Jeffery RoeslerAssistant Professor

Department of Civil and Environmental EngineeringUniversity of Illinois at Urbana-Champaign

Continuously Reinforced Concrete Pavement (CRCP) for Airfields

CEAT Brown Bag Lunch Seminar SeriesNovember 10, 2005

Acknowledgements

• Illinois Department of Transportation– Bureau of Materials and Physical Research

(Amy Schutzbach and Dave Lippert)

• University of California - Davis– Erwin Kohler, Ph.D.

CRCP Characteristics

• No joints• Steel reinforcement bars• Numerous transverse cracks

History• First used in 1921• Experimental sections in the 1940’s• More than 28,000 miles in the USA

Why Continuously Reinforced Concrete Pavements?

• Smoothness

• Low maintenance costs– No transverse joints

• Thinner slab thickness relative to jointed concrete pavement

CRCP Cross-Section

Typical CRCP Design Features

• Concrete thickness (8 to 17 in.)• Steel Content (0.5 to 0.8%)• Depth to steel (3.5in to h/2)• Crack spacing

– natural vs. induced• Steel Bar Size (#5, #6, #7)• Grade 60 steel• 2-layer vs. 1-layer Steel

Aggregate Subbase

Asphalt Concrete Base

Cross-section (single layer)

Cross-section (double layer)

Single Layer Steel

Two-Layer Chairs

Two-Layer Steel

Longitudinal Steel Placement

Bar Splices

Concrete Placement

CRCP Stress Diagram

•Crack spacing prediction and crack width prediction

Illinois

ClusterY-crackMeanderingDivided

Crack SpacingAverage : 4.2Range: 1.6 - 10.1Std. Deviation: 2.7

Transverse Cracks

Crack development

Lane 1

0 100 200 300 400 500Station (feet)

07/15/0303/11/0312/10/0211/12/0210/10/0209/10/0208/12/0207/11/0205/13/0204/11/0203/12/0202/12/0201/11/0212/14/0112/10/01

Lane 2

0 100 200 300 400 500Station (feet)

07/15/0303/11/0312/10/0211/12/0210/10/0209/10/0208/12/0207/11/0205/13/0204/11/0203/12/0202/12/0201/11/0212/14/0112/12/0112/10/01

Natural cracks

• Crack location and time of crack surveys

• More cracks developed early in Lane 2

• Some natural cracks occurred in Lane 2

Crack development

0

20

40

60

80

100

120

140

Dec Feb Apr Jun Aug Oct Dec Feb Apr Jun AugTime, 2001-2003

Num

ber o

f Cra

cks

Lane 1Lane 2

Active

Passive

Natural Crack shapes and patterns

• Non-uniform crack patterns are detrimental and common• They lead to spalling and punchouts• Out of 23 sections studied (*) :

– 20 had cluster cracks, and some had them in several locations– All had Y-cracks (2% to 23%)– CRCP sections in IL, IA, OK, OR, PA, and WI

Cluster cracks

Y-cracks Meandering crack

Pavement Width

Divided cracks

(*) Tayabji et al. Performance of Continuously Reinforced Concrete Pavements. Volume 2 - Field Investigations of CRC Pavements, Report FHWA-RD-94-179, 1998.

Tape Insert

Saw-Cut Cracks

Soff-Cut “Joints”

CRCP Failure

• Deterioration of transverse cracks (Spalling)• Punchouts

σx

σy

CRCP Distress Development

Punchout• Longitudinal cracks propagate • Structural failure• Segment breaks and displace downwards

LTE and other factors leading to CRCP failure

MECHANISTIC DESIGN CONSIDERATIONS FOR PUNCHOUT DISTRESS IN CONTINUOUSLY REINFORCED CONCRETE PAVEMENT(1990) Zollinger, DG; Barenberg, EJ.

