Concrete (PCC) Mixture Designs for O’Hare Modernization Program Principal Investigators Prof. Jeff Roesler Prof. David Lange PROJECT GOAL Investigate cost-effective.

Concrete (PCC) Mixture Designs Concrete (PCC) Mixture Designs for O’Hare Modernization Programfor O’Hare Modernization Program

Principal InvestigatorsProf. Jeff RoeslerProf. David Lange

PROJECT GOALInvestigate cost-effective concrete properties and pavement design features required to achieve long-term rigid pavement performance at Chicago O’Hare International.

AcknowledgementsAcknowledgements

Principal InvestigatorsProf. Jeff RoeslerProf. David Lange

Research StudentsCristian GaedickeSal VillalobosRob Rodden Zach Grasley

Others studentsHector FigueroaVictor Cervantes

Project ObjectivesProject ObjectivesDevelop concrete material constituents and proportions for airfield concrete mixes

Strengthvolume stabilityfracture properties

Develop / improve models to predict concrete material behavior

Crack width and shrinkage

Evaluate material properties and structural design interactionsjoint type & joint spacing (curling and load transfer)Saw-cut timing

FY2005-06 AccomplishmentsFY2005-06 Accomplishments

Tech Notes (TN) - TN2: PCC Mix Design TN3: Fiber Reinforced Concrete for Airfield Rigid PavementsTN4: Feasibility of Shrinkage Reducing Admixtures for Concrete Runway PavementsTN11: Measurement of Water Content in Fresh Concrete Using the Microwave MethodTN12: Guiding Principles for the Optimization of the OMP PCC Mix DesignTN15: Evaluation, testing and comparison between crushed manufactured sand and natural sandTN16: Concrete Mix Design Specification EvaluationTN17: PCC Mix Design Phase 1

www.cee.uiuc.edu/research/ceat

FY2006 AccomplishmentsFY2006 Accomplishments

Tech Notes (TN) - TN21: An Overview of Ultra-Thin Whitetopping TechnologyTN23: TN23: Effect of Large Maximum Size Coarse Aggregate on Strength, Fracture and Shrinkage Properties of Concrete

TNXX: Effects of Concrete Materials and Geometry on Slab CurlingTNYY: Concrete Saw-Cut Timing ModelTNZZ: Functionally Layered Concrete Pavements

www.cee.uiuc.edu/research/ceat

Presentation OverviewPresentation Overview

Large-sized coarse aggregate mixtures

Saw-cut timing model

Slab Curling

Field Demo Project

Recycled Concrete Aggregate

Crack width, cwDowels deemed necessary

Aggregate Interlock JointsAggregate Interlock Joints

Reduced LTE with small maximum size CA

Larger maximum size CA

Larger aggregate top size increases aggregate interlock and improves load transfer

Crack width, cw

Aggregate Interlock JointsAggregate Interlock Joints

Why Larger Size Coarse Aggregate?Why Larger Size Coarse Aggregate?

Potential benefitsLess paste lower cementitious content Shrinkage

Higher toughness Fracture and crack propagation resistance

Increase roughness of joint surfaces Increased load transfer between slabs Reduced # of dowels

Durability (??) D-cracking

Cost - Effectiveness

Experimental DesignExperimental Design

Effect of aggregate size (1.0” vs. 1.5”)

Effect of 1.5” coarse aggregate:Total cementitious content: 688 lb/yd3, 571 lb/yd3, 555 lb/yd3 and 535 lb/yd3

Water / cementitious ratio: 0.38 versus 0.44

Fly Ash / cementitious ratio: 14.5% versus 0%

Effect of coarse aggregate cleanliness

Mix Design ResultsMix Design Results

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

Phase II Mix SummaryPhase II Mix Summary

Mixture ID 688.38ST 688.38 571.44 555.44 fsp28 (psi) 570 454 524 490 MOR28 (psi) 802 639 794 663

E28 (ksi) 3,752 3,438 3,958 4,209

Mixture ID 688.38ST 688.38 571.44 555.44 Coarse Aggregate Size (in) 0.75 1.5 1.5 1.5 Coarse Aggregate (lb/yd3) 1850 1842 1938 1942

