SUMMARY OF FINDINGS FM 973 WMA/RAP/RAS TEST SECTION Mike Arellano, P.E, Austin District 2013 TxDOT Transportation Short Course October 15, 2013

Table of Contents

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Background

Development & Construction of FM 973 Test Sections

Lab Findings

Field Findings

Economics

Conclusions

Q&A

1

2

3

4

5

6

7

Background – Big Picture Issue

With limited funds for pavement preservation want to use new technology

Savings from using RAP/RAS

Performance with RAP/RAS

4

Background – Construction Issues with Recycle Asphalt Mixes

Compaction Issues – High

Air Voids

Tearing During

Compaction

Raveling/ Segregation

Background – Performance Issues with Recycled Asphalt Mixes

5

Longitudinal Cracking & Raveling

Fatigue Cracking

Top-Down Cracking

Background – Long-Term Performance Issues

FM 1460 – New Construction – Longitudinal, Block, and

Transverse Cracking for both RAS & RAP sections

– Raveling at the joints and transitions

– Economics • ~$158k in cost savings from grade

bumping • ~$50k in crack seal scheduled after

2 years of service • Unrealized future costs – future

routine maint. costs, unscheduled mill & inlay, reduced life cycle, etc…

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DEVELOPMENT & CONSTRUCTION OF FM 973 TEST SECTIONS

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Background – Goals for the Test Section

Goals of FM 973 –Acceptable amount of

RAS/RAP –Benefits of WMA and soft

binder –Evaluate Lab tests to

predict field performance –Field performance

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Development – Partnership in Innovation

FM 973 at a Glance

FM 973 Accelerated Pavement Test Section – From FM 969 to SH 71 – Existing Section: 8” HMA/ 11” FLBS – Soft silty/sandy clays – marginal subgrade – ADT = 10,700 – % Truck = 9.1% (ADT-975) – Heavy Trucks – Ready Mix Plant, Sand & Gravel Pit,

ABIA Freight, and other Industrial traffic

– Schedule Inlay: 2” Mill, Seal & Inlay – TY C PG 70-22 SAC B

Research Studies

Study Title PI(s) Organization

TxDOT 0-6614 Use of Recycled Asphalt Shingles in HMA Fujie Zhou TTI

TxDOT 0-6092 Performance Evaluation & Mix Design for High RAP Mixtures Fujie Zhou TTI

TxDOT 0-6613 Evaluate Binder & Mixture Aging for Warm Mix Asphalts Charles Glover TTI

NCHRP 9-49 Performance of WMA Technologies: Stage I--Moisture Susceptibility

Amy Epps Martin, Cindy

Estakhri TTI

NCHRP 9-49A Performance of WMA Technologies: Stage II--Long-Term Field Performance

Shihui Shen Washington State University

Section No. Type Binder RAP RAS

1 HMA 70-22 0 0

7 WMA Foaming 70-22 0 0

8 WMA Additive 70-22 0 0

9 WMA Additive 64-22 15 3

3 HMA 64-22 15 3

4 HMA 64-22 0 5

2 HMA 64-22 30 0

5 HMA 58-28 30 0

6 HMA 58-28 15 3

FM 973 Between FM 969 and HWY 71

• Type C mix • Limestone C, D, F, Mfg.

Sand + Field Sand • Section length ~ 2,040 ft • Sections 1 & 7: 400 tons • Sections 2-6,8,9: 800 tons Austin Bergstrom Int. Airport

Construction

PAVE _IR

LABORATORY FINDINGS

Section No. Type Binder RAP RAS

1 HMA 70-22 0 0

7 WMA Foaming 70-22 0 0

8 WMA Additive 70-22 0 0

9 WMA Additive 64-22 15 3

3 HMA 64-22 15 3

4 HMA 64-22 0 5

2 HMA 64-22 30 0

5 HMA 58-28 30 0

6 HMA 58-28 15 3

FM 973 Between FM 969 and HWY 71

• Type C mix • Limestone C, D, F, Mfg.

Sand + Field Sand • Section length ~ 2,040 ft • Sections 1 & 7: 400 tons • Sections 2-6,8,9: 800 tons Austin Bergstrom Int. Airport

Sections highlighted in yellow being used in this project

Upper limit of binder replacement

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Section Type Binder RAP RAS 1 HMA 70-22 0 0 2 HMA 64-22 30 0 3 HMA 64-22 15 3 4 HMA 64-22 0 5

01020304050607080

OT

Cycl

es

Overlay Test0

1

2

3

4

5

Rut D

epth

(mm

)

Hamburg Test@10000passes

Impact of Soft Binder

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Section Type Binder RAP RAS 2 HMA 64-22 30 0 5 HMA 58-28 30 0

0

5

10

15

20

25

PG64-22/30%RAP PG58-28/30%RAP

OT

Cycl

es

Overlay Test0

1

2

3

4

5

6

7

8

9

10

PG64-22/30%RAP PG58-28/30%RAP

Rut D

epth

(mm

)

Hamburg Test@10000passes

Objectives: NCHRP 9-49

Select conditioning/curing protocol for WMA

Evaluate if/when WMA = HMA

Evaluate moisture susceptibility of WMA

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Section No. Type Binder RAP RAS

1 HMA 70-22 0 0

7 WMA Foaming 70-22 0 0

8 WMA Additive 70-22 0 0

9 WMA Additive 64-22 15 3

3 HMA 64-22 15 3

4 HMA 64-22 0 5

2 HMA 64-22 30 0

5 HMA 58-28 30 0

6 HMA 58-28 15 3

FM 973 Between FM 969 and HWY 71

• Type C mix • Limestone C, D, F, Mfg.

