behavior of recycled concrete aggregate as unbound road base · october 4, 2011 unbound recycled...

October 4, 2011 Unbound Recycled Material Jim Tinjum, PhD, PE

University of Wisconsin-Madison Slide 1/43

UW – Madison

Geological

Engineering

Geological Engineering Transportation Geotechnics Civil & Environmental Engineering

Behavior of Recycled Concrete Aggregate

as Unbound Road Base

Tuncer B. Edil

Recycled Materials Resource Center

Geological Engineering Program

University of Wisconsin-Madison



Objective of Pool Fund Project

• Characterize properties of recycled concrete aggregate

(and also recycled asphalt pavement) as unbound base

• Determine how RCA behaves in the field and how to

design pavements using these materials

• Both lab and field scale tests

• variability in material properties

•purity of materials

•control of material quality and best construction practices

•climatic effects and durability

•Environemntal suitability



Project TasksTask I Structural capacity, long-term stability, design properties

Task IA

Task IB

Task IC

Task ID

Literature Review

Relationship between Mr and Composition of RCA or RAP

Scaling and Equivalency: Specimen Tests to Field-Scale Conditions

Climate Effects

Task II Construction & Maintenance

Task IIA

Task IIB

Compaction Level and Assessment

Field Performance and Maintenance

Task III Materials Control

Task IV Leaching Characteristics

Task V Extended Monitoring

Task VI/VII Final Report & Dissemination



Recycled Materials

Recycled Concrete Aggregate (RCA)



Objective of Today’s Presentation

o To characterize the engineering properties of RCA as unbound

road base without being treated or stabilized

o To assess the influence of

• compaction effort

• compaction moisture content

• freeze-thaw cycling

on the stiffness of RCA as unbound road base

o To determine the effect of varying RCA content on the

stiffness of natural aggregates used as unbound road base



LITERATURE SURVEY



Typical RCA Properties

Physical Properties

Specific Gravity2.2 to 2.5 (Coarse Particles)

2.0 to 2.3 (Fine Particles)

Absorption2% to 6% (Coarse Particles)

4% to 8% (Fine Particles)

Mechanical Properties

LA Abrasion Loss 20% to 45% (Coarse Particles)

Magnesium Sulfate Soundness Loss4% or Less (Coarse Particles)

Less than 9% (Fine Particles)

California Bearing Ratio (CBR) 94% to 148%

FHWA Report FHWA-RD-97-148



Gradation

Material

% Finer

Fine

(#200)

Coarse

(19.1 mm)

Conventional Crushed

Aggregate (MnDOT Class

5)

3 to 10% 90 to 100%

RAP1 to 8%

(Mean: 2.3%)

92 to 100%

(Mean: 95.0%)

RPM3 to 16 %

(Mean: 8.0%)

93 to 96%

(Mean: 95.8%)

RCA3 to 8%

(Mean: 5.1%)

50 to 100%

(Mean:82.4 %)



UW – Madison

Geological

Engineering


RESULTS OF SURVEY BY RMRC 2009

The Usage, Storage and Testing of Recycled

Materials



Material Use and Storage



Which of the following recycled materials do you use

as a granular base course?

34 Total responses

• RAP: 18 (53%)*

• RCA: 30 (88%)*

• RPM: 17 (50%)*

* More than one response

possible

0

10

20

30

40

RAP RCA RPM

Number of Responses

Material



When are the recycled materials used?

Total response:

36 agencies

0

10

20

30

RAP RCA RPM

Used in place immediately

Stockpiled and used later

Both

Number of responses

Material



In a given year, how much of the recycled material do

you use?

Total response:

33 agencies

0

10

20

30

RAP RCA RPM

Less than 1,000 tons1,000 to 5,000 tons5,000 to 10,000 tons10,0000 to 25,000 tons25,000 to 50,000 tons50,000 to 75,000 tonsMore than 75,000 tons

Number of responses

Material



Are any of the following tests used in specifications for

the material?

Total response:

32 agencies

0

10

20

30

40

50

60

RAP RCA RPM

Grain size analysis: Wet sieve

and hydrometerLiquid limitPlastic limit and plasticity indexGrain size analysis: Dry sieve

Number of responses

Material



0

5

10

15

20

25

RAP RCA RPM

Aggregate abrasion valueGyratorySulfate soundnessTexas wet-millMicro devalL.A. abrasion

Number of responses

Material

Which of the following aggregate quality tests for

toughness do you perform on the material prior to

placement?

