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Copy of Dynamic Modulus

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Kathy Anne

on 6 December 2012

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Transcript of Copy of Dynamic Modulus

Katherine Tivin

Graduate Seminar
December 6, 2012 Dynamic Modulus Modeling for ME-PDG using RAP in Surface Material Introduction

Mechanistic - Empirical Pavement Design

Procedure of Evaluating Dynamic Modulus

Data Analysis

Example

To do list Overview Inputs Performance Prediction Climate Traffic Materials Structure Smoothness Selection of Trial Design Distresses (cc) photo by theaucitron on Flickr Design
Reliability Performance Verification: failure criteria Design Requirements Satisfied? Final
Design Yes No Structural
Responses Strain Stress Deflection Mechanistic - Empirical Design Combines both mechanistic and empirical components
Mechanistic aspect determines pavement responses due to loading through mathematical models
Empirical aspect relates pavement response to pavement performance Resilient Modulus
shortcomings in Methodology led to development of Dynamic Modulus
Problems
Stress-strain relationship of granular material is non-linear
loading sequence subjects some soils to excessive stress
Overestimation of Mr Dynamic Modulus
measurement of visco-elastic properties of HMA under continuous sinusoidal loading
|E*| = δo / εo,
where δo is peak stress, εo is peak strain
measured at various temperatures
Colder -> Stiffer, Warmer -> Softer
Master Curve compiled from testing at various temps, frequencies, and fitting parameters AASHTO Procedures
PP 61: Developing Dynamic Modulus Master Curves for Hot Mix Asphalt (HMA) Using the AMPT
PP 62: Developing Dynamic Modulus Master Curves for Hot Mix Asphalt (HMA)
T 342: Determining Dynamic Modulus of Hot Mix Asphalt (HMA)
TP 62: Determining Dynamic Modulus of Hot Mix Asphalt (HMA)
TP 79: Determining the Dynamic Modulus and Flow Number for Hot Mix Asphalt (HMA) Using the AMPT
+ more!!! Procedure Step 1. Find Mix to Test
Field samples
Bin samples
Design a mix
selection of materials
design aggregate structure
optimum binder content
moisture sensibility Step 2: Compact the Mix
Use a SuperPave Gyratory Compactor to create samples
Samples are compacted based on height requirements (170 mm)
7% Air Voids are targeted
to target, make a 6650 gram sample
calculate air voids and readjust the weight Purpose of Dynamic Modulus

predict the performance of pavements in terms of fatigue cracking. The higher the dynamic modulus value, the better the pavement can resist against cracking
compare results (universal standard); master curves will be developed so that measures of stiffness can be compared at different frequencies or times Step 3. Core the specimen to obtain the inner core Step 4. Prepare Sample for AMPT Testing Step 5. Sample Conditioning Step 6. Sample Testing Master Curve Development Means of relating structural responses of asphalt pavement to characterize time- and temperature-dependency, strength, and load resistance
Master curves represent dynamic moduli at a selected reference temperature with respect to logarithm base 10 of the frequency until curves merge into a single smooth function (AASHTO Hirsch model) Data Analysis General form of Dynamic Modulus Master Curve Equation δβϒ RIDOT Research Evaluation of Recycled Asphalt Pavement in Rhode Island Roadway Surfaces using the Asphalt Material Performance Tester (AMPT) analysis of fatigue and rutting cracking
RAP is not currently allowed in surface material due to concerns of pavement failure Experimental Design Thank You for Your Time and Consideration


Questions? 30°C temperature reduction
Improved workability
HMA and WMA exhibited similar dynamic moduli
MEPDG prediction considers air void structure, binder characteristics, etc... How do we compare frequencies to the real world? Pavement Distresses
Fatigue cracking* - internected cracks caused by fatigue failure of asphalt surface or stabilized base
Block cracking (Thermal Cracking)
Joint Reflection Cracking
Lane/Shoulder Drop-Off/ Heave
Longitudinal cracking
Water bleeding/Pumping
Rutting* - depressions formed in wheel paths
Bleeding
Slippage
Swell
Corrugation
Depression
Potholes
Raveling/Weathering *ME-PDG uses Rutting and Fatigue cracking to evaluate asphalt performance in Dynamic Modulus, higher |E*| = more resistant to cracking Route 2 Background Undergraduate Degrees - Civil Engineering & German - University of Rhode Island

IEP Program, Technishe Universitaet Braunschweig, Braunschweig, Germany

Geo-Instruments, Shop Technician
Zueblin AG, Intern
Rhode Island Department of Transportation, Intern Example To do List Completed
Creation of Virgin mixes
Sampling of RAP

Left to Do
Testing of Virgin Mix
Creation of RAP Mixes
Testing of RAP Mixes
Sampling from Lynch
Design of Lynch Mix
Creation of Lynch Mixes
Testing of Lynch Mixes
Full transcript