HMA Surface Characteristics Study

MnROAD Research Conference

October 4, 2011,Minneapolis, MN

Mark Watson, MS, PE

Assistant Bituminous Engineer

Minnesota Department of Transportation

• Sidewalk had enough heat but …

• Lacked: cleanliness, portability, etc.

• Pavements need to be more than safe & durable

• Pavement Surface Characteristics Study – Optimization

• Safe, Durable, economical, green

• Friction, Texture, Ride, Noise, Permeability and Durability

Surface Characteristics

• History

• Measured Pavement Characteristics

• Observed Performance

• Summary

Outline

• 1870’s US Cities Started to use Wooden instead of Granite Blocks

• Wooden Roads Quieter but …

• Service life of ½ - ¼ that of Granite Brick/block

• Also tried mastic (native asphalt), but had traction issues (horse falls)

History

• Literature Review

• Test Section Construction • Phase 2, $10.1M

• Seasonal Testing & Monitoring

• Analysis of Experimental Data

• Deployment & Implementation

• Final Report

Work Plan

• 6 cells on Mainline and 5 cells on Low Volume Road

• Traditional HMA & New/emerging tech (variables: gradation, binder, recycle)

• Porous HMA

• Warm Mix Asphalt

• 4.75 Taconite

• Pavement Preservation • Fog Seal (various ages)

• Chip Seal (2 gradations)

Test Section Construction

• Cells are generally tested 2 -3 times per year

• Data collected every year for 4 year monitoring period of study: • Friction & Texture

• Ride

• Noise

• Permeability

• Durability

Seasonal Tests & Monitoring

• Dynamic Friction Tester (DFT) • Measures across a range of speeds

Tests & Monitoring: Friction

2009

20100

0.2

0.4

0.6

0.8

2040

6080

m vs. Speed, kph: Cell 6 DL, BWP

0.6-0.8

0.4-0.6

0.2-0.4

0-0.2

• Locked Wheel Skid Trailer • Most Commonly Used

• Tested both Ribbed & Smooth

Tests & Monitoring: Friction

Box and Whisker Plot

2 3 4 6 19 22 24 27 86 87 88

0

20

40

60

80

FN

40

SM

OO

T

CELL76 cases

• Circular Texture Meter (CTM) • Measures mean profile depth with a laser

International

Fiction

Index

Tests & Monitoring: Texture

Sep-09

Oct-10

00.250.50.75

11.251.5

111500 111600 111700 111800

Tim

e

Me

an P

rofi

le D

ep

th (

mm

)

Station

Cell 3: PL-Left Wheel Path

1.25-1.5

1-1.25

0.75-1

0.5-0.75

0.25-0.5

0-0.25

• Measurements over time

• Variations both within and between cells

Tests & Monitoring: Texture

• On Board Sound Intensity (OBSI) • Measures Tire Pavement Interaction Noise

Tests & Monitoring: Noise

96

98

100

102

104

106

108

110

Jun-08 Sep-08 Dec-08 Mar-09 Jun-09 Sep-09 Dec-09 Mar-10 Jun-10 Sep-10

OBSI (dBA) vs Time: Cell 27

Inside

Outside

• Measurements over time

• Variations both within and between cells

Tests & Monitoring: Noise

Box and Whisker Plot

2 3 4 6 19 22 24 27

97

99

101

103

105

107

RU

N_

AV

ER

A

CELL193 cases 161 missing cases

• Method based on LTPP (17 distresses) • Trained Personal, Detailed Evaluations

• Cell 6 (4.75mm): Low Severity Reflective Cracking (Bit over PCC)

• Cells 86 & 88 (Porous HMA): Low Severity Raveling

Tests & Monitoring: Durability

• Contract Awarded to Purdue to: 1. Review of Literature

2. Effect of Changing Seasons on HMA Surface Characteristics

3. ID of Significant Variables

4. Model of Sound Intensity

5. Draft Final Report

Data, Data and Data

• Surface Characteristics should be optimized with other HMA properties

• Study is producing valuable data

• Analyzed for use in sound model

• Aid in understanding of cost-benefits

• Long Term & Consistent Monitoring

Summary

Thank You!