Regulatory Guide 1.107
| ML13350A287 | |
| Person / Time | |
|---|---|
| Issue date: | 10/31/1975 |
| From: | NRC/OSD |
| To: | |
| References | |
| RG-1.107 | |
| Download: ML13350A287 (6) | |
- ~..' 6 U.S. NUCLEAR REGULATORY COMMISSION November 1975 REGULATORY GUIDE
OFFICE OF STANDARDS DEVELOPMENT
REGULATORY GUIDE 1.107 QUALIFICATIONS FOR CEMENT GROUTING FOR
PRESTRESSING TENDONS* IN CONTAINMENT STRUCTURES
A. INTRODUCTION
The presiressing tendon system of a prestressed con- crete containment structure is a principal strength dce- General Design Criterion 1. "Quality Standards and ment of the structure. Since tile ability of tile contain- Records," of Appendix A, "General Design Criteria for ment structure to withstand the ev, postulated to Nuclear Power plants," to 10 CFR Part 50, "Licensing occur during the life of the stru epends on the of Production and Utilization Facilities." requires that functional reliability of the sir.u e.s Jpal strength structures, systems, and components important to safety elements, any significant dOf 1io eoiis prestress- be designed, fabricated, and erected to quality standards ing elements due to corroent potential risk commensurate with thle importance of the safety func- to the public safety. cc,,y em for inhibiting tions to be performed. This guide describes quality stan- corrosion of tile prre lg.ents should possess a dards acceptable to the NRC staff for the use of port- high degree of r abi porming its intended func- land cement grout as the corrosion inhibitor for tion.
prestressing tendons in prestressed concrete containment Unl..d .dons.grouted tendons are not structures.
sava*t jcl
' inspection after they are grouted. It
B. DISCUSSION
is t~ re* n*n ial that the proposed grout and grout- S ure-tRe thoroughly evaluated before it is used The recommendations of this guide are applicable *ctruction of the containment structure. An when Portland cement grout is used as the corro al v e of grouting. in addition to providing corrosion inhibitor for the highly stressed tendons of prest se ction, is that a well-designed and well-constructed concrete containment structures. The recommend ns grouted tendon system provides a degree of bond be- of the guide are not intended for use in r t tween the tendons and the surrounding concrete. This grout for rock anchors. bond in turn helps the anchorage system to resist the fluctuating stresses that arise after construction of the To date, the staff has received appl pro- structure.
posing grout as the corrosion protection system for bar Section III, Division 2. "Code for Concrete Reactor tendons and strand tendon e recommendations of Vessels and Containments," of the ASME Boiler and this regulatory guide tbfT5U~pply to a grouted Pressure Vessel Code (Reference i) provides some re- tendon system when the t .icatedfrom either quirements for grout constituents and for the physical bars or strands. F ' n wire tendons, a program and chemical properties of grout. Regulatory Position based on similar dity s may be developed and da C. I of this guide briefly describes minimum quality stan- submitted toe fior iuation. dards for grout materials, referencing the ASME Code Articles where applicable and acceptable to the NRC
staff. The regulatory position also outlines important considerations affecting proper grouting. References 2.
"For the puipose" of this guide, a "tendon" is defined -,s a 3. and 4, as well as data furnished by applicants who tensioned steel element consisting of wires, strands, or bt's an- have proposed grout as tile corrosion inhibitor for pre- chored at each end to an end anchorage assembly. stressing steel, have been used to arrive at this position.
