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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
Group 2: Visual Inspection
Group 3: Stereo Optical Microscope Examination
Group 4: Staining Tests
Group 5: Petrographic Optical Microscope Examination
Group 6: Scanning Electron Microscope Examination
Group 7: Chemical Tests
Group 8: X-ray Diffraction Analysis
LABORATORY LOG OF PCC PAVEMENT CORES Sheet ____ of ____ Project Designation: State:
Highway: 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.
|
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 |
|||
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 |
||
Diagnostic Feature |
Options | Comments |
Bleeding? |
bleed channels |
|
Fractures? |
none through aggregates |
|
Air void infilling? |
yes partial no |
|
Air void shape |
spherical irregular |
|
Embedded item condition? |
good corroded |
|
Surface condition? |
cracked carbonated |
|
Aggregate reaction products? |
yes no |
|
Location of reaction products? |
air voids |
|
Gaps around coarse or fine aggregates? |
description |
|
Gap widths larger for larger particles? |
yes no |
|
Are the gaps filled? |
yes no |
|
Coarse aggregate type? |
gravel quarried |
|
Lithological types of coarse aggregate? |
specify types identified |
|
Orientation/parallelism of coarse aggregate? |
specify which and specify |
|
Fine aggregate type? |
natural other (specify) |
|
Lithological types of fine aggregate? |
specify types identified |
|
Paste color – note uniformity of color. |
white light gray |
|
Paste hardness – note uniformity of hardness. |
soft hard |
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 |
|
Fine Aggregates |
||
Diagnostic Feature |
Options |
Comments |
Degree of alteration? |
isolated extensive |
|
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 |
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 |
|
Secondary deposits? |
yes no |
|
Location of secondary deposits? |
air voids |
|
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 |
Narrative Description of Petrography Results: ________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Analyst |
Job ID |
Date |
Sample ID |
Petrographic OM Observations - Alterations of the Aggregates |
||
Coarse Aggregates |
||
Diagnostic Feature |
Selected Descriptors |
Comments |
Degree of alteration? |
isolated extensive |
|
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 |
|
Identify reaction products |
specify |
|
Fine Aggregates |
||
Diagnostic Feature |
Selected Descriptors |
Comments |
Degree of alteration? |
isolated extensive |
|
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 |
|
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
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
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
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
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 |
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 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 |
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 |
Look for loss of paste at road surface, exposed coarse aggregate, and/or scaling. Can be isolated to surface or through slab depth. |
Stereo 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 ( The air-void size distribution should also be noted as different size
distributions can yield similar values of |
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 |
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. |
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 |
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 |
Visual inspection |
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 |
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 |
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 |
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 |
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 |
Sulfate attack may result in paste “crumbling,” commonly at joints. Loose aggregate observed in resulting void. |
|
External source |
Soil 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 |
Records review SEM |
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 |
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 |
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. |
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 |
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. |
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 |
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 |
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 |
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 |
Chloride ions released from dissolved salts can form these phases with aluminate phases in the paste. |
Table C-6. Diagnostic features of ASR.
Diagnostic |
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 |
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. |
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 |
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 |
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 |
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 |
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. |
CSEM |
Calcium and magnesium silicate hydrates are common reaction products. |
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