Properties and Short- Term Laboratory Conditioning of...

Properties and Short-Term Laboratory Conditioning of Foamed Asphalt for WMA Applications 7 April 2016

Today’s Presenters

• Moderator Ed Harrigan, TRB/NCHRP

• Presenters Dr. David Newcomb, TTI

Dr. Fan Yin, TTI

Dr. Edith Arámbula Mercado, TTI

NCHRP is...

AASHTO’s research program

• The state DOTs, through AASHTO’s Standing Committee on Research... – Sponsor and support NCHRP

– Suggest research topics and select final projects

– Help select investigators and guide their work through oversight panels

NCHRP delivers...

Practical, ready-to-use results • Applied research aimed at state

DOT practitioners • Often become AASHTO

standards, specifications, guides, manuals

• Can be directly applied across the spectrum of highway activities: planning, design, materials, construction, maintenance, operations, safety

NCHRP Webinar Series • Part of TRB’s larger webinar

program • Opportunity to interact with

NCHRP investigators, learn about research products, and foster implementation and adoption.

For More Information

http://www.trb.org/NCHRP

Christopher Hedges Manager, NCHRP

[email protected]

http://www.trb.org/NCHRP

mailto:[email protected]

TRB WEBINAR ON SHORT TERM CONDITIONING OF ASPHALT

MIXTURES AND PROPERTIES OF FOAMED ASPHALT MIXTURES

Dr. David Newcomb Dr. Fan Yin

Dr. Edith Arámbula Mercado

INTRODUCTION NCHRP 9-52 (Aging) – Dr. Yin Short Term Aging

Protocol Long Term Aging Protocol Factors Affecting Aging

2

NCHRP 9-53 (Foaming) – Dr. Arámbula Mercado Foaming for WMA Methods for Measuring

Foam Properties Factors Affecting

Foaming Effects of Foaming on

Mixture Behavior Laboratory vs. Field

SHORT-TERM LABORATORY

CONDITIONING OF ASPHALT MIXTURES

NCHRP Report 815

AGING OF ASPHALT MIXTURES

• Stiffening with time

• Short-term during production and construction

• Long-term throughout pavement service life

• Significant effect on mixture properties and pavement performance

4

Short-Term Conditioning

AGING OF ASPHALT MIXTURES • Laboratory aging protocols per AASHTO R 30 Mix design: STOA 2 hours at Tc Performance testing: STOA 4 hours at 275°F Field aging: LTOA 5 days at 185°F

• Mixture components and production parameters Use of polymer modifiers Inclusion of recycled materials Advent of WMA technologies DMP replacing BMP Increased production temperature

5

Aging Characteristics


OBJECTIVES

• Validate laboratory STOA protocol to simulate plant aging of asphalt mixtures (Task I)

• Correlate field aging of asphalt mixtures with laboratory LTOA protocols (Task II)

• Identify factors affecting the aging characteristics of asphalt mixtures (Task III)

6


FIELD PROJECTS

7

Connecticut Florida Indiana

Iowa New Mexico South Dakota

Texas (2) Wyoming


FIELD PROJECTS

8

Field Project WMA Production Temperature Plant Type RAP/RAS Aggregate

Absorption Binder Source

Texas I

Connecticut

Wyoming

South Dakota

New Mexico

Iowa

Florida

Indiana

Texas II


9

LABORATORY TESTS • Resilient Modulus (MR) ASTM D 7369 MR Stiffness at 77°F/10Hz

• Dynamic Modulus (E*) AASHTO TP 79-13 E* Stiffness at 68°F/10Hz and E* Master Curve

• Hamburg Wheel Tracking Test (HWTT) AASHTO T 324 Rut Depth at 5,000 Load Cycles and Rutting Resistance

Parameter (RRP) at 122°F

Loading Pulse

Mixture Response


HWTT RRP DETERMINATION

10


0.0E+00

1.0E-01

2.0E-01

3.0E-01

4.0E-01

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 5000 10000 15000 20000 25000 30000

Stra

in

Rut

Dep

th (m

m)