Sand + Field Sand • Section length ~ 2,040 ft • Sections 1 & 7: 400 tons • Sections 2-6,8,9: 800 tons Austin Bergstrom Int. Airport

Sections highlighted in yellow being used in this project

Time Horizon: WMA = HMA

20

100

200

300

400

500

600

700

800

900

1000

0 1 2 3 4 5 6 7 8 9

Resi

lient

Mod

ulus

( R

oom

Tem

pera

ture

25C

)

Time (Weeks)

HMA

Evotherm

Foaming

HMA+RAP/RAS

Equivalent stiffness ≈ 3 weeks

Lab Mix-Lab Compacted (LMLC) Specimens

Moisture Susceptibility: HWTT @ 10,000

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4.4

5.9

8.1

2.4

5.1 5.8

9.0

12.3

8.9

12.5+

0

2

4

6

8

10

12

14

HMA Evotherm FOAMING HMA+RAP/RAS Evotherm+RAP/RAS

Rut D

epth

(mm

)

Mixture Type

Off-Site PMLCPMFC

Off-Site Plant Mix-Lab Compacted (PMLC) Plant Mix Field Cores (PMFC)

Moisture Susceptibility: TSR, MR Ratio

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Section MIX TYPE RAP, %

RAS, %

TSR, %

MR RATIO, %

3 HMA w/RAP/RAS 15 3 91 106

9 WMA Additive w/RAP/RAS 15 3 85 94

1 HMA 0 0 74 69

8 WMA Additive 0 0 73 74

7 WMA Foaming 0 0 65 63

Off-Site Reheated Plant Mix-Lab Compacted (PMLC) Specimens

FIELD FINDINGS

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Transverse Cracking

Raveling

Fatigue & Longitudinal

Cracking

Examples of Distress on FM 973

FM 973 Performance (14 Months) – HMA Sections

Section Binder RAP RAS

Distress

Long WP (LF)

Fat. Crk.

Long N-WP (LF)

Trans Crk.

Raveling Index

1 70-22 (Control) 0 0 10 0 25 0 3.0

2 64-22 30 0 35 0 25 0 3.5

5 58-28 30 0 40 4 25 0 3.5

3 64-22 15 3 150 2 260 7 3.5

6 58-28 15 3 20 0 100 1 4.5

4 64-22 0 5 430 8 130 18 3.5

FM 973 Performance (14 Months) – WMA Sections

Section Binder RAP RAS

Distress

Long WP (LF)

Fat. Crk.

Long N-WP (LF)

Trans. Crk

Raveling Index

1 70-22 (Control) 0 0 10 0 25 0 3.0

7 70-22 WMA

Foaming 0 0 25 0 20 0 3.5

8 70-22 WMA

Additive 0 0 30 0 25 0 4.0

9 64-22 WMA

Additive 15 3 20 0 30 1 4.5

3 64-22 15 3 150 2 260 7 3.5

ECONOMICS – COST/BENEFIT

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Economics – Initial Cost Savings of FM 973

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Initial Material Cost Savings from Grade Bumping AC

Section No. Type Binder RAP RAS Target

AC FRAP

AC RAS AC

AC Cost (No Recycled AC)

AC Cost (With

Recycled AC)

9 WMA Additive 64-22 15 3 5.3 5 20 $27,560 $20,540

3 HMA 64-22 15 3 5.3 5 20 $27,560 $20,540

4 HMA 64-22 0 5 5.4 0 20 $28,080 $22,880

2 HMA 64-22 30 0 5.2 5 0 $27,040 $19,240

5 HMA 58-28 30 0 5.2 5 0 $27,040 $19,240

6 HMA 58-28 15 3 5.3 5 20 $27,560 $20,540

Total Cost Savings $41,860

Percent Cost Savings 25%

Economics – Long-Term Maintenance Costs (Last 2 years)

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Year Routine Maintenance RM Expenses Non-RM

Expenses Total

1 None - - -

2 Crack Seal $9390 $2348 -$11,738

Initial Construction Cost Savings $41,860

Cost Savings Remaining (after 2 years of RM costs) $30,122

% Reduction of Cost Savings within 2 year of Service -28%

SUMMARY OF CONCLUSIONS

Conclusions – Recycled Materials

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Lab Field

RAP/RAS stiffen mix Control section (polymer modified) best

RAP stiffens more than RAS 5% RAS worst

RAP/RAS improves rutting, moisture susceptibility RAP sections better than RAS

RAP/RAS more cracking Soft virgin binders help

Soft virgin binders reduce stiffness

RAP/RAS sections require crack sealing

Conclusions – Recycled Materials

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Lab Field

Standardized mixture conditioning

WMA & HMA with PG 70-22 about same performance

FMLC @ plant vs reheating WMA chemical additive & WMA Foam about same performance

WMA more susceptible to moisture in short term

WMA improved performance of RAP/RAS

WMA stiffness after few months equals initial HMA stiffness

WMA reduces aging in long term - inconclusive

Conclusions – Implementation – Austin District

97% target density Minimum HWTT of 4 mm Use WMA with RAP/RAS mixtures High RAP/RAS with pretreatment Contractor demonstrate RAP/RAS more

resistant to cracking – Extracted/recovered binder – Overlay test

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WATER WATER

“Half Full” 95% Full