romanoff corrosion of steel piling 1962

8/3/2019 Romanoff Corrosion of Steel Piling 1962

1/22

JOURNAL OF RESEARCH of the National Bureau of Standards-C. Engineering and InstrumentationVol. 66C, No.3, July-September 1962

Corrosion of Steel Pilings in Soils 1Melvin Romanoff

(April 18, 1962)Steel pilings have been used for many years as st ructural members of da ms, fioodwalls'bulkheads, and as load-bearing foundations. While it s use is presumably satisfactory, noev aluation of th e material after long service has been m ade . In cooperation with th e American Iron and Steel Institute an d th e U.S. Corps of Engineers, th e National Bureau of Standards has undertaken a project to investigate th e extent of corrosion on steel piles after manyyears of service.Results of inspections made on steel pilings which have been in service in various underground structures under a wide variety of soil conditions for periods of exposure up to 40years are presented.In general, no appreciable corrosion of steel piling was found in undisturbed soil belowth e wa ter tab le regardless of th e soil types or soil properties encountered. Above the watertable an d in fill soils corrosion was found to be variable but not serious.I t is indicated t hat corrosion data previously pu b lished by the National Bureau ofStandards on specimens exposed under disturbed soil conditions do no t apply to pilingswhich are driven in undisturbed soils.

Introduct ionSteel pilings have been used underground for manyto transmit lo ads to lower levels or to resistpressures due to earth and water. Piped H-piles are used as load-bearing foundations fore first purpose; sheet piles are used as s tructuralmbers of dams, flood walls, bulkheads, and otherlaLLer purpo se. While its usepresumably sa t isfactory because no structuralhave been attributed to the corrosion ofpiles, there is considerable co ncern

damaging corrosion might occur on steel pilesin different soil cnvironments. This co ncernby the corrosion that occurs in disturbedils on actual str uctures, and by the rcsults oftype conducted bye National Bureau of Standards [1],2 in which0 ther metals in differentrange fromrate to a very high rate.As a basis for more accmate estimates of the usefulthe National Bureau ofin cooperation with the American Irond Steel Institute an d the U.S. Corps of Engineers,

ertaken a project to investigate the cxtent ofmany years of service.E x c ~ v a t i o n s to depths 01 15 I t were made adjacentvanous flood wall and dam structures along theRiver to expose sheet steel pilings whichbeen. in service from 7 to 20 yr. Soil samplesd sections of the piles were returned to the laborafor further study. The extraction of steeland H-piles from other locations permittedthe entire length of piles at greaters and for exposure periods up to 40 yr.

I A paper presented nt the Soil Mechanics and Foundations Division, Ameri canf Civil Engineers Conventi on at Houston, Texas, February 22, 1962.2 Figures in brackets indicate the liter ature references at the end of tbis paper.

In this paper are presented the results obtained todate from the inspections of steel pilings. The investigation will be continued by additional inspections of pilings in other parts of the country inorder to cover a wider range of soil environments.2 . Litera ture Survey

Although many references pertaining to Y thebehavior of steel piling have been made in ' theli terature during the past years, no systematicevaluation of the material after long service in soilshas been made. Many of the reports make genoralstatements without giving much or any informationregarding the history of the st ructure or actualmeasmements relating to the condition of the pilesexamined.Statements regarding the underground corrosionof steel piles are made in two texts on substructur edesign. Andersen [2] indicates that co rrosion is nota serious problem when steel piles are completelybelow ground-water level but it must be guardedagainst where .sea w 3 : t ~ r is present, where .(Sroundwater has a hIgh sahmty, or where the pIles aresubject to alternate wetting and drying. Hool andKinne [3] state that the amount of co rrosion on steelpipe piles in the ground is negligible. Piles thathave been in the ground for over 25 yr have shownupon removal that corrosion did not penetrate morethan Jt4 in. into the metal. They also report thatcorrosion is slight on sheet pile below ground-waterlevel.Mason and Ogle [4] inspected a large number ofsteel pile foundations in bridge structures in N ebraska. They found little, if any, corrosion at depthsgreater than 18 in. below the stream bed or groundwater level. I t was estimated that the decrease insection due to corrosion had not been more than 1percent in 20 yr , except in an area where the soilsare saline to a marked degree. In that locality

223


2/22


3/22

e, 0.005 in./yl' for wetting and drying exand 0.001 in ./yr for subsand exposwe. I ttimated that the time required for the perfora%-in. steel would be, respectively, 34 y r, 75, and 375 yr. In the abrasion zone, the steel lostaverage thickness of 0.117 in./yr.Rayner and Ross [13] issued a comprehensive reon the durability of sheet steel pilings in 94uctures which have been in service for variousabout 25 yr along the Atlantic Coastthe Gulf Coast of Florida. Compari on or ratesoss of thickness for steel piles used in t he bulkheadsthat lack of backfill for all or part of thegreatly increased the rate of loss. For beachthe rate of loss rapidly decreased as thend cover increased. Fo r groins and jett ies theof loss were uniformly high except for thoses. I t was concluded that sandearth cover materiallv decreased the loss of thickcs used in shore structures, the ratesss for all practical purposes being negligible forbo th sides. Four groups o[ pilesmoderately polluted sea water loions during the period of investigation, three ofe groups loca ted at Miami, Fla., which have beenrv ice [or 10 yr , and one group which had beenervice for 18 yr at Stamford, Conn. Approxiately 10 f t of the piles were driven below the groundThe average annual rates of loss of thiclmessvaried between 0.0009 and 0.0022 in. ate four sites. The maximum rate, which generallyurred within the zone 2 to 3 ft below the gronnde, was 0.00 3 in. /n .B]elTUm [14] made measurements on steel pilesca tions in Norway.rvations on a 17-ft length of pile which wasen 17 yr prior to inspection in a sil ty clay havingbetween 2,000 and 4,000 ohm-cm showedattack less than 0.003 in . Another 17-[t pile wasafter expos ure for 18 yr in a clay soil of marineIn spite o[ the low resistivity of this soil,ohm-cm, the corrosion varied from 0.01 to 0.02 in.e third pile, exposed to a low resistivity marine[or 6.5 yr , showed maximum co rro ion of 0.10co rresponds to an average rate o[ more0.01 in./yr in a 6-ft zone located between 11d 17 it below the ground line. Corrosion above orthe remaining pile areas did not2 in. , or a rate of 0.003 in ./y1'. No mentionmade of the water line elevation at any of the

ca tions where the Norwegian piles were pulled.e writer, in view of his e ~ ' " P e r i e n c e s in the examiof steel piles. suggests the possibilit.v that theerated attack, reported by Bj errum on the thirdle, mlJY have occurred in a water table zone.3. Inspection Procedure

3.1 . Piles Extracted From LocationSteel H-piles were pulled from two lo cations andsheet piles were pu lled from six loca tions. Theparticipated in all inspections on the pilingsexception of the H-pile extracted from the

Bonnet Carre Spillway. Th e data pertaining to thelatter inspec tion were obtained from the files of theCorps of Engineers, U.S. Army Division, LowerMississippi Valley .After the soil and corrosion products were cleanedfrom the pile surface by utilizing wire brushes andcrapers, the extent of corrosion was determined byvisual observation, pi t depth measurements madewith micrometers, and thickncss measurements madewith calipers.Pil e sections pulled from Lhe Ouachita River Damand Lock No.8, the Grenada Dam Spillway, the SardisDam pillway, and the Lumber River Cofferdamstructure were shipped to the National Bureau ofStandards. These were cleaned by sandblasting topermit a more comprehensive exam ination o[ thepile surfaces in the laboraLor .\TThe results of all Lhe inspecLions o[ the extra ctedpiles are given in section 4.1.3.2. Piles Inspected in Excavated Test HolE S

At loca tions where it was not possible to pull thepiles withou t disturbance to the existing structure,test holes were excavated adjacent to the sh eet steelpilings to expose a width o[ piling at each locat ion.At the start o[ the investigation it was planned toexpose the pilings to a maximum depth of 15 ftfrom the surface, but at most locat ions the watertable did not permit excavating to this dep th .Two excavations were made at each of four Corpsof Engineers stru ctures and on e excavation at eachof three Corps of Engineers stru ctures to examinesheet steel pilings which have been in serv ice in avariety of soil environments.The soil and corrosion products were removedfrom the exposed piling by wire bru shing andscraping. The condition [rom the top of the pilesto the depth of excavation was determined by visualobservation and pit depths were measured .A portion of the pile web, approxim ately 1 ft b 2 it, was cut from the area that showed th e maximumamOWl t of corrosion at each location. The r emovedportions were shipped to the Vicksburg DistrictFoundation and Materials Branch Laboratorv ofthe Corps of Engineers, and then to the N at(onalBureau of Standards for further examination.The results of examinations made on the piles inthe excavated test holes are given in section 4.2.

3.3. Soil Characteristics and PropertiesDeterminations of the soil types for the differenthorizons at the locations where piles were pulledwere made from soil samples adhering to the wallsof th e pilings. To serve as an additional check on thesoil types, engineers in charge of the structures pro-vided soil boring data for the excavations at BonnetCaITe Spillway, Grenada Dam Sp illway, WilmingtonMarine Terminal , and Sparrows Point. Soil samples removed from the pile surfaces were shipped tothe National Bureau of Standards laboratory formeasurements of so il resistivity and pH; at somelo cations, where shown in section 4, soil resis tivity

638975- 62- - 4 225


4/22

'0U1

U1

o'"

oo::qoo

~ ; l g 8 g g S 8 : ! : 8 8 ci . . . . . ....; ci

~ ~ 6 8 ; ; 8 2 ; 8 ~ ~ 2 ci ...... . . . .~ ~ ~ ~ ~ 8 8 6 ~ ~ ~ d riO

1- ~ ~ c O 1- ~ O O > l Q 00.....;O O - - ; O C ' l . . . . ; ~ C ' l - . : r C " l C ' l d ' . . .