Total response:

21 agencies

Offered but not selected:

• Aggregate impact value

• Aggregate crushing value

• Durability mill



0

2

4

6

8

10

12

RAP RCA RPM

Magnesium sulfate soundnessAggregate durability indexSulfate soundness

Number of responses

Material

Which of the following aggregate quality tests for

durability do you perform on the material prior to

placement?

Total response:

12 agencies

Offered but not selected:

• Canadian freeze-thaw



Materials

RCA: 7

RAP: 7

RPM: 2

California

Minnesota

Colorado

Wisconsin Michigan

Texas

New Jersey

OhioRCA, RAP

RCA, RAP RCA, RAP

RCA, RAP

RCA, RAP, RPM

RCA, RPMRCA, RAP RAP



Representative Materials

Gradation RCA

Coarser Texas

Medium Michigan

Finer California

o Class 5 (Natural Aggregate)



Gradation: RCAs and Class 5

0

10

20

30

40

50

60

70

80

90

100

0.010.1110100

Percent Finer (%)

Particle Size (mm)

RCA (TX)

RCA (MI)

RCA (CA)

Class 5 (MN)

RCA Lower Limit

(Literature)

RCA Upper Limit

(Literature)



Test Method

o Resilient Modulus (Mr) Test

where σd = deviator stress, εr = recoverable elastic strain

Mr = σd /εr



Resilient Modulus

2

1

k

rkM θ= where θ = bulk stress

k1 and k2 = fitting parameters

Power

Function:

k2

k1

θ = σ1+2(σ3)=1

σ1

σ3σ3

log (bulk stress)

log (resilient modulus)

1

0

500

1000

1500

0 100 200 300 400 500 600 700

Resilient Modulus (MPa)

B u lk S tress (kPa)

SMr (θ=208 kPa)

Summary Resilient

Modulus (SRM)



UW – Madison

Geological

Engineering


Freeze-Thaw Cycling



Freeze-Thaw Cycling

� Specimens

• Prepared in the same manner as resilient

modulus specimens

• Retained in the freezer for 24 hours

• Thawed at room temperature for 24 hours

� After the last cycle, specimens were extruded frozen

and thawed inside the resilient modulus cell

� Specimens were subjected to 5, 10, 20 cycles

TE1

TE1 Tuncer Edil, 10/1/2011



Temperature Records for RAPs and RCAs

-30

-20

-10

0

10

20

30

0 4 8 12 16 20 24

Freezing

Thawing

Temperature (Celsius)

Time (Hours)

-30

-20

-10

0

10

20

30

0 4 8 12 16 20 24

Freezing

Thawing

Temperature (Celsius)

Time (Hours)

RCARAP



0

100

200

300

400

500

600

700

Internal SRM (MPa)

RCA (TX)

RCA (MI)

RCA (CA)

0 5 10 20

Freeze and Thaw Cycles

Class 5 (MN)

RCAs: SRM vs F-T Cycles



0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

SRMN/SRM0

RCA (TX)

RCA (MI)

RCA (CA)

0 5 10 20Freeze and Thaw Cycles

Class 5 (MN)

RCAs: Normalized SRM vs F-T Cycles



0.2

0.4

0.6

0.8

1

1.2

SRMN/SRM0

RAP (TX)

RAP (CA)

RAP (MN)

Class 5 (MN)

RAPs: Normalized SRM vs F-T Cycles

Coarser

Medium

Finer

0 5 10 20

Freeze and Thaw Cycles

AC=4%

AC=5%

AC=7%



Verification of RCA Behavior with Seismic

Modulus TestVP

Length, LDensity, ρ

Constrained ModulusP- Wave Velocity



RCAs: Constrained Modulus vs F-T Cycles

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12

Constrained Modulus, (MPa)

Freeze Thaw Cycles

RCA (TX)

RCA (MI)

RCA (CA)

Class 5 (MN)



UW – Madison

Geological

Engineering


Compaction Conditions

Effect of Density (Compaction Effort)

and Compaction Moisture on Modulus



18

19

20

21

22

2 4 6 8 10

Dry Unit Weight, (kN/m

3)

