This report is an archived publication and may contain dated technical, contact, and link information

Federal Highway Administration >
Publications >
Research Publications >
01164 >
Appc.Cfm
Guidelines for Detection, Analysis, and Treatment of Materials-Related Distress in Concrete Pavements Vol II

Publication Number: FHWA-RD-01-164
Date: March 2002

Appendix C: Laboratory Data Collection Forms, Flowcharts, and Diagnostic Tables

C.1 LABORATORY DATA COLLECTION FORMS

To provide a uniform basis for approaching concrete analysis, the following data sheets are provided. The data sheets are organized into eight major groupings with a variable number of forms provided within each group. Analysts are expected to enter data and observations on these forms. A copy of these forms accompanies each core, following it through the analysis process. Additionally, a copy of the completed forms should be provided to the engineer along with the final laboratory report. The groupings and individual forms as presented in Guideline II are as follows:

Group 1: Core Receipt and Cataloging

Laboratory Log of PCC Pavement Cores.
Core Sampled for Laboratory Analysis.

Group 2: Visual Inspection

General Condition of Concrete.

Group 3: Stereo Optical Microscope Examination

Observations of the Concrete.
Alterations of the Aggregates.
Results of ASTM C457.

Group 4: Staining Tests

Summary of Staining Tests.

Group 5: Petrographic Optical Microscope Examination

Observations of the Concrete.
Alterations of the Aggregates.

Group 6: Scanning Electron Microscope Examination

General Conditions.
Summary of SEM Analysis.

Group 7: Chemical Tests

Summary of Chemical Tests.

Group 8: X-ray Diffraction Analysis

Analytical Conditions.

LABORATORY LOG OF PCC PAVEMENT CORES

Sheet ____ of ____

Project Designation: State: Highway:
Nearby City and Distance: Direction:
No. of Through Lanes (in direction sampled): Lane Sampled:
Beginning Milepost/Station: End Milepost/Station:
Operator: Core Diameter:
Coring Date: Core Barrel Tip Type:
Job ID:

Note: Each column shown below should be used to record information for all cores/pieces extracted from a single panel. “Depth” should be measured from the pavement surface to the bottom of the core/piece and recorded to the nearest 2 mm. Front direction is the direction of traffic.

CORE NUMBER	A	B	C	D	E	Other
CORE ID
LOCATION/STATION
*Offset From Joint*
*Offset From Shoulder*
*Number of Pieces?*
*Core Piece No. 1*
*Position* (Left, Right, Back, Front of core)
*Depth (mm)*
*Core Piece No. 2*
*Position* (Left, Right, Back, Front of core)
*Depth (mm)*
*Core Piece No. 3*
*Position* (Left, Right, Back, Front of core)
*Depth (mm)*
*Core Piece No. 4*
*Position* (Left, Right, Back, Front of core)
*Depth (mm)*
Remarks

Analyst		Core taken by		Date Cored
Date	Core ID		Job ID

CORE SAMPLED FOR LABORATORY ANALYSIS
Location (circle one): A B C D E Other?:	Picture: Top View
Core Diameter: mm
No. of Pieces:
Ht. Piece #1: mm
Wt. Piece #1: kg
Ht. Piece #2: mm
Wt. Piece #2: kg
Ht. Piece #3: mm
Wt. Piece #3: kg
Ht. Piece #4: mm
Wt. Piece #4: kg
Total Ht.: mm
Total Wt.: kg