Load Cycle

Measured Rut Depth Predicted Rut Depth Viscoplastic Strain

Permanent Strain Stripping Strain

Stripping Number

LCSN LCST

RRP

VALIDATION OF STOA PROTOCOLS

11

vs. & PMPC

HMA Stabilize@275F

WMA Stabilize@240F

Volumetrics: Gmm & Pba Stiffness: MR & E*

Rutting Resistance: HWTT

Construction Core HMA

2h@275F

WMA 2h@240F

LMLC

Lab < Plant

Lab > Plant

Lab = Plant

LMLC

Pro

pert

y

PMPC / Construction Core Property

Line of Equality

TASK 1

MIXTURE VOLUMETRICS FOR LMLC VS. PMPC

12

Theoretical Maximum Specific Gravity (Gmm)

2.3

2.4

2.5

2.6

2.7

2.3 2.4 2.5 2.6 2.7

PMPC

-G

mm

LMLC - Gmm

TX I NM CT WY SD IA IN FL TX II

Percent of Absorbed Asphalt (%Pba)

0.0

0.6

1.2

1.8

2.4

3.0

0.0 0.6 1.2 1.8 2.4 3.0

PMPC

-P b

a(%

)

LMLC - Pba(%)


Equivalent volumetrics for lab mix vs. plant mix STOA representative of asphalt absorption and aging during plant production

TASK 1

MR STIFFNESS at 25°C/10Hz

13

Equivalent MR stiffness for LMLC vs. PMPC Slightly lower MR stiffness for construction core vs. LMLC due to higher AV

LMLC vs. PMPC LMLC vs. Construction Core

0

1400

2800

4200

5600

7000

0 1400 2800 4200 5600 7000

PMPC

-M

R(M

Pa)

LMLC - MR (MPa)


0

1400

2800

4200

5600

7000

0 1400 2800 4200 5600 7000C

onst

ruct

ion

Cor

e -M

R(M

Pa)

LMLC - MR (MPa)


TASK 1

SUMMARY – VALIDATION OF STOA PROTOCOLS Validated laboratory STOA protocols of 2 hours at 275°F for HMA and 240°F for WMA to simulate plant aging • Volumetrics: LMLC = PMPC • E* stiffness: LMLC = PMPC • MR stiffness: LMLC = PMPC • Rutting resistance: LMLC = PMPC • Construction core vs. LMLC & PMPC Higher AV (9.0% vs. 7.0%) Use of plaster (degradation and debonding)

14

> construction core > construction core

TASK 1

QUANTIFICATION OF FIELD AGING

15

• Cumulative Degree-Days (CDD): sum of the daily high temperature above freezing for all the days from time of construction to the time of core sampling

Construction Season Geographic Location

Winter Oct. 2012

𝐶𝐶𝐶𝐶𝐶𝐶 = �(𝑇𝑇𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 − 32)

TASK 2

CDD CURVES

16

0

5000

10000

15000

20000

25000

30000

35000

40000

Dec-11 Jul-12 Jan-13 Aug-13 Mar-14 Sep-14 Apr-15

Cum

ulat

ive

Deg

ree

Day

s (°

F-da

ys)

Coring Date

Texas New Mexico Wyoming South Dakota

Iowa Indiana Florida

TASK 2

MRR = 1.81 MRR = 2.23

17

PROPERTY RATIO (PR) • To quantify effect of aging on mixture properties

• Samples before aging Field cores at construction

LMLC specimens with only STOA

• Samples after aging post-construction field cores

LMLC specimens with STOA + LTOA

𝑃𝑃𝑃𝑃 =𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝑎𝑎𝑎𝑎𝑃𝑃𝑃𝑃𝑃𝑃 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝑏𝑏𝑃𝑃𝑎𝑎𝑃𝑃𝑃𝑃𝑃𝑃 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴

TASK 2

18

CDD vs. PR (MR STIFFNESS)

