The MDOT
recently completed the sealing of the concrete bridge deck
at Wiscasset-Edgecomb with a modified high molecular weight
methacrylate. To gain an appreciation for the importance
of this accomplishment we need to step back to see why and
how we came to use a rapid-curing penetrating sealer designed
to structurally repair hairline cracks in concrete bridge
decks.
In 1993 the Research Engineer was asked
by the Bridge Maintenance Engineer for an evaluation
of the effectiveness of the latex modified wearing surface
that was designed to act as an abrasion and chloride
barrier for the protection of the precast-prestressed-segmental
concrete one cell box structure.
The wearing surface, which has an overall
length of 2737 feet and a roadway width of 36 feet,
was cored in twelve locations in 1993 to determine the
degree of chloride intrusion. The result was that the
wearing surface protection had started to break down
allowing the chlorides to penetrate into the concrete
slab. Three additional cores were cut in 1994 which
confirmed the earlier results. The Department had to
start considering some form of repair strategy. Due
to the importance of this type of structure and
"A". The product also had a low flash point
so there were major safety concerns which resulted in
a number of safety meetings. There were also the questions
of traffic control and the length of time needed for
lane closures to accommodate the products curing period
which is effected by temperature. The work required
the use of crews from Divisions 4 and 5 which involved
two managers, multiple crew leaders, and about 30 workers.
It was important that safety, job function, and application
process issues were resolved before the job started.
After much debate it was decided not to do the work
at night as planned, but to delay the project until
October 5th so that the traffic would be least affected.
Six days had been anticipated to complete the sealing
of the bridge, however, production far exceeded expectations
and the sealing was completed in three days.
To date everyone appears to be satisfied
with the results and are hoping that the bridge will
remain maintenance free for many years to come.
For more information, Please contact
Guy Berthiaume, 287-2257 (guy.berthiaume@state.me.us)
MAINE
Named 1999's Most Innovative State
by
N.A.S.A.O.
The National Association of State Aviation
Officials proclaimed Maine the "Most Innovative State"
of 1999 for development of a video-based pavement inspection
system. The Maine Department of Transportation adopted
existing highway technology for airport use. The Automated
Road Analyzer (ARAN) "inspects" the 32 publicly owned
airports. This data is being used for a statewide airport
pavement management system. Now, a two runway airport
can be videotaped in about two hours, where a manual
inspection can take as long as two days.
Congratulation to all those involved!
Recent Publications
Technical Report 95-02, Fourth Year Interim
for Reflective Cracking Control, Experimental Use of
Reinforcing Membrane and Grid on Thermal Cracks of HMA
Technical Report 96-25 & 97-19, Second
Year Interim for Experimental Use of Sawed and Sealed
Joints to Minimize Thermal Cracking of HMA
Technical Report 97-7, Final Report, An
Evaluation of Winter Maintenance Material Metering and
Placement Equipment
Technical Report 97-21, First and Second
Year Interim Report for Saw and Seal Airport HMA Pavement
Technical Report 97-24, Final Report, Alkali-Silica
Reactivity Aggregate Screening
Technical Report 98-3, Second Year Interim
Report for Potential Benefits of Adding Emulsion to
Reclaimed Base Material
Technical Report 99-5, Fast Ferry Report
- Phase 1
Technical Report 00-1, Final Report, Evaluation
of Permeability of Superpave Mixes in Maine
Technical Report 99-8, Construction Report,
Experimental Use of Geogrids as an Alternative to Gravel
Placement
Technical Report 96-10, Final Report, Determination
of Resilient Modulus of Maine Roadway Soils
Technical Report 98-08, Construction Report,
Experimental Utilization of Permeable Base |
the need to be
reasonably assured that this structure would not be
comprised, only two solutions seemed viable. One solution
was the placement of a waterproofing membrane over the
wearing surface and cover it with a hot mix asphalt
pavement. The second was removal and replacement of
the latex wearing surface. Both solutions would have
cost in the range of half a million dollars.
The Chief Engineer believed that there was some type
of concrete sealer that would act as a protective system
at a lesser cost. So between 1995 and 1999 the Product
Approval Committee tested cementitious epoxy, epoxies,
methacrylates, vinyl toluene acrylic polymers, silane/siloxane
water repellents, silanes, and siloxanes penetrating
sealers to determine the product type that would be
most effective in stopping chloride intrusion with a
latex wearing surface.