Sketch

Picture: Side View

Analyst	Job ID
Date	Core ID

Visual Inspection - General Condition of Concrete Attach additional documentation and photographs as needed.
Diagnostic Feature	Options		Comments
Ring when struck lightly with a hammer?	Yes	No
Does it break with your fingers?	Yes	No
Is the concrete well consolidated?	Yes	No
Is segregation apparent?	Yes	No
Orientation/parallelism of aggregates?	Yes	No
Visible surface deposits or exudate?	Yes	No
Are cracks apparent in the paste?	Yes	No
Are the cracks widespread?	Yes	No
Cracks through aggregates?	Yes	No
Are there cracks around aggregates?	Yes	No
Deposits in cracks?	Yes	No
Embedded items present?	Yes	No
Adequate cover over the embedded items?	Yes	No
Are embedded items corroded?	Yes	No
Underside voids on elongated aggregates?	Yes	No
Are air voids filled?	Yes	No
Does paste hardness seem normal?	Yes	No
Is paste hardness uniform throughout?	Yes	No
High paste content?	Yes	No
Gradation of aggregates?	gap	uniform
Coarse aggregate top size?
Coarse aggregate type?	crushed	natural
Coarse aggregate rock type?
Fine aggregate type?	crushed	natural
Fine aggregate rock type?
Alteration/reaction with aggregates?	Yes	No

Comments_______________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

Analyst		Job ID
Date		Sample ID
Stereo OM - Observations of the Concrete Attach additional documentation and micrographs as needed.
Diagnostic Feature	Options	Comments
Bleeding?	bleed channels pockets under aggregates
Fractures?	none through aggregates in paste around aggregates
Air void infilling?	yes partial no
Air void shape	spherical irregular ellipsoidal
Embedded item condition?	good corroded
Surface condition?	cracked carbonated weathered leached normal
Aggregate reaction products?	yes no
Location of reaction products?	air voids cracks through aggregates cracks around aggregates cracks in paste
Gaps around coarse or fine aggregates?	description estimate occurrence
Gap widths larger for larger particles?	yes no
Are the gaps filled?	yes no
Coarse aggregate type?	gravel quarried crushed gravel slag other
Lithological types of coarse aggregate?	specify types identified
Orientation/parallelism of coarse aggregate?	specify which and specify direction of orientation
Fine aggregate type?	natural other (specify) crushed
Lithological types of fine aggregate?	specify types identified
Paste color – note uniformity of color.	white light gray dark gray yellow green other (specify)
Paste hardness – note uniformity of hardness.	soft hard medium

Comments ______________________________________________________________

_______________________________________________________________________

Analyst	Job ID
Date	Sample ID

Stereo OM Observations - Alterations of the Aggregates Attach additional documentation and micrographs as needed.
Coarse Aggregates
Diagnostic Feature	Options	Comments
Degree of alteration?	isolated extensive moderate
Cracking in aggregates?	yes no
Internal cracks narrow from center of aggregate out?	yes no
Cracks through aggregates extend into the paste?	yes no
Dissolution or softening of aggregates?	yes no
Reaction rims?	yes no
Reaction products from alteration?	yes no
Location of reaction products?	air voids cracks through aggregates cracks around aggregates cracks in paste pockets adjacent to aggregates
Fine Aggregates
Diagnostic Feature	Options	Comments
Degree of alteration?	isolated extensive moderate
Cracking in aggregates?	yes no
Internal cracks narrow from center of aggregate out?	yes no
Cracks through aggregates extend into the paste?	yes no
Dissolution or softening of aggregates?	yes no
Reaction rims?	yes no
Reaction products from alteration?	yes no
Location of reaction products?	air voids cracks through aggregates cracks around aggregates cracks in paste pockets adjacent to aggregates

Narrative Description of Alteration _______________________________________________

_______________________________________________________________________

Analyst	Job ID
Date	Sample ID

Results of ASTM C 457

Method Used:	Length Traversed
	Area Traversed
Magnification
	No. of Stops

Air-Void System Parameters
Specification	Typical Range for Acceptable Air Entrained Concrete	Calculated Value for Original Air-Void System (infilling counted as air)	Calculated Value for Filled Air-Void System (infilling counted as paste)
Spacing Factor ( )	0.01 - 0.02 mm
Specific Surface (a)	23.6 - 43.3 mm^-1
Paste/Air Ratio	4 - 10
Void Frequency (n)