~ ~ ~ ; : g 8 8 ~ 8 : ; ~ ~ .0 . . . . . . . . . .O)C'lo>'7'lr--tQOO)C"l


5/22

4.1. Extracted Pilesa . Bonnet Carre Spillway, Or leans, Louisiana

A 12 -in., 65 -lb, test H-pile was driven to a depthut 122 ft below natural ground surface in anear the river side toe of the west approachto the Airline Highway Bridge across BonnetSpillway. 1933ed: 1950e oj piling: 17 yearsElevation + 2.0 to - 120 It 111S1. 4line at + 2.5 ft; water line at 0 ft .l characteristics:+ 2.5 to - 7 It: Soft dark gray organic sil ty clay.- 7 to - 40: Very soft dark gray highly organicand sil t layers with few thin layers of peat fwdthin layers of fine gray sand.- 40 to - 62: Very sort dark gray clay and siltghtly organic.- 62 to - 67: Dense yellowish brown silty sa,nelhard clay layers at bottom .- 67 to - 120: Light bluish grfl.y plastic clay,fl.t top, very stiff at bottom.

Soil resistivity a nd pHElevation

rtto - 7.5__ ___ MinMaxAvg.5 to - 17.5____ MinMaxAv g.5 to - 27.5 ____ Min

____ _______ _5 ______ _____ _____________ ____ __ __ _____ ..

oj pile:

MaxAv g

ll esistivity pHOhm-em920 (4-pinl _______________ _1,050 (4-pinl _______________ _960 (4-pinl __ _____________ _

540 (4-pinl __ _____________ _840 (4-pinl _______ - - _ - __ __ _770 (4-pinl _____ __________ _460 (4-piul _______________ _800 (4-pinl _______________ _680 (4-pinl _______________ _700 (Shep a rd Ca nesl __ ___ _ _750 (Shepard Canesl _ _ _ 6. 7400 (Laboratoryl _ _ _ _ _ _ 7. 8400 (Laborator yl ______ 8. 1

b. H- Piles at Sparrows Point, MarylandIIistory:In 1942, several 14-in. H-piles having an averageflange thickness of 0.55 in. were driven at the Sparrows Point Plant of the Bethlehem Steel Companyfor test purposes. Th e American Iron and Steel In stitute arranged with the Bethlehem Steel Companyto extract two of the piles and to permit the writerto inspect and report on the co ndition of the piles aspart of this investigatio n. The piles were 139 ft inlength, 136 I t of which was driven below the groundline. The two piles were eparated by a distanceof 100 ft.Date piles driven: 1942Date piles pulled: m b e l " 1960Age oj piling: 18 yearsPiling exposed: Elevfltion + 13 to - 126 ft . Groundline at + 10 ft.Soil characteristics:T11is area was originally a peninsula surrounded byslHtllow Wfl.ter and marslt which was filled to a.boutelevation + 10 [t with sla,g fl.nd cinders.

+ 10 to 0 It: Slag and cinder fill with some finesfln d. Water line at + 7.0 Jt for pile No. I- S, andat + 6.4 I t for pile No. II- S.o to - 10: 1'\ atural soil starts fLt 0 rt. Light graysilty clay co ntai.ning appreciable sand, underlain byfL stiff: brown sil ty clay and marbled gray clay.- 10 to - 25: Light brown sa lld y silt to fL sof tdark gray silty clay ttt - 15 It .- 25 to - 90: Transition from brownislt to darkgray silty clay mixed with peat and organic matterat some levels.- 90 to - 95: Dark brown silt underlain by fmebrown sand.- 95 to - 110: Transition rro nl sand of difl'erenttextures to dark brown sil t.- 110 to - 120: Coarse brown S


6/22

Condition oJ piles:The pattern and amount of corrosion on the twopiles were about th e same. Corrosion was confinedto two areas. One area extended from the top of thepiles, which was above ground level, and extendedthrough the zone exposed to the cinder and slag fillin the water table zone. The other corroded areaoccurred between elevations - l15 to - l l 8 ft wherethe piles passed through a sand and gravel bed.Pile II- S was cleaned by sandblasting prior toexamination, and pile I- S was cleaned with scrapersand wire brushes. Except as noted otherwise, thecorrosion measurements reported are the maximunlo bserved on the two piles.+ 13 to + 8 ft: Slight uniform corrosion and isolated pitting. Maximum depth of pitting, 35 mils.At least 50 percent of the mill scale was intact.Maximum reduction in flange thiclmess, 3 percent.+ 8 to + 6: This is the zone showing the maximumcorrosion on both piles. The water line was at + 7 ftfor pile 1-8, and at + 6.4 [t for pile II- S. The millscale was practically entirely removed; uniform cor

rosion and many pits were present. Most of thepitting occurred within the I-It area above and belowthe water line. The two maximum pi t depths measured on pile I- S were ll2 and 90 mils, a few pits werefound between 60 and 75 mils, and other pits lessthen 60 mils in depth. On pile II- S, there were 10pits between 55 and 72 mils in depth and other pi tsless than 50 mils in depth. The flange surfaces weremore severely attacked t han the web surfaces.Measurements made on the flange within I-ft ofthe water line showed tllitt the original cross sectionof pile I - S was reduced by an average of 29 percent.For pile II- S, the average reduction was 14 percent.

The reduction in pile thickness due to corrOSlOntapered off rapidly as the distance away from thewater line was increased. The average reductionin flange cross section on the zone between 1 ft and2 ft below and above the water line was 2 to 3percent. No perceptible reduction in flange thickness was noted 4 ft above or below the water line.+ 6 to - 4: Mill scale in tact over 90 percen t of thepile surfaces. Negligible metal attack and localized p i ~ s wh.ich 'yere less than 20 mils in depthexcept for a few pIts between 20 and 31 mils.- 4 to - l1 : Slight metal attack in a 4-in. 2 areawith a maximum pit depth of 18 mils on pile II- Sonly. Mill scale intact over 95 percent of surface

-11 to - l15: No measurable pit depths. Milscale in tact over 95 percent of surface.- l15 to - l18: At this depth the piles passedthrough a sand and gravel stratum. The steesurfaces were uniformly corroded and containedmany localized pits which generally ranged in depthup to 50 mils; 12 pits measured between 50 and 65mils and 2 pits had depths of 80 and 95 mils. Theaverage reduction in flange thickness measured 9and 4 percent, respectively, for pile I- S and fopile II- S.- 118 to - 126: Practically unaffected by corrosion. Mill scale more than 95 percen t in tact.Figure 1 shows the condition of pile II- S at thr edifferent levels.c . Corps of Engineers, Da m and Lock No.8 , Ouachita RiverArkansasHistory:

An end pile was pulled from the upstream abutment wall of the Corps of Engineers, D am and LocNo . 8 on the Ouachita River near El Dorado, Ark

FIGURE 1. S ections of the 139-ft H-piles pulled from Sparrows Point, l1faryland, after exposure for 18 yeaTs .Left, water table zon e consisting of fill material; center, clay soil stratum at about elevation - 30 It; and rigbt, coarse sand and gravel stratum underlain b y clabetween elevatIOns - 110 and -126 ft. The plie was cleaned by sandblastll1g . Note the excellent condition of the butt weld at the splice in the center photograp

228


7/22

e pile wa a shallow-arch h cet pile having a 15-in.wid th, fw d a web thickne which variedat the center to 0.67 in. near the edges.e len gth of the pile was 15 ft , Lhe top 2 ft of which] 921June 1961of piling: 40 yearsilin g exposed: Elevation 67.5 to 52.5 ft . Groundft ; water line at 76.5 ft. Thep of the pile was encased in concrete to elevationft.

78 .5 to 76.5 ft: Silty clay fill with some orgamc76 .5 to 64.5: Blue clay containing about 40 pernt sand.64.5 to 60.5: Stiff blu e cla,y containing about 10sand.60.5 to 52.5: Very st iff blue cla,y containing rtboutpercent sand.

Soil resistivity a nd pHE leyation Re sisti vi ty pH

It Ohm- ernSurfacc) ___ _ 2,900 (Shepard Ca ne'sl ______________ ___ _________ _ 3,200 (Laboratoryl _ _ _ _ 4. 31,540 (Labo rato ry) _ _ _ _ _ _ _ _ G. 2___ _ 1,540 (Laborato ry) ___________ 4.6

ion of pileThe entir e l ength of the pile was driven below thetable. Corrosion was confined to a 2-Jt secon th e ri ver side of the pile betw'een elevationto 6l.8 ft. Pitting occurred in 11 plrtces,about 1 in. 2 in area, along the fingers of the pile.he maximum pit depth was 26 mils an d othersup to 22 mils. evera l pits having a maxiof 20 mil were found in a 3-in2 ar ert ine center of the web. Ninety percent of the 11lillale was intact in tills moderately corroded zo ne.t least 95 percent of the original mill scale wasto be intact on the remaining areas of the pile,no measurable pi ts or corrosion beyond the millBased on the maximum pit, the total loss of pile thickness in the corzone co uld not exceed 5 percent of the original

The portion of the pile which co nLa.i ns the measpi ts is shown in figure 2.d . Grenada Da m Spillway, Grenada , Mississippi

istory:A type A sheet pile was pulled for examin fLtionthe end of the north upstream wingwall of theDam Spillway at Grenada, Miss. The pile14 ft in length , had rt driving width oI 1 in.a thickness of % n.ven: October 194pulled: July 1960

F IG URE 2. Sandblasted 3-ft sec tionf r'om th e 40-year-old piling ex tractedIrom an ab utment wall in the C01'PS of.8n gi neers Dam and Lock No. 8 onthe Ouachita River near E l Dorado,A 1" icansas.'rh e s3ction was exposed ahout 18 ft belowUw ground line and il.. is th e n l portion of thepilf' whi ch con ta ined pits of rnnasureable depth .'rh e Jnaximum pi t wns 2() m ils in depth.

Age of piling: 12 yertrsPiling expo sed: Elevation 251.5 ft to 237 .5 ft; groundelevation at 256 It, Wflle r htblc LlIuch below thebottom of pile.Soil characteristics:256.0 to 250.5 It: Fill so il, reddish bro\vn sandyloam .So il resistivity and pH

Elevation

ft256 to 246 ____ _ _ _ _ MinMaxA\'g

256 to 236 ____ ____ Mi nMaxAvg

256 to 226 ___ _____ Min

256 ___ __________ _250 _____________ _245.5 ___________ _241 __ ________ ___ _

MaxAvg

Resistivity pHOhm-em11 ,700 (4-pin) ____ __ ______ __ _15,400 (4-pin) __ ______ __ _ ___ _13,900 (4-pinl ___ _____ _____ --

4,600 (4-pinl __ _____________ _9,600 (4-pin) ___ ______ ______ _6,900 (L-pinl __ ___ ___ ____ __ _ _4, 300 (4-pin) ______ _____ ____ _7,300 (4-pin) __ ______ ____ ___ _6,200 (4-pin) __ _____ _____ ___ _2,800 (Shepard Canesl ___ _ ___ _> 4,000 (Laboratoryl ____ ___ 4. 9> 4,000 (Laboratoryl _____ __ 4.93,800 (Laboratory) _______ 3.6

229


8/22

--

FIGURE 3, . Sections (1 .5 ft by 1 ft) cut /Tom a piling which was pulled from the north llpstreamwmgwall of the Grenada Dam Sptllway at Grenada, M issl:ssipp i, after exposure for 12 years.Sections WE're cleaned by sandblasting.]) I03A . section of pile expo sed to fill soil.]) lO313, section of pile exposed to natura l soil.