TASK 2

19

FIELD AGING VS. LABORATORY LTOA – MR STIFFNESS

Field Project 2w@60C 5d@85C

Florida 1.22 1.38

Indiana 1.30 1.54

Iowa 1.32 1.65

New Mexico 1.89 2.21

South Dakota 1.58 1.95

Texas 1.60 1.94

Wyoming 1.44 1.80

Average 1.48 1.78

Stdev 0.23 0.28 2w@60C = 9,600 CDD (MR & HWTT RRP)

5d@85C = 17,500 CDD (MR & HWTT RRP)

TASK 2

SUMMARY – FIELD AGING VS. LTOA PROTOCOLS

• Proposed CDD to quantify field aging of asphalt pavements

• Proposed PR to evaluate mixture property evolution with field and laboratory aging

• Correlated field aging with laboratory LTOA protocols

20

LTOA Protocols CDD In-Service Time

Warmer Climates

Colder Climates

2 weeks at 140°F 9,600 7 months 12 months

5 days at 185°F 17,500 12 months 23 months

TASK 2

FACTOR ANALYSIS*

21 *STAT Validation by ANOVA Analysis

WMA Technology

Production Temperature

Plant Type

Recycled Materials

Aggregate Absorption

Binder Source

Varia

ble

Mix

ture

Control Mixture

Positive Effect

Negative Effect

Insignificant Effect

Short-term: mixture property Long-term: mixture property ratio

TASK 3

FACTOR – WMA TECHNOLOGY

22

Short-Term: MR Stiffness

0.0

1.0

2.0

3.0

4.0

0.0 1.0 2.0 3.0 4.0

WM

A M

RR

atio

HMA MR Ratio

TX NM WY SD IA IN FL

0

200

400

600

800

1000

0 200 400 600 800 1000

WM

A -

MR

(ksi

)

HMA - MR (ksi)

TX I NM CT WY SD IA IN FL

Long-Term: MR Stiffness Ratio

TASK 3

FACTOR – PLANT TYPE

23

Short-Term: MR Stiffness Long-Term: MR Stiffness Ratio

0

200

400

600

800

1000

0 200 400 600 800 1000

BM

P M

ixtu

re -

MR

(ksi

)

DMP Mixture - MR (ksi)

IN TX II

0.0

1.0

2.0

3.0

4.0

0.0 1.0 2.0 3.0 4.0

DM

P M

ixtu

re M

RR

atio

BMP Mixture MR Ratio

IN

TASK 3

24

Factors Significant?

Trends Explanations ST* LT*

WMA Technology Yes Yes

WMA vs. HMA ST: worse properties

LT: faster aging

• Reduced production temperatures

• WMA additives

Recycled Materials Yes Yes

RAP/RAS vs. control ST: better properties

LT: slower aging

• Over aged binders • Less virgin binders

available for aging

Aggregate Absorption Yes Yes

High vs. low abs. ST: worse properties

LT: faster aging

• More effective binders available for aging

Binder Source Yes N/A Same PG ≠ same properties

• Different oxidation kinetics

Production Temperature No No

Equivalent mixture properties Plant Type No No

* ST = short-term; LT = long-term

FACTOR ANALYSIS SUMMARY

25

Laboratory STOA HMA: 2h@275°F WMA: 2h@240°F

Plant Production & Construction

Laboratory LTOA Field Aging

CDD = ∑(𝑇𝑇𝑑𝑑𝑑𝑑𝑑𝑑 − 32)

MR Stiffness Ratio (Aged/Unaged)

Volumetrics MR & E* Stiffness

HWTT Rutting Resistance

LTOA

2w@140°F = 9,600 CDD 5d@185°F = 17,500 CDD

Novel HWTT Methodology

Mixture Property Ratio (Aged/Unaged)

WMA Technology

Recycled Materials

Aggregate Absorption

Binder Source

Production Temperature

Plant Type

Significant Effect on Aging Characteristics?