Fine Aggregate (lb/yd3) 1103 1083 1140 1142 Water (lb/yd3) 262 261 251 244

Cement (lb/yd3) 588 588 571 455 Fly ash (lb/yd3) 100 100 0 100

Air (oz/yd3) 12.7 19.4 16.1 15.6 Slump (in.) 7.5 6.25 2.25 8.0

Air Content (%) 6.5 8 6.5 3.7 Unit Weight (lb/ft3) 145.1 141.8 146.2 150.2

Larger-size coarse aggregate

Effect of larger-sizecoarse aggregate on strength

Drying Shrinkage – Phase IIDrying Shrinkage – Phase IITotal Shrinkage vs. Age

0

100

200

300

400

500

0 5 10 15 20 25 30Concrete Age (days)

Sh

rin

kag

e (m

icro

stra

in).

.

688.38 st

688.38

571.44

555.44

\

Mixture ID 688.38 st 688.38 571.44 555.44

sh3 (microstrain) 48 118 139 52

sh7 (microstrain) 193 233 250 158

sh14 (microstrain) 292 338 320 273

sh28 (microstrain) 417 405 380 335

Effect of larger-sizecoarse aggregate on shrinkage

Fracture Energy Results-Phase IIFracture Energy Results-Phase II

Age = 28-days

Load vs. CMOD curves for Wedge Splitting Samples

0

500

1000

1500

2000

2500

3000

0 0.5 1 1.5 2

CMOD(mm)

Fv

(N)

688.38st

688.38

555.44

Mixture ID 688.38 st 688.38 571.44 555.44

GF (Nm) 156 166 N/A 161

Effect of larger-sizecoarse aggregate on fractureproperties

PCC Mix Design – Phase IIPCC Mix Design – Phase II

Summary*Larger aggregates reduce strength by 20%, but…

28-day GF similar similar cracking resistance

Larger aggregates reduce concrete brittleness

1-day fracture energy with larger MSA greater joint stiffness / performance

No significant shrinkage difference

TN23 – April 2006

*Roesler, J., Gaedicke, C., Lange, Villalobos, S., Rodden, R., and Grasley, Z. (2006), “Mechanical Properties of Concrete Pavement Mixtures with Larger Size Coarse Aggregate,” accepted for publication in ASCE 2006 Airfield and Highway Pavement Conference, Atlanta, GA.

Saw-Cut Timing ModelSaw-Cut Timing Model

Concrete E and fracture properties(cf ,KIC) at early ages.Develop curves of nominal strength vs notch depth for timing.

Nominal strength vs ao/d for the 300mm slab

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.000 0.100 0.200 0.300 0.400 0.500 0.600

ao/d

No

min

al s

tren

gth

ls@6hr

ls@12hr

rg@6hr

rg@12hr

d

a

•Notch depth (a) depends on stress, strength, and slab thickness (d)

•Stress = f(coarse aggregate,T,RH)

Saw-Cut Timing and DepthSaw-Cut Timing and Depth

Saw cut depth / timing – EXPERIENCE

Fracture properties at early ages Critical Stress Intensity Factor (KIC)

Critical Crack Tip Opening Displacement (CTOCC) form this type of specimen

Wedge Splitting Test (WST) need geometric factors

d

a

Saw-Cut Timing and DepthSaw-Cut Timing and Depth

Process

FRACTURE FRACTURE PROPERTIESPROPERTIES

Tensile strength of the slab at 12 hours

0.00

0.20

0.40

0.60

0.80

1.00

0.00 0.10 0.20 0.30 0.40 0.50ao/d

Nom

inal

str

engt

hMP

a) 688.38

688.38ST

Wedge Split Test Wedge Split Test FEM Model FEM Model Saw Cut Depth Saw Cut Depth

Model Model

Concrete MixConcrete Mix

•Aggregate sizeAggregate size

•Cementitious content Cementitious content

Crack PropagatesCrack Propagates

WST setup and specimen

30mm

57mm

2mm

Notch detail

= a/b

200 mm

205mm

200 mm

80mm 40mm 80mm

ab

t

Wedge Split TestingWedge Split Testing

FEM Model Special Mesh around crack tip

Q8 elements

Symmetry and BC considerations

200

mm100 mm

Saw-Cut Timing and DepthSaw-Cut Timing and Depth

Saw-cut timing and depthSaw-cut timing and depth

FEM Model Results Determination of Fracture parameters

1/21

smaxIC b*t

)(f *P K

)(f *

b*t

P K 11/2

smaxIC

f1 vs a/b

y = 9.8214x - 1.4584R2 = 0.9779

y = 25.598x2 - 15.757x + 4.8066R2 = 0.9996

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0.40 0.42 0.44 0.46 0.48 0.50 0.52 0.54 0.56 0.58 0.60a/w

