Abrasion Resistance Testing of Concrete Railway Crossties
Transcript of Abrasion Resistance Testing of Concrete Railway Crossties
Slide 1
Abrasion Resistance Testing of Concrete Railway Crossties
Emily Van Dam, Ryan Kernes, David Lange, Riley Edwards
Slide 2RailTEC
Background • Currently majority of railway
crossties in North America are timber ties
• Major trends in railway putting increased stress on crossties
– Higher axle loads
– Higher overall tonnage
– Increased freight usage
– Increasing demand for high speed rail, which requires higher geometric tolerances
• Concrete crossties offer potential for greater strength, stiffness, and tie life to meet new demands
Timber railway crossties
Concrete railway crossties
Slide 3RailTEC
Rail Seat Deterioration (RSD)• Concrete is a brittle material
• A common problem in North America, RSD is the degradation of the concrete material beneath the steel rail and a polymer pad
• Safety concern that can limit tie life and necessitate maintenance
• Several mechanisms for RSD investigated previously and currently– Hydraulic pressure cracking
– Freeze-thaw damage
– Abrasion
– Crushing
– Hydro-abrasive erosion Example of RSD
Slide 4RailTEC
Abrasion Resistance of Concrete Ties• Abrasion suspected to be significant
cause of RSD
• Goal is to improve the abrasion resistance of the concrete ties
• In order to investigate abrasion resistance, meaningful test set-up and procedure is necessary
• Goal for the summer two-fold
1) Develop meaningful abrasion resistance test setup and procedure
2) Evaluate efficient methods of increasing the abrasion resistance of concrete materials
Example of severe RSD and walking out of the tie pad
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Abrasion Resistance TestsASTM Standards
Name StandardRevolving Disc C779 Method ADressing Wheel C779 Method BBall Bearing C779 Method CUnderwater Abrasion C1138Rotating Cutter C944Sandblasting C418Modified Robinson C627
Other StandardsStandard DescriptionTurkish Standard TS 699 Rotating steel discBritish Standard BS 812-113 Dorry Abrasion MachineAREMA Test 6 Abrasion/Wear Test
Revolving Disks Test – ASTM C 779Ahttp://whitemachine.com/images/C779B.jpg
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Large-Scale Abrasion Test Set-up
• Two actuators apply loading to concrete specimen
• Load magnitude/rate, displacement, presence of fines, and water are input variables
• Volume of material lost and depth of wear measured
• Representative abrasion mechanism
• Still being calibrated Large-scale test set-up at the University of Illinois
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Modification of Lapping Machine
• Consists of rotating steel wheel with 3 lapping rings held in place on surface
– Lapping rings permitted to rotate about their own axis
• Water continually piped onto lapping plate throughout test
• Sand added at constant rate throughout test by funnel placed directly above plate
Slide 8RailTEC
Testing Procedure• Specimens prepared in 8 in long, 4 in diameter cylinders
• 1 in thick specimens are cut from top and used in lapping machine
• Lapping machine is run with 3 specimens while water and sand is constantly added to lapping plate
• Every 20 minutes the specimens are rotated to a different location
• Each specimen tested for a total of 60 minutes
• Thickness of specimen measured at 4 locations before and after testing
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Test Matrix
Mix Design Curing Conditions
Mix # Fly Ash (%Replacement)
Silica Fume (% Replacement)
7 Day Moist
7 Day Submerged
7 Day Oven
10 Day Moist
1 0% 0% X X X X
2 0% 5% X
3 0% 10% X X
4 15% 0% X
5 10% 5% X
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Observations
• Abrasion was visible on all specimens tested
• Some problems maintaining constant sand flow rate
• Measure of wear depth possible source of inaccuracy
Before testing
After testing
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Abrasion Resistance vs Strength
2.5
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5 5.0 5.5 6.0 6.5 7.0
Dep
th o
f Wea
r (m
m)
Compressive Strength (ksi)
Control 7 Day Moist
Control 7 Day Oven
Control 7 Day Submerged5% Silica Fume
10% Silica Fume 7 Day
15% Fly Ash
10% Fly Ash 5% Silica Fume
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Different Mix Designs (7 Day Moist Room)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Dep
th o
f Wea
r (m
m)
Concrete Mix Design
Control
5% Silica Fume
10% Silica Fume
15% Fly Ash
5% Silica Fume, 10% Fly Ash
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Effect of Curing Conditions (7 Day)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Dep
th L
oss
(mm
)
Cure Condition
SubmergedMoistOven
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Effect of Length of Cure
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
7 Days 10 Days
Dep
th o
f Wea
r (m
m)
Cure Day
Control
10% Silica Fume
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Conclusions• Lapping machine is capable of producing significant wear and
usable results
• Small amounts of fly ash (15%) and silica fume (5%) improve the abrasion resistance
• Curing conditions make a significant difference in abrasion resistance
– Submerged cure produces the most abrasion resistant concrete
– Oven curing greatly improves compressive strength, but decreases abrasion resistance
• Increased time from 7 to 10 days increases the abrasion resistance of concrete
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Future Work• Improve the characterization of the lapping machine
– Quality control methods on amount of sand and water delivered to lapping plate
– Utilize more accurate measurement tools for depth of wear
• Test specimens at 28 day strength
• More combinations and specimens tested with silica fume and fly ash
• Mixes involving different aggregates (e.g. metallic, slag, etc.) and fiber reinforcement
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Acknowledgments
• NexTrans
• RailTEC
• Graduate student mentor Ryan Kernes
• Faculty advisor David Lange
• RailTEC undergraduate assistant Josh Brickman
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Questions?