• High rebar stress at crack• Wide cracks→ spalling• LTE• Bending stress

Performance Factors

• Crack spacing• Crack width• Construction Time

– Temperature / humidity / curing– Thermal contraction

• Concrete materials– Cement content, aggregates, proportions– Drying shrinkage

Crack Spacing Prediction

coeff.friction subbase AASHTO :psi. strength, tensileconcrete :

in. spacing,crack mean :Where,

2

21

1

028

ffL

dcPUf

hCf

L

t

b

bm

PCCt

+

⎭⎬⎫

⎩⎨⎧

⎟⎟⎠

⎞⎜⎜⎝

⎛−−

=

ζσ

Factors affecting crack width• Temperature:

– Daily and seasonal variations– Max drop in temperature (crack formation)

• Drying shrinkage – Non-uniform in depth– Specially important at early age

• Subbase friction– Opposes movement – Depends on subbase material

• Bond-slip– bond-slip zone near crack’s face– bond stress in the bond-slip zone is complex

ΔCW = α ·ΔT · L (unrestrained)

DG2002 CW model

• DG2002 CW model for CRCPMechanistic-Empirical Pavement Design Guide

Crack spacingDrying shrinkage

Temperature dropRestraints

⎟⎟⎠

⎞⎜⎜⎝

⎛−Δ+⋅⋅=

iPCC

i

PCCiSHRi E

fcTLCCCW iσ

ςαε2

fLh

Cdc

PULfbi

m

2210

1i

+⎟⎠⎞

⎜⎝⎛ −+

⋅⋅⋅

=ςσ

σ

Base frictionCurling (thermal and moisture)Steel reinforcement

Depth to Steel

Slab thickness = 8 in

30

40

50

60

70

80

90

0 1 2 3 4 5 6 7

Depth of steel (in)

Cra

ck s

paci

ng (i

n)

Tset=70F

Tset=110F

Tset=140F

Slab thickness = 14 in

30

40

50

60

70

80

90

0 1 2 3 4 5 6 7

Depth of steel (in)

Cra

ck s

paci

ng (i

n)

Tset=70F

Tset=110F

Tset=140F

Depth to Steel vs. CW

• Crack spacing = 48in.Slab thickness = 8 in

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

2 3 4 5

Depth of steel (in)

Cra

ck w

idth

(mm

)

Tset=70Fz=steelTset=70Fz=1Tset=70Fz=3Tset=110Fz=steelTset=110Fz=1Tset=110Fz=3Tset=140Fz=steelTset=140Fz=1Tset=140Fz=3

Slab thickness = 14 in

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

2 3 4 5 6 7

Depth of steel (in)

Cra

ck w

idth

(mm

)

Crack Spacing and Width

4.5610.351.326.2240.0815

1.304.270.211.44150.0314

0.361.690.240.78330.0643

0.692.710.270.9027-2

2.047.860.271.40150.1161

STDVMaxMinAverage spacingNr. of cracks

Crack spacing (m)Crack width (mm)at depth of steel*Section

*Kohler and Roesler, ASCE Journal of Transportation Engineering, 131 (9),2005

Construction Issues

• Concrete mix design – Concrete shrinkage– Lower zero stress temperature!

• Mix temperature (water, aggregates) • Mix proportions (max. size aggregate)

• Curing– Minimize climatic effects– Solar radiation, wind, evaporation

• Base temperature (asphalt concrete)

Effect of Air Temperature on CRCP Failures

0%5%

10%15%20%25%30%35%40%

50-60 60-70 70-80 80-90 90-100Air temperature (°F)

Per

cent

age

of F

ailu

res

Schindler and McCullough (2002)

Existing CRCP Design

• FAA – empirical– Limiting criteria (CS, CW, σs)

• Mechanistic-empirical (DG2002)– Punchout prediction

• AASHTO (1993)– can’t apply to airfield pavements

FAA Design Method for CRCP

• Use same thickness as JPCP• Crack Spacing = 2 to 10 ft.• Steel content = 0.5 to 1.0%

Steel content must satisfy all three criteria:1) Subgrade restraint2) Temperature Effects3) Concrete to Steel Ratio

Subgrade Friction / Restraint

Ps (%) = (1.3-0.2F)*fr/fs

• Ps (%) = percent steel• F = friction factor (1.8)• fs = steel working stress = 0.75fy

(0.75*60ksi)• fr = tensile strength of concrete

– 0.67*MOR

Temperature Change

Ps (%) = 50*fr / (fs-195T)

• T = maximum seasonal temperature differential for pavement (°F)

Concrete to Steel Ratio

Ps (%)= 100*ft/fy

• Select maximum steel content to satisfy three criteria

Design Criteria

• CRCP thick = 80 to 90% of JPCP thick for highways– FAA says same thickness as JPCP

• CS = 3 to 8 ft• CW= 0.5mm (0.02in)

Mechanism of PunchoutDevelopment (DG2002)

