U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000


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Construction

Latex Mondified Concrete Mix Design

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  • Submitted by lafarge annually or on a project specific basis if other supplier used, refer to specifics.
  • Submit to central lab for design approval

Latex

  • 3-copies submitted of manufacturer test reports
  • sample of admixture needs to be submitted to central lab, 20 days prior to use on project for acceptance testing.
  • One sample is usually adequate for most projects.
  • Storage
  • Cement - type I or type II, (from same supplier) only one type
  • Water - mixing, cleaning or wetting decks

Aggregates - CA

  • Gradation
  • Stockpiles - check for miosture the day of pour, protect from moisture cover with plastic etc.
  • If excessive moisture is present in fine aggregate it will reduce available mix water and may not be usable for placement.
    Definition of excessive moisture: if aggregate moisture higher than available mix water

Proportioning And Mixing Equipment

  • Submitted by supplier
  • State personnel should verify calibration of trucks
  • (be present if possible)

Calibration Of Trucks

  • Calibration of cement
  • Calibration of aggregates
  • Calibration of latex meter

Deck Preparation

  • Must meet requirements of specifications
  • Sound and mark deck for delamination
  • Jackhammers of 30kg/60 lbs for initial removal operations
  • Smaller chippers of 15kg/30lbs or smaller if the projectmanager feels that larger hammers are detrimental to bridge deck.
  • Operation of jackhammers no more than 60% from horizontal.
  • If less than 50% of deck thickness remains the deck should be taken full depth except in isolated random locations as determined by project manager.

Hydrodemolition

  • Calibration of equipment is necessary
  • Equipment must be operated by qualified personnel

Reinforcing Bars

  • Replace as necessary, lapped a minimum of 0.30mm/12" or as directed by project manager.
  • New bars and existing bars must have a minimum of 20mm or 3/4" clearance around exposed bars.

Cleaning Deck

  • Sandblast deck and rebar to gray metal (refer to new specs for additional requirements).

Forms for Full Depth Repair

  • Form for areas less than 0.5 sq/m (4 sq/ft) can be suspended from rebar.
  • Larger areas must be supported from primary members of superstructure or shored from below.

Pre-Placement Conference

  • Contractor, state and supplier should all be present and should be scheduled at least two days or more prior to placement
  • Cover specifications, methods of placement, inspection and potential problems

Dry Run Of Bridge Deck

  • Covered in detail in pre-placement section of training session.

Setting of Gradeline

  • Surveyor should shoot existing gradeline, plot profile and project new gradeline.
  • This must be submitted to project manager prior to approval.
  • Adjustments should be made to grade to produce a smooth riding surface and shall result in at least the minimum concrete fill as shown in plans/contract.
  • Bulk heads and deck joints should be installed to proper grade and longitudinal joints should avoid wheel paths as much as practical.

Placement/Application

Placement (Finishing Machine Must Meet Specification Requirements)

  • Pre-wet deck: wet deck for 2 hours before pour - inspector should verify.
  • Cover with plastic to keep moisture in and protect deck from spills.
  • Check rate of evaporation at or near deck surface, no more than .73 kg/m2/h (.15 lbs/ft2)
  • Ambient temperature of not less than 7 c (45 f)

Mortar Bonding

  • Starting out, pour a little latex modified concrete, then broom it over the deck and edges, spreading the mortar mixture.
  • Aggregates need to be removed. Keep the mixture ahead of the pour, but not so far it dries out (2m or 6' +/-)
  • Note: complete application/coverage of mortar is critical to bonding of overlay to existing surface.

Concrete Placement

  • Don't place more than 3 meters ahead of finishing machine, need to place continuously.
  • A delay of 5 to 20 minutes cover ends of concrete with burlap.
  • If stopped more than 20 minutes set a bulkhead in deck.
  • Make sure fluids don't settle in low/removed areas - have air compressor available to blow out fluid

Concrete Placement

  • Minimal hand finishing - wood floats & fresno only
  • Vibrator should be used at all partial depth areas and against edges, bulkheads and expansion joints

Testing

  • Air, temperature, unit weight; run as usual
  • Slump - wait 5 minutes set concrete aside and do not disturb
  • If not in specs, adjust mix and retest
  • Clean equipment immediately! Wear old clothing/shoes
  • Do occasional checks of water/cement ratio and latex yield at least 3-4 per truck.

Curing

  • Place double layer of clean burlap (approved equal)
  • Timing is everything! (better too soon than too late) 15 -20 min.
  • Lightly fog spray it, then place white plastic
  • Keep burlap wet for 48 hours. verify burlap is wet entire 48 hours
  • Cold weather curing (0 C/32 F)
  • Continue wet cure until cylinders break as per specs

Post Inspection

  • Straight edge deck. Follow criteria as in previous section (same tolerances)
  • After curing, check for delamination/bonding
  • If not acceptable, remove and replace (contractor expense)
  • Groove it, apply hmwm to cracks if any
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Updated: 11/07/2013
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000