250.5 to 246.6: Fill soil, tan silty sand.246.5 to 244.5: Natural soil layer, grayish bluefr ac tured shale.244.5 to 237.5: Transition from light brown togray clay. Gravel and dark gray shale intermingledthroughou t horizon. Many fino roots present.Oondition oj pile:251.5 to 246.0 It: M any scattered pi ts up to 50mils in depth. Seven pits measur ed between 68 and80 mils, and two pi ts 88 and 122 mils in depth .Pits were of similar depth on both sides of the pile,but much less numerous on the side facing thesp illway. About 50 percent of the mill scale wasintact on the spillway side and 10 percent on theother side. The reduction in cross section of thethree most cOI'l'oded areas measured between 6 to 8

percent of the original wall thi ckness.246.0 to 244.0: No measureablc pi ts beyond thethickness of the mill scale (8 mils) were found in this:zone. About 50 percent of the mill scale was intac tin this area.244.0 to 237.5: About 75 percent of the mill scalewas present over the surfaces in this zone. Nomeasurable pits were found except two at elevation241.0 f t which were 13 mils in depth . The averagewall thiclmess of a 17 X 22 in. section removed fromthis zone was 0.3 7 in. after cleaning by sandblasting.Sections of th e pile which were exposed to the filland natural soils are shown in figure 3.

230

e . Sardis Dam Outlet, Sardis, MississippiHistory:

A 3.5 ft length of steel sheet piling was cut from alength of pile pulled from the Sardis Dam Outletchannel on the Lit tle T allahatchie River near SardisMiss. The arch-type pile had a driving width of19 %in. and a wall thickness of % n.Date pile driven: Early 1939Date pile pulled: Octo bel' 1959Age oj piling: 20.5 yearsPiling exposed: Elevation 190.5 to 187 ftSurjace elevation: 194.5 f tWater table elevation: Above 194.5 ft.Soil characteristics:194.5 to 190.5 ft: Riprap fill.] 90.5 to 189.5: Gravel bed.189.5 to 187: Black lignitic clay with layers ofsand.Soil resist ivi ty and pH

Elevation Re sist ivity pHft Ohm-em190___ _ _ _ _ _ _ _ _ _ _ _ 610 (La boratory)__ _ _ _ __ _ _ __ _ _ __ _ 3. 0187___ __ __ __ __ _ _ _ 1,690 (Laboratory) _ _ _ ____ ___ ___ _ 2. 9


9/22


10/22

----- -----Soil characteristics:+ 6 to 0 ft: Cind er fill.+ 2 to + 1: Water table at low tide. River wateris nonbrackish fresh water. :Mean low water at 0ft. o to - 48: Soft black organic silt.- 48 to - 8 6: Black organic silt with some finesand and clay intermingled.- 86 to - 88: Fine brown sil ty sand, trace of mica.

- 88 to - 91: Gray to brown coarse sand and rivergravel.- 91 to - 114 : Sand and silty sand underlain byclay.Condition oj piles:Seven full lengths an d th e in terlock edges of 70piles were inspected. All the piles were in excellentcondition from th e mud line (elevation 0 ft where th enatural soil starts) down to the bottom of the piles.The piles are to be reused in the new dock stru ctureat the same site.+ 10 to 0 ft: Moderate co rrosion on surfacesexposed to water and the atmosphere on the riverside, and to cinder fill, water and atmosphere on theland sid e. Surfaces were uniformily corroded, theoriginal thickness of the piles being reduced by anaverage no t exceeding 10 percent. Widely scatteredpits present; most of the pi ts h ad depths less than75 mils, bu t a few had depths between 75 to 150mils.o to bottom of piles: Accumulation of slick clayover most of the surface. No measur able pits.Mill scale in tact over more than 90 percen t of th esurfaces.

h . Lumber Fiver Near Boardman , North CarolinaHistory:

The North Carolina State Highway Departmentextracted 120 piles which formed a rectangularshaped cofferdam for a bridge support over theLumber River near Boardman , N.C. The structurewas removed in conn ection with road improvementswhich required replacement of the old bridge.The steel piles were 20-ft len gths of interlockingI-beams having a driving width of 8 in. and a wallthickness of 0.25 in. The corners of the cofferdamconsisted of steel angles to which interlock sectionsof pilings were attached by steel rivets , spaced 9 in.apart.Date piles driven: 1921Date piles pulled: December 1958Age oj piling: 37 yearsPil ing exposed: 2.5 ft above ground to 17.5 ft belowthe ground line (+ 2.5 to -17.5 f t ). The portion ofthe piles above the ground line was subjected topartial or total immersion from water of the LmnberRiver about 50 percent of the year, and to theatmosphere when th e river was dry during theremaining half year. The sides of the pilings whichwere exposed to the excavated side of the cofferdamwere in contact with concrete, except fort he bottom3 ft which was entirely surrounded by soil.

Soil characteristics:o (ground line) to - 8 ft: Gray fine sandy loam .- 8 to - 14 : Bluish-gray plas tic silty clay.- 14 to - 17.5: Gray-black fine sand y 10fLm con-taining appreciable gravel.Soil resist ivi ty a nd pH

Elevation

i t- 3 ___________________________ _- 10___ _____________ ____ ______ _- 16 __________________________ _

Condition oj piles:

Resist ivityOhm-em1,2401, 1004, 900

pH

3 .42. 35. !)

Visual inspection of the pilings revealed that theyhad all corroded to about the same extent. .Asection of the cofferdam consisting of two fulllengths of piles and a corner angle was shipped tothe laboratory for further examination.Practically no mill scale remained on the pilesurfaces in the zone extending from 3 ft below theground line to th e top of the piles. In the lower zones,approximately 20 percent of the mill scale wasintact.Thin concrete deposits were found on the surfaceswhere the steel had been in contact with concreteon the excavated side of the cofferdam. There wasa thick scale of rusted corrosion products and soilover the entire surface exposed directly to the soilenvironments . The scale was flakey and easilyremoved by scraping.The fo llowing conditions were observed afterthe piles were cleaned by sandblas ting:+ 2.5 to 0 It : Section exposed to total 01' partialwater immersion, or atmosphere. Uniform corrosionof surface. Measm ements of the cross section inthe top 6 in. of the piles (elevation +2.5 to +2.0)showed a minimum thickness of 0.06 in. in places.This represents a loss of 76 percent in the originalpile thiclmess. The maximum thiclmess measuredon uncorroded sm-faces ncar the bottom of the pileswas 0.26 in . Piles in the zone between + 2.0 ft tothe ground line showed a maximum reduction inthickness of 60 percent .o to - 0.5 : This area showed an amount of corrosion similar to that on the adjacent areas above.The original pile thicknefs in this zone was reducedby a maximum of 40 percent, and iso lated pits rangedin depth up to 60 mils.- 0.5 to - 1.0: The pattern of corrosion in thiszone was similar to that noted above. 11aximumreduction in pile thickness was 36 percent .- 1.0 to - 3 .0: Uniform corrosion, general roughening of surface, numerous shallow pits and manyisolated pits up to 60 mils. Yfaximum reduction incross section was 28 percent .- 3 to - 17 .5 : In this zone the condi tion of thesm-face was similar to that described above, but wasless severely corroded. Many isolated pi ts measm-edup to 30 mils in depth, and relatively few up to 60

232


11/22

A maximum reduction in pile cross section ofpercent was noted in this zone.The corner angle along the entire piling sectionthe same extent of corrosion as the I- beams.rivets were uniformly corroded. The originalntour of the rivets was intact.A 3-ft corner section of the piling exposed immeely below the soil line is shown in figure 4.

4.2. Pilings Exposed in Excavationsa . Memphis Floodwal l, Memphis, Tennesseey:

Excavations were made to expose pilings at twothe river side of the Memphis Floodwall.e walls consist of type Z 27 sheet pilings having18-in. driving width, and a thiclmess of %-in . ate web and flanges. The pilings at station 56 + 14co ld applied coal-tar-basebefore driving, and the pilings at stationuncoated.piles driven: November 1953oj ins]JPction: March 1960ge of piling: 6.3 years

STATION 56+ 14exposed: An 8-ft width of the flood wall wasbetween elevation 223.0 to 216.5 ft .e elevation: 228 ftevation: 217.5 f til characteristics:228 to 223 It : Friable brown lean clay.223 to 221.5: Plastic and friable gray silty clay.22l.5 to 217.5: Plastic light brown clayey silt.water bclow 219.5 ft .217.5 to 216.5: Tight gray clay mixed with de

Soil resistivity and pHEl evation

j t8 t o 218________ MinM axAvg208______ __ Min

MaxAvg8 to 198__ __ _ _ _ _ MinMa xAvg

____ ____ __ _____ _______ _

___ __________ _

RCE ist i vi ty pHOhm-em1,220 (4-pin) ___ _________ ___ _8,600 (4-pin) ____ __ _____ ____ _4,400 (4-pin) ____ _____ ______ _

960 (4-p in) _____ _________ _6,900 (4-pin) ______ _________ _2,600 (4-pi n) ______ _________ _1,030 (4-pin) ______ __ __ _____ _3,400 (4-pin) ______ _______ __ _1,850 (4-pin) __________ ___ __ _1,900 (Shepard Canes) ______ _3,100 (Shepard Canes) __ __ __ _2,240 (Laboratory) _____ _ 7.82,300 (Shepard Canes) ___ ___ _1,700 (Shepard Canes) ___ ___ _1,4 ] 0 (Laborator y) _ _ _ _ _ _ 7. 62,200 (Shepard Canes) _____ _ _1,000 (Shepard Canes) ______ _

Condition oj pi les :The coal ta r coating wa intact over the enLiresurface except at elevaLion 220.5 to 219.5 f t wherethe coating was damaged in an area I-ft in verticaldirection by I-in. in width . The maximum depth ofpitting of the steel exposed by th e damaged coatingwas 35 mils (fig. 5). The steel beneath tb e Test ofthe coating was unaffected by co rrosion and the millscale was intact .

