What lies beneath
Concrete flooring in today’s industrial freezer spaces should easily outlast all other parts of the facility. A typical serviceable lifespan can reach 50 years or more. However, the floor often is overlooked when it comes to maintenance as many people ignore things that are not at eye level or seem rugged in construction. Without regular preventive maintenance of the under-floor heating system, though, the ground can freeze, allowing freezer floors to heave and crack, resulting in significant repair costs and even the loss of the entire facility.
Stellar, a design, engineering, construction and mechanical services firm that specializes in low-temperature facilities, has seen many floors in need of significant repair. Throughout its 25 years designing, building, renovating and repairing low-temperature facilities, Stellar has witnessed first-hand how the lack of regular preventive maintenance of freezer floors can lead to catastrophic and dangerous conditions, including building code violations and the complete destruction of the facility. Stellar likens freezer floor maintenance to oil changes in cars – with regular maintenance, significant damage and costs can be avoided. By repairing problems as soon as they are identified – rather than waiting – considerable savings can be achieved.
In any freezer, the under-floor soil must be heated to ensure it remains above 32°F for the life of the facility. This typically involves one of three types of heating systems – vent tubes, which draw in outside air that is circulated through the tubes buried in the soil; electric heat; and heated glycol, which runs through tubes in the soil.
Problems arise when the heating system malfunctions and stops heating the soil beneath the facility. Without the heat, the extreme cold in the concrete floor can transfer through the concrete, past the insulation and sub-slab and into the soil. Once this occurs, the moisture in the soil becomes ice, which expands and forms an ice lens (which looks somewhat like a flying saucer in shape). This lens pushes upwards, buckling and heaving the concrete floor above it. This phenomenon, called “frost heave,” causes logistical issues and safety concerns that can seriously disrupt a facility’s operations. Left unabated, the ice eventually can affect foundations, which in turn can compromise structural members. The formation of ice below a facility with a non-functioning under-floor heating system can occur very rapidly, depending on the moisture in the soils and the severity of the winter climate where the facility is located.
The first warning signs of frost heave are the development of cracks in the floor and a perceptible change in the floor’s grade. This most often is detectible by sight, but can also be identified by a perceptible shift in racking or pallet positions. Operations are affected and safety is compromised – racks are tilted and forklift trucks cannot maneuver on uneven floors or over large cracks.
Repairs to floors showing signs of frost heave must be made immediately. Often, owners ignore the signs and wait too long to make repairs. As the flooring condition continues to worsen, impacts are seen throughout the facility. For example, columns and roof members can bend to the point of failure, creating a dangerous and catastrophic condition that is not economically feasible to repair. If a facility reaches this point, often it must be demolished and replaced with a new structure.
If frost heave is detected before the facility’s structural integrity is compromised, the standard repair procedure is to replace the entire floor and repair the under-floor heating system. Depending on existing conditions, it may not always be necessary to take the freezer completely out of service for repairs. On a number of occasions Stellar has been able to correct the under-floor heating deficiencies and replace freezer floor slabs without disrupting existing operations for many clients. Stellar’s flooring-repair trademark solution involves thawing and remedial conditioning of the frozen soil, which is absolutely essential in guaranteeing the long-term success of any freezer floor repair work.
To avoid frost heave, plant operations and maintenance personnel must properly maintain under-floor heating systems. A monthly check of the system’s operation and effectiveness will ensure that any malfunctions are detected quickly. If problems are suspected, an investigation should be conducted immediately. If plant personnel require expert assistance in inspecting the floor and under-floor heating system, various vendors, including Stellar, can perform a thorough, cost-efficient inspection. Stellar also can develop a preventive maintenance program tailored to a facility’s specific needs.
About the Author
Johnny Johnson is the vice president of field services for Stellar, a design, engineering, construction and mechanical services firm, with extensive design-build project experience in the food and beverage market. In addition to its full suite of services, the company has more than 10 years of experience in the unique and challenging area of frost heave repair, having rectified frost heave conditions in freezer floors for a number of the nation’s leading food, beverage and cold storage companies. For more information, visit www.stellar.net or contact Johnson at (904) 260-2900 or firstname.lastname@example.org.
Frost heave warning signs
1. Cracks begin forming in your freezer floor
2. Your freezer floor’s grade is noticeably uneven
3. Racking or pallet positions are shifted, tilted or out of alignment
4. Forklift trucks have difficulty maneuvering over the freezer floor