f1

Saw-cut timing and depthSaw-cut timing and depth

FEM Model Results Determination of Fracture parameters

E*t

)(f *PCMOD 2

sp

)(f*

E*t

PCMOD 2

sp

CMOD*)(fCTOD 3 f2 vs a/b

y = 207.07x - 58.121R2 = 0.9736

y = 590.13x2 - 382.59x + 86.31R2 = 0.9995

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

0.40 0.42 0.44 0.46 0.48 0.50 0.52 0.54 0.56 0.58 0.60a/w

f2

f3 vs a/b

y = 1.2088x - 0.3456R2 = 0.9847

y = -3.3883x2 + 4.7542x - 1.2625R2 = 0.9991

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.40 0.42 0.44 0.46 0.48 0.50 0.52 0.54 0.56 0.58 0.60a/w

f3

K

*ECTODc

IC

Cf 2

SEM Model (Bazant)

Saw-Cut Depth ModelSaw-Cut Depth Model

/d)dg(a/d)cg'(a

Kcσ

ofo

ICnt

/daf'/dafπαcn/daπf/dag'oooo

22 2

32 93119712030121 α.α.α-../dafo

α.α../daf'o

279539422030

)(f *b*t

P K 11/2

smaxIC

K

*ECTODc

IC

Cf 2

Nominal Strength vs Notch Depth ChartNominal Strength vs Notch Depth Chart

Tensile strength of the slab at 6hrs

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.00 0.10 0.20 0.30 0.40 0.50

ao/dN

om

inal s

trength

(MPa)

555.44

555.44ST

/dafπαc/dago

no

2

Concrete

Saw-cut timing and depthSaw-cut timing and depth

ID 555.44 555.44 st 688.38 688.38 st

w/cm

Max aggregate size mm (inch) 38 (1 1/2") 25 (1") 38 (1 1/2") 25 (1")

Water kg/m3 145 145 155 155

Cement kg/m3 270 270 349 349

Fly ash kg/m3 59 59 59 59

Coarse Aggregate (SSD) kg/m3 1152 1142 1093 1098

Fine Aggregate (SSD) kg/m3 678 672 643 654

0.44 0.38Units

All mixtures were air entrained rangin from 4% to 8%

Retained (%)

Cumulative retained (%)

Cumulative passing (%)

Retained (%)Cumulative

retained (%)Cumulative passing (%)

1.5" 0 0 100 0.00 0.00 100.001" 59 59 41 0.00 0.00 100.00

3/4" 34 92 8 32.55 32.55 67.451/2" 7 99 1 55.70 88.25 11.753/8" 1 100 0 8.82 97.06 2.94#4 0 100 0 2.94 100.00 0.00

Total 100 100.00

Coarse Aggregate 11/2 inch max. size BSG=2.71 AC= 1.27%

Coarse Aggregate 3/4 inch max. size BSG=2.67 AC= 2.0% Sieve

Opening

Mix proportions

Aggregate gradations

Concrete Fracture PropertiesConcrete Fracture Properties

Critical Stress Intensity Factor (KIC)

Critical Crack Extension (cf)

555.44 555.44st 688.38 688.38st

(hr) (days)

0 0 0.0 0.0 0.0 0.06 0.25 0.01 0.01 0.02 0.028 0.33 0.05 0.03 0.07 0.0610 0.42 0.08 0.14 0.14 0.1112 0.50 0.19 0.15 0.32 0.25

AGEMIXTURE

KIC(Mpa-m1/2)

555.44 555.44st 688.38 688.38st

(hrs)

6 0.001 0.003 0.002 0.0018 0.005 0.008 0.007 0.00410 0.006 0.008 0.012 0.00612 0.006 0.023 0.024 0.018

c f (m)

AGEMIXTURE

Westergaard Slab Curling

Curling Stress in Concrete SlabCurling Stress in Concrete Slab

)12 -ν(

TCEασ

λλ

λ)λλ(λC

2sinh2sin

tanhtancoshcos21

8l

Lλ

42

3

112 )kv(

Ehl

Tensile strength of the slab at 6hrs

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.00 0.10 0.20 0.30 0.40 0.50

ao/dN

om

inal s

trength

(MPa)

