Pressured to provide more and better service with streamlined resources, economic belt-tightening is a way of life in today's healthcare arena. Those responsible for maintaining facility utilities are challenged to improve systems and their performance while reducing costs at the same time. Couple this challenge with the necessity of integrating durable building materials, and there is little wonder that concrete is a solution for many healthcare organizations -- especially in areas of their facilities that require immense strength, fire-resistance and even blast-resistance such as boiler rooms. Yet, for all its seeming permanence, concrete comes under attack from both natural and man-made forces almost from the time it is first poured and formed. The relative rate of degradation resulting from these assaults depends on a wide variety of factors of which only some are controllable. However, with a basic understanding of how to strengthen and repair a concrete building, healthcare organizations will benefit from reduced maintenance and long-term success.

The Invisible Problems

Over the course of the next few years, healthcare facilities will spend millions of dollars on facility infrastructure and repairs that generate little to no revenue return. While integration of new equipment for a new treatment option or a wing expansion that increases the number of hospital beds may add to the bottom-line, maintenance and repair of concrete structures is often overlooked since it produces no revenue. However, this approach is dangerous because concrete requires preventative maintenance. Although the process of deterioration or damage often takes years to manifest itself, the damage is exponential - worsening as time progresses - thereby developing into more expensive and extensive repairs.  And, the damage is especially prevalent in boiler rooms since these spaces are designed to be out of the sight of patients as well as tightly sealed. The steam and humidity that are consistently present in these rooms have nowhere to go, and the result is deterioration of the reinforced concrete. Another challenge resulting from location and design of boiler rooms is the fact that they are set in areas that are difficult to access and often are congested with mechanical equipment such as piping, making repair difficult. In many instances, equipment also is placed on the slab above the room, which makes repairs even more difficult as this equipment typically needs to stay in operation, or in the best case scenario, only be shutdown for a limited time. 

Because of these factors, deterioration is likely to result and typically occurs when the moisture and chemicals penetrate the concrete. A corrosion process is started that can go undetected until the concrete starts to crack and spall. In cases in which equipment is placed on the concrete slab above the boiler room, a coating or lining system is commonly used to prevent the chemicals and water from penetrating from above. In this case, the vapors and chemicals from below are trapped -- further accelerating the corrosion process.  And, situations in which the building roof is located directly above the boiler room, the waterproof roofing system can further the deterioration below.

Concrete: A Primer

In its basic composition, concrete has been around for almost 200 years. According to the Portland Cement Association (PCA), portland cement, which comprises 11 percent of the composition of concrete, was first patented in England in 1824 by Joseph Aspdin. He named it "portland" because of its resemblance to stone found in a quarry on the Isle of Portland. Today, portland cement is described by PCA as a calcium silicate cement. There are eight types of cement, the most common of which is Type 1 -- a general-purpose cement used in concrete for buildings, bridges and pavements. Other kinds of cement are manufactured for specialized applications such as dams, blast furnaces and industrial plants.

In addition to the 11 percent portland cement component, the remaining ingredients that make up concrete are 41 percent gravel or crushed stone, 26 percent sand, 16 percent water and 6 percent air. Concrete is formed with a mixture of paste and fine and coarse aggregates. The paste, a blend of cement and water, adheres to the surfaces of the coarse and fine aggregates - the sand and gravel. A process called "hydration"' then begins as the paste hardens and the whole mixture eventually assumes the final form of concrete.

There are any number of variables that can affect the strength and integrity of concrete. For example, water with too many impurities or with chemical compounds beyond certain thresholds will affect its durability. In addition, the relative size and coarseness of the aggregates plays a role in the size and thickness of the structural components in which they are to be used.

At some point, as the concrete hardens and sets, the material will have hardened to a stage where hydration transitions to a process called "curing." In its simplest terms, curing is the rate at which the concrete gives up its moisture content. Proper curing is absolutely critical to the integrity and strength of concrete. According to the PCA, "Curing has a strong influence on the properties of hardened concrete such as its durability, strength, water-tightness, abrasion resistance, volume stability and resistance to freezing and thawing."

Most, if not all of the factors listed above, play critical, interrelated roles in the degradation of concrete. Unfortunately, it is often impossible for today's engineering professionals to know how the concrete of an existing structure was mixed, poured and cured. However, the knowledge of the basic properties of concrete aid significantly in determining the best repair strategies.