PunchoutLongitudinal crack initiation

Direction of Traffic

Pavement edge

Deteriorated transverse crack

Punchout

Direction of Traffic

Pavement edge

Deteriorated transverse crack

Punchout

Loss of supportNarrow Crack spacing1

2

3

4

5

Tire footprint

Selezneva (2002)

Predicted Crack Width

Predicted Crack Width

0

2

4

6

8

10

12

14

16

18

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

Pavement age, years

Cra

ck W

idth

, mil

Crack Shear Capacity

mils. ,increment for timeh crack widt :in. slab, theof thickness:

increment for timecapacity shear initial :where,

05.0

0

032.00

icwh

is

ehs

i

PCC

i

cwPCCi

i−⋅⋅=

Transverse Crack Stiffness

capacityshear essdimensionl :constants :,,,,,

increment mecurrent tifor crack e transverson the stiffnessjoint :where

)(

sgefdcba

J

egedeaeJLog

c

eeeec

fes

cbsJ

fes

cbsJ

⎟⎟⎠

⎞⎜⎜⎝

⎛ −−⎟

⎠⎞

⎜⎝⎛ −

−⎟⎟⎠

⎞⎜⎜⎝

⎛ −−⎟

⎠⎞

⎜⎝⎛ −

−−−−− ⋅++=

Total Crack LTE

% crack, e transversacross LTE theon tocontributilayer base :entreinforcem allongitudin ofpercent :

entreinforcem steel by the provided transfer load Residual :inarea, loaded afor radius :

ini,increment for time computed stiffness relative of radius :where

1001

18.1/))log(183.0214.0(log1

1111001

Base

Base

c

TOT

LTEPbR

LTE

RJLTE

α

α

l

l ⎪⎪⎭

⎪⎪⎬

⎫

⎪⎪⎩

⎪⎪⎨

⎧

⎟⎠⎞

⎜⎝⎛ −

⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢

⎣

⎡

⎥⎦⎤

⎢⎣⎡ −−−+

−−∗=−

Shear Transfer Deterioration of Cracks

PCC

i

hcw

isΔ

If < 3.8 iiref

ijji

j

PCC

i

i ESRn

hcw

s ⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛

⎟⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜⎜

⎝

⎛

⎟⎟⎠

⎞⎜⎜⎝

⎛⋅+

=Δ ∑ − τ

τ67.5 10

11

0.005 (55a)

otherwise iiref

ijji

j

PCC

i

i ESRn

hcw

s ⋅⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛

⎟⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜⎜

⎝

⎛

⎟⎟⎠

⎞⎜⎜⎝

⎛−⋅+

+=Δ ∑ − τ

τ698.1 10

361

0.068004.0 (55b)

Concrete tensile stress at top

DEVELOPMENT OF RAPID SOLUTIONS FOR PREDICTION OF CRITICAL CONTINUOUSLY REINFORCED CONCRETE PAVEMENT STRESSES(2001) Khazanovich, L; Selezneva, OI; Yu, HT; Darter, MI ,

Prediction of failure Stress: crack spacing

σy

σx

D0

200

400

600

800

1000

1200

1400

0 2 4 6 8 10 12 14 16

Crack spacing (ft)

Ppal

stre

ss (p

si)

BottomTop

50 kips

40 kips

Load between cracks (centered)

0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14 16

Crack spacing (ft)

Ppal

stre

ss (p

si)

BottomTop

50 kips

40 kips

Load next to a crack

0

100

200

300

400

500

600

0 2 4 6 8 10 12 14 16

Next to crackBetween cracks

ΔT=0

ΔT=+20

Stress at top. Load=45 kips

Fatigue Damage

constantsn calibratio :,

magn. load todue increment at time stress applied :psi , ageat rupture of modulus PCC :

magn. load todue timeduring loading of No. allowable :where

1)log(

21

,

,

,

,

,1,

2

cc

jiiMR

jiN

Nn

FD

MRcN

ji

i

ji

ji

ji

C

ji

iji

σ

σ

∑=

−⎥⎥⎦

⎤

⎢⎢⎣

⎡⋅=

Punchout Modeling

constantsn calibratio :,,year of end at the damage fatigue daccumulate :

mileper punchouts of No. predicted total:where,

1

βα

α β

AyFD

PO

FDAPO

th

⋅+=

Accelerated Load Testing

• 10 to 60 kips load, at the edge

• >400,000 wheel passes applied

CRCP Sections

• Sec.1 - 5: natural cracks, simulated wheel loads applied, and results reported in this study.