ItSNAC REGULATORY GUIDES Commients should be tent to the Secretary of the Commission. U.S Nuclear RelgUlatory ComrsiesI*On. Westhingfor.. O C. ;l0t'S. Attention Doclreling enld aSlatol Secoisn Regulatory Guides ate issuao -a describe sod malke Ri ailiblta to the public pains of the methods acceptable to the NR( stalfl of impllmen*ridg spectlic Commission's equisiotimn to detlitevate lchnique used by the staff in 5evlu The guides are issued in the oltlowirta Ron broad divisionl cting speciic Problems Or postulated C-cideorio. of to provide guidance to applt cents. Regulatorv Guides are not subeth*its ot rogufliots..and compleince I Power Reactors 6 Products with them is not iemuerad Methods and tolutaoni different irom those set out in 2 Alsesarch and Test Resctors 7 Transporetiaon the guides will be acceptable if they providea bisis foe the findings requisite to 3 Fuels and Mterlilas Facilities I OcieplilioniltHealth the issuance or continuance of a permit or hiCient by theCommission 4 Environme1nttl and Siting 9 Antitrust Review Comments and suggestions for improvemlents in theos guides are encouraged 5 Materials and PIant Protection 10 General at all times. end guides will be revised. es appropriate, to accommodate com ments and to reflect new i.formation of elpetionr.e However. comments on Copies ot Published guides may be Obtained by wrrl"ltn request indicating the thiS guide. f received within about two months after its issuance. wr1t be pei divisions doeired to the V S Nucier Regulatory Commisseion. Washington. D.C
ticulafly useful in evaluating5 the need lor an serlf revision 20%5. Attention Difeclot. Office of Standards Development
', c,..
IAppendix A to this guide provides a list of relevant and: Materials)* methods and expressed in terms of literature that may be used by the applicant to establish amount of water in the grout composition.
procedures and criteria for the specific grouted tendon program. However, the listing of these references d In general, portland cement conforming to ASTM
not constitute a blanket endorsement by the staff of CI50, Type I or Type 11, Is suitable for the grout. How.
their content. ever, grouting under certain climatic or environmental conditions may dictate the use of other types of Specific areas of concern that shou!,ý ' ;ven cements. Chlorides aTe normally present in cement, but proper attention during the development tf a grouted the amount is usually not reported. The determination tendon system are discussed in the following paragraphs. of chlorides in cement should be a requirement when specifying the cement for grout.
The effectiveness of grout in performing its in- tended function of inhibiting corrosion depends mainly Admixtures should be free of any substance likely on two characteristics: to damage the prestressing steel. Use of aluminum pow.
det to produce expansion has been viewed by many
1. The grout should not cause chemical attack on engineers with skepticism. Under an alkaline environ.
the prestressing elements through its interaction with the ment (pH>9), the aluminum - vder generates minute material of the tendon steel or the material of the duct* bubbles of hydrogen gas that would not endanger the or both tensioned steel at the prevailing range of pressures and temperatures. However, the potential danger of nascent
2. "he grout should completely fill the te::don duct hydrogen attack on steel does exist if the tensioned steel on hay iening. contains flaws. The parameters affecting the use of aluminum powder are described in Reference 9.
Various deleterious substances ha;e been reported The protective mechanism of grout is primarily de- as potential sources of corrosion of prestressing steel. pendent on its ability to provide a continuous alkaline Most of the reported failures of prestressing elements environment around the tensioned steel elements. A
have been attributed (a) to the presence of chlorides in satisfactory environment results if the pH value of the the atmosphere or in the constituents of grout or (b) to wet grout is maintained above 9.5.
the presence of hydrogen sulfide in the atmosphere (Ref- erences 5, 6. and 7). Nitrates and sulfates generally In addition to the control on grout materials and on found in mixing water have been theorized to be poten. mixing and injecting the grout tV ensure the intended tial sources of stress corrosion of prestressing steel. How- protection of the prestressing ste:r, it is important to ever, it has been reported (Reference 8) that, in a con- take other precautions directly related to the corrosion crete environment, oxygenated anions such as sulfates protection of the prestressing steel:
and nitrates do not exhibit intense corrosion properties.
It has also been reported (Reference 3) that most of the 1. It is necessary that the tendon remain clean, dry, chlorides are neutralized during the hydration of port- free from deleterious corrosion, and undamaged up to land cement. The threshold values below which these the time it is grouted.
substances will not participate in initiating corrosion have not been established. Hence, a safe and prudent 2. When a preassembled tendon-sheathing assembly approach would be to make sure that these substances is to be placed before concreting, the tendon should be are limited to the lowest practical levels in grout con- protected against corrosive environment during assem.
stituents. The use of water contaminated with hydrogen bly, handling, storing, transporting, placing, and ten- sulfide should be prohibited. Use of demineralized water sioning.
is recommended.
