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Nebraska Chapter ACI page 8

GRAND ISLAND NORTHWEST HIGH SCHOOL PARKING LOT IMPROVEMENT

Original scope of the project was to remove 12227 sy of existing asphalt and replace with new 6” and 7” concrete paving. There were two alternates in the bid. The first alternate was to remove the existing asphalt and replace approximately 1/3 of the parking with new 7” concrete paving and the rest with 6” of new asphalt. The second alternate was to replace 1/3 with 7” paving but place a concrete overlay over the rest of the existing parking lot.

The second alternate was chosen

awarded

the

contract.

Concrete

and Stephens and Smith overlay was chosen for

was two

reasons: 1) it saved the school project was bid on June 4th and

$140,000. needed to

2) be

tight schedule. The complete August 8th

for the start of school. With the overlay process not a factor which really helped the schedule.

rain

delays

were

Grand Island Northwest HS parking lot after improvements Mix design, curing, and control joint spacing are critical on overlays. They used midrange water reducer to keep the 47B mix at a 0.42 w/c ratio. All of the strip pours were placed using a pump truck and 3-D Laser Screed. The average crew size was 10. Pours were set up at approximately 50 feet wide. This allowed for proper bull floating and applying the white pigment curing compound from both sides. Control joints were Soff Cut sawed. The specs required 12’ x 12’ panels on the unbonded area and 10’x10’ on the bonded. They elected to cut everything at 10’x10’. Total cubic yards placed on the project were 2608 cy with a thickness ranging from 4” to 9”.

DISCOVERY BRIDGE

Nebraska / South Dakota

PROJECT SUBMITTED BY: Enterprise Pre-Cast Concrete Inc. OWNER: 70% Nebraska and 30% South Dakota STRUCTURAL ENGINEER: NDOR CONTRACTOR: Jensen Construction Company CONCRETE SUPPLIER: Concrete Materials PRECAST SUPPLIER: Enterprise Pre-Cast Inc.

Setting the Tower

The new Discovery Bridge is the replacement for the old “Meridian Bridge” that spans the Missouri connecting Nebraska and South Dakota. The new bridge consist of steel girders with approximately 1600 linear feet of concrete decks utilizing Architectural Pre-Cast Concrete columns feature pieces.

Each of the 14 architectural columns are 80’ in height, utilizing a series of pre-cast pieces stacked on top of each other to create the finished look.

Each stacked piece is slightly different from the lower piece, thus multiple forms were used. The varying pieces were poured vertically, with a rubber form liner to mimic natural stone.

All pieces were poured with grey concrete, stained with penetrating stains and shipped to the jobsite to minimize the total erection process.

The Towers in Place

By utilizing architectural pre-cast columns, the bridge decks were able to be constructed, resulting in successful on time completion.

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