These materials must be flexible enough to deform with the sealant as the concrete expands and contracts However only use sepa rating materials when the crack has been sawed to provide a reservoir of the proper depth 4 3 Fuel and Blast Resistance Additional considera tions for the crack repair material are jet fuel and jet blast resistance The crack to be repaired may be located in an area in which fuel or lubricating or hydraulic f
53. ystem Technical content of UFC is the responsibility of the preparing tri service committee Recommended changes with supporting rationale should be sent to the respective service proponent office as follows e HQUSACE ATTN CECW E 441 G Street NW Washington DC 20314 1000 or the Recommended Changes to Engineering Documents page on the TECHINFO site listed below HQUSACE CECW E 441 G Street NW Washington DC 20314 1000 or the Recommended Changes to Engi neering Documents page on the TECHINFO site listed below Commander Atlantic Division Naval Facilities Engineering Command 1510 Gilbert Street ATTN NAVFAC Criteria Office Norfolk VA 23511 2699 or crit_innov_15 efdlant navfac navy mil by commercial telephone 757 322 4200 or DSN 262 4200 or by facsimile machine to 757 322 4416 e Air Force Civil Engineer Support Agency 139 Barnes Drive Tyndall Air Force Base FL 32403 5319 or larry spangler tyndall af mil UFC are effective upon issuance UFC are distributed only in electronic media from the following sources e USACE TECHINFO Internet site http www hnd usace army mil techinfo index htm NAVFAC Criteria Office Internet site http criteria navfac navy mil criteria e Construction Criteria Base CCB system maintained by the National Institute of Building Sciences on CD ROM and at Internet site http www ccb org Hard copies of UFC printed from electronic media should be che
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