STATION 60 + 00Piling exposed: An 8-ft width of the floodwall waexposed between elevation 222.5 and 213 .5 ft.Surjace elevation: 226.5 ftWater table elevation: Below 213.5 ftSoil characteristics:226.5 to 224 It: Brown lean clay.224 to 222.5: Gray silty clay.222.5 to 218.5: Friable brown silty clay. Somecind ers mixed with the clay between 223 and 220 ft .218.5 to 213.5: Friable and plastic reddish brownsilty clay. Very impervious to wateI'.

Soil resistivity a nd pHEl evation

ft226.5 to 216.5_____ MinMaxAvg226.5 to 206.5 __ _ _ _ MillMax

Avg226.5 to 196.5_____ Min

222__ ___________ _221. __ _221___________ _219.5 ___________ _218.5 ___________ _217__ ___________ _214___ __________ _213.5 ___ ________ _

Condition oj piles :

M axAvg

Resistivi ty pI-IOhm-em2,180 (4-pin) _______________ _5,700 (4-pin) _______________ _4,100 (4-pin) _______________ _

1,920 (4-pin) _______________ _7,900 (4-pin)____ ___________ _4,200 (4- pin) _______________ _1,030 (4-pin ) _______________ _2,300 (4-pin )__ _____________ _1,650 (4-pin) _______________ _3,200 (Sh epard Canes) ______ _2,500 (Sh epard Ca nes) ______ _2,200 (Laboratory) _____ _ _ 6.2,600 (Shepar d Canes) ______ _2,100 (Shepar d Canes) ______ _1,690 (Laboratory ) __ _____ 7. 81,630 (Laboratory) ___ ____ 7. 51,500 (Shepard Canes) ___ ___ _

The entire smJace of the pilings was in excellentcondition. More than 90 percent of the mill scalewas intact . There was very slight uniform metalattack in small localized areas. No measurable pitswere found on the entire surface. From elevation218 to the bottom of the excavated pit , the clayadbered very tightly to the piling. On removal ,the soil peeled off in la yers leaving free waLeI' on thesteel smf ace.A 2 ft by 1 ft section removed from th e pile ISshown in figm e 5.233


12/22

FIGURE 4. A 3-ft section of steel sheetpiling expo sed below the soil line ina eofj"e"dam stnlcture in the LwnbeTRiveT nem Boardman, NOTth Carolina.ExposurC', 37 years.

b. Vicksburg Floodwall, Vicksburg, Mississippi

History:Excavations were made to expose steel sheetpilings at two locations on the riverside of theVicksburg Floodwall. The walls were constructedof type Z 38 sheet piling which has a driving wid tIlof 18 in., a thickness of % n. at the web, and a thickness of Yz in . at the flanges.Date piles driven: January 1953Date oj inspection: :March 1960Age oj piling: 7.2 yearsSTATION 16+32

Piling exposed: A 38-in. width of the floodwall wasexposed between elevation 89 and 80.5 ft.SU1jace elevation: 93 ftWater table elevation: 80.5 ftSoil characteristics:93 to 86 ft: Bluish black fa t clay, sticky, plastic,and very retentive of water. Small paL ches of redand yellow sand d i s p ~ r s e d throughout the profile.86.0 to 85.5: Black sil ty plastic clay, containingmore than 50 percent cinders.85.5 to 84.5: Light brown sandy loam with cindersand gravel dispersed throughout.84.5 to 84.0: Layer of black cinders.84.0 to 80.5: Gray sandy silt containing cinders.Wet cinders on floor of excavation at 80.5 ft.

FIG UHE 5. Steel sheet piling sections (2 It by 1 It l cut from twolocations on the Nlemphis Floodwall af ter exposure fo r 6. 3yems.The sections were cleaned by sand blasting.AIOI, sectiOllo ! coated piling showing pi ts up to 35 mils in depth, occurring inarea of damaged coating.AI02, section of uncoated piling exposed to a silty clay con taining cindersshowing no rueasureable corrosion.

Soil resist ivity and pHElevat ion

It93 to 83 ______ ___ _ MinMaxA\ 'g

93 to 73 __________ MinlVIaxAvg93 to 63 __________ Min

88 ______________ _lVIaxAvg

88 to 87 __________ MinMax

85 ___ ____________ MinMa x

83 ______________ _82.5 _________ ___ _82 to 80___ _______ Min

Max80.5 _ _ _ _ _ _ _ _ _ _ _ _ _ Min

Max

Re s ist ivity pHOhm-em3,400 (4-pil1l __________ _____ _7,000 (4-pinl _______________ _6,000 (4-pin l ___________ _

2,200 (4- pin l ______ ________ _ _4,300 (4-pin l _______________ _3,300 (4-pin ) __________ _____ _920 (4-pin ) __________ _____ _2,400 (4-pin) ___ ____________ _1,550 (4-pi n) _______________ _

1,190 (Laborato ry) ______ 7.4850 (Shepard Canes) ______ _1,300 (Shepard Canes) ______ _

1,700 (Shepa.rd Canes) ______ _2,500 (Shepard Canes) ______ _2,500 (Laboratory) _ _ _ _ _ _ 7. 61,750 (Laboratory) _ _ _ _ _ _ 8. 21,550 (Shepard Canes) ____ __ _4,000 (Shepard Canes) ___ ____

850 (Shepard Canes) __ _ ___ _1,400 (Shepard Canes) ______ _

234


13/22

Soil resistivity an d pHE lenL tion

ftLo 8:3___ _ _ _ _ _ _ _ Mi nMa xAvg

93 to 73 __________ :vIin:vIaxAv g93 to 6:L _ _ _ _ _ _ _ _ :vIin

Ma xAv g89 to 84____ _ _ _ _ _ _ iVfin

1\ 1a;,:A\ 'g

88.5 __ _8 : ~ . 5 __ _8:! . . __ _8L ___ _8:3.5 to 80.5 _______ :vI in:'I1ax

Res islivity pH

Ohm-cm2,800 (4-pin) ______________ _9,200 (4-pin )_ _ __________ _5,000 (4-pin) _______________ _1,:300 (-I-pin ) __:3 ,700 (4-pin) __ _2,800 (4-pi n)____ _

7-10 (-l-pin) ____________ _2,000 (-l-pin) _____________ _J ,400 (4-pill) __ ________ _025 (Shepa rd Canes) __825 (Shepard Canes) __725 (Shepard Canes) __ ____ _910 (L aboratory) _ _ _ _ _ 7. 1J,700 (Shepard Canes) _ _ _ _3,\)00 (Laborator y) _ _ _ _ _ _ 8. 6

1,050 (L aboratory) ___ __ _ 7. 7J, lOO (Shepard Canes) __ ____ _J ,400 (Shepard CanC's) ______ _

IG URE 6. Sandblasted sections of Z-t ype sheet piling cut j1-om A\ -g J ,:300 (Shepard Canes) ______ _two di.o'eTent locations in the V icksbuTg FloodwaU af terexposure for 7 years.Although cinders were present ill. the soil at hoth locations, no Significant cor-B IOI , Section reITIo\'ecl from floocl\\'all at station J6+32.BI02. Section rellloved [rom floot! wall at sta tion 23+80.

oj pi les :Approximately 30 to 40 pOl'cent of the steel smlaceswiLh mill scale. Soil adhered in manyof about 1-in.2 like barnacles, beneath which

uniform metal attack or shallow pitting .up to 40 mils in depth was widely scatteredd confined Lo areas of less than 1 in. 2 At elevation8l.5 ft, there were a few pits with depths40 and 45 mils. Measmements made one three most conoded 1 in. 2 areas showed an averreduction in the cro ss section of the web of 4 to 6A section removed from the most corrodedof the pile is shown in figure 6.STATION 23+83

expo sed: A 41-in. width of the floodwall wasbetween elevation 89 an d 80.5 ft.93 ftr table elevation: 80.5 ft

s:93 to 84 ft : Bluish-gray clay with nodules of browndispersed throughout.84 to 83.5: Plastic and sticky light brown toclay containing some cinders.83.5 to 80.5: Dar];;: gray silty sand mixed withquantities of cindel's, gravel, stones, andThis horizon appears to be a fill matenal.at bottom of trench.

Condition oj piLes :Mill scale was inLacL on about 70 percent of Li ll 'pil ing surfaces. TllCl'e was no difference in th eappearance of the surface at Lhe different horizons.Where the mill scah'had been removed , UlNe was afilm of red rnst whieh was brushed o ff with ease.Under the rust, Lh e steel surfaces wel'e smooLh. No

1l1easureable pits were [ound on Lhe exposed pilings.1Ieasurements fail to show a per ceptible reduC'l ion inwall thickness (fig. 6).c . Sardis Dam Spillway, Sardis, Mississippi

History:An excavation ,vas made to expose a 7-ft widthof pilings from the upstream wingwall on. the eastside of the Sardis Dam Spillwa,y. The structureconsisted of arch-type sheet piles with a IS-in.driving width and a wall thickness of % in .Date piles driven: Early 1940Date oj inspection: March 1960Age oj piling: 20 yearsPiling exposed: A 7-ft width of the wingwall wasexposed from elevation 307 to 302 ft.SUljace elevation: 312 itWater table elevation: 305 ftSoil characteristics:312 to 305 It : Fill soil consisLing of uniform reddishsandy loam.305 to 302: Jatural soil, r eddish brown tightimpervious plastic clay.

