Project: 73,000 square foot shopping centre sunk up to 6”.
Installer: Lève-Béton PURLIFT
Challenge: The shopping mall was built in 2010 on a concrete structural 8” thick slab. A number of factors had contributed to the slabs having sunk, including one or more of the following:
The type of soil the mall was built on, grey clay.
The land the mall was built on used to be a marsh.
Train tracks close by whereby the trains are travelling at a high speed and create
heavy vibration as they go by.
The mall is occupied by big box stores and the unevenness of the slabs created trip
hazards in the stores as well as other challenges, such as keeping the shopping carts
from careening in different directions due to the sloping of the floor.
The builder could have removed and replaced the existing slabs, thus leading to major
revenue losses and storage costs for the retailers, not to mention the cost of leasehold
improvements once the floor was replaced.
Findings: The builder contacted Purlift to look at the possibility of lifting, levelling, and
stabilizing the floor in each store. Purlift sent a team of experts in that field in order to
determine if/how the floors could be repaired with a minimal amount of business
interruption. Purlift found that the problem could be resolved by injecting high-density
4lb. polyurethane foam beneath the slab. The slab would be pierced every 5’-7’ and the
material would be injected in a liquid state, infiltrating crevices as small as 1/32”, thus
filling the void and lifting the slab to its original position.
Results: Purlift started the work in November and worked through the busy Christmas
season, accomplishing the feat by working at night so the stores could stay open
throughout the day. The crew would start the job once the store closed for the night and left the site in the early morning so as not to disrupt the everyday working of the retail outlets. As a result, the retailer did not sacrifice 1 day of revenue and the work, done
without any heavy machinery or equipment, was completely non-intrusive with no downtime. Lifting the floor with all the racking, shelving, inventory, and storage equipment in place was not a problem as the polyurethane foam had no problem lifting the excess load sitting on the slab.
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