REC-ERC-89-4 Denver Off ice July 1989 U. S. Department of the Interior Bureau of Reclamation .._. INVESTIGATION OF ALKALI-SILICA JULY 1989 REACTIVITY IN FOUR DAMS IN THE 6. PERFORMING ORGANIZATION CODE SOUTHEASTERN UNITED STATES D-3731 7. AUTHOR(S) 6. PERFORMING ORGANIZATION REPORT NO. David Stark REC-ERC-89-4 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT NO. Construction Technology Laboratories 5420 Old Orchard Road 11. CONTRACT OR GRANT NO. Skokie IL 60077 5-CP-81-06560 13. TYPE OF REPORT AND PERIOD COVERED 2. SPONSORING AGENCY NAME AND ADDRESS Bureau of Reclamation Denver Office Denver CO 80225 14. SPONSORING AGENCY CODE DIBR 5. SUPPLEMENTARY NOTES Microfiche and hard copy available from Denver Office, Denver, Colorado. Ed:REC 6. ABSTRACT This investigation of the alkali-silica reactivity of four dams in the southeastern United States supplements a similar study on five dams in southwestern United States. The investigations involved an onsite inspection and laboratory studies of concrete cores. The investigative procedures included petrographic examination, relative humidity measurements, length changes of cores exposed to moist air at 100 OF and to sodium hydroxide solution, and osmotic cell measurements. A comparison or observations on the southeastern and the southwestern dams is made. The manifestations of distress due to the reaction are similar, and the effects of alkali content of the cement, different types of reactive aggregates, surface drying, and climate exposure conditions are noted. 7. KEY WORDS AND DOCUMENT ANALYSIS . DESCR JPJORS-- *alkali-silica reactivity/ *alkali-aggregate reactions/ concrete/ concrete cores/ aggregates/ petrographic investigations/ concrete dam IDEN JIFfERS-- Fontana Dam, NC/ Hiwassee Dam, NC/ New Savanna Bluff Lock and Dam, GA/ Oliver Lock and Spillway, AL . COSAJI Field/Group 08D COWRR: 0804 SRIM: 3. DISTRIBUTION STATEMENT 19. SECURITY CLASS 21. NO. OF PAGE! (THIS REPORT) ivoiloble from the Notional Technical lnformotron Service, Operations 42 UNCLASSfFlED bivision. 5285 Port Royol Rood, Springfield, Virginia 22161. 20. SECURITY CLASS 22. PRICE (THIS PAGE) UNCLASSfFlED REC-ERG89-4 INVESTIGATION OF ALKALI-SILICA REACTIVITY IN FOUR DAMS IN THE SOUTHEASTERN UNITED STATES David Stark Prepared Under Contract No. 5-CP-81-06560 JULY 1989 Concrete and Structural Branch Research and Laboratory Services Division Denver Office Denver, Colorado UNITED STATES DEPARTMENT OF THE INTERIOR * BUREAU OF RECLAMATION As the Nation’s principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserv- ing the environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through out- door recreation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major respon- sibility for American Indian reservation communities and for people who live in Island Territories under U.S. Administration. The research covered by this report was funded under the Bureau of Reclamation Program Related Engineering and Scientific Studies Allocation No. DR-441, “Repair of Concrete Affected by Alkali- Aggregate Reaction.” The information contained in this report regarding commercial prod- ucts or firms may not be used for advertising or promotional purposes and is not to be construed as an endorsement of any product or firm by the Bureau of Reclamation. The information contained in this report was developed for the Bureau of Reclamation; no warranty as to the accuracy, usefulness, or com- pleteness is expressed or implied. CONTENTS Page Introduction . 1 Conclusions ................................................................................ 1 Fontana Dam ............................................................................ 1 Hiwassee Dam ........................................................................... New Savannah Bluff Lock and Dam ........................................................ : Oliver Lock and Spillway .................................................................. 2 Investigative procedures ..................................................................... 2 Relative humidity measurements .......................................................... 2 Length change of concrete cores ........................................................... 3 Petrographic examination ................................................................. Osmotic cell data ......................................................................... t Discussion of results ........................................................................ 5 Fontana Dam ............................................................................ 