Based on the results of testing completed by the Product
Approval Committee the decision was made to have the
Bridge Maintenance Division place a methacrylate type
sealer on the deck at an anticipated cost of less than
one hundred thousand dollars.
In July of 1999 the procedure began for the final phase.
To say that a large amount of coordination was required
may be an understatement. The task involved using a
three component product that would cause a violent explosion
if components "B" and "C" came in contact with each
other before mixing with component
Development of Mix Design System
For
Full Depth Reclamation
The Maine Department of Transportation is partnering
with Worcester Polytechnic Institute, the National Center
for Asphalt Technology, and others on research that
will develop a rational and practical mix design system
for full depth reclamation. Full depth reclamation (FDR)
is a technique in which the existing hot mix asphalt
and partial underlying gravel is recycled in-place to
produce a stabilized course. This technique provides
a convenient way of restoring proper cross slope and
grade to the roadway while providing a crack resistant
base course. This can save material and money. Although
the practice of FDR is used widely, at times with the
addition of stabilizing materials such as emulsion and
cement, there is no accepted method of mix design. To
utilize its potential fully, there is a need to develop
a mix design system for selecting correct amounts of
additives. There is a need, as well, to evaluate the
effectiveness or performance of different additives
in the field.
The project will consist of development of a preliminary
mix design system using the Superpave gyratory compactor,
construction and performance monitoring of test sites,
and "tweaking" the mix design system based on the field
tests. Project objectives also include determining proper
compaction efforts required, proper curing procedures,
and proper structural numbers for FDR base material.
Worcester Polytechnic Institute will be conducting the
laboratory testing while MDOT will construct the test
and control sections along a portion of highway.
Other project partners are Gorman Bros., Inc. Of Albany,
New York, the Asphalt Institute, Koch Materials, Vermont
Agency of Transportation, Connecticut Department of
Transportation, and the New Hampshire Department of
Transportation.
This project is being funded by the Recycled Materials
Resource Center at the University of New Hampshire.
The Center was established in 1998 to promote the appropriate
use of recycled materials in the highway environment
and was formed in a close partnership with FHWA. For
more information on the
Center please check out their website at http://www.rmrc.unh.edu./
For more project information please
contact Rick Bradbury at 941-4597 (richard.bradbury@state.me.us)
or Dale Peabody at 287-5662 (dale.peabody@state.me.us)
Partnerships in Transportation Research
Establishing internal and external partnerships to
facilitate research can reap benefits. The FDR article
describes one partnership the Maine DOT is involved
with. Two other partnerships worthy to note are discussed
below.
The Department's Geotechnical Division along with the
University of Maine was able to secure $100,000 worth
of geosynthetics on a recently completed experimental
construction project along Rt. 1A in Frankfort, ME.
Reconstruction of this section of highway required measures
to stabilize and drain the roadway structure due to
extremely poor subgrade conditions. The geosynthetics,
including grids, membranes, and drainage geocomposites
were donated to this project by the Geosynthetic Materials
Association. These geosynthetics were instrumented and
performance evaluated by the University of Maine. The
project results were successful enough to convince the
Department and its partners to try other test sections
using geosynthetics. In a project funded through the
New England Transportation Consortium with materials
once again being donated by GMA, roadway test sections
will be constructed to evaluate effects of thin pavement
sections.
The State of Maine was recently awarded over $2 million
dollars to promote and enhance the use of composites
in transportation infrastructure.
This is largely a result of a Composites in Transportation
Infrastructure Partnership involving Maine DOT, FHWA,
University of Maine, and the Maine Composites Alliance.
Other partners include Central Maine Power Company and
the Department of Economic and Community Development.
This group has worked together to identify potential
applications for fiber reinforced polymer (FRP) and
FRP/wood composites in the transportation infrastructure.
Funded projects include FRP reinforced wood deck for
a marine facility, FRP reinforced wood railroad ties
for at grade crossings, FRP bridge deck drains, and
a FRP bridge deck. Additionally, the University of Maine's
Advanced Engineering Wood Composites Center received
funding to establish material specifications and design
guidelines for AASHTO consideration.
For more information, please contact
Dale Peabody, 287-5662 (dale.peabody@state.me.us) |
