Precast Concrete Panel Repair

The Problem

A large office warehouse complex whose buildings were constructed of tiltup concrete wall panels and wood joist roof system supported internally by pipe columns had contracted to have the exterior surface painted. The painting contractor had realized that there were an unusually large number of areas on the concrete walls that had delaminations. Although the painting contractor had no experience in structural repair, the owner elected to contract with an engineering firm that specialized in structural repair of buildings and put the painting contractor on a Time and Material contract to perform the repair with the engineering firm overseeing the work. After spending $3,000,000.00 and only completing 50% of the work, the owner stopped the work and canceled the existing contracts. The problem was compounded because the tenants were upset by the fact that the contractor was an impediment to their operations and was taking too long to finish the project.

The Solution

The original wall panel design incorporated a bent within the panel. The bent consisted of a beam along the top of the panel with columns on each side of the panel. The steel within the bent was corroding excessively due to calcium chloride that had been used in the original concrete mix. The beam connections from panel to panel provided a continuous frame around the perimeter of the building along the roof line. To satisfy the seismic requirements of the building code the wall system and the roof diaphragm had to be tied together. The engineer designed a wood truss system to augment the beam that was in the wall panel and then tied it to the all and the roof diagram. Restruction Corporation developed a construction engineered solution to install the wood truss system with a minimum impact on the tenants operations.

The extensive network of delaminations throughout the wall panels that had been excavated needed to be repaired. Several repairs that had been performed with shotcrete were severely cracked. Although the owner and the city were opposed to shotcrete because of so many bad experiences, we were able to convince them to allow us to demonstrate our capability in a few of the cavities. Shotcrete was going to save a great deal of time and money if we could perform to the satisfaction of all the parties. After several test panels and demonstration areas the engineer, the owner, and the city gave their approval.

The texture of the exposed concrete surface varied within the panels and from panel to panel. To standardize the surface texture Restruction Corporation developed a cementitious/latex skin coat. The engineer then stipulated that the surface was to be sealed with a silane sealer and then coated with a coat of paint. Several paints were tested before one was selected. The entire building was then painted and completed to the satisfaction of the owner and the job of the tenants.

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