ATTACHMENT 2 - UCF SPECIFICATIONS.pdf

UFC 3-270-01

21 February 2018

Change 1, 17 March 2022

UNIFIED FACILITIES CRITERIA (UFC)

O&M MANUAL:

ASPHALT AND CONCRETE

PAVEMENT MAINTENANCE AND

REPAIR

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED

UNIFIED FACILITIES CRITERIA (UFC)

O&M MANUAL: ASPHALT AND CONCRETE PAVEMENT MAINTENANCE AND

REPAIR

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.

U.S. ARMY CORPS OF ENGINEERS (Preparing Activity)

NAVAL FACILITIES ENGINEERING COMMAND

AIR FORCE CIVIL ENGINEER CENTER

Record of Changes (changes are indicated by \1\ ... /1/)

Change No. Date Location

1 7 March 2022 Added Chapter 22 on maintenance approach of specific areas critical to F-35B/C operations. Added Paragraph 21-3.6 Epoxy Coatings and 21-3.7 Joint Sealants.

Updated third paragraph of 20-1, 21-1, 21-3, 21-3.1, 21- 3.3, 21-4.4, 21-4.6, 21-5.1, and Appendix B References

– Army.

This UFC supersedes UFC 3-270-01, dated 15 March 2001; UFC 3-270-02, dated 15 March 2001; UFC 3-270-03, dated 15 March 2001; UFC 3-270-04, dated 15 March 2001; UFC 3-250-06, dated 16 Jan 2004; Air Force ETL 96-4, dated 9 July 1996; Air Force ETL 97-2, dated 28 July 1997; Air Force ETL 02-7, dated 7 August 2002; Air Force ETL 02-8, dated 5 September 2002; Air Force ETL 11-26, dated 21 December 2011; and Air Force ETL 14-2, dated 21 November 2014.

FOREWORD

The Unified Facilities Criteria (UFC) system is prescribed by MIL-STD 3007 and provides planning, design, construction, sustainment, restoration, and modernization criteria, and applies to the Military Departments, the Defense Agencies, and the DoD Field Activities in accordance with USD (AT&L) Memorandum dated 29 May 2002. UFC will be used for all DoD projects and work for other customers where appropriate. All construction outside of the United States is also governed by Status of Forces Agreements (SOFA), Host Nation Funded Construction Agreements (HNFA), and in some instances, Bilateral Infrastructure Agreements (BIA.)

Therefore, the acquisition team must ensure compliance with the most stringent of the UFC, the SOFA, the HNFA, and the BIA, as applicable.

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, U.S. Army Corps of Engineers (HQUSACE), Naval Facilities Engineering Command (NAVFAC), and Air Force Civil Engineer Center (AFCEC) are responsible for administration of the UFC system. Defense agencies should contact the preparing service for document interpretation and improvements. Technical content of UFC is the responsibility of the cognizant DoD working group. Recommended changes with supporting rationale should be sent to the respective service proponent office by the following electronic form: Criteria Change Request. The form is also accessible from the Internet sites listed below.

UFC are effective upon issuance and are distributed only in electronic media from the following source:

• Whole Building Design Guide web site http://dod.wbdg.org/.

Refer to UFC 1-200-01, DoD Building Code (General Building Requirements), for implementation of new issuances on projects.

AUTHORIZED BY:

LARRY D. McCALLISTER, PhD, PE, PMP, SES Chief, Engineering and Construction Directorate of Civil Works U.S. Army Corps of Engineers

JOSEPH E. GOTT, P.E.

Chief Engineer Naval Facilities Engineering Command

EDWIN H. OSHIBA, SES

Director, AF Civil Engineer Center

MICHAEL McANDREW Deputy Assistant Secretary of Defense (Facility Investment and Management) Office of the Assistant Secretary of Defense (Energy, Installations, and Environment) http://www.wbdg.org/pdfs/ufc_implementation.pdf http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4 http://dod.wbdg.org/

Change 1, 17 March 2022

UNIFIED FACILITIES CRITERIA (UFC)

NEW SUMMARY SHEET

Document: UFC 3-270-01, O&M: Asphalt and Concrete Pavement Maintenance and Repair

Superseding: UFC 3-270-01, Asphalt Maintenance and Repair; UFC 3-270-02, Asphalt Crack Repair; UFC 3-270-03, Concrete Crack and Partial-Depth Spall Repair; UFC 3- 270-04, Concrete Repair; UFC 3-250-06, Repair of Rigid Pavements Using Epoxy Resin Grouts, Mortars, and Concretes; ETL 96-4, Temporary Joint Sealing Details and Procedures for Pavements; ETL 97-2, Maintenance and Repair of Rigid Airfield Pavement Surfaces, Joints and Cracks; ETL 02-7, Preventing Concrete Deterioration Under B-1 and F/A-18 Aircraft; ETL 02-8, Silicone Joint Sealant Specification for Airfield Pavements; ETL 11-26, Using Asphalt Surface Treatments as Preventive Maintenance on Asphalt Airfield Pavements; and ETL 14-2, Preventing and Repairing Concrete Deterioration Under MV-22 and CV-22 Aircraft;

Description: UFCs 3-270-01, 3-270-02, 3-270-03, 3-270-04 and UFC 3-250-06 are hereby cancelled and combined into this UFC. To reflect the combination of these four UFCs into one document, the title of UFC 3-270-01 is changed from Asphalt Maintenance and Repair to O&M Manual: Asphalt and Concrete Pavement Maintenance and Repair. Many figures are updated and the document reviewed to ensure recent developments are included. In addition, the following Air Force Engineering Technical Letters (ETLs) are cancelled and incorporated into this UFC: ETL 96-4, ETL 97-2, ETL 02-7, ETL 02-8, ETL 11-26, and ETL 14-2.

Reasons for Document: This UFC provides engineers with information on the options for maintaining and repairing, as well as preserving and extending, the service life of pavements. It also provides information on which methods are appropriate to address observed pavement distresses. It also outlines materials, equipment, techniques, and cautions required to produce a cost-effective and durable pavement. The overlap in the five superseded UFCs and six cancelled ETLs made it difficult to ensure consistency between documents as modifications to each were added. Combining these UFCs and ETLs into one document facilitates user comprehension and maintains internal consistency during future updates.

Impact: These changes enhance user access to the technical guidance in the documents (one document instead of eleven). This effort reduces the cost to maintain this guidance by reducing ambiguity and reducing the number of documents. There is a potential decrease in initial and lifecycle costs due to increased options available to sustain the pavements throughout the life of the pavement and which will extend to the life of the pavement.

Unification Issues: There are no unification issues.

Disclaimer: Use of the name or mark of any specific manufacturer, commercial product, commodity, or service in this publication does not imply endorsement.