3. Before placing the tendon in the duct, it is im- portant to ascertain that the duct is free of moisture and The limits recommended for chlorides, nitrates, and other deleterious substances.
sulfates in Regulatory Position C. .e should not be exceeded in overall composition of the grout. The quan- 4. Galvanized sheathing may be used, but if it is, tities of these substances in the grout constituents may the contact surfaces of the tendons and the sheathing are be determined individually for each of the consitituents potential areas for hydrogen embrittlement. This is parti- by the applicable ASTM (American Society of Testing cularly critical If the time between the tensioning and grouting is long and the dact contains moisture with or without deleterious subst-, nces.
- For the purposes of this guide, a "duct" is a hole or void provided in the concrete for the post-tensioning tendon. A duct may be provided by embedding metal sheathing in cast-in-place **A list of relevant ASTM standaids is provided in Appendix B
concrete. of this guide.
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S. In general, the period between tensioning and Chloride 100 ppm grouting is critical from the standpoint of hydrogen Nitrates IG0 ppil embrittlement. Steps should be taken to minimize this Sulfates* 150 ppm time period. Acceptable corrosion protection methods (2) The pH1 value of the grout at inlet and should be employed during this period. outlet of the duct should be maintained above 9.5.
Effective corrosion protection of prestressing ten- (3) During the grouting period, the amount of dons can be provided by portland cement grout if appro- deleterious substances in the grout constituents should priate precautions are iaken to eliminate the potential be checked weekly and whenever the composition of the sources of corrosion, To this end, close quality control is constituents is changed or is suspected of having necessary for each constituent of the grout, the tendon changed.
material, and the tendon duct material and for the method of mixing and pumping the grout and ensuring 2. Physical Properties of the Grout that the tendon is surrounded from end to end with qualified grout. The physical properties of the cement grout should satisfy thb requirements of Article CC.2243.2 of the
C. REGULATORY POSITION
ASME Code. Adequate tests should be carried out in accordance with the test methods described in that article to demonstrate that the grout satisfies these requirements.
The following minimum quality standards should be maintained when portland cement grout is to be used for
3. Duct the corrosion protection of prestressing steel.
a. The duct size should be adequate to allow the insertion and tensioning of tendons without undue
1. Materials difficulty. The area of the grout that penetrates and surrounds the tendon at any section should be at least a. Portland Cement. Cement should conform to the equal to the cross-sectional area of the tendon. The duct requirements of ASTM C-150. The type to be selected sheathing and its splices should be of ferrous metal and should be suitable for the intý.;Ided use. may be galvanized. The duct sheathing and its splices should be watertight so that cement slurry cannot pass b. Fine Aggregate. Fine aggregate-filler may be used through while the surrounding concrete is being placed.
when permitted by the requirements of Article The duct sheathing and its splices, when surrounded by CC-2243.1 of the ASME Boiler and Pressure Vessel hardened concrete, should be capable of withstanding Code, Section IIl, Division 2 (Reference I). the maximum grouting pressure without leakage.
c. Water. The water should not contain ingredients b. Vents should be provided at any major changes harmful to the prestressing steel or the grout. Water in section of the duct, as well as at the high points.
contaminated with hydrogen sulfide (sulfide ion) should Drains should be provided at the low points.
be prohibited. The water to be used for grouting should be qualified for use by making comparative tests in 4. Equipment for Grouting accordance with the test methods ,nd tolerance levels described in Article CC-2223.2 of the ASME Code. a. The grouting equipment should include a mixer that is capable of continuous mechanical mixing and d. Admixtures. Acceptable admixtures may be used that can produce a grout free of lumps and undispersed if tests have demonstrated that their use improves the cement. To this end, tests should be performed to properties of grout, e.g., increases workability, reduces demonstrate the optimum range of mixing time and the bleeding, entrains air, expands the grout, or reduces sequence of placing the constituent materials in the shrinkage. The quantities of harmful substances in the mixer under extreme anticipated environmental condi- admixture should be kept to a minimum. Use of calcium tions.
