1 inspection, risk assessment, and …docs.trb.org/prp/15-4927.pdf1 inspection, risk assessment, and...

L. Jiang, M. Sherman, and J. Grieco 1

INSPECTION, RISK ASSESSMENT, AND MANAGEMENT PLANNING OF MASSDOT1

TRANSPORTATION STRUCTURES AFFECTED BY ALKALI-SILICA REACTION2

3

Liying Jiang4Simpson Gumpertz & Heger, Inc.5

41 Seyon Street, Building 1, Suite 5006

Waltham, MA 024537

Tel: 781-907-9374; Fax: 781-907-9009; Email: [email protected]

9

Matthew R. Sherman10Simpson Gumpertz & Heger, Inc.11

41 Seyon Street, Building 1, Suite 50012

Waltham, MA 0245313


15

John Grieco16Director of Research and Materials17

Massachusetts Department of Transportation18

400 D Street,19

South Boston, MA 0211020


22

Word count: 4,047 words + 9 tables/figures x 250 words (each) = 6297 words23

24

Submission Date: 01 August 201425

26


1

ABSTRACT2

3Alkali-silica reaction (ASR) is a frequent cause of concrete deterioration. ASR occurs when4

certain silica-containing aggregates react with hydroxyl and alkali ions to form an expansive5

silica gel, leading to cracking of the aggregate and concrete. Because ASR-induced concrete6

deterioration is a gradual time-dependent process, concrete structures undergoing ASR can often7

still serve their intended purpose provided that the effects of the ASR are understood, monitored,8

and managed.9

After identifying 40 structures with the potential for alkali-silica reaction (ASR) due to10

the use of suspect aggregates, the Massachusetts Department of Transportation (MassDOT)11

undertook a research program to develop a means of managing the potential effects of any ASR.12

Building upon work completed by the Federal Highway Administration and the Institution of13

Structural Engineers, the program established a protocol for field inspection and diagnosis of14

ASR, evaluation of the extent of any ASR-related damage and its potential effect on the15

structure, monitoring of its progression, and long-term management of each affected structure.16

This paper presents the protocol, including the preliminary field assessment (visual17

observation, cracking index measurements, and core sampling), supplemental laboratory18

evaluation (petrographic examination and Damage Rating Index tests), and resulting evaluation19

of the structural and performance implications. Using examples, particular emphasis will be20

applied to the resulting evaluation and management plans presented in the protocol that21

incorporates and guides the future management of the ASR in the structures.22

23

Keywords: Alkali-silica reaction (ASR), transportation structures.24

25

26


INTRODUCTION1

In early 2009, the Massachusetts Department of Transportation (MassDOT) identified 402

structures that have the potential for alkali-silica reaction (ASR) due to the use of suspect3

reactive aggregates (Figure 1). These structures include structural elements of major and minor4

bridges, highway sign foundations, strain pole foundations, highway sound barrier foundations,5

sidewalks, etc. Thus, MassDOT undertook a research program and retained Simpson Gumpertz6

& Heger Inc. (SGH) to develop a means of managing the potential effects of any ASR.7

The objective of the project is to establish a protocol for field inspection and diagnosis of8

ASR, evaluation of the extent of any ASR-related damage and its potential effect on the9

structure, monitoring of its progression, and long-term management of each affected structure.10

11

1213

FIGURE 1 ASR testing and evaluation program – structure locations14

BACKGROUND OF ASR15

What is Alkali-Silica Reaction (ASR)?16Alkali-silica reaction (ASR) is one of the most-common causes of concrete deterioration and17

occurs when certain types of silica-containing reactive aggregates (typically strained quartz,18

chert, and greywacke) react with the hydroxyl and alkali ions in the concrete to form a silica gel.19

The gel absorbs significant quantities of water, causing it to swell and crack the aggregates and20

surrounding cement paste. The gel can then migrate into the cracks where it can absorb21

additional water and continue swelling and causing additional cracking and interconnection of22

the cracks. ASR will continue as long as the concrete contains a sufficient supply of alkalis and23

has a relative humidity above approximately 85%. Moisture fluctuation can exacerbate the signs24

of distress.25


ASR was first recognized in 1940 publications by Thomas Stanton. Since its discovery,1

ASR has been reported to affect various structures around the world. Although New England2

concrete aggregates were thought to have been of generally high quality and ASR-free, reports of3