Phase Abundance Analysis
Phase	Volume Percent
Coarse Aggregate
Fine Aggregate
Paste
Original Air Content
Filled Voids

Comments______________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

Analyst	Job ID
Date

Sulfate/ASR Reaction Product Staining Attach additional documentation and micrographs as needed.
Core ID	Method Used	Positive Staining	Comments
		Yes No
		Yes No
		Yes No
		Yes No

Depth of Carbonation Attach additional documentation and micrographs as needed.
Core ID	Depth of Carbonation	Comments

Comments_______________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

Analyst	Job ID
Date	Sample ID

Petrographic OM - Observations of the Concrete Attach additional documentation and micrographs as needed.
Diagnostic Feature	Selected Descriptors	Comments
w/c in bulk?	specify method and value
w/c at surface if different than bulk?	specify method and value
Evidence of trapped bleed water?	water voids below horizontal aggregate faces
Air-void structure at surface intact?	specify
Calcium hydroxide depletion?	specify
Sub parallel cracking or delamination at surface?	specify
Paste density variations around the aggregates?	specify
Cracking?	cracks through aggregates cracks around aggregates cracks in paste
Secondary deposits?	yes no
Location of secondary deposits?	air voids cracks through aggregates cracks around aggregates cracks in paste
Identify deposits.	specify
Lithological details of coarse aggregate?	specify
Lithological details of fine aggregate?	specify
Mineral admixtures?	present not present
Identification	fly ash silica fume GGBF slag other

Narrative Description of Petrography Results: ________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

Analyst	Job ID
Date	Sample ID

Petrographic OM Observations - Alterations of the Aggregates Attach additional documentation and micrographs as needed.
Coarse Aggregates
Diagnostic Feature	Selected Descriptors	Comments
Degree of alteration?	isolated extensive moderate
Cracking in aggregates?	yes no
Internal cracks narrow from center of aggregate out?	yes no
Cracks through aggregates extend into the paste?	yes no
Dissolution of aggregate?	yes no
Reaction rims?	yes no
Reaction products?	yes no
Location of reaction products?	air voids cracks through aggregates cracks around aggregates cracks in paste pockets adjacent to aggregates
Identify reaction products	specify
Fine Aggregates
Diagnostic Feature	Selected Descriptors	Comments
Degree of alteration?	isolated extensive moderate
Cracking in aggregates?	yes no
Internal cracks narrow from center of aggregate out?	yes no
Cracks through aggregates extend into the paste?	yes no
Dissolution of aggregate?	yes no
Reaction rims?	yes no
Reaction products?	yes no
Location of reaction products?	air voids cracks through aggregates cracks around aggregates cracks in paste pockets adjacent to aggregates
Identify reaction products	specify

Narrative Description of Alteration _______________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

Analyst	Job ID
Date

SEM - General Conditions
SEM or CSEM	Operating Pressure
Samples Conductive Coated (Y/N)	Coating Method/Thickness
Samples Dehydrated (Y/N)	Dehydration Method

SEM - Conditions for Quantitative Microanalysis
SEM or CSEM	Operating Pressure
Accelerating Voltage	Beam Current
Working Distance	Standardless or full-quantitative (with standards) analysis?
Oxygen measured or determined by stoichiometry?	Analysis done by EDS or WDS?

SEM - Conditions for X-ray Mapping
SEM or CSEM	Operating Pressure
Accelerating Voltage	Beam Current
Working Distance	Map Resolution
Map Dwell Time	Elements Mapped

Comments ______________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

Analyst	Job ID
Date	Sample ID

Summary of Scanning Electron Microscope Analysis

Summarize observations and hypotheses. Note micrograph numbers and spectrum identifications when referenced. Attach all data in a folder labeled with the core number and the title SEM Data.
__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

Analyst	Job ID
Date

Summary of Chemical Tests
Determination of w/c
Specimen ID	Method Used	Measured w/c	Comments

