Concrete Jack Completes Unique Train Inspection Pit Underpinning and Foam Jacking Project in Washington, DC

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Concrete Jack crews installed 116 ECP Model 300 push piers and 14,000 pounds of HMI RR401 high density polyurethane to lift 2.2 million pounds of precast commuter rail inspection pit sections.

injecting high density polyurethane under mechanically-raised slabs

"While our foam jacking crews have raised and stabilized millions of square feet of concrete, this was our first underpinning job,"

When 58 sections of precast commuter rail inspection pit sections were discovered to be out of tolerance for installation, Concrete Jack's foundation repair and polyurethane concrete raising crews swung into action to return the sections back to within tolerance.

Using a combination of deep foundation push piers and high density polyurethane foam injection, the sections of precast concrete train inspection pits were lifted up to nearly two inches, within tolerance of 1/16 of an inch. ECP Model 300 wall-mounted push piers were used as the primary lifting method, and then HMI RR400 high density polyurethane foam was injected under the sections to fill voids and fine tune lifting. Due to the extreme dynamic loading associated with rail traffic, the mechanical connections between the piers and inspection pits were removed after polyurethane injection was completed, and the entire weight of the structure was transferred to the underlying layer of high density polyurethane.

Continuous surveying by a third party survey crew ensured work was within tolerance and that resettlement after lifting did not occur.

"While our foam jacking crews have raised and stabilized millions of square feet of concrete, this was our first underpinning job," states Clayton Perry, Business Development Manager, Concrete Jack. "Things went really well under the watchful eye of the owner's representative."

The compact equipment and ease of transporting and maneuvering the required equipment and materials required of the job was a major benefit given the tight site and need to cross multiple active Amtrak tracks to access the site. By utilizing high density polyurethane instead of a cementitious grout for the repair, approximately 10 truckloads of material were foregone, along with the associated logistical problems associated with stockpiling material onsite, where there was very limited space.

About Concrete Jack: Concrete Jack is a full-service foundation repair, concrete lifting, chemical grouting and cellular concrete contractor serving the entire Mid-Atlantic. Concrete Jack is based in Williamsburg, Virginia and serves commercial, industrial, municipal and residential customers. Concrete Jack is a factory trained installed for Earth Contact Products and Hydraulic Mud Pumps.

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Kirk Roberts

Kirk Roberts
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