Concrete repair in industrial environments

Industrial environments differ markedly from the commercial, public, transportation and residential markets by the sheer aggressive nature of their service. Enlightened industrial managers are now proactively developing budgets to address and slow the repair, demolition and replacement process.

By Tom Kline, Engineering Services Division Manager for Structural Preservation Systems, Inc.

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Industrial environments differ markedly from the commercial, public, transportation and residential markets by the sheer aggressive nature of their service. These facilities operate with a philosophy focused on minimizing operating costs yet maximizing production and generating wealth for stockholders. On a daily basis, plant owners examine the manufacturing process to improve existing products and processes or to create new product lines. Such a commitment to continuous improvement often results in the need for new facilities or modifications to the existing facility. This, however, is often easier said than done. Owners and company stockholders often view civil infrastructure and the expense of maintaining it as the cost of doing business to support the ever-important, income-generating process stream. It’s not uncommon for a complex structure, several stories high, to be referred to as a foundation for a vessel or piece of equipment critical to the manufacturing process. However, this stigma is slowly changing as our nation’s industrial infrastructure ages and as repairs and maintenance to extend the service life of these structures become necessary to optimize corporate profits. Enlightened industrial managers are now proactively developing budgets to address and slow the repair, demolition and replacement process. 

Case Histories

Taking Care of Business

Plant personnel often choose to work in industrial facilities because they enjoy the diversity of opportunities, where no assignment or duty is typical or routine. However, this same diversity of opportunities requires them to produce answers in disciplines they may not have been close to in a long time, if ever. Regardless of the amount of information they store either electronically or in hard copy in their office, the truth be told, the personnel in charge of an industrial plant’s infrastructure are rarely in their office. These individuals are generally charged with supervising, inspecting and monitoring the assets in their charge.

Non-Destructive Testing and Evaluation of a Support Column Exposed to a Hydrocarbon-Fueled Fire

Non-destructive testing and evaluation of a support column exposed to a hydrocarbon-fueled fire

One key factor that can have a large impact on an industrial environment is the deterioration of concrete structures. Caused by embedded metal corrosion; disintegration of the concrete matrix; the effects of moisture, thermal factors or varying loads; as well as faulty workmanship and/or inadequate or flawed design, concrete deterioration is a serious problem in an industrial setting. With the exception of faulty workmanship or design, these causes of deterioration have a consistent theme involving volume changes and/or alteration of the cement paste matrix within the concrete mass. The deterioration reduces the concrete’s integrity with losses in section and composite action with embedded reinforcing steel components. This is particularly a problem for in-service concrete that is unprotected and then exposed to acids, caustics, steam and refractory and cryogenic temperatures.

Load effects have been identified in many situations where an owner has implemented a change-of-use for a particular structure to upgrade or completely change the process equipment loadings. The need to improve process operations and reduce production costs have driven owners constantly to review and change their manufacturing processes with bigger, faster, better and more dependable equipment—which frequently means heavier equipment. It is not unusual for detected deterioration to have manifested into the secondary effects of embedded metal corrosion with the primary effect caused by cracking due to overloading. Essentially, the cracks provide conduits that allow moisture and atmospheric oxygen to contact the embedded reinforcing steel, initiating the corrosion process. 4Also, with many facilities located near seismically active areas of the country, earthquake loadings on older structures require upgrading to current seismic codes to resist such events, prevent further cracking and maintain process operations.

Failed Floor Slab Repair and Continued Deterioration Caused by Embedded Steel Reinforcing Bar Corrosion

Failed floor slab repair and continued deterioration caused by embedded steel reinforcing bar corrosion

In contrast, faulty workmanship and construction defects are particularly insidious because the effects may not be seen until much later in the structures’ service life, when it needs the reserve structural capacity (i.e., absence or misplacement of embedded reinforcing steel) and/or durability (i.e., porous, low strength or lack of protective concrete cover) to maintain functionality.5 Inadequate or flawed design can mean many things, but the majority of problems observed in the industrial market relate to reinforcing steel density in very stout reinforced-concrete structures. Specifically, these structures support very large loads in small footprints requiring designs where large diameter reinforcing steel bars lap together and are designed in close proximity to formwork faces. During placement, excessive rebar density operates as a sieve and prevents concrete mixture constituents from encapsulating the steel bars, forming internal and external voids (i.e., honeycomb) in the finished construction.

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