CONCLUSIONS Short-Term Conditioning

PROPERTIES OF FOAMED ASPHALT

FOR WMA APPLICATIONS

NCHRP Report 807

WARM-MIX ASPHALT • Additives or mechanical foaming process • Reduced production temperatures (~50°F)

27

Properties of Foamed Asphalt

Benefits

• Economic

• Environmental

• Performance

Limitations

• Susceptibility to rutting and moisture damage

• Correlation between laboratory and field performance

• Unknowns of the mechanical foaming process

WARM-MIX ASPHALT • Mechanical foaming accounted for ~84% of total

WMA produced in 2014 • Mechanical foaming mechanism

• Limitations Foaming measurements Foamed asphalt characteristics Foamed mixture properties Mix design procedure

28

Dipstick Method

ERmax

HL


Viscosity Reduction

Volume Expansion

Water injection into hot binder

OBJECTIVES

• Develop test methods and metrics to characterize

asphalt foaming.

• Evaluate the effects of foamed asphalt characteristics

on foamed mixture properties.

• Develop a mix design procedure for foamed asphalt

mixtures.

29


FOAMED ASPHALT MEASUREMENT METHODS

30

Laser Device

Camera

Container

Laboratory Foamer


LASER MEASUREMENT

31

Higher ERmax = higher instantaneous expansion Higher FI(t) = better stability

1400

1420

1440

1460

1480

1500

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0 30 60 90 120 150

Dist

ance

Rea

ding

(mm

)

Expa

nsio

n Ra

tio

Time (s)

Fitted ER Measured ER Distance Reading

ERmax

Foamability Index, FI(t)


𝐸𝐸𝑃𝑃𝑡𝑡 = 1 + 𝑎𝑎𝑃𝑃−𝑏𝑏𝑡𝑡 + (𝐸𝐸𝑃𝑃𝑑𝑑𝑑𝑑𝑑𝑑 − 𝑎𝑎 − 1)𝑃𝑃−𝑐𝑐𝑡𝑡

CAMERA MEASUREMENT

32

• Image analysis for surface foam bubbles – Diameter distribution, Dsfb-i(t)

– Amount, Nsfb(t)

• Foam bubble volume quantification

• Surface area index

SAI = SA/SA0 = f[ER(t), Dsfb-i(t), Nsfb(t)] Higher SAI = more foam binder surface available

= better aggregate coating

Laser Camera


FOAMED MIXTURE MEASUREMENT METHODS • Workability: ease with which asphalt mixture can be

placed, work by hand, and compacted • Coatability: degree of coating of the aggregate with

asphalt binder

33

Pre-heated Aggregate

Foamed Asphalt


WORKABILITY MEASUREMENT

34

Asphalt Loose Mix

Compaction Piston

F

h

L

d

Shea

r Str

ess (

τ) (k

Pa)

Gyration

Reduction in Shear Stress

Phase II

Phase I Phase III τmax

Lower τmax = better workability

4,700g


𝝉𝝉 =𝟐𝟐 × 𝑭𝑭 × 𝑳𝑳

𝝅𝝅 × 𝒅𝒅𝟐𝟐

𝟐𝟐× 𝒉𝒉

COATABILITY MEASUREMENT

35

Water Water

Coarse Aggregate Fraction

Coarse Foamed

Loose Mix Fraction

VS.

Soak under water for 1 hour

Coatability Index (CI): relative difference in SSD water absorption

Higher CI = better aggregate coating


WORKABILITY & COATABILITY MEASUREMENTS

36


FACTOR ANALYSIS

37

Foamed Asphalt

• Binder Source and Grade

• Water Content • Temperature • Additives • Shearing action • Foamer Type

Foamed Mixture • Binder Source and

Grade • Water Content • Additives • Foamer Type • Mixture Type


• Significant effects on foamed asphalt characteristics Volume expansion, ERmax

Foam stability, FI

Foam bubble surface area, SAI

• Significant effects on foamed mixture properties Workability, τmax

Optimum foaming water content Wopt = lowest τmax ≠ Wmax

Equivalent or better performance at Wopt vs. HMA

FACTOR ANALYSIS – FOAMING WATER CONTENT

38


FACTOR ANALYSIS – LABORATORY FOAMER TYPE

39

InstroTek Foamer PTI Foamer Wirtgen Foamer

73 psi 30 psi Gravity

Main Difference – Asphalt Flow Pressure


FACTOR ANALYSIS – LABORATORY FOAMER TYPE

• Volume Expansion (ERmax) & Foam Stability (FI) Wirtgen > InstroTek > PTI (no expansion)