Determination of Sulfate Concentration
Specimen ID	Method Used	Sulfate Concentration	Comments

Determination of Chloride Concentration
Specimen ID	Method Used	Chloride Concentration	Comments

Analyst	Job ID
Date

XRD - Analytical Conditions
Type of specimen (e.g., powder, slab)	Specimen mounting method? (Side drifted, pressed pellet)
X-ray tube kV and mA	X-ray tube target material
Was a primary beam filter used and what type?	Monochromater used? (Y/N)
Divergence slit (specify mm or degrees)	Receiving slit (specify mm or degrees)
Scan range (degrees 2q)	Scan rate (degrees/min)
Dwell time (seconds/step)	Step size (degrees/step)
Peaks identified by automatic or manual search (auto or manual)?	Background subtracted before analysis?

XRD - Results of Qualitative Analysis

Summarize observations and hypotheses. List phases identified. Note diffraction pattern identifications when referenced. Attach all data in a folder labeled with the core number and the title Qualitative XRD Data.
__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

C.2 FLOWCharts AND Diagnostic TABLES

This section contains copies of the flowcharts and diagnostic tables for reproduction. The flowcharts present a systematic method for diagnosing MRD in concrete pavements. The analyst inspects the concrete using the methods described in Guideline II, being guided by the hierarchy of questions presented in the flowcharts presented in figures C-1 through C-4 in this appendix (figures II-15 through II-17 in guideline). The responses to the questions presented in the flowcharts determine what analytical procedures will be performed. As the analyst moves through the flowcharts, there is the potential for more than one MRD being identified. The analyst needs to keep track of all possibilities identified and then use the diagnostic tables presented in tables C-1 through C-7 in this appendix (tables II-1 through II-7 in guideline) to help isolate the most likely MRD(s). The tables summarize the common diagnostic features associated with each MRD.

Possible Distress	Present		Additional Information
Error in mix proportioning	Yes	No	See recommended literature
Poor placement	Yes	No	See recommended literature
Poor finishing/curing	Yes	No	See recommended literature
Poor steel placement	Yes	No	See recommended literature
Carbonation at depths > 5-10 mm	Yes	No	See recommended literature

Alternative Text for Figure C-1

Figure C-1. Flowchart for assessing general concrete properties based on visual examination.

Possible Distress	Present		Additional Information
Shrinkage cracks or sample preparation cracks	Yes	No	See recommended literature
Corrosion of embedded steel	Yes	No	Table C-1
Paste freeze-thaw	Yes	No	Table C-2
Aggregate freeze-thaw	Yes	No	Table C-3
Sulfate attack	Yes	No	Table C-4
Deicer attack	Yes	No	Table C-5
Infilling material	Yes	No	Figure C-3

Alternative Text for Figure C-2

Figure C-2. Flowchart for assessing the condition of the concrete paste and air.

Possible Distress	Present		Additional Information
Corrosion of embedded steel	Yes	No	Table C-1
Sulfate attack	Yes	No	Table C-4
Deicer attack	Yes	No	Table C-5
Alkali–silica reaction	Yes	No	Table C-6
Alkali–carbonate reaction	Yes	No	Table C-7

Alternative Text for Figure C-3

Figure C-3. Flowchart for identifying infilling materials in cracks and voids.

Possible Distress	Present		Additional Information
Natural cracking of aggregate	Yes	No	See recommended literature
Sample preparation cracks	Yes	No	See recommendedlLiterature
Aggregate freeze-thaw	Yes	No	Table C-3
Natural weathering of aggregates	Yes	No	See recommended literature
Alkali–silica reaction	Yes	No	Table C-6
Alkali–carbonate reaction	Yes	No	Table C-7
Infilling material	Yes	No	Figure C-3

Alternative Text for Figure C-4

Figure C-4. Flowchart for assessing the condition of the concrete aggregates.

Table C-1. Diagnostic features of corrosion of embedded steel.