Change 1, 17 March 2022 i

TABLE OF CONTENTS

CHAPTER 1 INTRODUCTION

1-1 PURPOSE AND SCOPE

1-2 APPLICABILITY

1-3 GENERAL BUILDING REQUIREMENTS

1-4 REFERENCES

1-5 GLOSSARY

CHAPTER 2 TYPES OF MAINTENANCE AND REPAIR FOR PAVEMENTS

2-1 INTRODUCTION

2-1.1 Maintenance and Repair

2-1.2 Pavement Management

2-1.3 Quality Control

2-2 PAVEMENT MATERIALS

2-2.1 Safety

2-2.2 Importance of Weather

2-2.3 Asphalt Pavement Materials

2-2.4 Grading System for Asphalt Emulsions

2-2.5 Concrete Pavement Materials

2-2.6 Concrete Pavements Types

2-2.7 Cement Standards

2-3 PAVEMENT DISTRESSES

2-3.1 Asphalt Concrete (AC) Pavement Distresses

2-3.2 Portland Cement Concrete (PCC) Pavement Distresses

2-4 TYPES OF MAINTENANCE AND REPAIR

2-4.1 Global Preventive Maintenance (PM)

2-4.2 Localized Preventive Maintenance (PM)

2-4.3 Operational Maintenance

2-5 PAVEMENT REPAIR EQUIPMENT

2-5.1 Equipment Inspection

2-5.2 Equipment

CHAPTER 3 FULL-DEPTH ASPHALT PATCHES

3-1 INTRODUCTION

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3-2 PROCEDURAL STEPS (FULL-DEPTH PATCH)

3-2.1 Mark Repair Area

3-2.2 Make Saw Cut Through Pavement

3-2.3 Removal of Defective Material

3-2.4 Remove, Replace, and Compact the Base

3-2.5 Apply Tack Coat (and Prime Coat, If Used)

3-2.6 Place the Patch Material

3-2.7 Compact the Patch Area

3-2.8 Ensure Surface of Patch is Watertight

3-2.9 Problem Areas

CHAPTER 4 PROCEDURAL STEPS (PARTIAL-DEPTH PATCH)

4-1 INTRODUCTION

CHAPTER 5 SPRAYED ASPHALT SURFACE TREATMENTS

5-1 INTRODUCTION

5-2 PRIME COAT

5-2.1 Procedural Steps (Prime Coat)

5-2.2 Problem Areas (Prime Coat)

5-3 TACK COAT

5-3.1 Procedural Steps (Tack Coat)

5-3.2 Problem Areas (Tack Coat)

5-4 FOG SEALS AND REJUVENATORS

5-4.1 Procedural Steps (Fog Seals and Rejuvenators)

5-4.2 Problem Areas (Fog Seals and Rejuvenators)

CHAPTER 6 BITUMINOUS SURFACE TREATMENT

6-1 INTRODUCTION

6-2 SINGLE BITUMINOUS SURFACE TREATMENT (SBST)

6-2.1 Procedural Steps (SBST)

6-2.2 Problem Areas (SBST)

CHAPTER 7 DOUBLE BITUMINOUS SURFACE TREATMENT

7-1 INTRODUCTION

7-1.1 Procedural Steps (DBST)

7-1.2 Problem Areas (DBST)

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7-1.3 Sandseal (DBST)

7-1.4 Sand Application and Rolling

7-1.5 Sweep Excess Material

7-1.6 Problem Areas

CHAPTER 8 ASPHALT SLURRY SEALS AND MICROSURFACING

8-1 INTRODUCTION

8-2 MIXTURE MATERIALS

8-2.1 Emulsions

8-2.2 Aggregate

8-2.3 Filler

8-3 SLURRY SEAL PROCEDURAL STEPS

8-3.1 Prepare the Surface

8-3.2 Apply the Slurry

8-3.3 Rolling the Slurry

8-3.4 Problem Areas

8-3.5 Negative Impacts

CHAPTER 9 ASPHALT CRACK SEALING

9-1 INTRODUCTION

9-2 WHEN TO SEAL

9-2.1 Field Evaluations

9-2.2 Schedule

9-2.3 Climatic Conditions

9-2.4 Porous Friction Surfaces

9-3 SPECIFICATIONS

9-3.1 ASTM

9-3.2 Other Specifications

9-3.3 Testing

9-4 CRACK SEALING PROCEDURAL STEPS

9-4.1 Crack Size Guidelines

9-4.2 Crack Widening

9-4.3 Initial Crack Cleaning

9-4.4 Debris Removal

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9-4.5 Final Crack Cleaning

9-4.6 Inspection

9-4.7 Crack Cleaning Summary

9-4.8 Backer Rod Material

9-4.9 Inspection Prior to Sealing

9-4.10 Sealant Temperature and Application

9-4.11 Crack Sealing Delays

9-4.12 Inspection After Sealing

9-5 PROBLEM AREAS

9-5.1 Categories of Problems

CHAPTER 10 POROUS FRICTION SURFACES

10-1 INTRODUCTION

10-2 SEALING CRACKS

10-2.1 Prepare the Crack

10-2.2 Seal the Crack

10-2.3 Patching PFS

10-2.4 Raveling Control

10-2.5 Patching Using Standard Hot Asphalt Plant Mix

CHAPTER 11 DIAMOND-GRINDING ASPHALT CONCRETE PAVEMENTS

11-1 INTRODUCTION

11-2 NEED FOR GRINDING

11-3 GRINDING PROCESS

11-4 TEST SECTION

11-5 GRINDING PROCEDURE

11-6 ACCEPTANCE TESTING

CHAPTER 12 CONCRETE PAVEMENT CRACK SEALING

12-1 INTRODUCTION

12-2 KEY STEPS

12-3 GENERAL PRACTICE

12-4 TEST SECTION

12-5 CRACK SEALANTS

12-5.1 Hot-Applied Sealants

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12-5.2 Cold-Applied Sealants