ASR in New England are becoming more frequent as concretes with slowly reactive New4

England aggregates age and newer concretes use less reliable aggregate sources.5

6

Effect of ASR Distress on the Physical Properties of Concrete7ASR-affected concrete deterioration is primarily characterized by internal expansion leading to8

an interconnected network of cracks. This deterioration affects physical properties of concrete9

including compressive and tensile strength and the modulus of elasticity. The Institution of10

Structural Engineers (ISE 1992) (1) published physical properties measured on unrestrained11

concrete specimens for various amount of free expansion as summarized in Figure 2 below.12

13

1415

FIGURE 2 Residual mechanical properties vs. free expansion, from ISE 1992 (1), Table 4.16

17

Guidelines on Assessment and Management of ASR-affected Structures18Unlike other concrete deterioration processes such as cyclic freeze-thaw deterioration or19

corrosion of reinforcing bars, ASR cannot be easily treated or mitigated because the three20

conditions, alkali (from cement), reactive silica (from aggregates), and moisture (from rain or21

groundwater), are typically present in the concrete and difficult to eliminate after construction.22

However, typical ASR-induced concrete deterioration is a gradual process that changes the23

properties of concrete over time. A concrete structure undergoing ASR can often still serve its24

intended purpose and design functions until a limiting state (structural, aesthetic, or loss of25

function) is reached; therefore, many owners initiate programs to assess and manage ASR-26

affected structures.27

Protocols for managing the ASR are not well developed, but available options range from28

long-term structural-health monitoring and evaluation to structural retrofits or structure29


replacement. Two primary guidelines, providing for diagnosis and prognosis for ASR distress in1

transportation structures and typical building and parking structures, are as follows:2

3

FHWA-HIF-09-004 (2) – This report provides a basis for the correlation of visible4distress and deterioration in concrete structures to ASR, prescribes Cracking Index5

(CI) and cracking criteria to identify the extent of the ASR distress, describes the6

reductions of mechanical properties of concrete affected by ASR, and discuss the7

strategies for its management. ASR distress is quantified based on damage levels seen8

in many transportation structures.9

ISE 1992 (1) – This document provides standardized classifications and tables to10assist the user in rating the effects of ASR distress and in developing a management11

plan. It recommends a customized response based on multiple characteristics and key12

parameters, including expansion index, site environment, reinforcement details, and13

consequence of failure. This document provides some of the basis for FHWA-HIF-14

09-004 (2).15

16

According to both documents, after ASR is diagnosed, the CI can be used to estimate the17

expansion to date in the ASR-affected concrete. As described in these References, the CI is18

obtained by measuring and summing the crack widths along a set of lines drawn on the surfaces19

of a concrete member. Both documents also describe an expansion monitoring method that20

works in concert with the CI to allow for periodic in situ monitoring of expansion, providing a21

comparative and quantitative rating of any future ASR-induced expansion or deterioration.22

In addition, AASHTO PP 65-11 (3) can be useful in the evaluation of the ASR-affected23

structures. This standard provides a process for determining aggregate reactivity and selecting24

measures for preventing deleterious expansion in new concrete construction. This process25

consists of classifying the aggregate reactivity, the exposure, and the severity of the26

consequences of the structures due to ASR deterioration, and using two provided tables to27

determine the appropriate mitigation measures. Although the standard is intended to address new28

construction, its classifications and guidelines are useful in evaluating the obtained information29

from ASR-affected concrete.30

ASR INSPECTION AND EVALUATION PROTOCOL31

The general approach of the MassDOT ASR inspection and evaluation protocol, based upon the32

work conducted by the FHWA and ISE, is illustrated as a flowchart in Figure 3 and described in33

the following sections.34


12

FIGURE 3 ASR inspection and evaluation protocol flow chart3


1

2

Preliminary Field Assessment3SGH visited each of the 40 structures to conduct a field investigation, focusing on the ASR-4

related concrete deterioration. At each structure, SGH performed the following tasks:5