chloride should be prohibited.
b. The pump should be of the positive displacement e. Limits on DeleteriausSubstancesand pH. type and should be capable of exerting the required maximum pressure. A safety device should be provided to guard against exerting a pressure in excess of 300 psi
(1) The quantity of the following substances (expressed as parts per million parts of water) in overall grout composition should not exceed the following *Sulfates in the form of sulfur trioxide as a cement component limits: need not be considered.
1.107-3
A.. -
or a pressure that could damage the duct, duct splices, or 800 psi. The grout temperature should not exceed 90*F
surrounding concrete, whichever is less. The pumps during mixing and pumping.
should not suck air In with the grout.
d. The development of the grouting procedure c. A screen having clear openings of 1/8 inch should should consider the extremes of anticipated environ- be provided between the mixed grout and the pump to mental conditions. The procedure should ensure that the ensure that the grout does not contain lumps. If an ducts will be filled and that the tendon steel will be excessive amount of lumps remain on the screen, the completely surrounded by grout.
batch should be rejected.
e. All openings, air vents, and drains should be S. Grouting hermetically sealed after grouting to prevent the ingress of water and other corrosive agents.
a. Grouting should be carried out immediately after tensioning. The period between tensioning and grouting f. The grouting should not preclude the visual should be kept below 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The tendon should be examination of the exposed load-bearing components of protected from inclement weather during this period. If the tendon anchorage system (see Regulatory Guide for structural or climatic reasons an additional delay is 1.90, "Inservice Inspection of Prestressed Concrete expected, the tendons should be protected by methods Containment Structures with Grouted Tendons").
or products that would not jeopardize the effectiveness of the grout as a corrosion inhibitor. Flushing before 6. Tendon grouting is not recommended. When flushing has to precede the grouting, appropriate measures should be The tendon should be clean, dry, free from delete- taken to ensure rious corrosion, and undamaged up to the time when it is grouted. The preassembled tendon sheathing assembly
(1) That the level of harmful substances in the should be protected against corrosive influences from inplace grout does not increase above that in the the time of assembly to the time of grouting.
designed grout and
D. IMPLEMENTATION
(2) That the properties of the injected grout satisfy the recommendations in Regulatory Position C.2. The purpose of this section is to provide informa- tion to applicants and licensees regarding the NRC staff's b. The length of time that the grout can be used after plans for utilizing this regulatory guide.
mixing should be established by tests that verify Except in those cases in which the applicant proposes
(1) That the intended reaction of the admixtures. an acceptable alternative method for complying with such as expansive agents, continues when such a grout is specified portions of the guide, the guide will be used by injected in the duct and the NRC staff on the following bases:
(2) That this time is less than that required for the 1. Construction permit reviews for applications initial set of the grout as determined by the method of docketed after August 1, 1976, will be evaluated on the ASTM C191. basis of this guide.
2. Plants for which construction permits have been c. The average temperature of the tendon duct issued prior to August I, 1976, will have their operating during grouting should be kept above 400F. This license reviews made in accordance with the temperature should be maintained until the minimum commitment made by the applicant in the construction
(2-inch cube) strength of the job-cured grout exceeds permit.
1.107.4
APPENDIX A
REFERENCES
I. "Code for Concrete Reactor Vessels and Con- 1960. Copies may be obtained from the same address as tainments," American Concrete Institute Committee shown above in Reference 6.
359 and American Society of Mechanical Engineers Sub- committee on Nuclear Power, 1975. Copies may be ob- 8, Scott, G. N., "Corrosion Protection Properties of tained from the American Society of Mechanical Engi- Portland Cement Concrete," Journal of the American neers, 345 E. 47th St., New York, N.Y. 10017 or from Waterworks Association, Vol. 57, No. 8, Aug. 1965.
the American Concrete Institute. P.O. Box 19150, Red- Copies may be obtained from the American Water Works ford Station, Detroit. Mich. 48219. Association, 2 Park Avenue, New York, N.Y. 10016.
