EVALUATION OF BRIDGE DECK PATCHING MATERIALS

ABSTRACT

The deterioration of bridge decks in Pennsylvania is becoming an increasing concern.  With the abundance of recent media coverage on bridge collapses, and the poor state of the nation’s infrastructure, keeping the roads and bridges in safe, working condition has come to the forefront of the public’s attention.  With this public safety in mind, it is of the utmost importance to properly repair bridge decks that have deteriorated over time.

When deterioration is beyond repair, a full deck replacement is warranted, but if the deterioration only occurs in some portions of the deck there is another option.  The deteriorated concrete in those areas can be removed and rapid setting patching materials can be placed in its stead.  These rapid setting patching materials set quickly and achieve high early strength, allowing the bridges to reopen quickly after repair.

Unfortunately, many of these patching materials have proven themselves to be ineffective in the long run, due to heavy traffic loadings and vibration issues.  Therefore, it is necessary to test a variety of these patching materials that are on the market to determine their overall effectiveness.

By testing six of these materials with standard ASTM tests, material properties such as compressive strength, shrinkage, coefficient of thermal expansion, bond strength, resistance to freeze-thaw deterioration, and time of setting can be determined.  From this information, the best two candidates can be established, and further testing can be performed on them.  This additional testing includes determining the material’s corrosion resistance, abrasion resistance, as well as the ability of the patch to resist separation from iv

the base concrete.  From this testing, recommendations on which patching material should be used in future repairs can be made.

TABLE OF CONTENTS

LIST OF FIGURES ………………………………………………………………………………………..viii

LIST OF TABLES………………………………………………………………………………………….xiii

ACKNOWLEDGEMENTS……………………………………………………………………………..xvi

Chapter 1  Introduction and Literature Review …………………………………………………..1

1.1 Problem Statement………………………………………………………………………………1

1.2 Objectives ………………………………………………………………………………………….1

1.3 Scope…………………………………………………………………………………………………2

1.4 Literature Review ……………………………………………………………………………….2

1.4.1 Bridge Deck Deterioration ………………………………………………………….3

1.4.1.1 Deterioration of Reinforcement…………………………………………..3

1.4.1.1.1 Corrosion Due to De-Icing Salts………………………………..3

1.4.1.1.2 Other De-Icing Products …………………………………………..6

1.4.1.2 Deterioration of Concrete…………………………………………………..7

1.4.1.2.1 Freezing and Thawing………………………………………………7

1.4.1.2.2 Traffic Loading ……………………………………………………….8

1.4.1.2.3 Chemical Attacks…………………………………………………….8

1.4.2 Patching Materials……………………………………………………………………..8

1.4.3 ASTM Testing Methods……………………………………………………………..10

Chapter 2  Testing Program A – Standard ASTM Testing……………………………………12

2.1 Patching Material Selected …………………………………………………………………..12

2.1.1 Rapid Set Concrete Mix (CTS Cement Manufacturing Co.) with

Modifier A………………………………………………………………………………….13

2.1.2 Pavemend 15.0 (Ceratech, Inc.) …………………………………………………..13

2.1.3 Duracal (U.S. Gypsum Company)………………………………………………..14

2.1.4  T17 Polymer Concrete (Transpo Industries Inc.)…………………………..14

2.1.5 Sikatop Plus 122 (Sika Corporation)…………………………………………….14

2.1.6 High Power Fast Setting Concrete (U.S. Concrete Products) …………..15

2.2 Phase I Methodology: ASTM Testing……………………………………………………15

2.2.1 Water Based Materials ……………………………………………………………….16

2.2.1.1 ASTM C 39 – Compressive Strength of Cylindrical Concrete

Specimen……………………………………………………………………………..16

2.2.1.2 ASTM C 666 – Resistance of Concrete to Rapid Freezing

and Thawing…………………………………………………………………………16

2.2.1.3 ASTM C 266 – Time of Setting of Hydraulic-Cement Paste

by Gillmore Needles ……………………………………………………………..17

2.2.1.4 ASTM C 191 – Time of Setting of Hydraulic Cement by

Vicat Needle…………………………………………………………………………18

 

2.2.1.5 Packaged Dry, Rapid-Hardening Cementitious Materials for Concrete Repairs – Section 8.5 for Slant Shear Test………………….19