12-5.3 Fuel- and Blast-Resistant Sealants

12-6 SEALANT SHAPE FACTOR

12-7 BACKER ROD AND SEPARATING MATERIALS

12-7.1 Backer Rod Materials

12-7.2 Separating Materials

12-8 CRACK PREPARATION

12-8.1 Introduction

12-8.2 Cleaning

12-9 CRACK SEALING PROCEDURES

12-9.1 Introduction

12-9.2 Process

12-9.3 Cautions

12-10 TEMPORARY CRACK/JOINT SEALING PROCEDURES FOR PCC

12-10.1 Introduction

12-10.2 Repair Procedures Neoprene Compression Seal (NCS) Joints

12-10.3 Random Cracks

12-10.4 Field Molded Joints

12-10.5 Partial-depth Joints

CHAPTER 13 PARTIAL-DEPTH REPAIR OF CONCRETE PAVEMENTS

13-1 INTRODUCTION

13-2 NEED FOR PARTIAL-DEPTH REPAIR

13-2.1 Joint Spalling

13-2.2 Mid-slab Spalling

13-2.3 Partial-depth Repair Key Steps

13-3 SELECTION OF REPAIR BOUNDARIES

13-4 REMOVAL OF EXISTING CONCRETE

13-4.1 Sawing and Chipping

13-4.2 Milling Process

13-4.3 Partial Versus Full-depth Repair

13-5 CLEANING

13-6 JOINT PREPARATION

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13-6.1 Joint Bond-Breaking

13-6.2 New Joint/Crack Width

13-6.3 Shoulder Joints

13-7 PLACEMENT OF PATCH MATERIALS

13-8 FINISHING

13-9 TREATMENT OF SAW-CUT RUNOUTS AND PATCH/SLAB

INTERFACE

13-10 CURING

13-11 JOINT/CRACK RESEALING

CHAPTER 14 FULL-DEPTH REPAIR OF CONCRETE PAVEMENTS

14-1 INTRODUCTION

14-2 NEED FOR FULL-DEPTH REPAIR

14-2.1 Rigid Pavement Distress Types

14-2.2 Other Rigid Pavement Concerns

14-2.3 Full-Depth Repair Key Steps

14-2.4 Selection of Repair Boundaries

14-2.5 Sawing Cutting Repair Boundaries

14-2.6 Removal of Existing Concrete

14-2.7 Subgrade and Base Preparation

14-2.8 Dowel and Tie-Bar Placement

14-2.9 Drilling Dowel and Tie-Bar Holes

14-2.10 Dowel and Tie-Bar Installation

14-2.11 Continuous Reinforced Concrete (CRC) Pavement Repair

14-2.12 Expansion Joints

14-2.13 Filler Material

14-2.14 Concrete Placement

14-2.15 Concrete Finishing and Texturing

14-2.16 Curing

14-2.17 Joint Sealing

14-3 PRECAUTIONS

CHAPTER 15 CONCRETE PAVEMENT SLAB JACKING

15-1 INTRODUCTION

15-2 NEED FOR SLAB JACKING

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15-3 SLAB JACKING GROUT MATERIALS

15-3.1 Cement-Fly Ash Grout

15-3.2 High-density Polyurethane Polymer Deep Injection

15-4 INJECTION HOLE LOCATIONS

15-5 DRILLING INJECTION HOLES

15-6 GROUT PUMPING

15-7 ELEVATION CONTROL DURING SLAB JACKING

15-8 PLUGGING AND CLEANUP

CHAPTER 16 SUBSEALING JOINTED CONCRETE PAVEMENTS

16-1 INTRODUCTION

16-2 NEED FOR SUBSEALING

16-3 PAVEMENT SUBSEALING KEY STEPS

16-4 SUBSEALING GROUT MATERIALS

16-4.1 Polyurethane Polymer Subsealing

16-5 VOID DETECTION

16-5.1 Visual Inspection

16-5.2 Proof Rolling

16-5.3 Nondestructive Deflection Testing

16-6 INJECTION HOLE LOCATIONS

16-7 DRILLING HOLES

16-8 GROUT INJECTION

16-9 RETESTING SLAB CORNERS

16-10 PLUGGING AND CLEANUP

CHAPTER 17 PCC PAVEMENT DIAMOND GRINDING

17-1 INTRODUCTION

17-2 NEED FOR GRINDING

17-3 GRINDING PROCESS

17-4 TEST SECTION

17-5 GRINDING PROCEDURE

17-5.1 Roughness Removal

17-5.2 Fault Removal

17-5.3 Skid Resistance

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17-6 ACCEPTANCE TESTING

CHAPTER 18 CONCRETE PAVEMENT LOAD TRANSFER RESTORATION

18-1 INTRODUCTION

18-2 NEED FOR LOAD TRANSFER RESTORATION

18-3 LOAD TRANSFER RESTORATION (LTR) KEY STEPS

18-4 CORRECTION OF DEFICIENCIES

18-5 DOWEL LOAD TRANSFER RESTORATION (LTR) PROCESS

18-5.1 Dowel Size Requirement

18-5.2 Cutting Slots for Dowel Installation

18-5.3 Concrete Removal & Dowel Installation

18-5.4 Patching Material

18-5.5 Placing Patch Material

18-5.6 Finishing Activities

18-6 KEYED JOINTS LOAD TRANSFER RESTORATION PROCESS

18-6.1 Keyed Joint Key Steps

18-6.1.1 Keyed Joint Concrete Removal

18-6.1.2 Dowel Bar Placement and Installation

18-6.1.3 Tie Bar Placement and Installation

CHAPTER 19 CONCRETE PAVEMENT RETROFITTED EDGE DRAINAGE

19-1 INTRODUCTION

19-2 NEED FOR PAVEMENT-EDGE DRAINAGE

19-3 DRAINAGE SYSTEM CLASSIFICATIONS

19-3.1 Surface Drainage

19-3.2 Subsurface Drainage

19-4 EDGE DRAINAGE REQUIREMENTS

19-5 EDGE DRAINAGE CANDIDATES

19-5.1 Edge Drainage Key Steps

19-6 EDGE DRAINAGE MATERIALS

19-6.1 Drainage Pipe

19-6.2 Perforated Drainage Pipe

19-6.3 Fin Drains

19-6.4 Filter Material

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19-6.5 Dispersive Clays

19-6.6 Filter Fabrics

19-7 SUBSURFACE DRAIN INSTALLATION

19-7.1 Filter Material Placement

19-7.2 Drainage Pipe Outlets

19-7.3 Drainage Pipe Access

19-7.4 Caution

CHAPTER 20 MAINTENANCE OF HEAT-RESISTANT CONCRETE

20-1 INTRODUCTION

20-2 MAINTENANCE AND REPAIR

20-2.1 Pavement Markings

20-2.2 VL Pad Surface Grinding

20-2.3 Frequency and Depth

20-2.4 Diamond Grinding Procedures

20-2.5 Water Cutting

20-2.6 Surface Sealing

20-2.7 HTC Patching and Materials

20-2.8 PCC Patching

20-3 SUMMARY OF MITIGATION TIPS

20-3.1 Water/Cement Ratio

20-3.2 PCC Mix

20-3.3 Construction Quality

20-3.4 Proper Material

CHAPTER 21 REPAIR OF PCC DAMAGED BY POL

21-1 INTRODUCTION

21-2 PRIMARY DAMAGE MECHANISMS

21-3 REPAIR TECHNIQUES/MATERIALS

21-3.1 Sodium Silicate Application

21-3.2 Multifilament Fibers

21-3.3 Polymer Coatings

21-3.4 Surface-Applied Penetrating Chemically Reactive Silicates

21-3.5 Magnesium Phosphate Cement (MPC)

