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This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-HRT-06-069
Date: February 2006

Techbrief: Selecting Candidate Structures for Lithium Treatment: What to Provide The Petrographer Along With Concrete Specimens

FHWA Contacts: Richard Meininger, 202–493–3191, richard.meininger@fhwa.dot.gov
Fred Faridazar, 202–493–3076, fred.faridazar@fhwa.dot.gov

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The process of selecting candidate structures (and appropriate components of structures) for lithium treatment invariably involves sampling one or several components of the structures for laboratory investigations, particularly petrographic examination, and expansion tests (expansion tests optional). This sampling is done to (1) confirm whether alkali-silica reactivity (ASR) is an important part of the deterioration process, (2) determine the extent of the deterioration and, (3) if required, determine how much more expansion/deterioration is to be expected. Figures 1 and 2 show the types of cracking that can be a visual indication of a candidate for lithium treatment.

Photo. Extensive map cracking in several concrete barriers along State Highway 2 near Leominster, MA. This photo shows several horizontal cracks along two sections of concrete barriers, and the cracks are connected by several vertical cracks.
Figure 1. Extensive map cracking in several concrete barriers along State Highway 2 near Leominster, MA.

Photo. Closeup view of cracking on concrete barrier along State Route 2 near Leominster, MA. This photo shows a closeup view of the cracks in the concrete barrier; moisture surrounds the cracks and the cracks look dark brown.
Figure 2. Closeup view of cracking on concrete barrier along State Route 2 near Leominster, MA.

To help evaluate the potential cause(s) of distress, it is important to collect and report whatever data are available. The following types of information should be provided to the petrographer:

Photo. Coring equipment being used to extract a (10-centimeter) 4-inch diameter core from a concrete barrier. This photo shows a person using horizontal coring equipment to extract a concrete core from an ASR-affected concrete barrier.
Figure 3. Coring equipment being used to extract a 10-centimeter (4-inch) diameter core from a concrete barrier.

Photo. Close-up of extracted core from a concrete barrier. This photo shows a concrete core that was extracted from the barrier; the core is 10 centimeters (4 inches) in diameter and about 30 centimeters (12 inches) in length. The core sits on top of a concrete barrier.
Figure 4. Closeup of an extracted core from a concrete barrier.

Protocol for Selecting ASR-Affected Structures for Lithium Treatment (FHWA-RD-04-113) and the TechBrief for the report (FHWA-HRT-06-071) provide information on the basic petrographic observations and tests that can be performed in the laboratory.(7)

Assistance can be provided to the State departments of transportation in developing the proposal, especially in the analysis of the field evidence of the ASR, the evaluation of the petrographic features of the ASR, and the mechanical testing of samples taken from candidate structures. See figures 5, 6, 7, 8, and 9.

Photo. Polished surfaces of three concrete cores. The size, shape and color of the coarse aggregate particles and their distribution are shown. Photograph by Dr. P.E. Grattan-Bellew. This photo shows three concrete cores cut lengthwise. The cores are labeled, starting from the top, 10-2, T22-2, and 56-2. A metric scale is shown next to the third core sample and illustrates that the diameter of the core is near 10 centimeters wide (near 4 inches). The aggregates in the samples are clearly shown in all three samples.
Figure 5. Polished surfaces of three concrete cores. The size, shape, and color of the coarse aggregate particles and their distribution in the concrete are shown. (Photograph by Dr. P.E. Grattan-Bellew)(8)

Photo. Polished surfaces of three concrete cores. The extensive cracking in the cores is shown. Photograph by Dr. P.E. Grattan-Bellew. This photo shows a cross-sectional view of three concrete cores. Only two cores are labeled, starting from the top, A-4 C#2, and A-4 C#1. A metric scale is shown next to the top core sample and illustrates that the diameter of the core is near 10 centimeters wide (4 inches). The aggregates in the samples are clearly shown in all three samples.
Figure 6. Polished surfaces of three concrete cores. The extensive cracking in the cores is shown. (Photograph by Dr. P.E. Grattan-Bellew)(9)

Photo. An example of a polished concrete surface. This photo shows a microscopic view of a polished concrete surface. The aggregate particles along with small vertical cracking can be seen.
Figure 7. Example of a polished concrete surface.

An example of a thin section concrete sample. This photo shows a microscopic view of a concrete sample, showing the cement paste, a particle of reactive aggregate, and a ribbon of reactive product running through both of them. The crack runs from a point where the gel meets the cement paste and continues parallel to the gel.
Figure 8. An example of a thin section concrete sample.