• Sec. 6 - 10: induced cracks, not loaded Kohler and Roesler, Transportation Research Record 1900, pp 19-29, 2004

p=0.55%, #5h=254, d=89

p=0.80%, #6 p=1.09%, #7 p=0.80%, #6 p=0.80%, #6

p : percent of steel# : bar size (US system)h : concrete thickness (mm)

p=0.80%, #6 p=1.09%, #7 p=0.78%, #7 p=0.78%, #7

150 m

Lane 2

Lane 1

p=0.55%, #5

6 7 8 9 10

1 2 3 4 5

26 m

h=254, d=89 h=254, d=89 h=254, d=89 h=254, d=178

h=356, d=114h=254, d=89h=254, d=89h=254, d=89 h=356, d=89 & 178

d : depth of the steel layer (mm)

Crack spacing

4.6 ft

3.0 ft

2.6 ft

4.8 ft

n/a

(Advanced Transportation Loading ASsembly)

ATLAS

Sensors & Load Application

LVDTs to measure crack movement

Granular fill

LVDT holders

12 ft Ref.block

Subbase and subgrade layers

10 or 14” CRC Slab

Loading at pavement edge

Loading Levels

• Load history, total ESALs, and ESALs at failure for each section

050

100150

200250

- 25 50 75 100 125 150 175 200 225 250Lo

ad (k

N) Section 3

Reps= 163,400ESALs= 627 MESALs f= 548 M

0

50

100150

200

250

- 25 50 75 100 125 150 175 200 225 250Thousand Passes (Reps)

Load

(kN

) Section 4Reps= 64,300ESALs= 764 MESALs f= --

0

50100

150200

250

- 25 50 75 100 125 150 175 200 225 250

Load

(kN

)

Section 1Reps= 246,800ESALs=911 MESALs f=511 M

050

100150200250

- 25 50 75 100 125 150 175 200 225 250Thoussand Passes (Reps)

Load

(kN

) Section 2Reps= 118,600ESALs= 778 MESALs f= 230 M

13no5

750no4

650Yes3

800Yes2

900Yes1

Total ESALSFailureSection

Load Transfer Efficiency

High LTE 90-100% throughout the

loading test

High LTE at time of failure

Effect of temperature

Section 3

L T E 5 7 .2

5 0

6 0

7 0

8 0

9 0

1 0 0

1 1 0

0 5 0 1 0 0 1 5 0

P a s s e s (T h o u s a n d s )

LTE

(%)

1 0 k ip s

3 0 k ip s

5 5 k ip s

LT E 63.1

50

60

70

80

90

100

110

0 10 20 30 40 50 60 70

Passes (T housands)

LTE

(%)

10 kips

35 kips

45 kips

55 kips

Section 3

Section 4

Edge cracking

83 82 81 80

83 82 81 80

75

79 78 77 76 75

79 78 77 76

Profile • Longitudinal profile at the edge as loading

progressed • 20 mm peak permanent deformation

-35-30-25-20-15-10

-50

0 2 4 6 8 10 12 14 16 18 20 22 24 26Station (m)

Ele

vatio

n (m

m)

Existing Airport Applications

• Houston Hobby (1980’s)• O’Hare (1960’s and 1970’s)• Kennedy (1960’s)• Dallas-Fort Worth (early 1970’s)• Military Bases (CA, MD, GA, IL)

CRCP Summary

• Crack spacing• Crack width• Construction• Materials

• Load capacity

Comments / Questions

OMP Concrete Mix DesignDate 20-Oct 22-Sep 27-May 3-Jun 30-Aug 31-May 9-Sep 22-Sep 30-Aug

ID

688.38 (1.5" CA) CLEAN

AGG

688.38 standard (3/4 " CA)

688.44 (1.5" CA)

688.38 (1.5" CA)

571.44 (1.5" CA)

571.38 (1.5" CA)

571.44 Nof (1.5" CA)

535.44 (1.5" CA)

555.44 (1.5" CA)

water (lb/yd3) 261 262 303 261 251 217 251 235 244cement (lb/yd3) 588 588 588 588 488 488 571 535 455fly ash (lb/yd3) 100 100 100 100 83 83 0 0 100