235


14/22

Soil resistivity an d pHElevation Resistivity pH

it Ohm-em312 to 302 ____ ____ Min. 43,600 (4-pinl _____ __ _______ - __ _Max. 50,200 (4-pinl _____ ___ _____ _ ___ _Avg. 46,500 (4-pinl ____ ____ _________ _312 to 192 _____ ___ Min . 29,100 (4-pinl ____ ____ _________ _

Max. 36,000 (4-pinl ____ ___ __________ _Avg. 32,800 (4-pinl _____ __ __________ _312 to 182 ____ ____ Min. 23,800 (4-pinl ____ __ ___________ _

312 __ ___ ______ __ _310__ ___ ________ _306____ _____ ____ _303 __ __ _________ _302__ ___ ________ _302 _______ ____ __ _

Condition oj piles:

Max. 29,300 (4-pinl _____ __________ __ _Avg. 26,000 (4-pinl ________ _________ _> 10,000 (Shepa rd Canesl ________ _> 10,000 (Shepard Canesl ____ _ ___ _15,400 (Labor atoryl _ _ _ _ _ _ _ _ 5. 7> 4,000 (Laboratory l _ _ _ _ _ _ _ _ _ 6. 07,510 (Labo rator yl ___ ______ 5.43,000 (S hepard Canesl ____ __ ___ _

~ 1 i l l scale was intact over approximately 90 percent of the pile smfaces. In localized areas, whichwere predominant in the top 8-in. section of thepiles, there was slight metal attack and shallowpitting, not exceeding 10 mils in depth. In anarea covering a width of about 2 ft between elevation 304 and 302.5 ft, there were isolated pits whichmeasmed between 10 and 20 mils in depth, andthree pits between 20 and 28 mils. The averagereduction in pile thickness measmed in the threemost corroded areas in th is zone was between 3 and4 percent.d. Grenada Da m Spillway, Grenada, Mississippi

History:Two excavations were made to expose steel sheetpilings for examination on the north side and thesouth side of the upstream wingwalls of the GrenadaDam Spillway on the Yalobusha River. The pilingsconsisted of the arch-sheet type with a driving widthof 15 in. and a wall thickness of % n.Date pi les driven: October 1948Date oj inspection: March 1960Age oj pi ling: 1l.4 yearsUPSTREAM WINGWALL-NORTH SIDE

Piling exposed: A 6.7 ft width of the wingwall wasexposed between elevation 25l.5 and 246 ft .Surface elevation: 256 ftWater table elevation: Much bclow 246 ftSoil characteristics:256 to 246 It : Fill material consisting of friablereddish brown clayey sand or silt loam with clodsof grayish sandy clay and patches of very fine yellowish brown sand throughout the pit. Gravel, stones,pieces of dark gray shale, and fine roots present.

Soil resistivi t., and pHElevation

it256-246__ __ ____ __ Mi nMaxAvg

256-236__ _ _ _ _ _ _ _ _ Mi nMaxAvg

256-226___ ______ _ Mi n

255 ___ ______ __ __ _249 __ _______ ____ _247 _______ ______ _

MaxAvg

24.6 ______ _____ ___ Mi nMaxAyg

R es istivity I pH. _Ohm-em 1--2,000 (4-pllll __ ____________ _16,500 (4-pinl __ _________ I___ _13,900 (4-pinl ______________ _4,700 (4-pinl __ _________J __9,600 (4-pinl _______________ _6,900 (4-pinl ____ ___________ _4,300 (4-pinl ____ ___________ _7,200 (4-pinl ___ ____________ _6,200 (4-pin l ______ ________ _ _9,000 (Shepard Canesl ___ ___ _2,400 (L aboratoryl __ ____ 4.42,300 (Laboratory l ____ __ 4. 01,700 (S hep ard Ca nesl ______ _3,500 (Shepard Ca nesl __ . __ _ _2,400 (Shepard Canesl ___ ___ _I

Condition oj piles:Mill scale was intact on about 20 percent of thepile smfaces. Approximately 60 percent of the surface was uniformly corroded to shallow depths andcontained many scattered pits which generallyranged in depth between 40 and 90 mils. A fewpi ts between 90 and 108 mils in depth were present.The deepest pits were mainly concentrated betweenelevation 248 and 247 ft. The deeper pits werehighly localized and were found under nodules of soilparticles which appeared to be cemented to the steeland were difficult to scrape away. 11easmements ofthe three most corroded areas showed average re ductions in the thickness of the piles of 16 ,13 , and 10percent.

UPSTREAM WINGWALL-SOUTH SIDEPiling exposed: A 7-t width of the pilings in th ewingwall was exposed between elevation 25l.5 and246 ft.Surjace elevation: 256 ftlVater table elevation: Much below 246 ftSoil characteristics:256 to 248 ft : Reddish brown fine sandy loam withclods of light gray clay dispersed throughout theprofile. This is a fill soil containing many fin e roots.248 to 246: MLxture of fine rust colored very fin elight yellow silty sand intermingled with pieces oflight gray shale.

Soil resistivity and pHElev ation

ft256 to 246 _______ _ MinMaxAvg

Resist ivity pHOhm-em5,900 (4-pinl ___ ___ _________ _8,000 (4-pinl ___ ___ _______ __ _7,000 (4-pinl ______ _______ __ _

236


15/22

Soil resistiv i t y a nd pH - con t inu edt i o n

[I56 to 236____ __ __ ~ T i n yI a xAvg56 t o 226 _____ ___ Min

50 __ ______ _____ _4 8.5 _______ ___ _ _47 __ _________ __ _

}[axA\ 'g

4 6 _____ ______ ___

R es ist ivi ty pHOhm-em3,400 (4-pin) _______________ _6,900 (4-pin ) ___ ___ _____ _ __ _ _4, 300 (4-pin) ___ _______ __ ___ _

2,700 (4-pin) ___ __ __________ _3,800 (4-pin ) ___ __ _____ ____ _3,500 (4-pi n) _______ ____ _2,400 (Laborat or y) _ _ _ _ _ _ 4. 44,000 (Labora to ry) _ _ _ _ _ _ 6. 44,300 (Laborato ry ) _ _ _ _ _ _ 6. 95,000 (Shepard Ca nes) ______ _

had a coal ta r coating and was exposed to water.SUJ j ace elevation: +5 ItWater table elevation: - 0.5 ItSoil characteris tics:+ 5 to + 2 ft : Fill ma terial consisting of a mixtuJ"("of gray and brown silLy clay conlaining some graveland small shells.+ 2. to - 1..5 : N a t m ~ l soil consisting 0(' lig-ltt bluishgray ImperVI?US plas tIC clay wiLh paLcllf's o f t igh tbrown clay dlsperscd throug hou t lh e profile.Soil resis ti vi ty a nd pH

Eleva tion Resisti vi ty pHM axA \"g 11,000 (Shepa rd Canes) _ _ II Ohm-em7,900 (Shepa rd Ca nes)___ + 5 to - 5___ _ Mi n:vraxAvg

860 (4-pin) ______ ______ __ _

ion oj piles :25l.5 to 248 f t: [ill scale was present over 70n t of th e mface. : 'lany highly localized pi tsabout 15 percent of th e surface t he rcainiJ;.g 85 c e t of the. surface was unaffected byorrOSlOn. SL'{ pi ts were found b etween 100 and 172depth , eight pi ts between 50 and 95 mils, andher PIts measmedless than 50 mils. The corrosioncts and soil particles adhering to the steel inhis zone were en,sil,- scraped off.248 to 246: . About :30 percent of th e piling smfacesel'c.aJfected sCRt.lercd th e othcr areas beingnaffected by COlTOSlon. [ I l l scalc WitS in tact overre than 50 percent of th e surface. The seveneepes t pits ranged betwcen 10 5 and 160 mils inepth . Also present were 11 pits between 50 and 95and other 'pi ts. Ie than.50 mils in depth . The

average reductlOn 111 wall tlllckn es m easm ed in th ehree most corroded areitS was between 12 and 19ercent . In th is zone, the soil particles were easilyel smfaces but a black cru st ofI T oxide which was el1lb eclded in th e pi ts waslfficult. to break awny,

e. Berwick Lock, Berwick, Louisianaistory:Two excavations were made to expose steel pilingsthe cutoff walls on the west side and east side ofth e north end of the Berwick Lock which is locatedbetween th e Lower Atehafalaya River and Berwick.ay ncar Berwi?k! La. The arch-type sheet steolllmgs had a dnvmg width of 19% in. and a % n.wall thickness.Date piles driven: March 1949Date of inspection: April 1960A ge of piling: 11.1 years

NORTH END OF LOCK- WEST SIDEPili ng expo sed:. A 5-ft width of pil ings was exposedbetween elevatIon + 3.5 to - 1.5 ft. One side of thep i l i n g ~ whic.h was un coated , was totally exposed tothe sOlI enV Iron ment. The other side of the pi lings

+ 5 to - L5 _______ MinMaxAvg+ 5 t o - 25_ _ _ _ ~ 1 i l l :-'faxA\'g++ _________ ~ 1 i n + 2__________ _ _+ 2__________ _+ L____________ _+ L ____________ _0 ________ ____ _- 1.5 ___________ _

MaxAvg

960 ('l- pi n) ______ _ _900 (4-pin) ___ __ _ _990 (4-pin ) __ ___ _ _1, 260 (4-pin) __ ___ _1, 190 (4-pi nl _____ _

1, 380 ('I- pin) _____ _1, 550 (4-pi n) _____ _1, 440 (4-pill) ______ _680 (Shepa rd Canesl __ _950 (Shepard Ca nes) __820 (Shepard Ca nes) __

1, 000 (She pa rd Cancs) __ _1,400 (Laboratory)_ __ _ 8. 51, 290 (Labora to ry ) _ _ _ _ _ _ 8. 1850 (She pa rd Ca nes) _ _ _ _ ___ _800 (Shepar d Canes) ________ _850 (Shepa rd Canes) _____ ___ _

Conditio n oj piles :+ 3.5 to + .5 It: ~ l i l l scale was intact over 40e n t of Lhe swJace. The remaining surface wasumformly attacked and had many shallow pi ts lessthan mils in depth, and some deeper pits. Afew PitS ranged between 55 and 61 mils in depth ,and many others ra nged between 25 and 55 mils.The average reduction in wall th ickne s observ ed onth e th ree most corroded areas was between 6 andpercent .+ 1.5 to - 1.5 ft: Mill scale was in tact ov('1' about60 percent of the surface. Slight uniform corrosionwas present on the remaining surface and ther e weremany pits which did no t exceed 25 mils in depth .There was slig'ht Q'enel'al metal attack and pitLino'over the entire side of Lhe pilino.s whichexposed on th e water side. The l'iverb wutel' had aresistivity of 2,500 ohm-em , and a salt content of40 ppm.NORTH END OF LOCK- EAST SIDE