2. "Recommended Practice for Grouting of Post- 9. "Admixtures for Concrete." American Concrete Tensioned Concrete," Prestressed Concrete Institute Instiute Committee 212. Copies may be obtained from Committee on Post-Tensioning. published in PCI Jour. the Amcrican Concrete Institute. P.O. Box 19150. Red- nal, Nov./Dec. 1972. Copies may be obtained from the ford Station, Detroit, Mich. 48219.
Prestressed Concrete Institute, 20 North Walker Drive, Chicago, Ill. 60606. 1U. Harstead, G. A.. et al, "Testing for Large C. ived Prestressing Tendons," Proceedings of the Ameri-
3. "Report on Grout and Grouting of Prestressed can Society of Civil Engineers, Power Division, March Concrete," Proceedings of the Seventh Congress of the 1971. Copies may be obtained from the American
.Fideration Internationale de la Pricontrainte, 1974. Society of Civil Engineers. 345 E. 47th Street. New Copies may be obtained from the F1d~ration Inter- York, N.Y. 10017.
nationale de la Pricontrainte, Terminal House, Gros- venor Gardens, London SWIW OAU. II. Lange, H., "The Vacuum Process, A New Method for Injecting Prestressing Tendons." paper sub- mitted for the Seventh Congress of the Ft:deratio;. Inter-
4. "Specifications for Structural Concrete for nationale de la Pricontrainte, New York, N.Y. 1974.
Buildings," American Concrete Institute Committee Copies may be obtained from the FIdrWration Inter-
301, 1972. Copies may be obtained from the American nationale de la Prn'contrainte, Terminal House, Gro.
Concrete Institute, P.O. Box 19150, Redford Station, svenor Gardens, London SW1W OAU.
Detroit, Mich. 48219.
12. Schupack, M., "Development ofa Water Reten-
5. Leonhardt, F., Prestressed Concrete Design and :ive Grouting Aid to Control the Bleed in Cement Grout Construction, Wilhelm Ernst & Sohn, Berlin, Second Used for Post-Tensioning," presented at the Seventh Edition, 1964. Congress of the Fed~ration Internationale de ]a Pre'con- trainte, New York, N.Y., 1974. Copies may be obtained
6. Szilard, R., "Corrosion and Corrosion Protection from the same address as shown above in Reference 1I.
of Tendons in Prestressed Concrete Bridges," ACI Jour- nal, Jan. 1969. Copies may be obtained from the 13. Kajfasz, S., et al, "Phenomena Associated with American Concrete Institute, P.O. Box 19150, Redford Grouting of Large Tendon Ducts and Morphology of Station, Detroit, Mich. 48219. Defects," technical contribution to the Seventh Congress of the F6d6ration Internationale de la Pricontrainte,
7. Monfore, G. E., and Verbeck, G. J., "Corrosion New York, N.Y. 1974. Copies may be obtained from the of Prestressed Wire in Coacrete," ACI Journal, July address shown in Reference 11.
1.107-5
APPENDIX B
LIST OF RELEVANT ASTM STANDARDS
D512.67. "Test for Chloride ion in Industrial Water and C109-707, "Test for Compressive Strength of Hydraulic Industrial Waste Water"
Cement Mortars (Using 2-in. Cube Specimens)"
C 150-72, "Specification for Portland Cement Concrete" D992-71, "Test for Nitrate Ion in Water"
D51674, "Tests for Sulfate [on in Water"
C191-71, "Time of Setting Hydraulic Cement by Vicat Needle" D596-74, "Reporting Results of Analysis of Water"
C260-79, "Specifications for Air-Entraining Admixtures Dl 129-74. "Terms Relating to Water"
for Concrete" D! 293-65, "pH of Water and Wafte Water"
C494-71, "Specification for Chemical Admixtures for Concrete"
1.107-6