CA (lb/yd3) 1842 1850 1772 1842 1924 1982 1938 1984 1942FA (lb/yd3) 1083 1103 1042 1083 1132 1166 1140 1167 1142

AEA (oz/yd3) 19.4 12.7 19.4 19.4 16.1 16.1 16.1 15.1 15.6w/cm 0.38 0.38 0.44 0.38 0.44 0.38 0.44 0.44 0.44

CA/ FA 1.7 1.68 1.7 1.7 1.7 1.7 1.7 1.7 1.7cm 688 688 688 688 570.96 570.96 571 535 555w/c 0.44 0.45 0.51 0.44 0.51 0.44 0.44 0.44 0.54Fl\y Ash/ CM 0.15 0.15 0.15 0.15 0.15 0.15 0.00 0.00 0.18

Slump (in) 6.13 7.63 9.00 6.25 7.38 2.50 2.25 8.63 7.88Air (%) 7.0 6.5 6.0 8.0 2.9 7.3 6.5 2.9 3.7

Density (pcf) 143.8 145.1 141.8 141.8 150.4 143.9 146.2 150.9 150.2

fs7 (psi) 362 526 275 440 412 416 505 390 480 fs28 (psi) #DIV/0! 570 423 454 513 429 524 415 490 fc7 (psi) 3,393 4,045 3,267 3,241 3,608 3,369 3,329 2,338 3,327 fc28 (psi) #DIV/0! 4,217 4,131 3,785 4,344 3,744 5,366 3,369 4,212 Ec7 (psi) 3,236 3,476 4,177 4,031 3,879 4,224 3,326 3,426 3,692 Ec28 (psi) #DIV/0! 3,752 3,695 3,438 4,204 3,881 3,958 3,311 4,209

MOR28 (psi) #DIV/0! 802 668 639 688 651 794 619 663 MOR 7(psi) 557

Har

dene

d P

rope

rties

Fres

h pr

oper

ties

Shrinkage DataExperimental Shrinkage Data for all Mixes

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0 20 40 60 80 100 120

Age of Concrete (days)

Shrin

kage

(mm

/m)

688.38ST Total 688.44 Total 688.44 Autog. 688.38 Total688.38 Autog. 571.44 Total 571.38 Total 571.38 Autog.

571.44 NF Total 535.44 Total 555.44 Total

Detailed Strength SummaryConcrete

Mix

688.38 (1.5" CA) CLEAN AGG

688.38 standard

(3/4 " CA)

688.44 (1.5" CA)

688.38 (1.5" CA)

571.44 (1.5" CA)

571.38 (1.5" CA)

571.44 Nof (1.5" CA)

535.44 (1.5" CA)

555.44 (1.5" CA)

A 6.25 8 9.00 5.25 7.5 2.5 3.25 8.75 7.5B 6 7.25 9.00 7.25 7.25 2.5 1.25 8.5 8.25A 7.5 6.5 6.0 7.5 3.0 7.0 7.8 2.8 3.8B 6.5 6.5 6.0 8.5 2.8 7.5 5.3 3.0 3.6A 143.2 144.4 142.0 141.6 150.2 144.6 143.0 151.0 150.0B 144.3 145.8 141.6 142.0 150.6 143.2 149.4 150.8 150.4A 340 520 296 478 352 406 432 386 451 B 383 531 254 403 472 426 577 394 509 A 575 N/A 450 506 413 410 422 433 B 564 423 458 520 446 638 408 547 A 3,281 3,925 3,152 3,222 3,630 3,417 3328 2,273 3,299 B 3,506 4,165 3,381 3,261 3,586 3,320 3330 2,402 3,356 A 4,252 3,943 3,718 4,360 3,934 3,833 3391 4,212 B 4,181 4,320 3,853 4,328 3,555 6,898 3348 N/AA 2,992 3,440 4,232 3,935 N/A 4,176 3162 3,435 3,695 B 3,480 3,512 4,122 4,126 3,879 4,272 3489 3,418 3,690 A 3,885 3,345 3,400 4,293 3,710 3,628 3,126 4,209 B 3,618 4,045 3,477 4,115 4,053 4,288 3,496 N/AA 834 639 638 658 664 715 646 658 B 770 697 639 717 638 873 592 667 A 557 B 690

Slump (in)

Ec7 (ksi)

Density (pcf)

Air (%)

fs7 (psi)

fs28 (psi)

fc7 (psi)

fc28 (psi)

Ec28 (ksi)

MOR28 (psi)

MOR7 (psi)

Preliminary Findings

Larger coarse aggregate size (1.5”) lowers MOR and splitting strength at 28 days.