6

Visual Observations - The main objective of the visual survey was to review the7exposed concrete surface and to investigate if the concrete structure exhibits common8

visual symptoms of ASR, such as apparent pattern-cracking, broad brownish zone and9

damp appearance at cracks, pop-outs of reactive aggregate, ASR gel exudation, as well10

as structural deformation and relative movement and displacement. Figure 4 illustrates11

typical visual symptoms of ASR on some MassDOT structures. If the concrete structure12

is suspected to have been affected by ASR, it is important to document the degree and13

extent of the ASR deterioration, typical crack width, and exposure condition of the14

concrete structure or various structural elements.15

16

17

18

19

20

21

22

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24

25

26

27

28

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FIGURE 4 Typical visual symptons of ASR on MassDOT structures.3031

Cracking Index (CI) Measurements - If the concrete structure is suspected to have been32affected by ASR and the cracking condition appears to have exceeded the CI criteria33

(CI value greater than 0.018 in./yd or any individual crack widths greater than34

0.006 in.), CI measurement at each structure or structural element is warranted. The35

objectives of the CI measurements were to establish a baseline of the extent of cracking36

in a structure member (expansion-to-date), to evaluate the strength and durability of the37

existing concrete, and to quantitatively monitor the propagation of crack widths and38

expansion of the concrete. At each CI location, the task involves documenting the39

concrete condition, conducting CI measurements using an optical magnifying40

comparator at each reference line of four interconnected 10 in. by 10 in. square41

reference grids on the concrete surface (Figure 5), and installing gage points at the42

corners of the reference grids to allow baseline expansion monitoring measurements to43

be made.44

45


1FIGURE 5 Example of Illustration of Crack Widths at a CI Location2

3

Core Sampling - If the concrete structure is suspected to have been affected by ASR,4core samples from representative ASR-distressed areas were extracted for use in5

petrographic examination and to determine the Damage Rating Index (DRI).6

7

Supplemental Laboratory Evaluation8If the concrete structure exceeded the established cracking criteria CI and ASR would not have a9

“negligible” effect on the structure (as defined later in Table 1), a sampling and supplemental10

laboratory investigation was undertaken using the following techniques.11

12

Petrographic Examination - The main objective of the petrographic examination is to13diagnose the potential cause(s) of the concrete deterioration (ASR, freeze-thaw,14

shrinkage, etc.), to examine the pattern of internal cracking (depth, presence in the15

aggregates) and the presence and distribution of the reaction product (ASR gel, reaction16

rim), and to evaluate the quality of the concrete (water to cement ratio, cement shortage,17

air content, and the presence of other cementitious materials such as fly ash or slag,18

etc.). In each case, the detailed petrographic and microscopic examinations were19

conducted in accordance with applicable procedures outlined in ASTM C856 –20

Petrographic Examination of Hardened Concrete. Typical petrographic features of21

ASR, as observed from ASR-affected MassDOT structures, include reactive rims22

around the aggregate, internally fractured aggregate, fractures extending from aggregate23

into the surrounding paste structure, or the presence of ASR gel. Figure 6 illustrates the24

microstructure of ASR-affected concrete from an ultrathin section under a25

magnification of 50X.26

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3

4

5

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7

8

9

10

11

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FIGURE 6 Magnified (50X) view of the microstructure in the body of concrete showing a13

reactive coarse aggregate particle with ASR gel (yellow arrow) that is partially filling the14

crack in the aggregate particle and that extends outward and partially filling the fracture15

in the surrounding paste structure.16

Determination of Damage Rating Index (DRI) - In addition to petrographic examination,17DRI tests were used on the polished sections from the core samples to quantify the18

degree of ASR-related damage and to evaluate the overall condition of the concrete19

below the exposed surface. The DRI method was developed by Dr. Grattan-Bellew in20

the 1990s. It evaluates the condition of concrete by counting the number of typical21

petrographic features of ASR on polished concrete sections at a magnification of 16X.22

The DRI is a quantitative representation of a normalized (to an area of 16 sq in.) count23

of these features each of which is weighted to represent its relative importance in the24

overall deterioration process. A review of two DRI research publication (4, 5) for25

laboratory and field specimens indicate that typical ASR-damaged concretes exhibit26