• Foam Surface Area (SAI) Wirtgen > InstroTek PTI: limited amount of foam bubbles

• Workability (τmax) & Coatability (CI) Wirtgen ≠ InstroTek ≠ PTI Individual Wopt Equivalent or better properties at Wopt vs. HMA

40


MIX DESIGN PROCEDURE

• Water content optimization Workability Coatability

• Performance evaluation Stiffness Rutting resistance Moisture susceptibility

41


MIX DESIGN PROCEDURE

42


Materials Selection

Add/Modify Mixture Components

Superpave Mix Design AASHTO R35

Performance Evaluation

Specimen Fabrication Foamed Mixture at

Wopt%

Indirect Tensile (IDT) Strength per

AASHTO T 283

Resilient Modulus (MR) per modified ASTM D 7369

Hamburg Wheel Tracking Test (HWTT) per AASHTO T 324

Fail AASHTO/DOT Specification

Pass AASHTO/DOT Specification

Optimum Binder Content

Lowest Max Shear Stress

(τmax)

Workability Evaluation on Foamed Mixture at

1, 2, and 3% water

Coatability Evaluation on Foamed Mixture at

Wopt% CI > 70%

Optimum Water Content

(Wopt%)

No

Yes

Or

Or

MIX DESIGN VALIDATION

43

Laboratory Testing

Workability Evaluation for Foamed

LMLC at Various Water Contents

Determination of Optimum Foaming

Water Content (Wopt%)

1st Plant Visit

Sampling of Raw Materials

Sampling of Plant Produced Foamed

Mixture at 5.5% Water Content


MIX DESIGN VALIDATION

44

Laboratory Testing

Workability Evaluation for Foamed

LMLC at Various Water Contents

Determination of Optimum Foaming

Water Content (Wopt%)

2nd Plant Visit


Mixture at Wopt% and HMA

Adjustment of Plant Foaming Water

Content to Wopt%

Workability Evaluation for Plant Produced HMA and Foamed Mixture at

5.5% and Wopt%

1st Plant Visit

Sampling of Raw Materials


Mixture at 5.5% Water Content


PERFORMANCE • Resilient Modulus • IDT Strength • Hamburg

SUMMARY

45


Volume Expansion: ERmax Foam Stability: FI

Foam Surface Area: SAI

Foamed Asphalt

SGC Compaction Data Workability: τmax

Water Absorption Method Coatability: CI

Foamed Mixture

Effect of Water Content

ERmax, FI, and SAI: Wirtgen > InstroTek > PTI τmax and CI: Wirtgen ≠ InstroTek ≠ PTI

(Individual Wopt)

Effect of Foamer Type

W%

ERmax

FI

SAI

τmax

Mix Design Procedure for Foamed Asphalt Mixtures

(Wopt% = 1.0-2.0% in most cases)

Laser & Camera

Methods and metrics to

characterize foamed asphalt

Methods and metrics to evaluate foamed mixtures

WEBINAR SUMMARY

46

CONTRIBUTION OF RESEARCH STUDIES NCHRP 9-52: SHORT-TERM LABORATORY CONDITIONING OF ASPHALT MIXTURES Laboratory Aging Protocols New Method to Quantify Field Aging (CDD) Relationships between Field and Lab Aging Effects of Factors on Aging Effects of Aging on WMA New Interpretation of HWTT

47

CONTRIBUTION OF RESEARCH STUDIES NCHRP 9-53: PROPERTIES OF FOAMED ASPHALT FOR WMA APPLICATIONS Understanding of Foaming Factors Affecting Foaming New Test Methods for Foaming Characteristics Understanding of Foaming Effects on Mixtures Considerations of Coating and Workability Mix Design Procedures

48

49

Thank you!

Questions?

Properties and Short- Term Laboratory Conditioning of...

Documents

Transcript of Properties and Short- Term Laboratory Conditioning of...