Evaluation of cracked bridge decks treated with various high molecular weight methacrylate resins for the Montana Department of Transportation

72 Pages·2000·1.2 MB·English

by  Wiss, Janney, Elstner, and Associates

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EVALUAIIUN Uh
CRACKED BRIDGE DECKS TREATED
WITH VARIOUS
HIGH MOLECULAR WEIGHT
METHACRYLATE RESINS
FOR THE
MONTANA DEPARTMENT OF TRANSPORTATION
WJE NO. 981825
July 27, 2000
DOMEHTS COLLECTION
STATE
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EVALUATION OF
CRACKED BRIDGE DECKS TREATED
WITH VARIOUS
HIGH MOLECULAR WEIGHT
METHACRYLATE RESINS
FOR THE
MONTANA DEPARTMENT OF TRANSPORTATION
WJE NO. 981825
DATE DUE
W7 July 27, 2000
P-
Paul D. Krauss, P.E.
Project Manager
WISS, JANNEY, ELSTNER ASSOCIATES, INC.
330 Pfingsten Road
Northbrook, Illinois 60062-2095
847-272-7400
FAX: [phone]

Wiss, Janney, Elstner Associates, Inc.
July 27,2000
EVALUATION OF
CRACKED BRIDGE DECKSTREATED
WITH VARIOUS
HIGH MOLECULAR WEIGHT
METHACRYLATE RESINS
FORTHE
MONTANA DEPARTMENTOFTRANSPORTATION
W.JE NO. 981825
INTRODUCTION
Wiss, Janney, Elstner Associates, Inc. (WJE) was requested to perform condition assessments of
selected bridge decks that have been repaired using high molecular weight methacrylate (HMWM)
HMWM
resins. The purpose ofthe investigation was to determine the effectiveness ofthe resins
to penetrate and bond cracks in bridge decks. The Montana Department of Transportation
(MTDOT) has repaired cracks in many bridge decks over the past ten years using different
formulations ofHMWM. This study was to determine ifthe early applications are still effective
and todetermine ifthedifferent formulationsare performingsimilarly.
The field inspections consisted ofvisual inspections and core sampling at crack locations. Visual
inspections were performed ofthe treated decksurfaces. Special attention was given to identifyany
HMWM
new cracks that have occurred since the treatment. Core sampling was performed at
selected locations. Laboratory studies included petrographic examination ofthe cores to determine
thecrackcharacteristicsand the depthofresin penetration.
BACKGROUND
Cracking in bridge decks may be caused by plastic shrinkage, drying shrinkage, thermal effects,
dead or live loads, reactive aggregates, and aggregates damaged by freezing. Many ofthese cracks
do notpose structural problemsand do notneed to be repaired.

Wiss, Janney, Elstner Associates, Inc.
HMWM
Some cracks endanger the long-term durability ofthe deck and should be repaired. resins
can be used to fill bridge deck cracks that do not move significantly. Filling the cracks also helps
keepchloridesoutofthecracksand away from theembedded steel.
HMWM
In the monomer form (unpolymerized liquid). resins have two physical properties that
make them good crack fillers. They are low-viscosity materials (flow properties similar to diesel
fuel), so they flow readily by gravity into even hairline cracks. Penetration into very fine cracks
can be better than penetration into large cracks, possibly due to capillary effects and the excellent
HMWM
surface-wetting propertiesofthe resin.
HMWM
monomers also have relatively low volatility, so they won't evaporate before they
polymerize. They differ in this respect from methyl methacrylate resins, which are not suitable
forcrack filling becausethe monomer is highlyvolatile.
HMWM
monomers are good solvents, enabling them to bond through minor contamination on
surfaces. However, workers should remove curing compounds or asphaltic materials from the
deck because the monomer will dissolve them and then thicken, reducing its ability to penetrate
finecracks.
Besides being reasonably clean, the cracks must also be dry. Water prevents crack penetration by
the monomeranddilutesthe resin, resulting in poorpolymerization and bond.
Adding a metallic drier and peroxide to the HMWM monomer initiates polymerization. Workers
then sweep, squeegee, orspray the resin on the bridge deckat a rate ofabout 1 gallon per 100 sq ft.
The resin flows into cracks and polymerizes, filling and then bonding the cracks. Broadcasting
drysandblastsand into the resin before ithardens improves skid resistance.
HMWM
resins should be applied when the deck and air temperatures are between 55 and 90°F.
Special formulationsareavailableto help improve curingduringcold orhotweather.
Field Surveys
Mr. Paul D. KraussofWJE performedthe bridge inspections between August 16 to 20, 1999. Local
contractors provided the lane protection and coring. Twenty-six bridge decks were examined and