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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
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2
3
4
5
6
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Background – Big Picture Issue
With limited funds for pavement preservation want to use new technology
Savings from using RAP/RAS
Performance with RAP/RAS
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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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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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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
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
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 – 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%
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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