Implementing Bituminous

Underseals to Reduce

Reflective Cracking

Tim Clyne, MnDOT

MAAPT 63rd Annual Asphalt Conference

December 7, 2016

What’s the Problem?

Cracking Mechanism

https://www.researchgate.net/figure/277890592_fig1_Figure-21-Reflective-cracking-mechanism-5

What is an Underseal?

Seal Coat prior to bituminous overlay

Impervious membrane to stop moisture intrusion

Acts as super tack coat

Delays / reduces Reflective Cracking

“Texas Underseal”

Stress Absorbing Membrane Interlayer (SAMI)

Underseal Sequence

https://www.dot.nd.gov/conferences/construction/presentations/2016/Texas%20Underseal-Wollmuth.pdf

Spec. 2356

TH 101 Chanhassen

SP 2736-44

Paved in 2010

3” Mill

Underseal vs. Control

3” Overlay (SPWEB340E)

In 2 lifts

TH 101 Chanhassen

TH 101 – Before

TH 101 – After (Underseal)

TH 101 – After (Control)

TH 5 West of Waconia

SP 1002-102

Paved in 2014

2” Mill

Underseal

3.5” Overlay (SPWEA340C)

In 2 lifts

TH 5 West of Waconia

TH 5 – Before

TH 5 - After

TH 61 & 10 Hastings

SP 8205-137

Paved in 2016

2” Mill

Underseal

2” Overlay (SPWEB440F)

TH 61 – Before

Super-Duper Underseal

TH 100 Edina

SP 2733-89

Paved in 2015 & 2016

Mill & Patch Concrete

UTBWC

~3” Overlay (SPWEB440F)

In 2 lifts

TH 100 – Before

TH 100 – After

TH 280 St. Paul

SP 6241-102

Paved in 2016

Mill 4” Bituminous

UTBWC

3.25” Overlay (SPWEA440F)

In 2 lifts

TH 280 – Before

TH 280 – After

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

5 101 61 10 100 280

Rid

e Q

ua

lity

In

de

x

Highway

Pre-Overlay 2016

Ride Quality Comparison

Summary

Not sure why, but it works!

Reduced / delayed reflective cracking

Improved ride quality

Will continue in the future

Tim Clyne

651-234-7350

tim.clyne@state.mn.us