Coarse aggregate size no affect on compressive strength at 28 days.

Higher Fly ash/CM ratio reduces the compressive strength and MOR,

15% fly ash, the W/CM ratio changes (0.38 to 0.44) was not strong

Fracture energy (GF) significantly higher for 1.5” MSA at <7days

Two vs. One Layer Reinforcement

• Texas DOT used for 15 years– Should perform better?

• No performance information

• Cluster cracking (Zollinger 1999)– Result of curing and depth of steel

• Don’t coincide two layer of transverse reinforcement

• Longitudinal reinforcement on top of each other

2 vs. 1-Layer Reinforcement

• No theoretical analysis• Can’t be used in DG2002 (by Zollinger)

• ATLAS– No failures on sections 4 and 5– response difference in 2 vs. 1-layer steel

ATLAS Responses (S4 vs. S5)

Table 3 Rebound deflections

Section\Load 10kips 35kips

4 0.09-0.13 0.30-0.64

5 0.10-0.11 0.37-0.53

Table 5 Crack openingCrack closing

(microns) Standard crack width

atTop

Mid-top

Section 4

cr.1 25-54 14-27 48

cr.2 43-66 41-50 50

cr.3 43-78 28-51 42

cr.4 25-50 14-30 25

Section 5

cr.1 10-51 3-9 67

Two-layer constructability

• No difference in consolidation on test sections

020406080

100120140160180200

4a 4b 5a 5bSample core

Con

cret

e de

insi

ty (l

b/ft3

)

DrySaturated

Summary

Section comparison:– Thicker sections less vertical deformation

– Not able to detect effect of percent of steel• Smaller CS and CW

– Insufficient cracking in double layer steel section

Projects Publications• Kohler, E.R. and Roesler, J.R. (August 2005), “Crack Spacing and Crack Width

Investigation from Experimental CRCP Sections,” submitted for publication to International Journal of Pavement Engineering, 25pp.

• Kohler, E.R. and Roesler, J.R., (August 2005), “Non-destructive Testing for Crack Width and Variability on Continuously Reinforced Concrete Pavements,” submitted for publication to Transportation Research Record, Journal of Transportation Research Board, Paper No. 06-1530, 20 pp.

• Kohler, E.R. and Roesler, J.R. (2005), “Crack Width Measurements in Continuously Reinforced Concrete Pavements,” ASCE Journal of Transportation Engineering, Vol. 131, No. 9, pp. 645-652.

• Kohler, E.R. and Roesler, J.R. (2004), “Active Crack Control for Continuously Reinforced Concrete Pavements,” Transportation Research Record 1900, Journal of Transportation Research Board, National Research Council, Washington, D.C, pp. 19-29.

• Kohler, E. and Roesler, J.R. (2005), “Repeated Load Behavior of Continuously Reinforced Concrete Pavement,” 8th International Conference on Concrete Pavement, August 13-18, 2005, Colorado Springs, CO, 17 pp.

• Kohler, E. and Roesler, J. “Avances en la investigación de pavimentos CRCP,” XVSimposio Colombiano Sobre Ingenieria de Pavimentos - 2005, Bogota, Colombia, March 9-13, 12 pp.

• Kohler, E.R. and Roesler, J.R. (2004), “Crack Width Determination for Continuously Reinforced Concrete Pavements,” Second International Conference on Accelerated Pavement Testing, September 25-29, 2004, Minneapolis, Minnesota, 19 pp.

Projects Reports• Kohler, E. and Roesler, J., “Accelerated Pavement Testing of Extended Life

Continuously Reinforced Concrete Pavement Sections,” Draft Final Report, Transportation Engineering Series No., Illinois Cooperative Highway and Transportation Series No., University of Illinois, Urbana, IL, June 2005, 200 pp.

• Kohler, E., Long, G., and Roesler, J., “Construction of Extended Life Continuously Reinforced Concrete Pavement at ATREL,” Transportation Engineering Series No. 126, Illinois Cooperative Highway and Transportation Series No. 282, UILU-ENG-2002-2009, University of Illinois, Urbana, IL, December 2002, 54 pp.