555.44

555.44ST

Saw cut Saw cut DepthDepth AGE (hr) 6 8 10 12

MIXTURE

688.38 0.15 0.20 0.25 0.30555.44 0.18 0.24 0.30 0.37

Stress (Mpa)

Saw Cut Depth Charts

Low Cementitious ContentLow Cementitious Content

Tensile strength of the slab at 6hrs

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.00 0.10 0.20 0.30 0.40 0.50

ao/d

Nom

inal

str

engt

h(M

Pa)

555.44

555.44ST

Tensile strength of the slab at 8hr

0.00

0.10

0.20

0.30

0.40

0.00 0.10 0.20 0.30 0.40 0.50ao/d

Nom

inal

str

engt

h(M

Pa)

555.44

555.44ST

Tensile strength of the slab at 10 hours

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.00 0.10 0.20 0.30 0.40 0.50ao/d

Nom

inal

stren

gth

(MPa)

555.44

555.44ST

Tensile strength of the slab at 12 hours

0.00

0.20

0.40

0.60

0.80

1.00

0.00 0.10 0.20 0.30 0.40 0.50

ao/d

Nom

inal

str

engt

h(M

Pa)

555.44

555.44ST

Saw Cut Depth Charts

High Cementitious ContentHigh Cementitious Content

Tensile strength of the slab at 6 hours

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.00 0.10 0.20 0.30 0.40 0.50ao/d

Nom

inal

str

engt

h(M

Pa) 688.38

688.38ST

Tensile strength of the slab at 8 hours

0.00

0.10

0.20

0.30

0.40

0.50

0.00 0.10 0.20 0.30 0.40 0.50ao/d

Nom

inal

str

engt

h(M

Pa)

688.38

688.38ST

Tensile strength of the slab at 10hours

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.00 0.10 0.20 0.30 0.40 0.50

ao/d

Nom

inal

str

engt

h(M

Pa)

688.38

688.38ST

Tensile strength of the slab at 12 hours

0.00

0.20

0.40

0.60

0.80

1.00

0.00 0.10 0.20 0.30 0.40 0.50ao/d

Nom

inal

str

engt

hMP

a) 688.38

688.38ST

Summary of Notch Depth Summary of Notch Depth RequirementsRequirements

6 8 10 12

0.15 0.2 0.25 0.3555.44 0.05 0.07 0.09 0.26

555.44st ------ 0.05 0.09 0.23

0.18 0.24 0.3 0.37688.38 0.02 0.08 0.12 0.36

688.38st 0.02 0.07 0.09 0.26Notch depth

required

Age(hours)

Temp. stress(Mpa)Notch depth

required

Temp. stress(Mpa)

0

0.1

0.2

0.3

0.4

6 8 10 12

Age (hours)

No

tch

de

pth

(ao

/d)

555.44

555.44st

688.38

688.38st

Saw-cut timing and depthSaw-cut timing and depthSummary

Saw cut depth increases with concrete age dramatic increase in depth after 10 to 12 hr.

Larger maximum aggregate size increases saw cut depth High cementitious materials especially

Curling QuestionsCurling Questions

How does shrinkage effect slab size?

What are the combined effect of moisture/temperature profile?

What is the role concrete creep?

How do other concrete materials behave – FRC & SRA?

Slab CurlingSlab Curling

Effects of materials and slab geometry on moisture and temperature curling

HTCR 5.0

CRHTTtot

)1(2

),(),(),()()(

)1(2

)()()(),(

v

ztztzttEtC

v

ztEtCzt CRHTT

))(ln(

98.0

)(175.01

3

1

3

1)()(

3

0

zRHzRH

kkv

zRTz

w

TotalHT

dzzRH

zRH

kkv

zRT

hzz

h

h w

TotalHTNLLHT

2/

2/

3

0

))(ln(98.0

)(175.01

3

1

3

1)(1)()(

Time

Stress

Pc

Vapor Diffusion

after Grasley (2006) & Rodden (2006)

Field vs LabField vs Lab

50

55

60

65

70

75

80

85

90

95

100

8 9 10 11 12 13 14 15

Elapsed Time (days)

Inte

rnal

RH

(%

)

Surface - 1

Surface - 2

1/2" - 1

1/2" - 2

1"