5 Hiwassee Dam ........................................................................... 5 New Savannah Bluff Lock and Dam ........................................................ 6 Oliver Lock and Spillway .................................................................. 7 Osmotic cell tests ........................................................................ 7 Summary .................................................................................. 8 Bibliography ................................................................................ 9 Appendix A - Fontana Dam .................................................................. 11 Appendix B - Hiwassee Dam ................................................................ 17 Appendix C - New Savannah Bluff Lock and Dam ............................................. 23 Appendix D - Oliver Lock and Spillway ....................................................... 31 Appendix E - Osmotic cell data .............................................................. 37 . III INTRODUCTION 2. Potential for further expansive alkali-silica reactivity appears to exist in cores from Fontana This report describes an investigation into the Dam. development of alkali-silica reactivity in concrete in four dams located in southeastern United States. The 3. The primary reacted rock type is a metagray- following structures were investigated: wacke to quartzite aggregate. Minor amounts of schist also have reacted. All are present in both the 1. Fontana Dam-near Fontana, North Carolina; coarse and fine aggregate. 2. Hiwassee Dam-near Murphy, North Carolina; 4. Nearly all of the concrete in the dam is still sufficiently damp to permit expansive reactivity to 3. New Savannah Bluff Lock and Dam-near occur. Only concrete tested within a few inches of Augusta, Georgia; and surfaces exposed to ambient conditions at upper, interior locations in the dam appears to be suffi- 4. William Bacon Oliver Lock and Spillway-near ciently dry to preclude expansive reactivity. Tuscaloosa, Alabama (hereafter identified as Oliver Lock and Spillway). 5. Concrete near the roadway at the top of the dam, and in adits at elevations 1315 and 1700, contains Each of these structures had been investigated aggregate with potential for expansive reactivity. The previously for cracking and other effects due to alkali- greatest potential appeared to exist in concrete cores silica reactivity. Reports on these investigations, from near the roadway at the top of the dam, despite developed by the United States Army Corps of the finding that, to date, the most severe reactivity Engineers Waterways Experiment Station [l-5]*, appears to have already occurred at that location. have been used for background information. 6. Concrete near the roadway and at upper interior The present investigation was directed toward locations in the dam appears to contain alkali determining remaining potential for expansive alkali- available for continued expansion and abnormal silica reactivity, and identifying factors contributing differential volume change due to alkali-silica to reactivity. The investigation was based on the reactivity. determination of relative humidities at several locations in the dams, and on laboratory testing of Hiwassee Dam a limited number of concrete cores taken from the dam. Results from this study can be used for 1. Alkali-silica reactivity has occurred in concrete guidance in possible rehabilitation or reconstruction in Hiwassee Dam. The most severe reactivity, needs in the future. accompanied by cracking and abnormal expansion, has occurred near the roadway at the top of the dam. CONCLUSIONS Degree of reactivity, with little or no expansion or differential volume change, appears to have been Following are conclusions drawn from findings of minor in concrete at low levels in the dam. this investigation. These conclusions are based on results of a limited number and size of concrete 2. Metagraywacke, quartzite, and schist, which samples from various locations in the structures, occur in both the coarse and fine aggregate, have and, therefore, may not necessarily apply to the reacted to produce excessive expansion and structure as a whole. cracking. Fontana Dam 3. Concrete in virtually all portions of the dam investigated is still sufficiently damp to permit 1. Alkali-silica reactivity has occurred in concrete expansive alkali-silica reactivity to occur. in this dam, but severity of the reaction appears to vary significantly from area to area. Severe reactivity 4. Little, if any, unreacted but potentially