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

Slide 5RailTEC

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

Slide 6RailTEC

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

Slide 7RailTEC

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

Slide 9RailTEC

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

Slide 10RailTEC

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

Slide 11RailTEC

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

Slide 12RailTEC

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

Slide 13RailTEC

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

Slide 14RailTEC

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

Slide 15RailTEC

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

Slide 16RailTEC

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

Slide 17RailTEC

Acknowledgments

• NexTrans

• RailTEC

• Graduate student mentor Ryan Kernes

• Faculty advisor David Lange

• RailTEC undergraduate assistant Josh Brickman

Slide 18RailTEC

Questions?