Diagnostic Feature	Method of Characterization	Comments
Spalling and delamination of concrete over reinforcing steel	Field Evaluation Visual Inspection	Visual inspections can be used to readily identify areas affected by corrosion of embedded steel. It is characterized by rusting steel at the bottom of the spalled out area and rust stains on the loose pieces.
Visible corrosion products	Field Evaluation Visual Inspection Stereo OM Petrographic OM	The “rust” seen may contain crystalline magnetite but is primarily amorphous.

Table C-2. Diagnostic features of paste freeze-thaw damage.

Diagnostic Feature	Method of Characterization	Comments
Surface scaling or subparallel cracking	Field evaluation Visual	Look for loss of paste at road surface, exposed coarse aggregate, and/or scaling. Can be isolated to surface or through slab depth.
Surface scaling or subparallel cracking	Stereo OM Petrographic OM	Look for delamination/ subparallel cracking at surface or evidence of an overworked surface such as decreased air content at the surface.
Inadequate air- void system	Stereo OM	Measure air-void parameters consistent with ASTM Method C 457. Typical parameters for good concrete are as follows: Spacing Factor () = 0.1 - 0.2 mm Maximum Spacing ( ) = 0.2 mm Typical Specific Surface (a) = 23.6 - 43.3 mm^-1Paste/Air Ratio - 4 - 10 The air-void size distribution should also be noted as different size distributions can yield similar values of and a.
Secondary deposits filling air voids	Staining	Deposits stained cannot be analyzed by any other method to determine their composition.
	Stereo OM	Deposits result as water freely moves through the distressed paste. In extreme cases, the air-void system may be further compromised when significant numbers of voids are filled with secondary deposits. Common deposits include calcium hydroxide, calcium carbonate, ASR reaction products, and various sulfates including ettringite.
	Petrographic OM	Secondary deposits are commonly identified using the petrographic OM.
	SEM	The SEM operated at high vacuum is very useful for determining the composition of secondary deposits. Direct output of phase composition allows for absolute identification.
Microcracking around aggregates	Stereo OM Petrographic OM	Cracking will be in the paste. If cracks pass through aggregates, check table C-3 for coarse aggregate freeze-thaw, table C-6 for ASR, and table C-7 for ACR. Cracks will fill with secondary deposits.
Microcracking around aggregates	LVSEM	Severe cracking in the paste occurs if PCC is observed in a CSEM. Hydration products and ASR reaction products dehydrate in the high vacuum in the CSEM.

Table C-3. Diagnostic features of aggregate freeze-thaw deterioration.

Diagnostic Feature	Method of Characterization	Comments
Cracking near joints/cracks Staining/Spalling	Field evaluation	Has a very characteristic cracking pattern concentrated at corners, joints, and cracks (SHRP 1993). Increased permeability results from the cracking. Calcium hydroxide is leached and re-deposits on surface where it carbonates.
Cracks through nonreactive coarse aggregates	Visual inspection Stereo OM Petrographic OM SEM	Cracks through nonreactive coarse aggregates are very typical of D-cracking. Be very careful to completely rule out alkali–aggregate reaction. See tables C-6 and C-7 for diagnostic features of ASR or ACR.
Nonuniform gaps around coarse aggregates	Visual inspection Stereo OM	Gaps between the aggregate and paste form. These gaps may result from the dissolution of calcium hydroxide at the aggregate/paste interface or coarse aggregate dilation due to freezing. Subsequent redeposition of calcium hydroxide or calcite may occur in the cracks. Check for sulfate or ASR reaction products in cracks surrounding aggregates. A negative result helps to confirm aggregate freeze-thaw.
Known freeze-thaw susceptible aggregate Large top size aggregate	Records review Visual inspection Stereo OM SEM	Check aggregate sources for known freeze-thaw performance Aggregate freeze-thaw is more common in large aggregates (> 38 mm) and rare in aggregates smaller than 12.5 mm.
Poor void structure in the aggregate	Petrographic OM CSEM LVSEM	As a percentage of the total aggregate void space, excessive amounts of voids in the aggregate with diameters less than 5 microns is thought to be detrimental to aggregate freeze-thaw resistance.

