Corrosion of Steel Pilings in Soils

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OCO•&•.JaSScfflsssssssssssQ O I »O T CC "M O 5 i2 O o • "~o •SbKOOOII o piCs. £L, ^ r** £L, £,o o c>ool^GC OC »O CT' Tfi O C3O OO OC U~iirt O C ii '55 « S ~AW w:^^*.determinations were made at the site with ShepardCanes or by the 4-pin method.Determinations of the soil type at the sites wheretest holes were excavated adjacent to the pilingswere made by visual inspection from the surface tothe floor of the pit. Soil resistivities were measuredat different levels by inserting Shepard Canes in thewalls and floor of the excavation. Additional soilresistivitv measurements were made at each site bythe 4-pin method at 10-ft, 20-ft, and 30-ft pinspacings to give the average resistivities of thevolume of soil from the surface to the depths corresponding to the respective spacings. The latterwere made at the time of the pile inspection and atapproximately 15 day intervals thereafter for aperiod of 7 months. The 4-piii resistivity measurements tabulated in section 4 represent an average ofthe many determinations.During excavation of the test holes, samples ofundisturbed soil, each sample having a volume of notless than }i ft, 3 were taken at different depths;chemical and physical properties of the sampleswere determined at the Waterways Experiment Station Laborator^v. Additional samples of the same soilscollected in tightly sealed pint jars were shipped tothe National Bureau of Standards for laboratorymeasurements of pR. and resistivity, the latter corrected to 70 °F. Data pertaining to the soil type,resistivity, and £>H are given with the inspectionresults for each location in a following section.Other physical and chemical properties of the soilsat the elevation from which portions of the pilingswere removed are listed in table 2.3.4. Thickness MeasurementsThe average thickness measurements reported forthe extracted piles represent an average of manymeasurements made by means of calipers in the pilezone indicated, and takes into account corrosion onthe two sides of the pile surface.Average thickness measurements on the piles inspected in the test holes were confined to the 1 ftby 2 ft pile samples which were removed and shippedto the laboratory. After cleaning by sandblasting,the three most corroded 1-in. 2 areas were selected oneach sample showing significant corrosion. Eacharea was divided into 25 sections on both sides of thepile sample and the pit depths in each section weredetermined. The sum of the average of the 25 pitdepths on the two surfaces of each area was used tocalculate the average reduction in pile thickness atthe base of the pits, 3 These values actually represent the average reduction in pile thickness of themost corroded areas, 1 in. 2 in size, on the piles.4. Results of InspectionsHistorical facts pertaining to the steel pilings ofvarious structures, the characteristics of the soils,and the condition of the piles are presented herewithfor the piles inspected after extraction from the soil,and for those inspected in the test holes, respectively.3 Hereafter the reduction in thickness refers to this limitation.
4.1. Extracted Pilesa. Bonnet Carre Spillway, New Orleans, LouisianaHistory:A 12-in., 65-lb, test H-pile was driven to a depthof about 122 ft below natural ground surface in aswamp near the river side toe of the west approachramp to the Airline Highway Bridge across BonnetCarre Spillway.Date pile driven: 1933Date pile pulled: 1950Age oj piling: 17 yearsPiling exposed: Elevation +2.0 to —120 ft msl. 4Ground line at +2.5 ft; water line at 0 ft.Soil characteristics:+2.5 to —7 ft: Soft dark gray organic silty clay.— 7 to —40: Very soft dark gray highly organicclay and silt layers with few thin layers of peat andfew thin layers of fine gray sand.