DRI values of 250 to 370, with an extreme reported value of 670. The typical DRI27

values on the polished sections from ASR-affected MassDOT structures fall within this28

boundary range, suggesting that a minor to appreciable degree of ASR has been29

occurring on these structures. Figure 7 illustrates typical DRI test results from two30

concrete samples from pole foundations for overhead signs that were affected by31

minor-to-moderate ASR.32


1

FIGURE 7 Damage Rating Index (DRI) of polished sections from two concrete samples2

from pole foundations for overhead signs.34

ASR Risk Assessment and Management Planning5In addition to providing the methodology for the field and laboratory testing, the protocol6

provides a framework for consistent interpretation of the test results. This was a critical7

component of the protocol because it provided clear “next steps” for the field personnel8

responsible for the structures, but who may not be familiar with ASR and its effects. As9

described in the following sections, the protocol provides a consistent response that is10

commensurate with the severity of the ASR, the potential effect of any ASR on the structure, the11

degree of existing ASR, and the severity of the exposure of the structure.12

13

Basis documents for assessment14

The AASHTO PP 65-11 (3) and ISE 1992 (1) provided base concepts for the risk assessment and15

planning portion of the protocol. In particular:16

17

The AASHTO PP 65-11 (3) document provided the concept of establishing an ASR18

risk level by using the potential concrete expansion, exposure condition, and19

structural classification to provide a recommended level of ASR prevention and20

mitigation to achieve a typical service life.21

The ISE 1992 (1) document provided the concept of evaluating key in-service22parameters, including expansion index (I through V), site environment (dry,23

intermediate), reinforcing detailing class (1 through 3), and consequence of failure24

(slight and significant), to establish an ASR severity rating on which a management25

plan can be based for each specific ASR-affected structure.26

.27

SGH Assessment and management of ASR – affected structures28

While the AASHTO PP 65-11 (3) standard and ISE 1992 (1) provide very useful information on29

ASR assessment and associated management strategies, these approaches and management30


strategies are not directly suitable to manage ASR-affected MassDOT structures due to the1

following reasons:2

3

The AASHTO PP 65-11 (3) only provides preventive measures for new construction,4and does not provide direct information about ASR assessment of existing ASR-5

affected structures.6

The “consequence of failure” classifications in the ISE 1992(1), “slight” and7“Significant,” are too limited to efficiently apply to the variable types of the8

MassDOT structures. Defining “failure” due to ASR-distress is difficult, and may9

mean different things (such as reduced serviceability or appearance, loss of bond,10

large–scale concrete spalling that may cause personal injury, or increased structural11

risk of unknown degree) to different users.12

The ISE management strategies are very demanding and impractical and do not align13with other MassDOT risk management practices. For example, the 2 and 4 month14

inspection frequency given by the ISE 1992 (1) for ASR ratings of “severe” and15

“moderate”, respectively, would require a diversion of resources from other projects16

not commensurate with the actual risk. Similarly, the ISE requirement to perform17

monthly detailed inspections and monitoring of cracks and to perform a full18

investigation of the structural detailing for “severe” ASR would similarly require that19

resources be diverted from structures that present a greater overall risk.20

21

To account for the role of key parameters, including the consequence of failure,22

expansion characteristics, environmental exposure, and reinforcement detailing, on the expected23

performance of ASR-affected structures and to direct the associated management strategies, the24

evaluation protocol developed for the project incorporated them into the custom evaluation25

matrices shown in Table 1-“Severity Ratings of ASR-Affected MassDOT Structure or Element”26

and Table 2 - “Assessment Rating and Management Plan for ASR-Affected MassDOT Structure27

or Element” to guide the management of MassDOT’s ASR-affected structures. These two tables28

were based on the ISE 1992 (1); but modified to incorporate additional factors that are relevant29

to typical MassDOT structures. Table 1 describes a proposed procedure to rate the severity and30

importance of ASR on the element or structure based on all the affecting parameters described31

above, and Table 2 provides a management plan based on the ASR rating.32


TABLE 1 Severity Ratings of ASR-Affected MassDOT Structure or Element1

Rating

Effect of ASR on Function

Negligible

MinorSignificant Property Value/ Personal Injury

Ample Warning Sudden Failure

Reinforcing Detailing Class - Good Fair Poor Good Fair Poor Good Fair Poor

Exposure: Mild (Dry environment, internal RH < 75%)

Expansion Index

I 0 0 0 0 0 0 0 0 0 0

II 0 0 0 0 0 0 1 0 0 1

III 0 0 0 0 0 1 1 0 1 1

IV 0 0 1 1 1 1 1 1 1 2

V 1 2 2 2 1 1 1 1 2 2

Exposure: Intermediate (Internal RH between 75% ~ 85%; vertical surfaces w/o exposure to deicing salts;