Table C-4. Diagnostic features of sulfate attack.

Diagnostic Feature	Method of Characterization	Comments
Map cracking	Field evaluation	Paste expansion commonly results in map cracking over entire surface. In some cases, it is isolated to joints/cracks.
Deteriorated paste	Field evaluation	Sulfate attack may result in paste “crumbling,” commonly at joints. Loose aggregate observed in resulting void.
External source of sulfur only	Soil analysis Deicer analysis	Identify a sole source of sulfate that is external to the concrete to confirm external sulfate attack. Having both external and internal sources confounds the diagnosis.
Internal source of sulfur only	Records review SEM XRD	Identify a sole source of sulfate that is internal to the concrete to confirm internal sulfate attack. Having both external and internal sources confounds the diagnosis.
Paste expansion	Stereo OM Petrographic OM SEM	Expansion occurs, usually over a large area. Gaps form around aggregates with the gap width proportional to the aggregate diameter.
Significant sulfate deposits in cracks and voids	Staining Stereo OM	Stained deposits or stained paste cannot be accurately analyzed by SEM to determine their composition. A common sulfate deposit is ettringite. This is commonly recognized by acicular needle-like crystals infilling voids and cracks.
	Petrographic OM	Common sulfate deposits can be identified. Mixtures with other phases may be more difficult to identify.
	SEM	All deposits are readily identified using the SEM in high vacuum mode. Co-deposition with other phases may be more closely studied.
Significant sulfate deposits in the cement paste	Petrographic OM	Fluorescent dye epoxy impregnation assists in identifying microcracks in the paste. Cracks unfilled with epoxy should be assumed were created during sample polishing.
Significant sulfate deposits in the cement paste	LVSEM/ESEM	Cracks resulting from sulfate expansion can be viewed in an LVSEM/ESEM but caution should be exercised in identification of micron scale microcracks. Even in an ESEM, some dehydration does occur, leading to possible cracking. Cracks unfilled with epoxy should be assumed were created in the SEM or during sample polishing. If viewing an unimpregnated specimen, cracks unfilled with secondary deposits should be assumed were created in the SEM or during sample preparation.
Microcracking	Stereo OM Petrographic OM	For filled cracks, the cracks may have been present from other distress and secondary deposits formed in the cracks. Fluorescent dye epoxy impregnation greatly improves the identification of microcracks in the paste. Cracks not filled with epoxy are probably artifacts of sample preparation.
Microcracking	SEM	A characteristic spectrum for dehydrated ettringite has approximate element ratios of 1:2:4 (Al:S:Ca) by weight.

Table C-5. Diagnositc features of deicer scaling/deterioration.

Diagnostic Feature	Method of Characterization	Comments
Staining at joints or cracks	Field evaluation	Staining results from calcium hydroxide depletion and subsequent carbonation at surface.
Scaling or crazing of slab surface	Field evaluation Visual inspection Stereo OM	Common visual diagnostic feature. Similar and possibly related to paste freeze-thaw damage. See table C-2 for more on paste freeze-thaw damage.
Calcium hydroxide depletion near joints	Stereo OM Petrographic OM SEM	Calcium hydroxide (CH) is most soluble near the freezing point of water. Cyclic freezing and thawing from repeated deicer applications can accelerate the dissolution of CH near joints/cracks.
Secondary deposits of chloroaluminates	Petrographic OM SEM	Chloride ions released from dissolved salts can form these phases with aluminate phases in the paste.

Table C-6. Diagnostic features of ASR.

