1. Whitetopping:
The Minnesota Experience
Matthew (Matt) Zeller, PE
Concrete Paving Association of MN
Nebraska Concrete Paving Association
39th Annual Concrete Paving Workshop
Tuesday January 16th, 2018
Cornhusker Marriott Hotel, Lincoln, NE
2. Concrete Overlays:
The Minnesota Experience
Nebraska Concrete Paving Association
31st Annual Concrete Paving Workshop
Tuesday January 19th , 2010
Cornhusker Hotel, Lincoln, NE
Matt Zeller, PE
Concrete Paving Assoc. of MN
3. Concrete Overlays
Concrete over existing asphalt or concrete
Ultra-thin (less than 4”)
Thin (4” to 6”)
Conventional (greater than 6”)
Old Teminology
Unbonded Overlay (UBOL)
Whitetopping
5. 2017 Overlay Breakdown
Market SY
Air 24,995
City 34,321
County 837,568 595,523 SY OL 595,523 Thin OL
MnDOT 2,228,992 1,026,406 SY OL 680,000 Thin OL
TOTAL: 3,125,876 52% overlays 41% Thin Overlays
12. Overlays
PCC vs ACC
Concrete
Over concrete
Over asphalt
Short life
Long life
Asphalt
Over concrete
Reflective cracks
Over asphalt
Reflective cracks
Short life (typical)
Long life ???
45. Benefits of Concrete Overlays
Provides cost effective solutions - $ for $ the best
long term rehabilitation option
Construct quick and conveniently
Typically, no need to remove existing pavement
Little pre-overlay repairs required in most cases
Uses standard concrete paving equipment
Accelerated practices can be used - can be opened in a
day
46. Benefits of Concrete Overlays
Can be repaired easily
Durable - Olmsted Co 10 (1982 – 35 years old)
One major repair after 33 years
Looking for 20+ more years
Inherent sustainable properties
Cool
Long life
Improved mileage
47. Benefits of Concrete Overlays
Increased safety
Better skid resistance
No rutting or shoving
Improved visibility
Partial bond creates composite section adding to
design life
Short panels reduce curling and warping stresses
as well as minimizing expansion/contraction
52. The Experiment
• Paved Cells 524 to 124, so 124 was the youngest before loading
• Cells 124 to 524 Longitudinal Test
• Cell 124 – Torture test
• Cell 224 – 5-3/4 hours old
• Cell 324 – 8-1/3 hours old
• Cell 424 – 10-1/2 hours old
• Cell 524 – Control
• Cell 624 Transverse Test
When I visited 8 years ago…
Today I will have a bunch of words first, then a lot of photos of what we did.
We (Minnesota) typically talk in UBOL and WT terms still. But as you will see in the next few slides overlays are becoming a very large part of our program.
Thin overlays are 6” or less
Our county market has really grown in the past several years and a big part of that growth is due to whitetopping projects.
One of the tools we provide our counties is a price trend based on recent lettings
Some other tools we have on our website to help designers
Now, let’s talk a little more about overlays.
I’m going to focus more on whitetopping type projects today since we discussed the UBOL’s a few year ago and not a lot has changed. I do have a couple UBOL related slides though to hit what we are doing there.
UBOL on the interstate where we removed the shoulder full depth to add a new lane. UBOL was 3 years old.
We have started using fabric as our bond breaker almost exclusively now for UBOLs
Many of you have heard about MnROAD, but just a reminder where it is.
Built in 2008 after I presented in the Winter.
Built in 2008.
MnROAD Cell 5 UBOL – original concrete broken with guillotine before UBOL
3” FRC UBOL on city street design
Much of the information we have learned at MnROAD has gone into the Overlay Guide and the BCOA design methodology. The new UBOL design methodology will also incorporate much of what we have learned at MnROAD.
And now some recent projects. Dueling contractors – PCi Roads one direction, Shafer the other.
Note sealing the joints. We believe it is worth the time and money to seal. Efforts being made to ensure all joint deploy so we do not have only some joints taking up all the movement of the pavement.
Their first concrete overlay project, 7.5 miles
Built in 2009. Still very smooth.
Built under traffic. One way loop. Very well signed.
Quite heavy trucks
Widened old slab – 20’ to 24’. Tie bar issues?
Another one lane at a time. Remained open to local traffic including apple orchard and gravel pit.
Inlay left C&G in.
Inlay down to old gravel.
Inlay. Lesson learned – isolate C&G so joints do not reflect through.
Briefly cover different overlay types. Note difference in thickness and joint spacing between different overlay types.
MnDOT letting 12.5 mile 5” FRC project February 2018