—40 to —62: Very soft dark gray clay and siltlayers, slightly organic.— 62 to —67: Dense yellowish brown silty sandwith hard clay layers at bottom.— 67 to —120: Light bluish gray plastic clay,hard at top, very stiff at bottom.Elevationft+ 2.5 to —7.5,.—+ 2.5 to -17.5—_+ 2.5 to — 27.5__-+ 2.5. ___________-1.5-.... _______-22... __________— 45Soil resistivity andMinMaxAvgMinMaxAvgMinMaxAvgResistivityOhm-cm920 (4-pin)____________1 7050 (4-pin). ___________960 (4-pin)_. _...____.540 (4-pin).840 (4-pin)-___________770 (4-pin)____________460 (4-pin). ___________800 (4-pin) — ___. ____..680 (4-pin) — — ______700 (Shepard Canes) _ _ _750 (Shepard Canes)400 (Laboratory).400 (Laboratory) _„____p~H.fi 77 88 1Condition of pile:The space between the flanges of the pile wascompletely filled with soil and a layer of soil adheredto the outer edges of the flanges. Examinationafter cleaning showed no measurable corrosion.Mill scale was intact over almost the entire surfaceexcept for the 3-ft section in the area of the watertable between elevation +1.5 and —1,5 ft. In thiszone a crust of light colored hard substance coatedthe metal. Slight metal attack was found underthe crust.*msl refers to mean sea level. All elevation values in the paper refer to msl,nless otherwise noted.b. H-Piles at Sparrows Point, MarylandHistory: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. The American Iron and Steel Institute arranged with the Bethlehem Steel Companyto extract two of the piles and to permit the writerto inspect and report on the condition of the piles aspart of this investigation. The piles were 139 ft inlength, 136 ft of which was driven below the groundline. The two piles were separated by a distanceof 100 ft.Date piles driven: 1942Date piles pulled: November 1960Age of piling: 18 yearsPiling exposed: Elevation +13 to —126 ft. Groundline at +10 ft.Soil characteristics:This area was originally a peninsula surrounded byshallow water and marsh which was filled to aboutelevation +10 ft with slag and cinders.+ 10 to 0 ft: Slag and cinder fill with some finesand. Water line at +7.0 ft for pile No. I-S, andat +6.4 ft for pile No. II-S.0 to —10: Natural soil starts at 0 ft. Light graysilty clay containing appreciable sand, underlain bya stiff brown silty clay and marbled gray clay.—10 to —25: Light brown sandy silt to a softdark gray silty clay at —15 ft.— 25 to —90: Transition from brownish to darkgray silty clay mixed with peat and organic matterat some levels.— 90 to —95: Dark brown silt underlain by finebrown sand.— 95 to —110: Transition from sand of differenttextures to dark brown silt.— 110 to —120: Coarse brown sand and graveland some fine gray sand.— 120 to —126: Brownish and gray stiff clay.Soil resistivity and pHPile No. Elevationft-24*-24*-51-54*-54*-83-83*_92-102-120-1-4-24-51-92ResistivityOhm-cm2, 5005, 1001, 4101,8203,0001,5001,7001, 3702, 1007, 20012, 4001, 1304,0002,5001, 4502, 500PH3.74.85.67.35.46. 16.36.36.46.46.64. 74.96.86. 1"Laboratory measurements made on soil samples taken from extracted pile.All other measurements made on soil sample borings obtained 1 ft from pile.
Page 1 and 2: ScienceDocs.NBS MONOGRAPH 58Corrosi
Page 3 and 4: UNITED STATES DEPARTMENT OF COMMERC
Page 5 and 6: Corrosion of Steel Pilings in Soils
Page 7: exposure, 0.005 in./yr for wetting
Page 11 and 12: The pile was a shallow-arch sheet p
Page 13 and 14: Condition of piles:Metal attack occ
Page 15 and 16: mils. A maximum reduction in pile c
Page 17 and 18: ElevationSoil resistivity and pHRes
Page 19 and 20: Elevationft256 to 236_____ __256 to
Page 21: 290.5 to 282.5 : Reddish brown coar
Page 24 and 25: exposure in the laboratory under ae
Page 26 and 27: level or in the water table zone. A

Corrosion of Steel Pilings in Soils

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