Diagnostic Feature	Method of Characterization	Comments
Map cracking with or without exudate Evidence of pavement expansion	Visual inspection	ASR is characterized by widespread map cracking. Can be more severe at joints and may be preferentially oriented perpendicular to the direction of least restraint (e.g., in pavement slabs, longitudinal cracks often predominate). Exudate common but not always observed. Evidence of joint closing or shoving of shoulder or fixed structures are possible indicators of expansion.
ASR reaction product in cracks and voids	Stereo OM Petrographic OM	A glassy clear to white amorphous reaction product resulting from an alkali–silica reaction. ASR reaction product is found within reacted particles, cracks, and air voids. The presence of ASR reaction product alone does not indicate ASR distress, as it must be of sufficient volume and composition to cause deleterious expansion.
ASR reaction product in cracks and voids	SEM	ASR reaction product can be chemically characterized with the SEM operating at a high vacuum. Primarily high alkali (low calcium) ASR reaction products are expansive.
Reaction rims on aggregates	Visual inspection Stereo OM Petrographic OM SEM	Reaction rims are often seen on most reactive aggregate. Reaction rims are common on aggregates that are undergoing ASR. Good gravel aggregates can exhibit rims that appear similar to ASR reaction rims. These are typically the result of weathering. Reaction products present help confirm ASR.
Aggregate known to be reactive	Records review	Check to see if the aggregates used were from a source that is known to be reactive.
Microcracking radiating from reacted cracked aggregates Softening of the aggregate	Visual inspection Stereo OM Petrographic OM LVSEM/ESEM	Reacted aggregates may break down internally and often partially dissolve. As the aggregate degrades, the ASR reaction product produced may be expansive and cause cracking to occur. The cracks are within the periphery of the aggregate but around the center. Often the cracks will narrow from the center of the aggregate out. Coarse and fine aggregates can both cause ASR distress. Common reactive aggregates are composed of or include chert, flint, siliceous shale, strained quartz, and porous volcanic glasses.

Table C-7. Diagnostic features of ACR.

Diagnostic Feature	Method of Characterization	Comments
Map Cracking with or without exudate Evidence of expansion	Visual inspection	ACR is characterized by widespread map cracking. Can be more severe at joints. Exudate common but not always observed. Evidence of joint closing or shoving are possible indicators of expansion.
Cracks radiating from the coarse carbonate aggregate into the paste	Visual inspection Stereo OM Petrographic OM LVSEM	Deterioration from ACR results from the expansion of the aggregate that causes cracks in the aggregate, which propagate into the paste. The expansion is the result of reaction products produced in the dedolomization reaction.
Aggregate known to be reactive	Records review	Check to see if the aggregates used were from a source that is known to be reactive.
Characteristic texture of ACR reactive aggregates	Petrographic OM	Most ACR reactive aggregates have a characteristic texture. ASTM C 856 states the basic texture as being relatively larger rhombic dolomite crystals in a fine-grained calcite matrix with clay and silt-sized quartz. Substantial amounts of both dolomite and calcite are present. Other textures have been reported as reacting, with a common thread being soluble magnesium phases that react to form expansive products.
Characteristic texture of ACR reactive aggregates	CSEM LVSEM	Calcium and magnesium silicate hydrates are common reaction products.

Previous | Table of Contents | Next

Page Owner: Office of Research, Development, and Technology, Office of Infrastructure, RDT

Topics: research, infrastructure, pavements and materials
Keywords: research, infrastructure, pavements and materials
TRT Terms: research, facilities, transportation, highway facilities, roads, parts of roads, pavements, Concrete--United States--Testing, Pavements, Concrete--United States--Maintenance and repair, Concrete pavements, Portland cement concrete, Pavement distress
Scheduled Update: Archive - No Update needed

This page last modified on 03/08/2016

Appendix C: Laboratory Data Collection Forms, Flowcharts, and Diagnostic Tables

C.1 LABORATORY DATA COLLECTION FORMS

CORE ID

C.2 FLOWCharts AND Diagnostic TABLES