2.2.1.6 ASTM C 531 Modified – Linear Shrinkage and Coefficient of Thermal Expansion of Chemical-Resistant Mortars, Grouts,

Monolithic Surfacings, and Polymer Concretes ………………………..20

2.2.1.7 Workability and Ease of Use………………………………………………21

2.2.2 Non Water Based Material………………………………………………………….22

2.2.2.1 ASTM C 882 – Bond Strength of Epoxy-Resin Systems

Used With Concrete by Slant Shear…………………………………………22

2.2.2.2 ASTM C 39, ASTM C 666, ASTM C 266, ASTM C 191,

ASTM C 531 M, Workability and Ease of Use…………………………22

2.3 ASTM Testing Results ………………………………………………………………………..22

Chapter 3  Testing Program B – Specialized Testing…………………………………………..30

3.1 Patching Material Selected …………………………………………………………………..30

3.2 Phase II Methodology: Specialized Testing……………………………………………31

3.2.1 Patch Placement…………………………………………………………………………36

3.2.1.1 Pavemend 15.0 – Patch Placement………………………………………40

3.2.1.2 Rapid Set with Latex Modifier – Patch Placement ………………..41

3.2.2 Three-Point Bending Test……………………………………………………………45

3.2.2.1 Three-Point Bending Test Procedure…………………………………..45

3.2.2.2 Three-Point Bending Test Results……………………………………….47

3.2.3 Abrasion Resistance Testing – Repetitive Tire Load Simulation ……..52

3.2.3.1 Repetitive Tire Load Simulation Procedure………………………….52

3.2.3.2 Repetitive Tire Load Simulation Results……………………………..55

3.2.4 Abrasion Resistance Testing – Sandblasting Test…………………………..57

3.2.4.1 Sandblasting Test Procedure………………………………………………57

3.2.4.2 Sandblasting Test Results…………………………………………………..59

3.2.5 Corrosion Testing………………………………………………………………………61

3.2.5.1 Corrosion Testing Procedure………………………………………………61

3.2.5.2 Corrosion Testing Results………………………………………………….69

3.3 Specialized Testing Summary ………………………………………………………………80

Chapter 4  Summary and Conclusions……………………………………………………………….82

References……………………………………………………………………………………………………..89

Appendix A  Testing Program A – Standard ASTM Testing………………………………..91

A.1 Compression Testing – ASTM C 39……………………………………………………..91

A.2 Freeze-Thaw Testing – ASTM C 666……………………………………………………95

A.2.1 Freeze-Thaw Testing in Regular Water………………………………………..95

A.2.2 Freeze-Thaw Testing in Salt Water……………………………………………..103

A.3 Setting Time – ASTM C 191 (Vicat Test)……………………………………………..108 A.4 Slant Shear Test – ASTM C 882/928 ……………………………………………………108

A.5 Thermal Expansion and Shrinkage Testing – ASTM C 531 M…………………110

Appendix B  Testing Program B – Specialized Testing……………………………………….117

B.1 Three-Point Bending Test Photographs…………………………………………………117 B.2 Repetitive Tire Load Simulation Photographs………………………………………..122

B.3 Corrosion Testing……………………………………………………………………………….124

 

Chapter 1

 

Introduction and Literature Review

1.1 Problem Statement

With the aging of bridges in Pennsylvania, an increasing concern is the deterioration of concrete bridge decks over time, and subsequently, the best way to repair them.  Complete deck replacement, although often the best for the bridge, is far from the most economical solution.  Therefore, a number of rapid setting concrete patching materials have been used by PennDOT to repair areas of deterioration along the deck.  Unfortunately, some of these materials have proven themselves to be ineffective in the long-term due to durability issues from vibration and heavy traffic volume.  Therefore, there is a need to research, test, and evaluate the various patching materials on the market to determine their effectiveness in variable conditions.  The variables include the area of the patch, depth of the patch, and environment (corrosive agents and traffic load).

1.2 Objectives

1. Determine the most suitable quick setting patching material for patches of varying area and depth.
2. Determine the corrosion protection provided by the patch to the underlying reinforcement and verify that the patch does not increase corrosion rates in bars contained in the base material.
3. Develop a recommended testing protocol for evaluation of patching materials.