5"

7"

11" - 1

11" -2

14" - 1

14" - 2

50

55

60

65

70

75

80

85

90

95

100

0 5 10 15 20 25 30

Elapsed Time (days)

Inte

rnal

RH

(%

)

0"

1/2"

1"

3"

7"

11"

14"

Field

Lab

RH Profile - LabRH Profile - Lab

-7.5

-6

-4.5

-3

-1.5

0

1.5

3

4.5

6

7.5

0.6 0.7 0.8 0.9 1 1.1

RH (%)

Lo

cati

on

in

Sla

b (

in)

Actual RH

Second Order

STD Cube Moisture StressesSTD Cube Moisture Stresses

-700

-600

-500

-400

-300

-200

-100

0

0 5 10 15 20 25 30

Elapsed Time (days)

Ten

sile

Str

ess/

Str

eng

th (

psi

)

Tensile Stress

Tensile Strength

Summary of CurlingSummary of Curling

Moisture profile effects

Temperature

Set temperature

Shrinkage Reducing Admixtures

Fiber Reinforced Concrete

Joint Type AnalysisJoint Type Analysis

How can we choose dowel vs. aggregate interlock joint type & joint spacing?

Need to predict crack width & LTEShrinkage, zero-stress temperature, creepAggregate size and type (GF)

Slab length & base friction

If we use aggregate interlock joints there is a significant cost savings

h

Field Demo ProjectField Demo Project

Joint Opening MeasurementJoint Opening Measurement

Two week joint openingTwo week joint opening

-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

6/22 6/24 6/26 6/28 6/30 7/2 7/4 7/6 7/8

DATE

JOIN

T-O

PE

NIN

G (

in)

ABCD

AC

BD

Concrete Free ShrinkageConcrete Free Shrinkage

SHRINKAGE 688.38 ST MIX

0

200

400

600

800

0 4 8 12 16 20 24 28Age (days)

Shrinka

ge (m

m/m

m)…

….

Total shrinkage - Lab Mix

Total shrinkage - Field Mix

Autogrenous shrinkage - Field Mix

Step 1: Predict crack opening, w

Step 2: Predict differential

deflection, δdiff

Step 3: Determine

LTE

Inputs:RH, T, L, E, , C

Inputs:w, CA topsize,

Step 4: Acceptable

LTE?

Inputs:δfree, δdiff,

Inputs:FAA

recommendation

iPCC

i

PCCiSHRi E

fcTLCCCW

i

2

fL

hC

dc

PULf

bi

m

2

210

1i

Base frictionCurling (thermal and moisture)Steel reinforcement

Crack spacing

Drying shrinkage

Temperature drop

Restraints

*after Zollinger

Crack Width Model Approach

Recycled concrete aggregate (RCA)Recycled concrete aggregate (RCA)

RCARCA

Slight strength reduction

Higher shrinkage potential

Lower modulus

Lower concrete density

Potential cost saving ++

Can RCA (coarse) provide similar mechanical properties for airfield rigid pavements as virgin aggregates?

UIUC First TrialUIUC First Trial

RCA from Champaign recycling plantConcrete came from pavements, parking garages, etc.

Mix of materials with unknown properties

Material washed, dried, and sieved to match natural fine aggregate

Soaked for 24 hrs, surface dried, and then 100% replacement of natural fine aggregate

Saturated RCA vs Lab AggregatesSaturated RCA vs Lab Aggregates

-100

-80

-60

-40

-20

0

20

0 5 10 15 20

Age (d)

Shr

inka

ge s

trai

n x

10-6 lab stock

lab ssdRCA SSD

•Similar autogenous shrinkage curves

Mechanical Property Test PlanMechanical Property Test Plan

Simple lab crusherThree Point Bend (TPB) test Fracture properties

(Spring 2006)

Full-scale crushing at contractorFracture / strength properties

Shrinkage

(Summer 2006)

Sample PreparationSample Preparation

1. Crush Process

Sample Preparation (Con’t)Sample Preparation (Con’t)

2. Gradation 3. Mixture Design

Gradation - Maximum size 25 mm

0

20

40

60

80

100

Particle Size (mm)

Per

centa

ge

pas

sing (%

)