Ex. pier caps, sound walls, above-grade columns and piers)

Expansion Index

I 0 0 0 0 1 1 1 1 1 1

II 0 0 0 0 1 1 1 1 1 1

III 0 0 1 1 1 1 2 1 2 2

IV 0 0 1 1 1 2 3 2 2 4

V 1 2 2 2 3 3 3 3 3 4

Exposure: Severe (Wet environment, deicing salt exposure, horizontal surfaces; ex. retaining walls, foundations, abutments,decks, barrier walls)

Expansion Index

I 0 0 0 0 1 1 1 1 1 1

II 0 0 0 0 1 1 1 1 1 1

III 0 0 1 1 2 2 2 2 2 4

IV 0 1 1 1 2 2 4 4 4 4

V 1 2 2 2 3 3 4 4 4 4

Expansion Index: Reinforcing Detailing Class:2I: < 0.5 mm/m (0.018 in./yd) Good – Stirrups, hooked ends, or welded laps3II: 0.5 mm/m ~1.0 mm/m (0.018 in./yd~0.036 in./yd) Fair – Conventional (corner lapped stirrups)4III: 1.0 mm/m ~1.5 mm/m (0.036 in./yd~0.054 in./yd) Poor – no through ties, no or side-lapped stirrups5IV: 1.5 mm/m ~2.5 mm/m (0.054 in./yd~0.090 in./yd)6V: > 2.5 mm/m (0.090 in./yd) * For classification, assume typical reinforcement7

details were used if drawings are unavailable.89

Effect of ASR on Function: Check Box10

Negligible No structural implications or safety concerns beyond those of non-ASR-affected concrete

(sidewalks, aprons, etc).

Minor(If all of thesecriteria apply)

Only a limited portion of the element is affected by ASR.

ASR damage will cause no significant loss of performance.

ASR damage does not pose a risk of personal injury due to sudden failure.

Significant redundancy exists within a large structural element or element is redundantwithin the overall structure.

No or only gradual change in effect of ASR damage expected within the next 4 years.

SignificantProperty

Value/PersonalInjury*

“Ample warning” – Effect of ASR will occur with noticeable advance warning such assignificant cracking, deflection or displacement. This will typically be the case for bridgedecks, bridge piers, foundation walls, abutment walls, barrier rails etc);

“Sudden failure” – Effect of ASR will occur with no advance warning. This will typicallybe the case for pre-stressed elements and shear- and development-based modes, includinganchorage, localized bearings, and shear-controlled bearings.

Note: * This also includes the cases that “minor” does not apply for entire structure or an element.11

13

TABLE 2 Assessment Rating and Management Plan for ASR-Affected MassDOT Structure or Element1

Colorcode

RatingEffect of ASR onPerformance of

Element or StructureManagement Plan

0 Negligible No ASR-specific response required. Reassess only if new information or changes are noted in course of other routine work.

1 Minor

Visually inspect every two years for signs of large changes in condition (new spalling, staining, “alligatorcracking” with cracks wider than 1/32 in.)

For bridge structures, add note to NBIS report to alert inspectors of potential ASR during future inspections. If possible, minimize moisture intrusion to increase service life. Repeat detailed ASR inspection and risk assessment during second MassDOT NBIS inspection cycle for

bridges or after 4 years for structures not covered by routine inspections.

2 Moderate

Visually inspect annually for signs of large changes in condition (new spalling, staining, “alligator cracking”with cracks wider than 1/32 in.)

If possible, minimize moisture intrusion to increase service life. Perform detailed crack survey and CI measurements as part of NBIS inspections for bridges or with local staff

for other structures every two years and repeat ASR risk assessment. If a new ASR rating is assigned, modifycurrent management plan and act accordingly.

3 Appreciable

Visually inspect and perform detailed crack survey and CI measurement every six months untilimplementation of a management and maintenance plan.

Prepare and implement a structure-specific management and maintenance plan. This may include one or moreof the following options depending on factors such as the expected time to scheduled replacement,replacement value of the structure(s), relative cost analysis, and local monitoring capabilities. Structural analysis and evaluation and/or prediction of remaining service life using reduced concrete

properties due to ASR distress. This option may require additional field investigation, non-destructivetesting, and extensive laboratory testing to determine reduction of concrete properties and potentialfuture ASR expansion.

