Inclined Tube Test – Will it really help improve post-tensioning grouts?

Trey Hamilton, PhD, PEByron D. Spangler Professor of Civil Engineering

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PT Grout

Transfer post-tensioning force

Strand protection

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Grout Classification

Class A-non-aggressive applications

Class B-aggressive applications

Class C-prepackaged grout for both

Class D-specialized grouts

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Prepackaged Grout Constituents

Portland Cement (ASTM C150)

Fly ash (ASTM C618, Class C and Class F)

Slag cement (ASTM C989, Grade 120)

Silica Fume (ASTM C1240)

HRWR

Other admixtures

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Grout Performance Characteristics

Fresh

Low viscosity to allow pumping and filling

Bleed resistance

Segregation resistance

Minimum volume change

Hardened

Duct filled solid with good grout

Adequate compressive strength

Low permeability

High pH

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Prepackaged Grout Laboratory Testing Chlorides (ASTM C1152) < 0.08% by weight of grout

Set time (ASTM C953) 3 to 12 hours

Compressive Strength (ASTM C942) 5000 psi at 28 days

Permeability (ASTM C1202) <2500 coulombs (@ 30V)

Volume change (ASTM C1090) 0.0% to +0.1% (at 24 hours)

Pumpability and Fluidity (Modified flow cone ASTM C939)

Bleed

Wick-induced (Modified C940 – 40 in. long x 3-in. diam.) 0.0%

Pressure Bleed Test (ASTM C1741) varies

ACT Corrosion test (if required)

Wet Density (mud balance)

Inclined tube test (EN 445) 0.3% by volume allowed

*conducted at the min and max water dosage recommended

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Inclined Tube Test

Based on EN445

Focus is “bleed and stability”of grout

Two tubes are grouted to evaluate re-grouting

Transparent tubes at ~80 mm dia. and 5 m long.

12 strands in each tube(15-16 mm)

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“Bleed” test comparison

Inclined Test Schupack Pressure Test

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Modified Inclined Tube Test (MITT)

Shortened strand bundle (ease grout sampling)

Dissection of duct

Moisture content measurements

Transparent duct?

30 deg.

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Grout Mixing

Used 4 bag mixes with colloidal plant

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Fresh Properties

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Grout Injection

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Sampling (24 Hours)

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Moisture Content

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Effect of aging-soft grout

Exposure Time (days)

Soft

Gro

ut

(g)

0 4 8 12 16 20 24 280

25

50

75

100

125

150

175

200

225

250

275

PT1-4 (0.42)PT2-4 (0.55)PT3-3 (0.63)PT4-6 (0.51)PT5-1 (0.06)PT6-1 (0.16)PT1-5 (0.22)PT2-5 (0.08)PT3-4 (0.54)PT5-2 (0.12)PT6-2 (0.14)PT7-1 (0.07)

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Effect of aging-moisture content

Distance from Low End of Duct (in.)

Mo

istu

re C

on

ten

t (%

)

0 20 40 60 80 100 120 140 160 180 2000

10

20

30

40

50

60

70

80

90

100

0-day1-day3-day7-day14-day28-day

1-day3-day7-day

Distance from Low End of Duct (in.)

Mo

istu

re C

on

ten

t (%

)

0 20 40 60 80 100 120 140 160 180 2000

10

20

30

40

50

60

70

80

90

100

0-day1-day3-day7-day14-day28-day

1-day3-day7-day14-day

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Filler and soft grout

w/s

Soft

Gro

ut (g

)

0.2 0.3 0.4 0.5 0.6 0.7 0.80

20

40

60

80

100

120

140

160

180

2000 % fill35 % fill45 % fill

w/c

Soft

Gro

ut (g

)

0.2 0.3 0.4 0.5 0.6 0.7 0.80

20

40

60

80

100

120

140

160

180

2000 % fill35 % fill45 % fill

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Bleed

water to cement ratio

Schupack b

leed (

mL)

0.2 0.3 0.4 0.5 0.6 0.7 0.80

10

20

30

40

50

60

70

80

90

1000% fill35% fill45% fill

water to cement ratio

ble

ed

wate

r (m

L)

0.2 0.3 0.4 0.5 0.6 0.7 0.80

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

24000 % filler35 % filler45 % filler

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Modified Inclined Tube Test

Test for bleed and segregation

Effect of fillers/admixtures on segregation (benefit/risk)

Effects of age on segregation (shelf life)

Effect of excess water on segregation (robustness)

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Can we get by with a shorter tube?

15 ft (5 m)

5 ft (1.6 m)

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77

8

3

0

10

20

30

40

50

60

70

80

90

15-ft (5 m) tube with

strand

5-ft. (1.6 m) tube with

strand

5-ft. (1.6 m) tube

without strand

So

ft G

rou

t (g

m)

Soft Grout-Scaling issues?

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Bleed water

175

0 0

0

20

40

60

80

100

120

140

160

180

200

15-ft (5 m) tube with

strand

5-ft. (1.6 m) tube with

strand

5-ft. (1.6 m) tube

without strand

Ble

ed

(m

l)

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Is an incline necessary? Deviated Tendons

Transverse

tendons on

superelevation

Cantilever tendons

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Is an incline necessary?

4.6°

30°

100 gm soft grout

100 gm soft grout

Traces of soft grout

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Is an incline necessary?

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Is an incline necessary?

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Is an incline necessary?

Length along duct (in.)

Mo

istu

re c

on

ten

t (%

)

0 20 40 60 80 100 120 140 160 180 2000

10

20

30

40

50

60

70

80

90

100

Horizontal tendon (0 inclinationSuperelevated Tendon (4.6 inclination)Normal Inclined Tendon (30 iclination)Vertical Tendon (90 inclination)

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Closing comments

Test for bleed and segregation

Effect of fillers/admixtures on segregation (benefit/risk)

Effects of age on segregation (shelf life)

Effect of excess water on segregation (robustness)

Current configuration and geometry is on target

Incorporate modifications into PTI specifications

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MITT Mockup?

Require that (at least one) inclined test be conducted prior to construction

Conduct test on site using equipment and personnel that will be used during construction

Temperature during mockup sets the limit for the duration of the construction project

Grout suppliers could use this to help ensure proper procedures are being used and to resolve initial technical issues

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Special Thanks to “The Grout Team”

Marcelino Aguirre Marlo Chumiquoe

Rodrigo AntunesDevon Minich

Shelby Brothers

Mark (La Marka) Pina Mark Lisek