Piling expo sed: A 5 f t width of the wall was exposedbetween elevation + 3.5 and 0 ft .SU1jace elevation: +5 f tWater table elevati on: + 1 f tSoil characteristics:+ 5 to + 3 ft: F ill consisting of a m ixture of sl ightly

237


16/22

friable reddish brown and gray tight clay containinggravel and many stones.+ 3 to 0: Natural soil consisting of brown fatplastic clay.Soil resistivity and pH

Elevation

ft+ 5 to ________ MinMa xAvg

+ 5 to - 15 _______ MinMaxAvg+ 5 to - 2iL ______ jVIin

Ma xAvg

Resistivi ty pH

Ohm-cm960 (4-pin) ________________ _1,280 (4-pin ) ________________ _1, 130 _______________________ _1, 150 _______________ ___ _____ _1, 530_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ __ ___ _] , 370 ___________ ____________ _] , 210 _______________________ _1, 610 _______________________ _1,480 _______________ ___ _____ _

+ 4 ______________ Min 950 (Shepar d Canes) ___ _____ _Mil,x 1, 300 (Shepard Canes) ______ __ _+2.5 ___________ _ 1,050 (Laborato ry) ________ 8. 1+ 1.5 ___________ _ 1,220 (Laboratory) ________ 7.9+ L _____________ :vrin 870 (Shep ard Canes) ________ _Ma x 1, 000 (Shep ard Canes) ________ _0___ ___ __________ Min 750 (S hepar d Canes) ________ _Max 1, 200 (Shepard Canes) ________ _

Condition oj pi les :+ 3 to + 1 It: Mill scale was present on 40 percentof pile surfaces. There was uniform corrosionand pitting where the mill scale was missing. Thetlu'ee deepest pits were between 75 and 90 mils indepth. About 30 pi ts measured between 20 and75 mils in depth, and many other pits were shallowerth an 20 mils. The average reduction in pile thickness observed in the thl'ee most corroded areaswas between 8 and 11 percent.+ 1 to 0: About 75 percent of the mill scale wasintact in tIllS zone. The pile surfaces were smooth,had li ttl e metal attack, an d [tIl pits were lessthan 20 mils in depth .The condition of the coated piles exposed to thewater side was similar to that described for thepiling on the west side of the lock.

f. Algiers Lock, New Orleans, LouisianaHistory:An excavation \vas made to expose type Z 32 sheetpilings in the cutoff wall on the east side of thesouth end of Algiers Lock, which is lo cated on theAlgiers Canal at the Mississippi River , New Orleans,La. The pil es have a driving width of 21 in. andwall thicknesses of % n. at the web and ~ ; , in . at theflanges .Date piles driven: :May 1948Date oj inspection: April 1960Age oj piling: 11.9 yearsPi ling expo sed: A 5-[t width of the cu toff '\"all ,,-asexposed between elevation + 3.5 to + 1 It

Surface elevation: + ftWater table elevation: + 2 ftSoil characteristics:+ 5 to 3.5 It : Brown silty clay fill material.+ 3.5 to + 1: Brown silty clay with po ckets oftight plastic grayish blue clay dispersed throughoutthe profile with large quantities of organic matter,rotted wood, gravel, and small ston es.Soil resist i\ 'ity a nd pH

Elevation

It+ 5 to - 5 ________ MinM axAvg+ 5 to - 15________ Mi nMa xAvg+ 5 to - 25 _______ Mi nMaxAv g+ 5 ______________ Min

Max+ ____________ --I+ 2 _____________ _ .\Ifin

I ~ I a x + 1.___________ __Condition of piles:

Resistivity pHOhm-cm800 (,I-pin ) ________________ _840 (4-pinL _______________ _820 (4-pin) ________________ _

57.5 (4-pin) ________________ _650 (4-pin ) ________________ _600 (4-pin) ________________ _345 (4-pin) __ _____________ _460 (4 -pin ) ________________ _no (4-pin ) ________________ _700 (Shepa rd Canes) ________ _1,150 (Shep a rd Canes) ________ _

1, 300 (Shepa rd Canes) ________ _1,140 (Laboratory) ________ 8. 41,290 (Laboratory) ________ 7. 7650 (S hep a rd Ca nes) ________ _] , 200 (S hepard Canes) ________ _1,300 (Shepard Canes) ________ _

Mill scale was present over approximately 85-percent of the surface. Nodul es of clay adheredto the steel sur face in sea ttered small areas, generally not exceeding 1 in. 2 in siz e, beneath which werelight metal attack or pitting. The deepest pitmeasured 40 mils in depth . Nine pits measuredbetween 22 and 32 mils in depth, and other pit s.measul'edless th an 20 mils. The average reductionin wall thickness measured on the thTee most corroded areas of the sample pile section cut from thewall was between 3 and 4 percent.

g. Enid Dam Spillway, Enid, MississippiHistory:An 8-f t width of steel sheet pilings was exposed onthe north side or the upstream wingwall in the EnidDam Spillway. The piles consisted of interlockingarch-type beams having a driving width 0 1' 18 in.Date p?'Zes dr/ven: September 1949Date of inspection: 1961Age oj piling: 11.7 yearsPil1ng exposed: An 8-ft width of the pilings wasexposed between elevation 288 and 282.5 ft.SUijace elevation: 29 3 ftWater table elevation: Much below 282.5 ftSoil characteristics:293 to 290.5 ft: Brown sil ty clay, somewhatplastic.

238


17/22

290.5 to 282.5: Reddish brown coarse sand containing much silt and gravel.Soil resist ivity and pH

E levationIt_____ ________ _

_____ _____ _______ ___ _______ ____ _.5 ___________ _

of piLes:

Resist ivity I pHOhm-em8,500 (Shepard Canes) _____ _________ _8,000 (Shepard Canes) ______________ _

10,000 (Shepard Canes) ____________ _> 4,000 L a b o r l ' ~ ' ) _ _ _ _ _ _ _ _ _ _ _ _ 5. J10,200 (Laboratory) _ _ _ _ _ _ _ _ _ _ _ _ _ .5. 39,500 (Shepa.rd Ca.nes) ___ ___________ _

;"/Ji ll a ~ e wa s ir:tact over more tl1


18/22

..,..o

I.ocation 11 Ageofpil in g Soillypes

'f ATILE 3. Summary oj inspections on stee l pilingsPiling exposed b Soil resistivity e pi i Partial chemical composi tion (mgeq!l00 g soil) Condition of piling d 8mface with original I Maximum reductionmill scale in tact of th ickness in local

Abovel In IB elowwater water water I l \ [ in i-table table table mu IIzone MaXi- IMilli-IMax!'1 co,l " co .1 CInlum mum mumAboveSO, 1 wa tcrtable

Inwatertablezone

areas Below IAbovcl In IBelowlAbovel In IBelowwater water water water water water watertable table table table table table tablezone zone - - - - -1 - -1 - I - - - I - - - I - - - I - - ' - - ' - - ' - - - ' - - - I ~ - I - - - - - - ' - - - ' - - ' - - - , - - - , - - - - - - , - - -

Extracted Piles:Bonnet Ca rreSpillwaySparrows Point,M d.Ouachita Ri verLock No.8Gr' nada Dam;North sideSardis Da m ___ ___ _

Yr1718

4012

20

Sand, organic siltand cL yFill- cinders, slagan d sandNatural- sand, siltand claySilty clay and clay __

Fill- sand y loamand Silty sandNat ura l- shale andan d organic clay

X XX X

XxFill- riprap ___ .. ___ ., . __Natural- sand and

XXXX

XX

Ohm-cm Ohmcm400 1,050I, 130 4,0001,3 70 12,4001,540 3,2002,8003,800

lii,40015.400

6101,690

G.73.74.94.3

3.6

S. I6.67.36.24.94. 93.02.9

O5a 1.40 1 II. 94 1 O. 04 uP,35

P, 122M

MP,1I2

us

u (S

p. GOP,30

percelltl percent lPercent I ercent IpercentlPercent~ 5 + 0 95 + Nil Nil Nil50+ 90+ 29 1 Ni l

95 + 1 .. . _ . . . . . . J Nil (95 + ,.

307[, I .. . _.J __ .. 1 Nil

Nil

1911Chef Mentenr PassWilm ington Marine TeflniDaL ___

3223 MP,75Iignitic claySit ysandandclay _ I ___ .. 1 X 1 X I 300 I 440 I 6.9 1 7.S I_____ I ___ .. ______ I _ __ I______ __FTII- c ll lders. . _ __ .. X __ ____ ' ---- .. . -- .. -. -- -- .. - .. . ----- - .. -- .. ...... --- ------ -----1 ,I50Natwal- Olgam c __ .. . __ X X . . . . . . ___ . ___ _ . _______ __ __ . . . . . . ______ ___ _____ . . . . . __ . _ __ 75 1 85 1--'".. . . . . . . . . 10 N il Nil,145M 90 + 10 i Nil

Lum ber Rivcr ____ _Piles in excavations:

37 silt, sand, claySand y loam an dsilty clay X X 1, 100 4,000 2.3 5.9 P,60 P,60 20 40 I1 12Memphis Floodwall, Sta. 56 + 14gMemphis Floodwal!, S ao 60+ 0Vicksbm g Floodwa ll , Sta. 16+32Vicksburg Floodwall, Sta. 23 + 83Sardis Da m . _ ..

Clay an d silty claY __ 1 XClay an d silty clay. X

xX

1,000 I 8,600 I 7.61 7.81 .00 I 0. 52 1 O'OSI .591,030 7,900 6.8 7.8 .00 .43 .03 .21

uu

P,35U

95+90+30

95+1 .. _ . _J Nil90+ 1 . _ .. . 1 Nil

N ilN il

Sandy loam, clayand cindersSilty sand, clay andcindersXX

X 850X 625

Fill- sandy loam____ X __ ______ ____ > 10.000Na tural- clay_______ . X X 3.000Fill- clayey sand X __ __ . . . . _ _ . 1,700alld silt loam

7,0009.200

50,2007,51016,500

7.47. 15.44.0

8.28.65. 76.04. 4

.01

.05

. 00.00.00

.351.24O. OS.00.02

. 04

.03

.00.03. 04

.00

.00

.00.021.10

P,40MM

P,108

P,45M 70M S

4070 Ni l

Ni lNi l

90 1 90 1 . .. J . J . _ ..Gre na da Dam,North sideGre nada Da m,South sideBerwick Lock,West sideBerwick Lock,E ast side

20111111

Fill- sandy loam ____ X" .. . __ .. __ __ .. 2,400 8.000 4.4 6.4 .. - - -- - - -- .. - -- -- - P , I721--------

1-----'"Natural- silty sand _ X .. . __ .. __ . ____ 4,300 11,000 6 . 9 . 0 0 .04 .06 0.00 P,160 ____________ . . . .Fill- S il ty clay_.____ X .. . __ .... . _... 6S0 1,550 8.5 .. . . . . . ___ .. _____ .. P,61 ____ .. ________ ..