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21-3.6 Epoxy Coatings

21-3.7 Joint Sealant

21-4 REQUIREMENTS

21-4.1 Cleaning

21-4.2 When to Seal

21-4.3 Distress Repairs

21-4.4 Existing Distress Effects

21-4.5 Where to Seal

21-4.6 High-Temperature Aggregates

21-5 PCC SODIUM SILICATE SURFACE SEALING

21-5.1 Sodium Silicate Solution

21-5.2 Surface Cleaning

21-5.3 When to Seal

21-5.4 Joint Sealing

21-5.5 Paint Markings

21-5.6 Environmental Conditions

21-5.7 Surface Seal Application

21-5.8 Final Evaluation

21-6 CLEANING POL CONTAMINATION FROM PCC AND PCC JOINTS. 175

21-6.1 Stains

21-6.2 Dawn (or Simple Green) Dishwashing Detergent and Hot Water

21-6.3 Tri-Sodium Phosphate (TSP)

21-6.4 Sodium Hydroxide

21-6.5 Super Washing Soda

21-6.6 Phosphoric Acid Cleaner

21-6.7 Bacteria and Enzymes that Remove Oil Stains in Concrete

21-6.8 Replacement

CHAPTER 22 F-35B AND C CRITICAL AREAS

22-1 BACKGROUND

22-2 ASPHALT CONCRETE PAVEMENT

22-2.1 Distresses in Asphalt Concrete Pavement

22-2.2 Maintenance of Asphalt Concrete Pavement

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22-3 PLAIN JOINTED CONCRETE PAVEMENT

22-3.1 Distresses in Plain Jointed Concrete Pavement

22-3.2 Maintenance of Plain Jointed Concrete Pavement

22-4 MAINTENANCE OF CONTINUOUSLY REINFORCED CONCRETE

PAVEMENT

22-5 REQUIRED MATERIAL FOR MAINTENANCE AND REPAIR

22-6 DEFINITION OF CRITICAL AREAS

22-6.1 Short Take-off (STO) Areas

22-6.2 Flight Carrier Landing Practice (FCLP) Critical Areas

22-6.3 Vertical Landing Pad (VLP) Critical Areas

22-6.4 LHD STOVL Critical Areas

22-7 FIGURES

APPENDIX A REFERENCES

APPENDIX B BEST PRACTICES

APPENDIX C GLOSSARY

FIGURES

Figure 2-1 Installation of Backer Rod

Figure 3-1 Diamond Tip Saw Blade

Figure 3-2 Abrasive Blade

Figure 3-3 Damaged Pavement Removed By Sawing

Figure 3-4 Small Milling Head Attachment

Figure 3-5 Hand-Spraying Edge of Cut

Figure 3-6 Overfill Prior to Compaction

Figure 3-7 Vibratory Plate Compactor

Figure 3-8 Steel Wheel Roller

Figure 3-9 Check Level of Patch Surface

Figure 3-10 Seal The Edges

Figure 5-1 Spray Bar and Nozzle Settings

Figure 5-2 Asphalt Distributor

Figure 6-1 Applying Aggregate with Tailgate Spreader on Dump Truck

Figure 6-2 Applying Aggregate with Self- Propelled Hopper-Type Spreader

Figure 6-3 Use Paper for Straight Edge

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Figure 6-4 Aggregate and Sprayed Asphalt Spread Pattern

Figure 8-1 Slurry Seal Spreader Machine

Figure 9-1 Alligator Cracking

Figure 9-2 Reflective Cracking

Figure 9-3 Longitudinal Cracking

Figure 9-4 Hairline Crack

Figure 9-5 Small Crack

Figure 9-6 Medium Crack

Figure 9-7 Large Crack

Figure 9-8 Crack After Cleaning

Figure 9-9 Filling Crack with Sand Emulsion Mixture

Figure 9-10 Examples of Backer Rod Materials

Figure 9-11 Sealing the Crack

Figure 9-12 Crack After Sealing

Figure 10-1 View of a Porous Friction Surface (PFS)

Figure 10.2. Porous Friction Pavement Using Hot-Asphalt Plant Mix

Figure 11-1 Diamond Grinding Equipment

Figure 11-2 California Profilograph

Figure 12-1 Crack Sealant Reservoir Shape Factor

Figure 12-2 Existing Spalled NCS Joint

Figure 12-3 Repaired NCS Joint, Compression Seal Removed

Figure 12-4 Existing NCS Random Spall Area

Figure 12-5 Repaired NCS Random Spall Area, Compression Seal In Place

Figure 12-6 Repaired NCS Random Spall Area, Section of NCS Removed

Figure 12-7 Existing Random Crack

Figure 12-8 Repaired Random Crack

Figure 12-9 Existing Spalled Field Molded Joint

Figure 12-10 Resealed Field Molded Joint with Separating Tape

Figure 12-11 Resealed Field Molded Joint with Backer Rod

Figure 12-12 Existing Partial-Depth Spalled Joint

Figure 12-13 Repaired Partial-Depth Joint with Backer Rod

Figure 13-1 Pavement Joint Spall

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Figure 13-2 Incompressible Causing Spalling at a Joint or Crack

Figure 13-3 Sounding with Hammer

Figure 13-4 Typical Spall Repair Boundaries

Figure 13-5 Repair Boundary Sawing and Use of Chipping Hammer

Figure 13-6 Milling Techniques

Figure 13-7 Cleaning Repair Area (Sandblasting/Water Blasting, and Air Blowing)

Figure 13-8 Compressible Insert

Figure 13-9 Failure Due to Non-use of Compressible Insert

Figure 13-10 Finished Patches

Figure 14-1 Shattered Slabs

Figure 14-2 Utility Cut

Figure 14-3 Diamond Blade Sawing

Figure 14-4 Crc Pavement Full-Depth Repair Layout

Figure 14-5 Concrete Removal Using Backhoe

Figure 14-6 Additional Saw Cuts (Breakup Method)