1.3 Scope

To determine the most suitable patching material for various conditions dependent on a variety of variables, such as environment, patching depth, and patching area, the following tasks are performed:

1. Conduct a literature review to determine the top six patching material candidates to test incorporating materials from each of the major groups of patch type/material. 2. Perform standard ASTM tests as recommended by the National Transportation Product Evaluation Program (NTPEP) (National Transportation Product Evaluation Program 2005) on these six materials to determine the top two materials.
2. Develop and conduct specialized tests for these two patching materials which will address issues not covered by standard ASTM tests.
3. Based on ASTM and specialized testing, determine the most appropriate patching material for the various conditions described above.

1.4 Literature Review

The following sections review the various types of deterioration that can occur in bridge decks, both in the reinforcement as well as the concrete.  Also, the various types of PennDOT patching materials are discussed along with the ASTM tests that determine basic material properties of the chosen patch materials.

1.4.1 Bridge Deck Deterioration

To determine the best way to repair deterioration in bridge decks, one must first understand the various mechanisms by which deterioration can take place.  The following is a description of the major mechanisms that lead to deterioration.

1.4.1.1 Deterioration of Reinforcement

1.4.1.1.1 Corrosion Due to De-Icing Salts

Corrosion is defined as the deterioration of a metal by way of an electrochemical process, in which the metal reacts with its environment (i.e. oxygen and water).  When steel is subjected to oxygen within a moist environment, the metal tends to break down, wishing to revert to its ore form (Richardson 2002).

To fully understand how steel corrodes within concrete, it is first important to understand how steel does not corrode inside concrete.  After all, it is a common observation to see a piece of steel that has been left exposed to the environment deteriorates as a result of the corrosion process.  So what is different about the steel within reinforced concrete?  The answer is in the environment that the concrete creates for the steel.  As stated above, the corrosion of steel requires both oxygen and water.  If enough concrete cover is provided for the reinforcement, and this concrete is impermeable, the steel is protected since two major ingredients of corrosion are missing.

Unfortunately for the steel, though, concrete is not a completely impermeable material.

Although concrete may appear to be completely solid, it actually is not, due to a system

of voids that naturally occur when the concrete is cast.  These voids allow for the diffusion of oxygen and water towards the reinforcement.  Therefore, the concrete cover shields the rebar somewhat, but does not completely prevent interaction between the steel and the outside environment (Richardson 2002).  The amount of cover may be able to slow down the rate of corrosion, but the true protection against corrosion lies in the alkalinity of the concrete.  Concrete is a basic material with a pH between 12 and 13.  At this pH level, an oxide film, known as a passive film, forms around the reinforcement.  This passive film, which is primarily composed of hydrated iron oxides, is only a few nanometers thick (Bertolini 2004).  The film is dense and impenetrable, and can even regenerate when it is damaged, as long as the environment remains alkaline.  When in place, it is far better than any man-made protection, such as galvanizing or epoxy coating, and can safeguard the integrity of the reinforcement for as long as it exists (Broomfield 2007).

Unfortunately, the passive film is not completely invulnerable to the environment.  Two main culprits lead to the depassivation of the steel in concrete: carbon dioxide and chlorides.  Carbon dioxide that is present in the atmosphere can eventually diffuse through the concrete cover and reach the passive film.  Once this occurs, the pH drops to about 9 and the stability of the passive film is lost (Bertolini 2004).  Chloride ions, which are found in deicing salts commonly used in winter weather, also can penetrate the concrete.  Once enough ions reach the reinforcement, local damage to the passive film can occur (Poulsen 2006).

When the passive film is destroyed by carbonation or chloride ions, the steel is vulnerable to the corrosion process.  This process begins by the iron giving up its electrons in an anodic reaction, as denoted by Reaction 1 below (American Concrete

Institute 1987):

Reaction 1: Fe      Fe²⁺ + 2e^–.

This reaction must be accompanied by a cathodic reaction where the electrons are consumed, in order to keep charge neutrality.  This is where the oxygen and water come into play, as shown in Reaction 2 (American Concrete Institute 1987):

Reaction 2: 2e^– +H₂O + ½O₂      2OH^–.

Refer to Figure 1-1 to see the entire electrochemical reaction.

 

 

Figure 1-1: Corrosion Current (Broomfield 2007)

The entire process is not complete at this point, though, since the iron has only broken down into the ferrous ion.  As is often observed, when steel corrodes, rust is the final product.  This occurs through a series of reactions.  First, the ferrous ions react with the hydroxyl ions to produce ferrous hydroxide, as shown in Reaction 3 (Broomfield

2007):

Reaction 3: Fe²⁺ + 2OH^–      Fe(OH)₂.