90207050406040

J9SNi l11Natural- clay_______ X X X 800 1.290 8. 1 .03.79.05.14 S S S 60 1 60 N il 1 NilAlgicrs Lock____ .. _ 8 40 75~ ~ f ~ : ~ r t c r ~ i i : : : : : : .._X .. : : : : : : : : __ . __ __ ~ : ~ : ~ ~ ~ ~ S 1 Ni l1 ._.11J2]!:nid D am ________ 12

(above piling)Na tural-Silty clayaud organiC claySilty clay, sand andsilt xX 345 1. 300 7. 7

8, 000 10,200 5. 1

See sections 4.1 and 4.2 for additional information pertaining to location, type and length ofpiling examined.bA n HX H indicates the soil level with reference to the water table in which piling was examined.'rh e water table zone inclndes 2 ft above and below the water line. A dash indicates that piling wasno t examined at that lev('1.o In cl udes all soil resistivity determina tions measured by Shepard Canes, 4pillmethod. or in thelaboratory.d Condition of piling is described in acco rdance with the following code:

V, no corrosion, surrace is entirely una ffected as indicated by the pr esence or mill scale over prndi-cally the ent ire surface. The sUl'face may be roughcncd in small arcas but 110 pit s havc a c1epthgreaLr than the t hi ckn ess of the mill scale.

8.45. 3

.02 . 63 .05 .00 ,__ . . . . . . P,40 85" 1M 90 Ni l

M, uniform metal at tack indicated by remov al of mill scale ovcr large areas an d roughening of thesurface. Pi t depths do no t exceed the thickness of the mill scale.S, shallow metal attack, sumcient corrosion to have removed a perceptible amount of mctal inlocalized areas. Pits do Dot exceed 25 mils iu deptb.P, pitting, grooving or scaling to a dcpth greater than 25 mils. The numbers indicate the maximumpi t de pth (in mils). It should be noted that the average reduction in thickness does no t rcfcr to the cntire section ofpiling, but to a very small area, usually 1 in. 2 of the most corroded area of the piling. Refer to section3.4 for further cxplanal.ion. "Nil" indicates that the reduction in thickness is negligible.( Pilings passed through a sand and gravel stratum at a deptb of abo ut - 116 ft. A 3ft,section ofthe pile at this level showed moderate corrosion as indicated in section 4.1.

it 'rhi s was the only coated piling inspected.


19/22

GURE 7. Co rrosiveness of soil sam ples from Bonnet Carre Spillway as indicated by electrode weir/ilt lo sses after 6 months in modifiedDenison corrosion cells.Electrode se ts A and C se t up under ae ra ted an d un aeratcd conditions, respectively, with soil samp les oh tained at 22 ft dep th from surface of grouml.~ 1 e c L o d c sets 13 C1nd ]) set up lUH\er aerated and unaeratcd conditions, respective ly, with soil sa mplf'S ob tained at 45 fl deplh.

Electrode

.1\ __ ______ ____ _____ _B ___ . ___ . __________C ___ . __ .. __ _______ _J) __ . __ . ______ _____ _

structures, such as pipelines, in disturbedEmphasis was placed on survey methodsg measurements of pH , soil electrical re sistiredox potential, and bacterial activity.I t is eviden t from an evaluation of the data in3 t hat the survey methods recommended bypresently are the methods widely usedengineers, are misleading in that they ovel-the corrosion of steel pilings driven in soils.r example, the 122-ft length of H-pile pulled frome Bonnet CaITe Spillway after e:ll.1)osure for 17 yrs subj ected to varying soil types at differentunder poorly aerated conditions. At the

e the pile was inspected, soil samples co llectedthe pile walls at depths of about 22 ft and 45 f tsmface were shipped to the National Buof Standards. The soils consisted of clay havingresistivity of 400 ohm-em and a pH between 7.8d 8.1. Chemical analysis detected the presence ofquantities of soluble salts in the form ofnates, bicarbonates, sulfates and chlorides, theer being predominant (table 3). Th e propertiesthis soil are nearly similar to those of a Docas clayfound at Site 64, one of the most corrosive soilsthe NBS corrosion field tests. At this site, carbonl pipe specimens with a wall thickness of 0.154. were perforated by corrosion within 5 yr and hadweight losses.241

Loss in weigbtoZlft'2.031.82O UJ'!O. ] 5

The soil samples from the Bonnet Cane Site weresubjected to the modified Denison cOlTosion cell tes tin the laboratory [1,16J; by means of this cell thebehavior of iron or steel in different soils can beinves tigated under con trolled conditions of moistw:eand aeration. In the aerated condition, the moisturecontent is controlled to make the soil sufficiently perm eable for access of oxygen to the cathode. In theunaerated condition, all th e soil is puddled at th etime of setting up the cells, th us limi ting access ofoxygen to the electrodes. The sm all amount ofoxygen available in the unaerated cell is rapidly depleted during the initial corrosion process and th ereplenishment of oxygen at th e cathode becomesdifficult because of the puddled soil.An es timate of the co rrosiveness of a soil is determined in the Denison cell by a measurement of thegalvanic current between the electrodes or preferablyby the combined weight losses of the two electrodes _Good correlations were obtained between the weigh tlosses of corrosion cells set up for six months underaerated conditions using soils from NBS test sitesand the weight losses occurring in the field at, thetest sites on Wlought ferrous pipe specimens exposedfor 10 yT [1,16J.The results obtained with t.he modified Denisoncell on th e Bonnet OnTe soil sa 111 pIes for six 111.011 ths'


20/22

exposme in the laboratory under aerated and unaerated conditions are shown in figure 7.I t was previously pointed out that the soil samplesfrom the piling which was extracted fronl the BonnetCarre Spillway had properties similar to those of theseverely corrosive Docas clay soil in the NBS fieldtests. The laboratory corrosion cell set up under theaerated conditions produced weight losses of thesame order of magnitude for the Bonnet Carre (fig.

7, A and B) and Docas clay soils [1,16] indicatingthat the Bonnet Carre soilis equally as cOl'rosive as theDocas clay soil under aerated conditions. Theweight losses of ferrous pipe specimens which wereexposed in the disturbed soil at the Docas clay siteare in relatively good agreement with the resultsobtained in the laboratory under aerated conditions.On the other hand, the piling extracted from theBonnet Cane Spillway after exposure for 17 yrwas unaffected by cOlTosion at all depths below thewater table zone, and showed but a negligible amount,of corrosion in the water table zone. This is incomplete accord with the results from the laboratorycell test which showed a relatively negligible amountof corrosion (or the cell electrodes set up under unaerated conditions as compared with that of the cellelectrodes se t up under aerated conditions.The data presented in section 4 and summarizedin table 3 show that, in general, the amount ofcorrosion of th e pilings exposed below the watertable zone at any of the sites was not sufficient tohave an appreciable effect on the strength of thepilings for the periods of exposure. The water tablezone is defined as the zone lying between 2 ft ofthe water table.

At Sparrows Point, a 3-It section of each of th e twoH -piles contain ed some modera te corrosion belowthe water table at elevation of about - 116 ft.These sections of the piles passed through a coarsesand and gravel bed through which ground waterflowed more freely than in the other strats . Thecorrosion can possibly be attributed to th e action ofdissolved carbon dioxide. The sections of the pilesabove the sand and gravel stratum to the waterline zone and below the sand and gravel stratum tothe bottom of th e piles were almost entirely coatedwith mill scale. The condition of three sections ofone of the H -piles pulled from Sparrows Point isshown in figure 1.Corrosion was found on steel piles exposed belowthe water table at the Sardis Dam, Chef MenteurPass Bridge, and the Lumber River structures.The pits were highly localized as indicated by thela rge amount of mill scale intact on the pile surfaces.Only small or negligible reductions in wall thicknesses were observed.

The portions of pilings which appeared to be themost vulnerable to corrosion were the sections,exposed in fill soil located above the water tablelevel or in the water table zone. In the wDter tablezone, corrosion was found on the pilings extractedfrom the SpalTows Point and Lumber River locations; reductions of 29 and 40 percent were observedin the cross sections of the piles after 18 and 37 yr,

respectively. Corrosion tapered off rapidly andwas not appreciable below the water table zone.Significant corrosion occurred above the watertable only in fill soils at Grenada Dam, BerwickLock , and at the 'iiVilmington Marine Terminal(table 3). The corrosion at these locations washighly localized as shown by the reductions in wallth ickness of the piles.Inspections of the pilings in the test holes atGrenada Dam were made early in the investigation.The pitting type of corrosion found on th e pilesexposed to the fill soil were of concern to personnelof the Corps of Engineers. As a result, a pilesection was pulled from th e north wingwall structureto observe the condition of the pile at greater depthsNo corrosion of any significance was found in thenatural soil below the fill layer.

The data indicate that th e depths of max.imumpitting give no indication of the extent of corrosionon pilings. A review of each case history in section4 shows that the number of deep pits are relativelyfew for th e large areas of pile surface involved, andthat most of the measured pit depths are considerably less than the maximum reported in table 3Furthermore, corrosion by pitting covers a Telatively small area of the pilings, especially below thewater table zone. Significant pitting was not observed on many of the piles below the water lineAn example of this is illustrated in figure 2 for thepiling pulled from the Ouachita River Lock after 40yr of exposure.