Figure 14-7 Lift-Out Method

Figure 14-8 Pressure Relief Cuts For Lift-Out Method

Figure 14-9 Patch Area Compaction

Figure 14-10 Drilling Multiple Holes at Mid-Depth for Dowel Bars

Figure 14-11 Dowel Bar Installation

Figure 14-12 Thickened-Edge Expansion Joint

Figure 14-13 Doweled Expansion Joint

Figure 14-14 Typical Finishing Techniques for Full-Depth Repairs

Figure 15-1 Grout Mixing Equipment

Figure 15-2 The Polymer Deep Injection Process

Figure 15-3 Grout Pumping

Figure 15-4 Elevation Control

Figure 15-5 Temporary Plugs

Figure 16-1 Polymer Subsealing Process

Figure 16-2 Falling Weight Deflectometer

Figure 16-3 Four-Hole Pattern at Joint for Grout Injection

Figure 17-1 Grinding Equipment

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Figure 17-2 Gang-Mounted Diamond Saw Blades

Figure 17-3 Diamond-Ground Surface

Figure 17-4 California Profilograph

Figure 18-1 Load Transfer at a Joint

Figure 18-2 Gang-Mounted Multiple Saw Blades for Slot Cuts

Figure 18-3 Dowel Placement in Slot

Figure 18-4 Types of Dowel Bar Misalignment and Effect on Performance

Figure 18-5 Use of Chipping Hammers to Remove Concrete

Figure 18-6 Use of Compressible Insert

Figure 18-7 Placing and Consolidating Patch Material

Figure 18-8 Keyed Joint

Figure 18-9 Gang-Operated Dowel Drill

Figure 19-1 Typical Retrofitted Edge Drainage System

Figure 19-2 Geocomposite Edge Drain Features & Installation Details

Figure 19-3 Trenching Equipment for Installing Pipe Edge Drains

Figure 19-4 Outlet Pipe Design

Figure 20-1 Heat-Damaged Concrete

Figure 22-1 STO Critical Area Scenario 1

Figure 22-2 STO Critical Area Scenario 2

Figure 22-3 FCLP Critical Area

TABLES

Table 2-1 Common Asphalt Emulsion Grades

Table 2-2 Cement Classification Standards

Table 6-1 Aggregate Gradations for SBST

Table 6-2 Sbst Binder And Aggregate Application Rates

Table 7-1 Aggregate Gradations for DBST

Table 7-2 Dbst Binder & Aggregate Application Rates

Table 7-3 Aggregate Gradations for Sandseal (SS)

Table 7-4 Potential Negative Impacts of Surface Treatments To Airfields

Table 8-1 Aggregate Gradations for Microsurfacing and Slurry Seals

Table 17-1 Feathering Distances

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Table 18-1 Dowel Size Requirements

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This Page Intentionally Left Blank

CHAPTER 1 INTRODUCTION

1-1 PURPOSE AND SCOPE.

This UFC contains information on materials, equipment, and procedures for repairing and maintaining hot mix asphalt (HMA) and portland cement concrete (PCC) pavements. Typical maintenance and repair (M&R) methods, and problems that might be encountered in using these methods, are discussed. Guidance is provided for using each of these M&R methods. Additional information can be found in the references listed in Appendix A.

This UFC is intended for use as a field UFC for airfield and roadway pavement repair for all U.S. Navy, Army, and Air Force pavements. The described techniques are applicable for airfields, roads, parking lots, and other pavement uses. Probable causes of pavement problems are discussed and suggested M&R measures described in order to correct pavement surface problems at the source.

Not covered in this UFC are maintenance and repairs of surface water drainage systems, pavement markings, ground lighting, and unpaved margins.

1-2 APPLICABILITY.

This UFC applies to all military Service elements and contractors involved in the planning, design, and construction, maintenance, repair, or preservation of DOD pavements worldwide. This UFC is for the M&R of asphalt and concrete pavements.

Follow standard practices to ensure good performance and to obtain required pavement service life. Projects where standard practices were not followed resulted in poor performance. In many cases, those providing oversight were not knowledgeable about standard practices. This UFC outlines standard practices and will result in better oversight of work and help identify problem areas during application of the M&R process.

1-3 GENERAL BUILDING REQUIREMENTS.

Comply with UFC 1-200-01, DOD Building Code (General Building Requirements). UFC 1-200-01 provides applicability of model building codes and government-unique criteria for typical design disciplines and building systems, as well as for accessibility, antiterrorism, security, high performance and sustainability requirements, and safety.

Use this UFC in addition to UFC 1-200-01 and the UFCs and government criteria referenced therein.

1-4 REFERENCES.

Appendix A contains a list of references used in this UFC. The publication date of the code or standard is not included in this UFC. In general, the latest available issuance of the reference is used.

1-5 GLOSSARY.

Appendix C contains acronyms, abbreviations, and terms.

CHAPTER 2 TYPES OF MAINTENANCE AND REPAIR FOR PAVEMENTS

2-1 INTRODUCTION.

The purpose of M&R of asphalt and concrete pavements is to extend the useful life of the pavement, maintain a smooth riding surface, reduce mission impact, and prevent water from entering the underlying soil.

2-1.1 Maintenance and Repair.

Typical maintenance on asphalt and concrete pavements consists principally of the care of joints, sealing of cracks, surface treatments, replacement of random broken slab panels, full-depth and partial-depth repairs, dowel bar restoration, diamond grinding, slab-jacking, sub-sealing, petroleum, oil, and lubricant (POL) contamination removal, and the correction of minor settlement and drainage faults. Repair consists of the work required to restore a distressed pavement so it may be used at its original designed capacity and/or accommodate the current mission as provided for by applicable Service instructions.

2-1.2 Pavement Management.

Use an effective pavement management and inspection system that provides timely M&R to keep a pavement in optimal condition. Identify the root cause of the pavement distress and address the underlying problem. To implement an effective pavement management and inspection program, use UFC 3-260-16FA, Airfield Pavement Condition Survey Procedures, and UFC 3-270-08, Pavement Maintenance Management. These UFCs describe all asphalt and concrete pavement distresses and severity levels.

2-1.3 Quality Control.

Perform quality control, whether work is performed in-house or by contract, to obtain effective durable maintenance and repairs. Use an independent certified testing laboratory, referred to herein as the QC lab. Quality control (QC) functions are performed by the QC lab, which are necessary to monitor the work. Mix designs, soil cement design, soils analysis for compaction control, and supporting construction process monitoring are performed by the QC lab. The minimum daily monitoring requirements are described in specified UFGSs. Submit QC lab qualifications for review and approval to the government contracting officer or their designated technical representative. The government contracting officer or their designated technical representative will review the qualifications of the laboratory and, if necessary, visit the QC lab. Include, as a minimum, local area industry standards, , ASTM C78, Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading), ASTM C1260, Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method), ASTM C1077, Standard Practice for Agencies Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Testing

Agency Evaluation, ASTM D3666, Standard Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials, and respective state highway department certifications, when applicable, in evaluation criteria used to determine the suitability of the QC lab.