Then, the ferrous hydroxide reacts with oxygen and water to produce ferric hydroxide, as shown in Reaction 4 (Broomfield 2007):

Reaction 4: 4Fe(OH)₂ + O₂ +2H₂O      4Fe(OH)₃.

And finally, the ferric hydroxide breaks down into the hydrated ferric oxide, commonly known as rust, as shown in Reaction 5 (Broomfield 2007):

Reaction 5: 2Fe(OH)₃     Fe₂O₃·H₂O + 2H₂O.

The problem with rust is that it has seven times the volume of steel with none of its excellent mechanical properties.  So not only is the rust incapable of holding the tensile load that the steel was designed to take, but it also expands within the concrete, causing a build up of stresses that leads to cracking and spalling of the concrete, which can allow even more chlorides to penetrate to the reinforcement.  Therefore, the integrity of both the steel and the surrounding concrete has been compromised, leading to possible failure of the entire system (Broomfield 2007).

A phenomenon of corrosion known as the “halo effect” is of particular concern for bridge deck patching.  When corrosion causes a need for repair, the spalling concrete is removed from the area of deterioration, and repaired material is put in its place.  Unfortunately, in the area surrounding the replaced concrete, there is a build up of chloride ions.  This abrupt difference in chloride content between new and old concrete can create large corrosion potentials, leading to rapid corrosion in the area around the repair, thus causing a “halo” of deterioration around the repair material (Whitmore 2005).

1.4.1.1.2 Other De-Icing Products

In addition to standard de-icing salt (NaCl), other products are also used as deicing products.  These include magnesium chloride (MgCl₂), potassium chloride (KCl), calcium chloride (CaCl₂), and urea (CON₂H₄).  The chloride compounds all contribute to the corrosion process described above (Kirchner 2001).  Urea, a non-chloride deicer, has been tested and was found to cause even greater deterioration in the concrete while also being harmful to the environment.  This greater deterioration is the result of adverse freeze-thaw effects that the urea has on the concrete, reducing the concrete’s strength and elasticity (Farha 2002).

1.4.1.2 Deterioration of Concrete

1.4.1.2.1 Freezing and Thawing

Moisture from precipitation and other sources can saturate the voids found in concrete.  It is this water that is the source of the problem with respect to freezing and thawing.  In climates where the temperature can fluctuate above and below the freezing point, such as the climate that covers all of Pennsylvania, water in the voids of the concrete will freeze and expand when the freezing point is reached, thus increasing the pressure within the concrete.  When temperatures increase, the ice will melt and the system will again be at the starting point.  This repeated cycle of freezing and thawing that accompanies temperature changes repeatedly stresses the concrete and leads to deterioration.  A common deterioration associated with freezing and thawing is scaling, which is a crumbling of the surface mortar over a large area (Cordon 1966).

1.4.1.2.2 Traffic Loading

Deterioration from vehicular loads is due to abrasion damage caused by the contact between the wheel and the road.  In particular, studded tires, chained tires and blades of snow ploughs can scrape at the surface of the bridge deck, thus causing damage through years of repeated abuse (Russell 2004).

1.4.1.2.3 Chemical Attacks

A number of mechanisms of concrete deterioration exist due to the reaction of the concrete with various chemicals.  Most notable are sulfates that react with components of the cement and cause the concrete to expand and the cement paste to soften and disintegrate (Mindess 2003).  This occurs as a result of three reactions.  The sulfate ions react with the calcium ions, hydrated calcium aluminate, and carbon dioxide to form gypsum, calcium sulfoaluminate (ettringite), and thaumasite, respectively.  These products have larger volumes than the reactants, thus causing a build up of internal pressure that leads to cracking and eventual deterioration (Walker 2000).

