inclined tube test – will it really help improve post-tensioning … · 2018. 7. 11. · 275...
Post on 27-Apr-2021
3 Views
Preview:
TRANSCRIPT
Inclined Tube Test – Will it really help improve post-tensioning grouts?
Trey Hamilton, PhD, PEByron D. Spangler Professor of Civil Engineering
2 of 41
PT Grout
Transfer post-tensioning force
Strand protection
3 of 413 of 31
Grout Classification
Class A-non-aggressive applications
Class B-aggressive applications
Class C-prepackaged grout for both
Class D-specialized grouts
4 of 414 of 31
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
5 of 41
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
7 of 417 of 31
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
8 of 41
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)
9 of 419 of 31
“Bleed” test comparison
Inclined Test Schupack Pressure Test
10 of 41
Modified Inclined Tube Test (MITT)
Shortened strand bundle (ease grout sampling)
Dissection of duct
Moisture content measurements
Transparent duct?
30 deg.
11 of 41
Grout Mixing
Used 4 bag mixes with colloidal plant
12 of 4112 of 31
Fresh Properties
13 of 41
Grout Injection
14 of 41
Sampling (24 Hours)
15 of 4115 of 31
Moisture Content
16 of 4116 of 31
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)
17 of 4117 of 31
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
18 of 4118 of 31
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
19 of 4119 of 31
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
20 of 4120 of 31
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)
21 of 4121 of 31
Can we get by with a shorter tube?
15 ft (5 m)
5 ft (1.6 m)
22 of 4122 of 31
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?
23 of 4123 of 31
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)
24 of 4124 of 31
Is an incline necessary? Deviated Tendons
Transverse
tendons on
superelevation
Cantilever tendons
25 of 4125 of 31
Is an incline necessary?
4.6°
30°
100 gm soft grout
100 gm soft grout
Traces of soft grout
26 of 4126 of 31
Is an incline necessary?
27 of 4127 of 31
Is an incline necessary?
28 of 4128 of 31
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)
29 of 4129 of 31
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
30 of 4130 of 31
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
31 of 4131 of 31
Special Thanks to “The Grout Team”
Marcelino Aguirre Marlo Chumiquoe
Rodrigo AntunesDevon Minich
Shelby Brothers
Mark (La Marka) Pina Mark Lisek
top related