Formal monitoring with a scheduled frequency, if indicated by structural analysis and evaluation. Thisoption may require using additional monitoring techniques, such as “tell-tale” markers or crackdisplacement gages.

Permanent repair and/or strengthening. Replacement of the structure.

4 Significant

Visually inspect and perform detailed crack survey and CI measurement every three months untilimplementation of a management and maintenance plan.

Prepare and implement a structure-specific management and maintenance plan, as described for “Rating 3”above.

2

14

CASE STUDIES1The implementation of the protocol on three MassDOT structures is presented below.2

3

Case Study 14The subject concrete components are sidewalks, handicap ramps, median islands, and traffic5

signal foundations. They are located at the intersection of Plymouth Street and the Exit 7 ramp of6

Route I-195 Eastbound. The structure was constructed about 12 years ago and it has been7

exposed to weathering, moisture, and splash/spray roadway deicing salts since.8

Visual observations on the exposed concrete surfaces indicated that the concrete was in9

good condition with none-to-minor indications of common visual symptoms of ASR. There were10

no visual indications of expansion-related distress and the structural significance is low in this11

case. Since the cracking condition was below the threshold required to justify further field12

sampling or testing, based on ASR Inspection and Evaluation Protocol Flow Chart (Figure 3), CI13

measurements or core sampling or laboratory testing was not performed at this structure.14

The key parameters were determined as follows:15

Exposure Condition = “Severe”16

Expansion Index = “I”17

Effect of ASR on Function = “Negligible”18

Reinforcement Detailing Class = “Poor”19

20

Using the ASR assessment rating system and management plan (Tables 1 and 2), this21

potentially ASR-affected structure was determined to have an ASR severity rating of “0 –22Negligible” with no ASR-specific response required.23

24

Case Study 225The subject concrete components are pole foundations for cantilevered sign posts located along26

Rte 24 between Bridgewater and Freetown. The structures were constructed about 12 years ago,27

and have been exposed to weathering, moisture, and splash/spray roadway deicing salts since.28

Visual observations on the exposed portions of three concrete foundations indicated that29

the concrete exhibited common visual symptoms of ASR. The crack widths of the suspect30

pattern cracking varied from 0.003 in. (very fine cracking) to 0.040 in. (prominent cracking).31

There were no visual indications of expansion-related distress, such as anchor-bolt32

movement/slippage or large-scale concrete spalling that would indicate impairment of the current33

structural integrity. Since the cracking condition has exceeded the threshold required to justify34

further field sampling or testing, CI measurements were performed at representative cracking35

area of two pole foundations and core samples were extracted at three pole foundations. The CI36

results on two sign foundations ranged from 0.053 in./yd to 0.093 in./yd, significantly greater37

than the CI threshold (0.018 in./yd). Petrographic examination on three core samples indicated38

that the concrete exhibited extensive pattern-cracking due to ASR and DRI tests on polished39

sections from two core samples showed that the DRI value ranged from 447 to 559. Overall, the40

field investigation and laboratory testing concluded that the concrete in these pole foundations41

exhibited moderate-to-severe ASR.42


44


Expansion Index = “V”46

Jiang, Sherman, Grieco 15

Effect of ASR on Function = “Significant Property Value/Personal Injury – Sudden1Failure”2

Reinforcement Detailing Class = “Good”3Using the ASR assessment rating system and management plan (Tables 1 and 2), these4

ASR-affected sign foundations were determined to have an ASR severity rating of “4 –5

Significant.” This requires visually inspect and perform detailed crack survey and CI6

measurement every three months until implementation of a structure- specific management and7

maintenance plan, such as structural analysis and evaluation and/or prediction of remaining8

service life using reduced concrete properties due to ASR distress, formal monitoring with a9

scheduled frequency if indicated by structural analysis and evaluation, permanent repair and/or10

strengthening, or replacement of the structure.11

12

Case Study 313The subject concrete components are concrete elements, including concrete deck, center pier and14

pier cap, and parapet walls, on the Miller Street Bridge over Interstate 495 in Middleborough,15