Water Content (%)

Density (Relative Compaction) Effect

95 % of MDU

OMC

90 % of MDU

85% of MDU



0

100

200

300

400

500

600

700

800

RAP (TX)

RAP (CA)

RAP (MN)

95 90 85

InternalSRM (MPa)

Compaction Effort (%)

RCA (TX)

RCA (MI)

RCA (CA)

Class 5 (MN)

Effect of Relative Compaction on Modulus



RCA

Class 5

0

100

200

300

400

500

600

700

800

RAP

Summary Effect of Relative Compaction on

Modulus

Compaction Effort (%)95 90 85

Internal SRM (MPa)

RAP 37%

decrease

RCA 41%

decrease

Natural Aggr

47%

decrease



18

19

20

21

22

2 4 6 8 10

Dry W

eight, (kN/m

3)

Water Content (%)

Compaction Moisture Effect

95 % of Modified Proctor

-2% +2%

OMC



PSDs of RAPs and RCAs Used in Moisture

Effects Testing

Particle Size (mm)

Percent Finer (%)

Particle Size (mm)

Percent Finer (%)

0

10

20

30

40

50

60

70

80

90

100

0.010.1110100

RCA (OH)

RCA (CO)

RCA Lower

Bound

(Literature)

RCA

Upper

Bound

(Literature)

Medium

Finer



RCA (CO)

RCA (OH)

100

200

300

400

500

600

700

800RAP (TX)

RAP (OH)

- 2% OMC + 2%

InternalSRM (MPa)

Effect of Compaction Moisture on Modulus

Coarser

Finer

Finer

Medium



RCA (CO)

RCA (OH)

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

RAP (TX)

RAP (OH)

- 2% OMC + 2%

SRMwc/SRMOMC

Effect of Compaction Moisture on Normalized

SRM



RCA (CO)

RCA (OH)

29%

decrease

7 %

decrease

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6 RAP (TX)

RAP (OH)

- 2% OMC + 2%

SRMwc/SRMOMC

Summary of Compaction Moisture Effect on

Normalized Modulus

RCA 28 %

increase

RAP 17 %

increase

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RAP (OH)-Before

100

200

300

400

500

600

700

800

4 6 8 10 12

RAP (TX)-Before

RAP (OH)-After

RAP (TX)-After

Moisture Content Before and After Test

Coarser

Finer

Internal SRM (MPa)

Water Content (%)



RCA (OH)-Before

RCA (OH)-After

RCA (CO)-After

100

200

300

400

500

600

4 6 8 10 12 14 16

RCA (CO)-Before

Water Content (%)

RCA: Effect of Compaction Moisture on

Modulus

Finer

Medium

Internal SRM (MPa)



UW – Madison

Geological

Engineering


Effect of RAP or RCA Content on

Stiffness of Natural Aggregate Blends



Materials Selected for Blends

RCA Natural

Aggregate

Minnesota Minnesota

(Class 5)



PSD of RCA (MN) and Class 5 Used in Blends

0

10

20

30

40

50

60

70

80

90

100

0.010.1110100

Percent Finer (%)

Particle Size (mm)

Class 5 (MN)

RCA (MN)

RCA Lower Bound

(Literature)

RCA Upper Bound

(Literature)



Compaction Curve: RCA (MN) Blend

18

19

20

21

22

0 2 4 6 8 10 12 14 16

Dry Weight, (kN/m

3)

Water Content (%)

Class 5 (MN)

Blend (50-50)

RCA (MN)



100

200

300

400

500

600

700

800

RAP (CA)

RAP (CO)

0 50 100

InternalSRM (MPa)

RAP or RCA (%)

RCA (MN)

SRM vs



0.5

1

1.5

2

RAP (CA)

RAP (CO)

0 50 100

SRM Blend/SRM Class 5

RAP or RCA (%)

RCA (MN)

Results

RCA 30%

increase

RAP 68%

increase



Quantitative Assessment of

Environmental and Economic Benefits

of Using Recycled Construction

Materials in Highway Construction



Schematic of Two Pavement Designs:

Reference-Conventional Materials vs. Alternative-Recycled Materials

Alternative

(Recycled materials)

Reference

(Conventional materials)



Life Cycle Analysis (LCA)