Before proceeding with the work, construct a test section to demonstrate the capability to perform to the intent of the specification. Demonstrate within the test section the ability to do pavement removal, subgrade preparation, base placement, and concrete mixing, placing, and finishing for both partial- and full-depth repairs.

Incorporate the construction of joints, protection of the work, and QC procedures into the test section. Use all procedures and materials used to construct an acceptable test section as the standard of evaluation for performing the work. Incorporate equipment, materials, and procedures used for the approved test section into the work.

2-2 PAVEMENT MATERIALS.

2-2.1 Safety.

Safety hazards, such as fire/explosion hazards, toxicity, and reactivity, are associated with pavement repair materials and equipment. Always provide a Material Safety Data Sheet (MSDS) from the manufacturer with the material. Review the MSDS for personal protective equipment (PPE) and other safety precautions before use.

2-2.2 Importance of Weather.

2-2.2.1 Weather Effects – Asphalt.

2-2.2.1.1 Preferably, perform patching or resurfacing work only during dry weather and on dry surfaces. Place courses only when the surface temperature of the underlying course is greater than 40 degrees F (4 degrees C) for course thicknesses greater than 3 inches (75 millimeters) and 45 degrees F (7 degrees C) for course thicknesses 3 inches (75 millimeters) or less. When hot asphalt mixtures are placed on cold pavements they may quickly cool, making adequate compaction difficult. Moreover, asphalt and asphalt mixtures do not bond adequately to damp surfaces.

2-2.2.1.2 Mixtures containing emulsified or cutback asphalt require more curing time in high humidity. Low temperatures also reduce the rate of evaporation of emulsified or cutback binders during curing. Cationic emulsions generally are less affected by the weather than anionic emulsions. As a result, many agencies specify cationic emulsions for M&R work. Cutback asphalts are now seldom used due to environmental concerns;

however, cutback asphalt may be encountered outside of the US.

2-2.2.1.3 Moisture affects seal coats and other surface treatments in the first few hours after placement. Rainfall prior to the time the liquid asphalt solidifies allows the leaching away or separation of asphalt from the aggregate. This results in the loss of some or all of the applied surface treatments.

2-2.2.1.4 Repairs cannot always be made in warm, dry weather. Therefore, QC, quality assurance (QA), equipment, and procedures are required when repairs are made during poor weather conditions as the repairs are less likely to perform satisfactorily. Sometimes mission requirements take precedent, which requires repairs as soon as practical even though they may only be temporary. Further, delaying repairs may allow small surface defects to become major failures.

2-2.2.2 Weather Effects – Concrete.

2-2.2.2.1 Weather conditions at a job site, hot or cold, windy or calm, dry or humid, may be vastly different from the optimum conditions assumed at the time a concrete mix is specified, designed, or selected. Concrete can be placed in hot or cold weather conditions, provided adequate precautions are taken to alleviate the negative impacts of high or low ambient temperatures.

2-2.2.2.2 The precautions required to ensure a quality end product will vary depending on the actual conditions during concrete placement and the specific application for which the concrete will be used. Do not place concrete when the air temperature is below 40 degrees F (4 degrees C) in the shade. When the air temperature is likely to exceed 90 degrees F (32 degrees C), use concrete having a temperature not exceeding 90 degrees F (32 degrees C) when placed. Keep the surface of placed concrete damp with a water fog until the approved curing medium is applied.

In general, if the temperature at the time of concrete placement will exceed 77 degrees F (25 degrees C) or below 50 degrees F (10 degrees C), develop a plan to negate the effects of temperatures.

2-2.2.3 Hot Weather Effects on Concrete.

Any operation of concreting done at atmospheric temperature above 77 degrees F (25 degrees C) is termed hot weather concreting. The effect of hot weather may be as follows:

• A higher temperature of fresh concrete results in a more rapid hydration and leads to reduced workability/accelerated setting. This reduces the handling time of concrete.

• Concrete mixed, placed, and cured at higher temperature typically develops higher early strength than concrete produced and cured at normal temperature, but at 28 days or later the strength is generally lower.

• Rapid evaporation may cause plastic shrinkage and cracking and subsequent cooling of hardened concrete will introduce tensile stresses.

• Rapid drying of the existing repair surface will lead to premature failure due to poor or failed bond.

2-2.2.4 Cold Weather Effects on Concrete.

Any concreting operation done at a temperature below 50 degrees F (10 degrees C) is termed cold weather concreting. In the absence of special precautions, the effect of cold weather concreting may be as follows:

• When the temperature is falling to about 50 degrees F (10 degrees C) or below, the development of strength of concrete is retarded compared with development at normal temperature. Thus, the time period for removal of form work has to be increased as well as the time to allow for traffic.

• Permanent damage may occur when the concrete in fresh stage is exposed to freezing temperatures before hardening. Concrete may suffer irreparable loss in its properties to an extent that compressive strength may get reduced to 50 percent of what could be expected for normal temperature concrete.

• Large temperature differentials within the concrete member may promote cracking and adversely affect its durability.

2-2.2.5 Precautions.

Precautions may include some or all of the following for hot weather placement:

• Moisten subgrade, steel reinforcement, and form work prior to concrete placement.

• Erect temporary wind breaks to limit wind velocities and sunshades to reduce concrete surface temperatures.

• Cool aggregates and mixing water added to the concrete mixture to reduce its initial temperature. The effect of hot cement on concrete temperature is only minimal.

• Use a concrete consistency that allows rapid placement and consolidation.

• Protect the concrete surface during placement with plastic sheeting or evaporation retarders to maintain the initial moisture in the concrete mixture.

• Provide sufficient labor to minimize the time required to place and finish the concrete, as weather conditions substantially affect the times to initial and final set.

• Consider fogging the area above the concrete placement to raise the relative humidity and satisfy moisture demand of the ambient air.

• Provide appropriate curing methods as soon as possible after the concrete finishing processes have been completed.

http://www.cement.org/cement-concrete-basics/working-with-concrete/impact-of-hot-cement-on-the-concrete-mix http://www.cement.org/cement-concrete-basics/working-with-concrete/impact-of-hot-cement-on-the-concrete-mix

• In extreme conditions, consider adjusting the time of concrete placement to take advantage of ambient temperatures, such as early morning or night time placement.

Note: With proper planning and execution, concrete can be successfully placed and finished to produce high-quality, durable concrete at hot or cold temperatures.

2-2.3 Asphalt Pavement Materials.