I t should also be noted that there is generally amarked difference between the maximum depth opitting and the reduction in cross section areaFor example, maximum pi t depths of the order o145 mils found on th e pilings from the Chef MenteuPass Bridge might cause considerable concern for fluid-carrying structure regardless of the conditionof other portions of the structure. On the othehand, because of the localized and iso la ted naturof attack, pit depths of this magnitude do not havan appreciable effect on the strength or useful lifof piling structures because the reduction in pilcross section after exposure for 32 yr is not significantAt the time of driving the H -piles at SparrowPoint and the 100-It lengths of the sheet piles athe 'iiVilmington Marine Terminal, sections forminthe full pile length were joined by butt welds. Thwelds showed no evidence of corrosion at the timof inspection after the piles were pulled. A weldejoint on the Sparrows Point pile is shown in figure 1

Stray currents have been detected and measurethroughout th e entire area where the two pilewere extracted at Sparrows Point. Several monthafter the piles were pulled, an engineer of the Bethlehem Steel Company and the writer conductemeasurements on a 9-ft section of 36-in. cast irowater pipe which was located about 600 ft from thpiles. A maximum current of 40.5 amp with aaverage of 13.5 amp was measured over a 20-hperiod. On another pipe of similar dimensionlocated approximately 100 ft from the site of pilI-S, str s,y-current measurements averaged 3 am

242


21/22

with a maximum of 4 amp over the 20-hr period.The absence of highly localized corrosion on thepilings indicated that they were not acting as conductors for the stray currents in the area.I t is also of in terest to mention tbe excellentcondition of a group of identification numbers whichwas stamped in the steel with %in. dies on the 40-yrpile from the Ouachita River Lock. Although themill scale was broken by the dies, the numbers and

the surrounding area were unaffected by corrosio n,as were the roll marks on the pile indicating themanufacturers identification and patent number.At all locations, roll marks on the piles wheredetected were legible and were in the same conditionas the surrounding surfaces (figs. 4, 5, and 6).In general the data obtained from the pilinginspections do not show any correlation betweenoil properties and the condition of the pile surfacesin the different soil environments, with th e possibleexception of pH. NIaximmn corros ion was observedon th c pilings exposed to extremely acid soils in thewater table zone at J.1umber River (]JH 2.3) ands Point (pH 3.7), and below Lhe waLer tablezone aL Sardis D,tm (pI-I 2.9). The soils in thepiling investigat ion cover as wide a range of properties as the soils included in the early NBS fieldtests. The results or the earlier tesls showed thatthere is at least a rough correlation beLween theorrosion of iron or steel and certain soil properties,uch as resistivity, pH and chemical composition.The major difrerence between the soils at tbeBS test sites and Lhe soils into which the pilingsere driven appears Lo be the oxygen content.he data from the ea rh- soil-corrosion tes ts and mostdata reportecl previously on service strucures were obtained on specimens or structuresin backfilled soil. The backfilling causes ain the oArygen content of theand promotes corrosion of iron and steel byaeration. On the other hand , theundisturbed soils is no t

are driven into the ground.I t would seem that the soil types which rangesands to ti.ght impermeable clays atat the same locations, would

oxygen has been depleted by the initial corrosionprocess and corrosion ceases thereafter because of theinability of the soil to replenish the oxygen.The importance of oxygen as a factor in the co rrosion process was previously indicated, by thebehavior of steel in the modified Denison corrosioncell set up under aerated and unaerated conditionsin the laboratory on soil samples from the BonnetCarre Spillway (fig. 7) .The data obtained from the inspections of steelpilings indicate that there is not sufficient oxygenavailable in undisturbed soils to cause appreciablecorrosion on driven pilings regardless of the soilproperties. Even wet cinders which were presentin the water table zone adjacent to the floodwallsexcavated at Vicksburg and Memphis had nocorrosive effect on the steel pile surfaces.Appreciable quanLities of soluble saIL in the formof sulfates and other ions were present in lhe so ilto which Lhe piLings from Lhe Memphis Floodwalland Berwick Lock were exposed. The inlemaldrainage aL the siles, soil pH, and Lhe presenc e oforganic maLle)' consliluLed condilions under whichsulfale-reducing bacteria would be expected Lothr ive. Howevcr , no cvidence of accclerated cor)'osion by lile anaerobic badelia w('re delecLed onthe piles at Lhese siLes. In facl, at none of lhe locaLion s where pilings WCl'e examined were sulfidesdetected in the cOlTo sion pl'oducls.Exam inaLion of the dala in LithIc 3 and section 4shows Lila,L in geneml so il lype, d),ainage, so il)'esisL ivity, pH, or cheillical com pos ilion of soils areof no imporLance in determining lhe conosion ofsteel pilings driven in undislurbed soils. This iscontrary to c\"Crylhing published perLaining to thebellavior of iron and steel under disLurbed 0)' back

fi]l ed soil conn i Lons. Hence, soil corrosion datapublished in NBS Circular 579 [1] are not app licahleand should not be used fa)' eSlimaling the behaviorof steel pilings driven in undisLurbed soils. Likewise,smvey n1.elhods, as recommended by Skipp [15]and othe rs, are of no pmctical value in predictingthe extent of corrosion of stecl pilings underground.6. Summary

in oxygen content to promote Steel piling's which have been in service in val'iousby differential aeration. Accelerated cor- underground stl'Llctures for periods ra nging heLweenbe expected to occur 7 and 40 yr were inspected by pulling piles at 8e to galvanic effects resulting from the presence locations and making excavaLions to expose pileand exposed bare metal in adjacent sections at 11 locations. The conditions at Lhethe data from the piling inspec- sites varied widely, as indicated by Lue soil Lypesthat there is not enough oxygen which ranged from well-drained sands Lo imperviousa short distance below the ground line, clays, soil resistivit ies which ranged from 300 ohmd especially below water table zones, to promote cm to 50,200 ohm-em., and soil pH which mngedby differential aeration or other causes. from 2.3 to 8.6.The data indicate thaL Lile Lype and amount ofoArygen is e sential for corrosion to corrosion observed on the sLecl pilings driven intoundistmbed nalmal soil, regardless of the soilEvidently some COITO ion of steel piles takes place characteristics and pl'operLies, is not sumcient toafter the piles are driven as indicated by the significantly affect the sLrength or useful life ofof mill scale in small areas and lo calized pilings as load-bear ing stmctures.at some of the loca tions. The corrosion is Moderate corrosion occmred on several pilesidently arrested after the limited amount of exposed to fill soils which were above the water table

243


22/22

level or in the water table zone. At these levels th epile sections are accessible if the need for protectionshould be deemed necessary.It was observed that soil environments which arcseverely corrosive to iron aoo steel bmied underdisturbed conditions in excavated trenches were notcorrosive to steel pilings driven in the undisturbedsoil. The difference in corrosion is attributed tothe differences in oxygen concentration. The data

indicate that undisturbed soils are so deficient inoxygen at levels a few feet below the ground line orbelow the water table zone, that steel pilings arenot appreciably affected by corrosion, regardless ofthe soil types or the soil properties. Properties ofsoils such as type, drainage, resistivity, pH or chem.ical composition are of no pract ical value in deten:nining the corrosiveness of soils toward steel pilingsdriven underground. This is contrary to everythingpreviously published pertaining to the behavior ofsteel under disturbed soil conditions. Hence, it canbe concluded that National Bureau of Standardsda ta previously published on specimens exposed indistw-bed soils do not apply to steel pilings whichare driven in undisturbed soils.

The author acknowledges the support in tlJisprogram of the American Iron and Steel Institute,the U.S. Corps of Engineers, an d the WatenvaysExperiment Station of the Corps of Engineers.The author is especially grateful to the followingindividuals who rendered assistance by participatingin various phases of the investigation: HaroldArdahl, Corps of Engineers, Lower MississippiValley Division; Walter B. Farrar, Corps of Engineers, Office of Chief Engineer; F. E. Fahy, Chairmanof the Piling Subcommittee of the A.I.S.I. Committee on Building Research and Technology;C. P. Larrabee, Uni ted States Steel Company ;T . D. Dismuke, Bethlehem Steel Company; andW. D. Tryon, Williams-McWilliams Industries, Inc .

7. References[1] Melvin Romanoff, Underg round corrosion, NationalBureau of Standards Circu lar 579. U.S. Gove rnmentPrin ting Office, Washington 25, D.C. , (1957).[2] Paul Anderson, Substructu rc Analys is a nd Design, p.139, 2d Ed ., The Ron ald Press, York , N e,Y York(1956) .[3] G. A. Hool a nd S. Einne, F oundat ions, Abutmen tsa nd Footings, p. 204, 2d Ed. , McGraw-Hill BookCompany, In c., Nc \\" York , N.Y. , (1943).(4] J. G. Mason an d A. L. Ogle, Steel pile foundations inN ebr aska , Civil Eng. 2, ~ o . 9, 533 (1932).[5] Louis Beaudry, Quay wall design and construc tion, Eng.J. (Canada) 14, 394 (1931).[6] Stecl shells in service 39 years st ill sound a nd serviceable,Eng. News-Rccord 100, 15, 590 (Apr. 12, 1928).[7] Life of steel shee t piling, Iron Age 129, No . 23 , 1247(Ju ne 9, 1932).[8] B. M. Ga lla\yay, A report on some factors affecting t helife of ste el pilings in th e Texas Gu lf Coast area,T exas Tran sportation In st itu t e, Co llcge Station ,T exas (Oct. 1955).[9] G. G. Greulich, Extracted steel H-piles found in goodcondition, Eng. N e,,s-Record, 1t5, No.8 , 41 (Aug.24, 1950).[10] C. V. Brouillettc and A. E. Hanna , Corrosion surwy of

steel sheet piling, Tech. Report 097, U.S. v a l CivilEngin eering Laboratory , Port Hueneme, California(Dec. 27, 1960).[11] M. N. Lipp, Some data on beach protection works, CivilEng. 6, No.5, 291 (1936).[12] C. \ \T. Ross, Deterioration of steel sheet pile groins atPalm Beach, Fla., Corrosion 5, No . 10,339 (1949).[13] A. C. R ayner an d C. W. Ross, Durability of steel shee tpilings in shore st ru ctures, Tech. Memo. No. 12,Beach Erosion Bortrd, Corps of Engineers, U.S. Army(Feb. 1952).[14] Laurits Bjerrum, Xorwegian exper ience with steel pilefOLl ndat ions to rock, J. Boston Soc. Civil E ng. 44,No.3, 155 (1957) .[15] B. O. Skipp, Corrosion and site in ves tigation, CorrosionTechno!. 8, No.9, 269 (Sept . 1961).

[16] W. J. Schwerdtfeger, Laboratory measurement of th ecorrosion of ferrous meta ls in soils, J. Research XB S50, 329 (1953).

(Paper 66C3- 99 )

romanoff corrosion of steel piling 1962

Documents