Photo. Polished surface of a concrete core photographed in ultraviolet light. The arrows show the gel that has filled in the cracks in the quartzite aggregate and in the cement paste. Photograph by Dr. P.E. Grattan-Bellew. This photo shows a microscopic view of a concrete sample under ultraviolet light. The sample appears purple. A “white ribbon” runs along the middle of the core, and there are four arrows pointing to this ribbon of ASR gel. The quartzite aggregate is located in the top third and bottom third of the sample, and the label QZT is shown in these areas. A scale is shown on the right side of the image, 2 millimeters (0.08 inches) in length.
Figure 9. Polished surface of a concrete core photographed in ultraviolet light. The arrows show the gel that has filled in the cracks in the quartzite aggregate and in the cement paste. (Photograph by Dr. P.E. Grattan-Bellew)(9)

FHWA currently is conducting a series of research activities under the lithium technology program; its research activities are overseen by Fred Faridazar. He can be reached at 202–493–3076 or fred.faridazar@fhwa.dot.gov.

References

  1. Federal Highway Administration. (2001). Guidelines for Detection, Analysis, and Treatment of Materials-Related Distress in Concrete Pavements Volume 1: Final Report (Report No. FHWA-RD-01-163). Washington, DC: Federal Highway Administration.
  2. Federal Highway Administration. (2001). Guidelines for Detection, Analysis, and Treatment of Materials-Related Distress in Concrete Pavements Volume 2: Guidelines Description and Use. (Report No. FHWA-RD-01-164).Washington, DC: Federal Highway Administration.
  3. British Cement Association. (1992). The Diagnosis of Alkali-Silica Reaction—Report of a Working Party. 2nd Edition. British Cement Association: Wexham Springs, Slough (UK), 44 pp.
  4. Stark, D. 1991. Handbook for the Identification of Alkali-Silica Reactivity in Highway Structures. (Report No. SHRP-C-315). Washington, DC: Strategic Highway Research Program, National Research Council. (Revised 2002—revised version available at http://leadstates.tamu.edu/asr/library/C315/.)
  5. Federal Aviation Administration. (2004). Handbook for Identification of Alkali-Silica Reactivity in Airfield Pavement. (Report No. AC 150/5380-8). Washington, DC: Federal Aviation Administration.
  6. Canadian Standards Association. (2000). Guide to the Evaluation and Management of Concrete Structures Affected by Alkali-Aggregate Reaction. (CSA A864-00). Canadian Standards Association: Mississauga, ON, Canada.
  7. Federal Highway Administration. (2004). Protocol for Selecting ASR-Affected Structures for Lithium Treatment. (FHWA-HRT-04-113). Washington, DC: Federal Highway Administration.
  8. Grattan-Bellew, P.E., “Petrographic Evaluation of Concrete Cores from Massachusetts Jersey Barrier Project,” Materials & Petrographic Research G-B Inc., Ottawa, ON, Canada, May 2005.
  9. Grattan-Bellew, P.E., “Petrographic Investigation of Concrete Cores from Arches #3 and #4 of a Bridge in Alabama,” Interim Report, Materials & Petrographic Research G-B Inc., Ottawa, ON, Canada, July 2005.

Other Sources
Federal Highway Administration. (1997). Petrographic Methods of Examining Hardened Concrete: A Petrographic Manual. (FHWA-RD-97-146). Washington, DC: Federal Highway Administration. (The updated version will be available on the FHWA Web site at http://www.fhwa.dot.gov/publications/research/infrastructure/pavements/pccp/97146/.)

Researchers—This study was performed by The Transtec Group, Austin, TX. The research team includes Dr. Kevin Folliard (University of Texas at Austin), Dr. Michael Thomas (University of New Brunswick), Dr. Benoit Fournier (CANMET/ICON), and Ms. Yadhira Resendez (The Transtec Group).

Distribution—This TechBrief is being distributed according to a standard distribution. Direct distribution is being made to the Divisions and Resource Center.

Availability—This document will be available as an appendix in the report Interim Recommendations for the Use of Lithium to Mitigate or Prevent ASR. This document may be obtained from the FHWA Product Distribution Center by e-mail to report.center@fhwa.dot.gov, by fax to 301–577–1421, or by phone to 301–577–0818.

Key Words—Aggregates, alkali-silica reaction, alkali-aggregate reaction, cracking, diagnosis of ASR, expansion, field inspection, gel, lithium, lithium treatment, petrographic examination, prognosis of ASR.

Notice—This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.

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