1"3/4"1/2"3/8"# 4# 10

Plain Concrete

Synthetic Fiber Reinforced Concrete

Mix ID PCC FRCPP Material Kg/m3 lb/yd3 Kg/m3 lb/yd3 Water 183 308 183 308

Type I Cement 360 607 360 607 Coarse aggregate 976 1645 976 1645 Fine aggregate 807 1360 807 1360

Synthetic Fibers --- --- 7.2 12.1

Sample Preparation (Con’t)Sample Preparation (Con’t)

P

50 mm

CMOD

600mm

700mm

150mm

80 mm

4. Dimensions

Sample Preparation(Con’t)Sample Preparation(Con’t)

3 beams Tested 7 dayPosition control displacementCMOD = 3 Max

3 Cycles Load – CMOD curve

Test Test

Plain Concrete Fracture BehaviorPlain Concrete Fracture Behavior

0

0.5

1

1.5

2

2.5

3

3.5

4

0 0.4 0.8 1.2 1.6 2CMOD (mm)

Load

(kN

)

PCC RCA

FRC Fracture BehaviorFRC Fracture Behavior

0

0.5

1

1.5

2

2.5

3

3.5

4

0 0.4 0.8 1.2 1.6 2CMOD (mm)

FRC RCA w/ Fibers

Fracture EnergyFracture Energy

0

0.5

1

1.5

2

2.5

3

3.5

0 0.2 0.4 0.6 0.8

CMOD

Load (kN

)  

AreaFracture

CMODLoadPlotUnderAreaG f

Results (Con’t)Results (Con’t)

050

100150200250300350400450500

(N/m

)

Plain FRC

RCCA

Virgen

RCA Virgin RCA Virgin

ResultsResults

050

100150200250300350400450500

(N/m

)

RCA Fiber RCA

Sample 1

Sample 2

Sample 3

Average

RCA vs FRCARCA vs FRCA

CMOD - LOAD CURVE

0

0.5

1

1.5

2

2.5

3

3.5

4

0 0.5 1 1.5 2 2.5 3 3.5

CMOD

Load

(kN

)

FRCA # 1

FRCA # 2

FRCA # 4

RCA # 1

RCA # 2

RCA # 3

PLAIN

Summary of Fracture PropertiesSummary of Fracture Properties

FRCA - Fracture Energy (N/m)

Pc (N) KIC (Mpa m1/2)

CTODc

(mm) Gc (N/m)

Sample 1 329 2,623 0.86 0.024 36.00 Sample 2 436 2,627 0.80 0.021 33.03

Sample 3 493 3,006 0.98 0.029 49.22

Average 420 2,752 0.88 0.025 39.42 C.O.V (%) 19.79 7.99 10.63 16.29 21.87

Virgin Aggregate 399 3,833 1.01 0.013 36.1

Difference -5.15% 28.20% 12.79% -92.80% -9.18%

Initial FindingsInitial Findings

RCA reduce the concrete fracture energy by 50%

RCA does not affect the fracture energy in fiber reinforced concrete (peak load still less)

Summer 2006 Summer 2006 RCA Concrete MixturesRCA Concrete Mixtures

Type of Coarse Aggregate Virgin (V) Recycled (R) V & R

Fibers Yes No Yes No No

Mix ID VF VP RF RP MP

Mix date 7.11.06 7.11.06 7.21.06 7.21.06 7.24.06

Mixture lb/yd3 lb/yd3 lb/yd3 lb/yd3 lb/yd3

Water 308 308 308 308 308

Cement Type I 607 607 607 607 607

Coarse Aggregate 1645 1645 1645 1645 1645

Fine Aggregate 1360 1360 1360 1360 1360

Synthetic Fibers 3 --- 3 --- ---

BSGSSD = 2.42AC = 5.7%

RCA TestsRCA Tests

Fresh properteis

Slump, Density, Air

Compressive Strength (7 days)

Split Tensile (7 days)

Three Point Bending at 7daysGF

Gf

CTODc

Drying Shrinkage – 28 days

Work remaining for FY2006Work remaining for FY2006

Joint type and size analysis – con’t

Saw-cut timing model - TN

Materials and geometry effects on curling - TN

Functionally-layered concrete pavements - TN

Recycled concrete aggregate – Recycled concrete aggregate – con’tcon’tP

hBottom layer

Top layer

ao

h

1h

2

QUESTIONSQUESTIONS

www.cee.uiuc.edu\research\ceat

Thanks!