Asphalt concrete, commonly called asphalt, blacktop, or pavement, is a composite material commonly used to surface roads, parking lots, and airfields. It consists of mineral aggregate bound together with asphalt, laid in layers, and compacted. The terms "asphalt (or asphaltic) concrete," "bituminous asphalt concrete," and "bituminous mixture" are typically used in engineering and construction, which define concrete as any composite material composed of mineral aggregate adhered with a binder. The abbreviation "AC" is sometimes used for "asphalt concrete" but can also denote "asphalt content" or "asphalt cement," referring to the liquid asphalt portion of the composite material. A variety of specialty asphalt concrete mixtures have been developed to meet specific needs, such as stone-matrix asphalt, which is designed to ensure a very strong wearing surface, or porous asphalt pavements, which are permeable and allow water to drain through the pavement for controlling storm water.

Mixing of asphalt and aggregate is accomplished in one of several ways described below.

2-2.3.1 Hot Mix Asphalt Concrete (HMAC).

Hot mix asphalt concrete (commonly abbreviated as HMAC or HMA) is produced by heating the asphalt binder to decrease its viscosity and drying the aggregate to remove moisture prior to mixing. Mixing is generally performed with the aggregate at about 300 degrees F (roughly 150 degrees C) for virgin asphalt, 330 degrees F (166 degrees C) for polymer modified asphalt, and asphalt cement at 200 degrees F (93 degrees C).

Perform paving and compaction while the asphalt is sufficiently hot. In many countries, paving is restricted to summer months because in winter the compacted base will cool the asphalt too much before it is able to be packed to the required density. HMAC is the form of asphalt concrete most commonly used on high-traffic pavements such as those on major highways and airfields.

2-2.3.2 Superpave Mix Design.

One of the principal results from the Strategic Highway Research Program (SHRP) was the Superpave mix design method. Superpave, short for "superior performing asphalt pavement," is a pavement system designed to provide longer-lasting roadways. The Superpave mix design method was designed to replace the Hveem and Marshall methods. The volumetric analysis common to the Hveem and Marshall methods provides the basis for the Superpave mix design method. The Superpave system ties asphalt binder and aggregate selection into the mix design process, considers traffic and climate as well, and evaluates the finished product. The compaction devices from https://en.wikipedia.org/wiki/Composite_material https://en.wikipedia.org/wiki/Composite_material https://en.wikipedia.org/wiki/Road_surface https://en.wikipedia.org/wiki/Parking_lot https://en.wikipedia.org/wiki/Airport https://en.wikipedia.org/wiki/Construction_aggregate https://en.wikipedia.org/wiki/Binder_(material) https://en.wikipedia.org/wiki/Asphalt https://en.wikipedia.org/wiki/Engineering http://www.pavementinteractive.org/superpave-mix-design/hveem-mix-design http://www.pavementinteractive.org/superpave-mix-design/marshall-mix-design the Hveem and Marshall procedures have been replaced by a gyratory compactor and the compaction effort in mix design is tied to expected traffic.

2-2.3.3 Marshall Mix Design.

The basic concepts of the Marshall mix design method were originally developed by Bruce Marshall of the Mississippi Highway Department around 1939 and then refined by the U.S. Army. Currently, the Marshall method is used in some capacity by about 38 states. The Marshall method seeks to select the asphalt binder content at a desired density that satisfies minimum stability and range of flow values. The Marshall method continued to be refined through the 1950s, with various tests on materials, traffic loading, and weather variables. Today, the Marshall method, despite its shortcomings, is probably the most widely used mix design method in the world. It has become so widely used because it was adopted and used by the U.S. military all over the world during and after WWII and it is simple, compact, and inexpensive.

2-2.3.4 Stone Mastic Asphalt (SMA).

SMA can be used as wearing course for roads, paths, and other traffic surfaces. It is a standard method of construction on motorways, federal roads, and city streets with heavy and very high demand traffic. For maintenance of traffic surfaces, SMA is especially suited for thin layers. One of SMA’s special advantages is that, within limits, it can be paved in different thicknesses to even out a surface without worrying about possible differences in post compaction.

Wearing courses made with SMA are especially stable and durable. They have proven their superior performance even in areas with heavy traffic and independent of any climatic influence. A wearing course made from SMA with the correct design and mix production as well as proper paving shows the following characteristics due to the high chippings content together with the mastic-like mortar:

• Better resistance to permanent deformation

• High-wearing resistance

• Less cracking due to cold or mechanical stress

• Coarse surface texture

• Good macro roughness

• Good long-term behavior

2-2.3.5 Porous Friction Course (PFC).

Porous or permeable friction courses (PFC) are HMA mixtures placed at the surface of a pavement structure in a thin layer to produce several benefits for the traveling public in terms of safety, economy, and the environment. It is a sacrificial wearing course consisting of an aggregate with relatively uniform grading, little or no fines and mineral filler, and it is designed to have a high air void content compared to dense-graded mixtures. Special repair procedures specifically applicable to these porous friction surfaces are presented and discussed in Chapter 10.

2-2.3.6 Warm Mix Asphalt (WMA) Concrete.

Warm mix asphalt concrete (commonly abbreviated as WMA) is produced by adding either zeolites, waxes, asphalt emulsions, or sometimes even water to the asphalt binder prior to mixing. This allows significantly lower mixing and laying temperatures and results in lower consumption of fossil fuels, thus releasing less carbon dioxide, aerosols, and vapors. Not only are working conditions improved, but the lower laying-temperature also leads to more rapid availability of the surface for use, which is important for construction sites with critical time schedules. The use of these additives in HMA (2.2.3.1 above) may afford easier compaction and allow cold weather paving or longer hauls. Use of WMA is rapidly expanding.

2-2.3.7 Cold Mix Asphalt Concrete.

Cold mix asphalt concrete is produced by emulsifying the asphalt in water with (essentially) soap prior to mixing with the aggregate. While in its emulsified state, the asphalt is less viscous and the mixture is easy to work and compact. The emulsion will break after enough water evaporates and the cold mix will, ideally, take on the properties of cold HMAC. Cold mix is commonly used as a patching material and on lesser-trafficked service roads.

2-2.3.8 Cut-back Asphalt Concrete.

Cut-back asphalt concrete is produced by dissolving the binder in kerosene or another lighter fraction of petroleum before mixing with the aggregate. While in its dissolved state the asphalt is less viscous and the mix is easy to work and compact. After the mix is laid down the lighter fraction evaporates. Because of concerns with pollution from the volatile organic compounds in the lighter fraction, cut-back asphalt has been largely replaced by asphalt emulsion.

2-2.3.9 Mastic Asphalt Concrete.

