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Characterization of Alaskan Hot-Mix Asphalt containing RAP Jenny Liu, Sheng Zhao and Beaux Kemp 06/25/15 Project Update:

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Page 1: Project Update: Characterization of Alaskan Hot-Mix ...cem.uaf.edu/media/139417/characterization-of-alaskan-hot-miz-asphalt... · Characterization of Alaskan Hot-Mix Asphalt containing

Characterization of Alaskan Hot-Mix

Asphalt containing RAP

Jenny Liu, Sheng Zhao and Beaux Kemp

06/25/15

Project Update:

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Outline

Introduction

Problem Statement

Background

Objectives

Work Completed

Work in Progress

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Recycled Asphalt Pavement (RAP)

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Problem Statement Tendency of greater use of recycled/reclaimed asphalt

pavement (RAP)

Decreasing supplies of locally available quality aggregate

Growing concern over waste disposal

Rising cost of asphalt binder

In Alaska, 15% RAP is allowed in the wearing course, up to 25% RAP in the binder or base course. Projects will see an increased use of RAP

Mechanistic analysis procedures (AKFPD software) require material engineering properties as input

It is essential to properly characterize HMA mixes containing RAP material in Alaska

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Background

Most recycled material in U.S.

Annually 100 million tons

Recycles aggregates and asphalt binder

4 to 6% binder by weight

Saving 14% to 34%

with 20% to 50% RAP

4Photo credit: http://paving-sacramento-ca.com/

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Current Status of RAP Application

Performance

At low or medium content level, Equivalent (or better) performance was expected compared to virgin mix

At high content level, compromised fatigue and low temperature performance

High RAP content is promoted

More than 25% by weight of mix

How to increase RAP content

Using softer binder to compensate aged RAP binder

Adding recycling agents

Combining RAP with warm mix asphalt (WMA)

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RAP in Alaska

Limited previous research

How RAP contents affect Superpave PG of the blended binder (Saboundjian and Teclemariam 2010)

Effects of 15% RAP on airport runway (Connor and

Li 2009)

Current AK specification

15% in the wearing course, 25% in base

Performance data on HMA containing RAP for surface course application is limited

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Objectives

To properly characterize Alaskan HMA materials containing RAP, yielding:

Mix modulus (stiffness) values at different temperatures, to be used in pavement design/analysis procedures

Rutting performance at intermediate and high temperatures

Low-temperature thermal cracking performance

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Work Completed

Task 2 - Development of Materials Collection Plan

Task 3 - Specimens Fabrication and Performance Tests

Development of Testing Plan

HMA mixtures with RAP in Northern Region of Alaska

Materials collection

Sample fabrication and volumetrics verification

Testing for dynamic modulus

Task 4: Characterization of Asphalt Binder with RAP

Preliminary Binder Testing

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Development of Materials Collection Plan

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Mix # Region Mix Type Mix Name RAP % Binder PGAggregate

Source

1

Central

Control Type II-B 0 PG 52-28

AS&G (MP 39 Glenn Hwy)

2 Control Type II-B 0 PG 58-34

3 Control Type II-A 0 PG 58-34

4 RAP25 Type II-A 25 PG 58-34

5 RAP25 Type II-B 25 PG 58-34

6 RAP35 Type II-B 35 PG 52-28

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Northern

Control Type II-B 0 PG 52-28

Tanana Valley

8 Control Type II-B 0 PG 52-40

9 RAP25 Type II-B 25 PG 52-28

10 RAP25 Type II-B 25 PG 52-40

11 RAP35 Type II-B 35 PG 52-28

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Development of Binder Testing Plan

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Properties Parameters EquipmentBinder

statusTesting T (°C) Standard

Binder Grading See standard DSRUn-Aged and

RTFOSee standard ASTM D-7643

Viscoelastic

behavior

complex

modulus (G*)

and phase

angle (d)

DSR RTFO

Three for each

(± 6°C and

high PG)

AASHTO T 315

Master CurveSee standard

DSR RTFOSee standard

AASHTO T 315

MSCR See standard DSR RTFO

Two for each

(-6°C and high

PG)

AASHTO T 350

Low

TemperatureSee standard BBR RTFO and PAV See standard AASHTO T 313

Low

TemperatureSee standard DTT RTFO and PAV See standard AASHTO T 314

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Development of Performance Testing Plan

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Test PropertiesTesting

Temperature (°C)

Dynamic Modulus (lE*l)

Modulus

4.4

21.1

37.8

54

lE*l Master Curve -

Flow Number Rutting 54

IDTLow-TemperatureThermal Cracking

0

-10

-20

Three Replicates

Target Air Voids: 7% ± 0.5%

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Materials Collection for Northern Region Mixes

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Aggregates RAP

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Verification of Composition Properties

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RAP Binder Content Verification RAP and Aggregates Gradation Verification

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Development of Mix Design

Based on JMF provided by the same contractor that supplied materials

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Volumetric Properties

Purpose: target air voids

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Gmm Testing Mixing HMA in the Lab Sample Compaction

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Sample Fabrication

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Dynamic Modulus Samples IDT Samples

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Dynamic Modulus (lE*l) Testing

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Typical lE*l Results

lE*l tested at 4.4°C

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Results of PG 52-28 mixes Results of PG 52-40 mixes

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Typical lE*l Results

lE*l tested at 21.1°C

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Results of PG 52-28 mixes Results of PG 52-40 mixes

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Typical lE*l Results

lE*l tested at 37.8°C

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Results of PG 52-28 mixes Results of PG 52-40 mixes

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Typical lE*l Results

lE*l tested at 54°C

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Results of PG 52-28 mixes Results of PG 52-40 mixes

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Master Curves of lE*l

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Results of PG 52-28 mixes Results of PG 52-40 mixes

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Findings from lE*l

Higher RAP content, higher modulus

The results are consistent on both PG 52-28 mixes and PG 52-40 mixes produced with materials from Northern Region in Alaska

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Preliminary Binder Testing

DSR rutting index

Three binders: PG 52-28, PG 52-40, PG 58-34

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Binder Testing Results

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DSR rutting indexTested at 10 Hz,within ±6°C of high PG T Spec:|G*|/sinδ,kPa,≥1.00

Properties |G*|(kPa) δ(rad)

Temperature (°C) 46 52 58 64 46 52 58 64

PG 52-28 4.59 1.94 0.81 - 1.51 1.53 1.54 -

PG 52-40 2.64 1.60 0.99 - 1.05 1.00 0.96 -

PG 58-34 - 2.64 1.49 0.90 - 1.25 1.22 1.17

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Work in Progress

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Task 3 - Specimens Fabrication and Performance Tests

IDT tests for Northern Region mixes

Materials collection for Central Region mixes

Task 4 - Characterization of Asphalt Binder with RAP

To complete the binder testing as planned

Task 5 - Data Processing and Analyses

Data analysis using Thermal Stress Analysis Routine (TSAR) software

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IDT Tests

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Central Region Testing Matrix

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Mix # Region Mix Type Mix Name RAP % Binder PGAggregate

Source

1

Central

Control Type II-B 0 PG 52-28

AS&G (MP 39 Glenn Hwy)

2 Control Type II-B 0 PG 58-34

3 Control Type II-A 0 PG 58-34

4 RAP25 Type II-A 25 PG 58-34

5 RAP25 Type II-B 25 PG 58-34

6 RAP25 Type II-B 35 PG 52-28

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TSAR Analysis

Using data collected from BBR test

29Photo credit: TSAR manual

Determine the critical temperature that corresponds to thermal cracking based on BBR for the proposed new AASHTO binder specification

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