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