Mastic asphalt concrete or sheet asphalt is produced by heating hard-grade blown bitumen (oxidation) in a green cooker (mixer) until it has become a viscous liquid, after which the aggregate mix is then added. The bitumen aggregate mixture is cooked (matured) for around six to eight hours and, once it is ready, the mastic asphalt mixer is transported to the work site where experienced layers empty the mixer and either machine or hand lay the mastic asphalt contents on to the road. Mastic asphalt concrete is generally laid to a thickness of around 0.75 to 1.1875 inch (20 to 30 millimeters) for footpath and road applications, and around 0.375 inch (10 millimeters) for flooring or roof applications. In addition to the asphalt and aggregate, additives, such as polymers, and antistripping agents may be added to improve the properties of the final product.

Natural asphalt concrete can be produced from bituminous rock, found in some parts of the world, where porous sedimentary rock has been impregnated with upwelling bitumen.

2-2.4 Grading System for Asphalt Emulsions.

Most asphalt surface treatments contain an emulsified binder. Do not use solvent-based or cutback materials unless approved by the local environmental authority. Use emulsions appropriate for local conditions to ensure proper break and set time. Coal tar emulsions, usually used only as fuel-resistant sealers, are not discussed in this UFC.

Emulsions are classified (ASTM D977, Standard Specification for Emulsified Asphalt), on the basis of how quickly the asphalt droplets coalesce, resulting in “breaking” of the emulsion. RS, MS, QS, and SS refer to rapid-setting, medium-setting, quick-setting, and slow-setting, respectively. The breaking time increases from RS to SS. RS emulsions cannot be combined with aggregate. MS emulsions can only be mixed with coarse aggregate. QS and SS emulsions can be mixed with any aggregate.

Designations 1 and 2 in emulsion nomenclature refer to the viscosity of the emulsion, with 2 being more viscous. The h designation refers to a base asphalt that is harder (lower penetration). Some emulsions have a HF designation, referring to high float. HF emulsions can provide a thicker asphalt film on aggregates, which is thought to enhance durability. Emulsions suspended by cationic surfactants are designated with a C. No designation refers to emulsions with anionic surfactants. Table 2-1 gives common emulsion grades for different types of surface treatments.

Table 2-1 Common Asphalt Emulsion Grades

Surface Treatment Typical Asphalt Emulsion Grade Used

Liquid fog seal RS-1, MS-1, HFMS-1, SS-1, SS-1h, CRS-1, CSS-1h, CQS-1h Liquid and sand spray seal

RS-1, RS-2, HFRS-2, HFRS-2h, MS-1, HFMS-1, CRS-1, CRS- 2, CRS-2h

Slurry seal SS-1h, CSS-1h, CQS-1h Microsurfacing CQS-1h

2-2.4.1 Emulsion Breaking and Curing.

Breaking an asphalt emulsion refers to separating water from the asphalt and the evaporation of water. Some emulsions break when sufficient water has evaporated.

Others break through chemical means. Breaking time is reduced by adding chemicals.

Curing asphalt emulsions involves the development of mechanical properties as the asphalt particles coalesce and the water is removed through evaporation. Typical curing times range from 30 minutes to 24 hours. Cure times are a function of environmental conditions, application rate, substrate properties, and product dilution ratios. Follow the manufacturer’s recommendations for closing the pavement to traffic.

2-2.4.2 Shelf Life.

Some asphalt materials have a limited shelf life; therefore, give particular attention to the manufacturer’s recommended shelf life when selecting a material. Shelf life typically ranges from three months to two years and depends on storage conditions, such as temperature, humidity, and packaging.

2-2.5 Concrete Pavement Materials.

A concrete pavement consists of a surface layer of concrete placed over a base (granular or stabilized) and subbase (typically granular) over the subgrade, which may incorporate a fill material. Concrete is a mixture of paste and aggregates. The paste, composed of cementitious materials and water, coats the surface of the fine and coarse aggregates. Through a chemical reaction called hydration, the paste hardens and gains strength to form concrete. The cementitious material primarily consists of portland cement but may also incorporate fly ash, slag cement (ground granulated blast furnace slag), silica fume (not common), or proprietary materials. Concrete is made with or without additives (e.g., air entraining, water-reducing) to achieve the required workability, strength, and durability properties. Concrete generally achieves its initial set within about one hour after water is added and will become fairly hard within six to eight hours of placement. Normal concrete will achieve about 90 percent of its long-term strength within about 30 days and will continue to gain strength at an ever-decreasing rate for many years as long as moisture is retained within the consolidated concrete mass and there is no adverse chemical reaction either internally or due to external action. Normal concrete is typically designed to achieve about 4,000 pounds per square inch (psi) (27.5 megapascals) compressive strength at 28 days. Rapid-set or high-early-strength concrete can be designed to achieve strengths of about 2,500 to 3,000 psi (17.2 to 20.7 megapascals) within 12 to 24 hours to allow for early opening of repair areas to traffic. Many rapid-set materials include proprietary cementitious materials.

2-2.5.1 Portland Cement Concrete (PCC).

PCC is generally accepted as the most appropriate material for the partial-depth repair of existing concrete pavements. Typical mixes combine Type I, Type II, or Type III portland cement with aggregate not larger than one-half the minimum repair thickness.

Use a material that is a low-slump mixture of air-entrained concrete having a water-to-cement ratio not exceeding 0.44. Type I or Type II PCC can be used when the patch material can be protected from traffic for at least 24 hours. For faster-setting materials such as Type III cements, patches can be opened as soon as the material can withstand loads without plastic deformation. Type I or Type II portland cement, with or without admixtures, is more widely used than most other materials because of its relatively low cost, availability, and ease of use. In cooler weather, insulating layers can be used to retain the heat of hydration and reduce curing time.

Several proprietary portland cement-based repair materials are also available to achieve high early strength and can be used for partial-depth repairs.

2-2.5.2 Gypsum-Based Concrete.

Gypsum-based concrete (calcium sulfate) repair materials gain strength rapidly and can be used in any temperature above freezing. However, gypsum concrete may not perform well when exposed to moisture and freezing weather. Additionally, the presence of free sulfates in the typical gypsum mixture may promote corrosion of reinforcing steel in pavements.

2-2.5.3 Magnesium Phosphate Concrete.

Magnesium phosphate concretes set very rapidly and produce a high-early-strength, impermeable material that will bond to clean, dry surfaces. However, this type of material is extremely sensitive to water, either on the substrate or in the mix (even very small amounts of excess water can reduce strength). Furthermore, magnesium phosphate concrete is very sensitive to aggregate type (for example, some limestone aggregates are not acceptable). In hot weather (i.e., above 90 degrees F [32 degrees C]), many commonly available mixes experience short setting times (e.g., 10 to 15 minutes).

2-2.5.4 Calcium Aluminate Cement.

Calcium aluminate cements gain strength rapidly, have good bonding properties (on a dry surface), and very low shrinkage.