1.4.2 Patching Materials

A wide variety of patching and patch-related materials are listed in the PennDOT publication, “Bulletin 15,” which is a list of all materials that are allowed to be used in PennDOT projects (Pennsylvania Department of Transportation 2006).  Broken down by category, they are:

Packaged Dry Cement

Rapid Set Concrete Mix

Rapid Set Concrete Patching Materials – Cementitious, Non-Metallic, Non-Staining

BC Quick Patch #2	Euco-Speed
Swift Set 120	Speed Crete 2028
IFSCEM 110	Speed Crete Green Line
Bonsal F-77 Construction Grout	Express repair
Power Set 120	5 Star Highway patch
Power Set 120A	5 Star Structural Concrete
IFSCEM 115	5 Star Structural Concrete V/O
Tyberpatch HS	Gill 33B & P Superbond
Pavemend 15.0	Durapatch Hiway
CGM Highway Patch	Crystex
Chemspeed 65	Rapid Road Repair
Pave Patch 3000	FastSetTM Non-Shrink Grout
Perma Patch	FastSetTM Dot Mix
HD-50	CG FastSetTM Concrete Mix
Thoroc 10-60 Rapid Mortar	Sikatop III
Road Patch II	Sika Set Road Patch
Thorite	SikaQuick 2500
Set Instant Concrete	SikaQuick 1000
Emaco T415 Repair Mortar

 

Rapid Set Concrete Patching Materials – Magnesium Phosphate Cement based Materials

Duracal

Duracal-S

Magna 100

Set 45 regular Set 45 Hot weather Euco-Speed M.P.

Darex 240

 

Rapid Set Concrete Patching Materials – Polymer Mortar and Concrete

Emaco 2020

RM 698 Epoxy Patch

Duracryl

Dural 317

Flexolith

T17 Polymer Concrete

 

Polymer Modified and Special Cements, Mortars and Concrete

BC Non-shrink grouting &   Aggregate	HiCap Light Patching Compound
Speed Patch	HiCap Patching Compound
ThoRoc HB2 Repair Mortar	Flexkrete Technologies 102
Thorogrip Anchoring Cement	PipeWipe
Emaco T415 Mortar	Type IP Blended
Emaco R320 CI	T-SF Blended
Emaco S88-CI	Permacrete
Emaco R320	Blend Crete
Emaco R310	Shotcrete MS
Emaco S66-CI	FastSetTM Cement
Rapid Set Cement	FastSetTM Repair Mortar
Rapid Set Concrete Mix	FastSetTM Non-Shrink Grout
Chem Comp III	FastSetTM Dot Mix
CTS Type K	Speedcrete Red Line
Day Chem Ad Bond (J-40)	Sikatop Plus 111
HD-25	Sikatop Plus 121
Type S Cement	Sikatop Plus 122
Type M Cement	Sikatop Plus 123
Type N Cement	Sikadur 42 Grout Pak
Eurocrete Thin Top Supreme	Sika Cem 133
FastSetTM Commercial Grade Concrete Mix	High Power DOT Grade Repair Mortar
Concrete Top Supreme	High Power Cement
Dural Top Fast Set	Thin Top Supreme
Dural Top Gel High Power Fast Setting	Duracal
Concrete

(Pennsylvania Department of Transportation 2006)

1.4.3 ASTM Testing Methods

According to AASHTO’s National Transportation Product Evaluation Program

(NTPEP), the following ASTM tests should be run on rapid setting patching materials (National Transportation Product Evaluation Program 2005).  Table 1-1  lists the tests recommended for water based materials and Table 1-2 lists the tests recommended for non water based materials.  These tests are chosen because they are capable of determining the basic mechanical properties needed for preliminary material selection.   Table 1-1: Testing for Water Based Materials

Test	Specification
Compression, Cylinders	ASTM C 39
Freeze/Thaw	ASTM C 666 and ASTM C 666 with salt water
Set Time	ASTM C 266 (Substituting ASTM C 191)
Bond Strength using Slant Shear	ASTM C 928
Thermal Expansion and Shrinkage	ASTM C 531 modified

 

 

Table 1-2: Testing for Non Water Based Materials

Test	Specification
Compression, Cylinders	ASTM C 39
Freeze/Thaw	ASTM C 666
Set Time	ASTM C 266 (Substituting ASTM C 191)
Bond Strength using Slant Shear	ASTM C 882
Thermal Expansion and Shrinkage	ASTM C 531 modified

 

(National Transportation Product Evaluation Program 2005)

Besides the research framework created by the National Transportation Product Evaluation Program, there is not a great deal of research that has been conducted in this area, and this establishes the need for this project.  There is, however, a similar study being conducted by Oklahoma DOT in conjunction with the University of Oklahoma, but no results from the testing were available at the time of publication of this thesis.

EVALUATION OF BRIDGE DECK PATCHING MATERIALS

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