HMA Longitudinal Joint

Construction Evaluation

Research Seminar Eddie Johnson & John Garrity

December 15, 2015

The Weak Link

Longitudinal Joints

About 4% (280 miles) of all the bituminous roads rated in

2015 have Medium and/or High Severity Longitudinal Joint

Distress.

The problem is worse than this because the current pavement

vans do not always see the centerline joint due to driver

wander.

About 9% (606 miles) of bituminous roads rated in 2010 had

either Medium and/or High Severity Longitudinal Joint

distress when the vans field of view was wider.

Medium and High Severity

Longitudinal Joint Distress

High Severity Longitudinal Joint Distress

High Severity Longitudinal Joint Distress

Current Initiative

Longitudinal Joint Improvement

– Industry tasked with providing a potential

improvement to joint construction method.

Industry responded with “Maryland”

method of joint construction.

Maryland Joint Construction Method

Longitudinal joints constructed adjacent to the existing HMA pavements overlap the existing pavement by 1” to 1.5” and be about ¼” higher.

HOT COLD

Excess Material 1 to 1.5 Inches

Overlap

First Roller Pass

Roller

First Pass

Hot Cold

Approx. 6” Overlap

Roller

First Pass

Hot Cold

6 to 12 Inches

Creates a Confined

Edge & Raised Area Second Pass

Second Pass

Roller

First Pass

Hot Cold

First Roller Pass

1” to

1.5” Inches

Remaining

Uncompacted +

TH 100 Joint Overlap

Crushed Aggregate of Overlap

Coring & Permeability Testing

Permeability: Midlane versus

Treated Maryland Joints (2014)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 100 200 300 400

Pe

rce

nt

of

Dat

a

Coefficient of Field Permeability, 10-5 cm/s

Joint with Adhesive

Joint with Tack

Midlane

Took very little data for Adhesive and Tack

Permeability: Top Lift Locations

(2014)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 200 400 600 800

Pe

rce

nt

of

Dat

a

Coefficient of Field Permeability, 10-5 cm/s

Joint

Tangent

Midlane

Standard Joint

Permeability: Top Lift Locations

(2015)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 200 400 600 800 1000

Pe

rce

nt

of

Dat

a

Coefficient of Permeability, 10-5 cm/s

Standard Joint andTangents

Confined

Joint

Midlane

Unconfined

Density: 2015 Projects

0

0.02

0.04

0.06

0.08

0.1

0.12

80 85 90 95 100

No

rmal

Pro

bab

lity

Dis

trib

uti

on

% Maximum Core Density

2015 Data; m=90.4 s=3.5

Density: 2015 Projects

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

80 85 90 95 100

No

rmal

Pro

bab

lity

Dis

trib

uti

on

% Maximum Core Density

Level 3; m=91.6 s=3.8 Level 4; m=89.0 s=2.7

Density: 2015 Projects

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

80 85 90 95 100

No

rmal

Pro

bab

lity

Dis

trib

uti

on

% Maximum Core Density

Standard; m=89.5 s=4.1 Maryland; m=91.4 s=2.9

Density: 2015 Projects

0

0.02

0.04

0.06

0.08

0.1

0.12

80 85 90 95 100

No

rmal

Pro

bab

lity

Dis

trib

uti

on

% Maximum Core Density

Mat Confined Joint Unconfined

Density: 2015 Projects

0

0.02

0.04

0.06

0.08

0.1

0.12

80 85 90 95 100

No

rmal

Pro

bab

lity

Dis

trib

uti

on

% Maximum Core Density

Mat: Maryland Mat: Standard

Density: 2015 Projects

0

0.02

0.04

0.06

0.08

0.1

0.12

80 85 90 95 100

No

rmal

Pro

bab

lity

Dis

trib

uti

on

% Maximum Core Density

Confined: Maryland Confined: Standard

Density: 2015 Projects

0

0.02

0.04

0.06

0.08

0.1

0.12

80 85 90 95 100

No

rmal

Pro

bab

lity

Dis

trib

uti

on

% Maximum Core Density

Joint Center: Maryland Joint Center: Standard

Density: 2015 Projects

0

0.02

0.04

0.06

0.08

0.1

0.12

80 85 90 95 100

No

rmal

Pro

bab

lity

Dis

trib

uti

on

% Maximum Core Density

Unconfined: Maryland Unconfined: Standard

Density Averages: 2015 Projects

848586878889909192939495969798

Standard Maryland

% M

axim

um

Co

re D

en

sity

Construction Type

Mat

Unconfined

Joint Center

Confined

Core Density of Maryland Joint

(2014)

84

86

88

90

92

94

96

98

1 2 3 4 5 6

% G

mm

Core Set, Top Lift of Wear Mix

Midlane

Tangent

Joint

Summary

Maryland Joint Method:

– Appears to be less permeable than standard

practice.

– Indicates better longitudinal joint density

Expectations – Better Performance

Designing for Improved LJ’s

Specifying 9.5mm (-1/2”) mix on final surface.

Utilizing echelon paving when practical.

Including longitudinal joint density

requirement.

Mill and fill one lane at a time so both joints

are confined.

Density is Driven By…..

Good Mix Design

Adequate Density

Proper Lift Thickness

Longitudinal Joint Enhancements

Joint Adhesives

Fogging of longitudinal joint after

construction.

Current Specification Considerations

Modify Level 4 and Level 5 mixes to 60

gyrations.

– Would require contractor to add 0.1-0.2 more

asphalt binder in mixture. And, should improve

ability to densify those mixes.

» Concern…..potential for rutting??

Thank You