MA. The structures were constructed about 15 years ago, and have been exposed to weathering,16

moisture, and splash/spray deicing salts since construction.17

Visual observations on the exposed concrete surfaces of these structural elements18

indicated that the suspect pattern-cracking was primarily located at the edges of the concrete19

deck with minor instances on the center piers and parapet walls. There were no visual indications20

of expansion-related distress (such as displacement between the concrete deck and parapet walls,21

or large-scale concrete spalling) impairing the structural integrity. Since the cracking condition22

has exceeded the threshold required to justify further field sampling or testing, CI measurements23

were performed and core samples were extracted at representative cracking area of each24

structural element. The CI results ranged from 0.143 in./yd to 0.166 in./yd on the south nose of25

the center pier cap, ranged from 0.042 in./yd to 0.049 in./yd on the north edge of the concrete26

deck, and ranged from 0.059 in./yd to 0.125 in./yd on the south parapet wall. Petrographic27

examination reveals that the concrete extracted from the parapet wall, does not have any28

indications of ASR distress; however, the concrete has the potential for developing ASR due to29

the use of the reactive aggregate. All of the evidence from the core sample extracted from the30

edge of the bridge deck consistently indicated a minor-to-moderate degree of ASR damage and31

possible cyclic freezing-thawing damage. DRI tests on polished sections from two core samples32

extracted from the concrete deck showed that the DRI value ranged from 153 to 264. Overall,33

the field investigation and laboratory testing concluded that the concrete in the bridge deck,34

center pier and pier cap exhibited moderate-to-severe ASR, while the concrete in the parapet35

walls did not exhibit ASR distress but has the potential for developing ASR.36


Center Pier and Pier Cap38


Expansion Index = “V”40

Effect of ASR on Function = “Significant Property Value/Personal Injury – Ample41Warming”42

Reinforcement Detailing Class = “Good”43Concrete Deck44



Expansion Index = “III”1

Effect of ASR on Function = “Significant Property Value/Personal Injury – Ample2Warming”3

Reinforcement Detailing Class = “Fair”4Parapet Walls5


Expansion Index = “I”7

Effect of ASR on Function = “Significant Property Value/Personal Injury – Ample8

Warming”9

Reinforcement Detailing Class = “Fair”1011

Using the ASR assessment rating system (Table 1), the center pier and pier cap were12

determined to have an ASR severity rating of “3 – Appreciable,” the concrete deck was13

determined to have an ASR severity of “2 – Moderate,” and the parapet walls were determined to14

have an ASR rating of “1 – Minor.” Specific management plan, in accordance with Table 2,15

should be applied to the various structural elements of this bridge structure accordingly.16

17

CONCLUSION18Although ASR cannot be easily treated or mitigated, concrete structures undergoing ASR can19

still serve their intended purpose provided that the effects of the ASR are understood, monitored,20

and managed.21

Through this study, MassDOT developed an ASR inspection and evaluation protocol,22

including preliminary field assessment (visual observations, cracking index measurements, core23

sampling), supplemental laboratory testing (petrographic examination and damage rating index),24

and ASR risk assessment and customized management strategies for various ASR-affected25

MassDOT structures (Tables 1 and 2). In addition to providing the methodology for the field26

and laboratory testing, the protocol provides a framework for consistent interpretation of the test27

results that is commensurate with the severity of the ASR, the potential effect of any ASR on the28

structure, the degree of existing ASR, and the severity of the exposure of the structure.29

Using this protocol, MassDOT was then able to evaluate 40 structures suspected of30

containing ASR-affected aggregates.3132


REFERENCES1

21. Institution of Structural Engineers (ISE), Structural Effects of Alkali-Silica3

Reaction, Institution of Structural Engineers, London, England, July 1992.4

2. Fournier, B., M-A Bérubé, K.J. Folliard, and M. Thomas, Report on the Diagnosis,5

Prognosis, and Mitigation of Alkali-Silica Reaction (ASR) in Transportation Structures,6

Report No. FHWA-HIF-09-004, Federal Highway Administration, Office of Pavement7

Technology, Washington, DC, Jan. 2010.8

3. AASHTO PP 65-11 Standard Practice for Determining the Reactivity of Aggregate and9

Selecting Measures for Preventing Deleterious Expansion in New Concrete Construction,10

American Association of State Highway and Transportation Officials, 2011.11

4. P.E. Grattan-Bellew, Laboratory Evaluation of Alkali-Silica Reaction in Concrete from12

Saunders Generating Station, ACI Material Journal, Vol 92, Pages 126-134, March-13

April 199514

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