Environ-

mental

Metric

Conventional Materials Recycled Materials

Differ-

enceMaterial

Productio

n

Transpor-

tation

Con-

struction

Material

Production

Transpor-

tation

Con-

structio

n

CO2 (Mg) 3630 323 111 3028 163 54 -20%

Energy (GJ) 66,680 4318 1476 58,023 2187 723 -16%

RCRA

Hazardous

Waste (Mg)

629 31 9 611 16 4 -6%

Water (L) 17,185 735 144 15,637 372 70 -11%



Life Cycle Cost Analysis (LCCA)

Categories Reference Alternative Saving

Agency Cost ($) 9,044,570 7,107,230 1,937,340 (21%)

User Cost ($) 10,570 8,380 2,190 (21%)

Total ($) 9,055,140 7,115,610 1,939,530 (21%)



Conclusions Extrapolated to a Nationwide Scale

Point of

ImpactQuantity Equivalent to

Energy (PJ) 368

• Annual energy use for 3.67 million householders

(EIA 2005 survey)

• 68% of annual wind power generation in 2008

(EIA 2009)

Water

(million L)63

• 1.4 million persons daily water use for shower

(43.9 L/capita)

CO2e

(million

Mg)

26• Equivalent to the removal of 5 million passenger

cars per year from roadways

LCCA

(billion $)62

•Average annual salary for 1.5 million Americans

($39,500/yr)

* Based on an assumption of 150,000 km annual road construction (Carpenter et al 2007)



Environmental Concerns



PVF

0 5 10 15 20 25 30 35 40 45

Eh

50

100

150

200

250

300

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

Eh of RCA from five sites

PVF

0 5 10 15 20 25 30 35 40 45

EC(m

s/cm

)

0

1

2

3

4

5

6

7

8

9

10

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

EC of RCA from 5 sites

PVF

0 5 10 15 20 25 30 35 40 45

pH

7

8

9

10

11

12

13

14

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

pH of RCA from five sites

pH of RCA Column test(From 7-7-2010 to 9-16-2010)

The five kinds RCA are respectively: California RCA, Colorado RCA, Michigan RCA,

Minnesota RCA and Texas RCA



PVF

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Concentration(ppb )

1

10

100

1000

10000

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

Al-Aluminium

MDL

Calibration range

Note: Compared with the lowest MCL

MCL(CO & TX) 50 ppb

PVF

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Concentration(ppb )

0.01

0.1

1

10

100

1000

10000

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

Ba-Barium

MDL

MCL (CA) 1000ppb

Calibration range

PVF

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Concentration(ppb )

0.01

0.1

1

10

100

1000

10000

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

Fe-Iron

MDL

MCL (USEPA) 300ppb

PVF

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Concentration(ppb )

0.1

1

10

100

1000

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

Cr-Chorumlum

MDL

MCL(CA) 50ppb

Elements MCL At lease once: Al, As*, Ba, Cr, Fe, Pb, Sb*, Se, Sr, Tl,

Take the 23 elements into consideration Ag, Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Mn,

Mo, Ni, Pb, Sb, Se, Sn, Sr, Ti, Tl, V, and Zn(From 7-7-2010 to 8-18-2010)



PVF

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Concentration(ppb )

0.01

0.1

1

10

100

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

Pb-Palladium

MDL

Far below MDL

MCL(MI) 15ppb

Note: ICP analysis slighty negative

PVF

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Concentration(ppb )

0.1

1

10

100

1000

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

Se-Selenium

MCL (MN) 30ppb

MDL

PVF

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Concentration(ppb )

0.1

1

10

100

1000

10000

CA RCA

CO RCA

MI RCA

MN RCA

TX RCA

Sr-Strontium

MDL

Calibration range

MCL(USEPA) 4ppb



Conclusions

o Freeze-thaw cycling reduces the SRM of RAP and natural

aggregate.

• The modulus loss of RAP over 20 cycles is comparable to that of

natural aggregate (i.e., 28% vs 21%).

• RAP with finer gradation experienced more modulus loss mostly

in the first 5 cycles.

o RCA consistently displayed an unusual trend with freeze-

thaw cycling first modulus decreasing up to 5 cycles

followed with increasing up to 20 cycles



Questions?

behavior of recycled concrete aggregate as unbound road base · october 4, 2011 unbound recycled...

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