Physics and Chemistry Lessons

In addition to the institutional mistakes contributing to concrete degradation, a range of natural and man-made factors come into play. Although the concrete found in most boiler room walls is typically on the interior of a structure and therefore is not affected by the freeze and thaw cycles of Mother Nature, man-made forces cause degradation. These sources include degradation caused by design deficiencies from year's past (knowledge of the use of concrete has improved tremendously over the years) or a failure to maintain the concrete. Additionally, if chemicals or some other mildly aggressive agents are spilled onto a concrete surface and are not properly cleaned up in a timely manner, they could cause degradation or exacerbate an already existing problem. High-pressure or high-temperature venting and physical forces such as flexing, overloading or repeated impact are other potential contributors to the deterioration process.

Foremost among all causes of concrete degradation is the internal damage caused by the corrosion of the embedded reinforcing steel - a man-made factor. This scenario is especially prevalent in boiler rooms where steam and condensation trapped by waterproof systems accelerate the corrosion process. In addition to deterioration of the steel itself, the corrosion also affects the concrete surrounding it, which results in cracking, spalling and delamination. Since virtually all of the concrete found in structures is steel-reinforced, this is a widespread problem that may cause concrete to spall and eventually fall and damage vital process equipment or piping. Such a scenario also poses a threat to maintenance personnel in the area. 

Unfortunately, the methods in which concrete deterioration manifests itself typically do not indicate the true depth, complexity or severity of a problem. Virtually from day one, concrete comes under attack from environmental factors, and the deterioration process is both insidious and continuous. The first small crack in its protective lining invites intrusion by moisture or corrosive agents. Eventually and inevitably, the outward symptoms of scaling, cracking and spalling gradually begin to appear. Without exception, concrete degradation problems do exist to some degree. The only variables are how and when they will manifest themselves, and whether they will have reached the stage at which they jeopardize ongoing operations and have an impact on profitability.

Preventative Maintenance and Inspection

The underlying danger in undertaking repair efforts is that the repairs, rather than producing a solution, may become part of a costly, but all too common, cycle of repairing the repairs. To understand how to avoid becoming trapped in this vicious cycle, it is important to determine the root cause of the degradation through an inspection process. Obviously, the sooner an issue is identified, the more economical and less intrusive the repair is likely to be. As such, preventative maintenance is crucial and inspections should occur on a yearly basis.

The first step in any maintenance program should be a visual inspection. If the visual inspection shows no sign of deterioration, no other actions need to taken at that time and an additional inspection should be scheduled for the following year. However, if the visual inspection reveals signs of deterioration -- such as cracking, rust staining or effloresce -- additional tests, both non-destructive and destructive, should be performed. These include, but are not limited to, acoustical impact (hammer sounding), chloride concentration, carbonation and petrographic analysis of cores extracted.  The results of these tests will determine the level of deterioration and lead to the implementation of a proper repair method and strategy.  Simply, proper maintenance and inspections are critical to prevent costly repairs in the future.

Choosing the Right Ingredients

Defined in the simplest possible terms, successful concrete repair integrates new materials with existing materials to form a composite structure that can withstand environmental conditions and operational processes, while at the same time providing extended service life. Further, a successful repair undertaking is one in which normal operations and processes are allowed to continue while the repairs are taking place. Once the decision is made to undertake a concrete repair project, the next step involves examining repair strategies and selecting the best course of action. Today's available technologies are advanced far beyond the simple concrete patch - a range of solutions can be utilized to implement an effective concrete repair program. A basic understanding of these options - surface repair, protection, stabilization, strengthening and waterproofing - will allow selection of the best program for your facility. A concrete repair specialist can help determine both the underlying cause of the problem and the optimal solution.

With so many possible strategies available to the repair designer, a typical repair strategy may implement solutions from more than one category in order to achieve the best results. Determining the most appropriate repair is best accomplished by involving all parties associated with the repair, including the engineer, concrete repair specialist, processing manager and hospital facility director. Factors such as on-going hospital operation and service life require consideration. Deciding on the most appropriate concrete repair materials is often an exercise in compromise. Even the most seasoned repair technicians find it difficult to select one product that meets all of a project's needs. At a minimum, the materials chosen should fill the repair cavity completely, avoid shrinking during the curing cycle and behave in a similar manner as the existing substrate when subjected to loads, temperature fluctuations and/or changes in moisture content.

In today's healthcare environment, it is crucial to keep the equipment in place and in operation. Disruption of service simply isn't an option. As such, repair strategies should include plans to ensure vital components of the hospital are not disrupted for any length of time. Careful planning and coordination with hospital staff since the rooms are usually isolated in the building Are essential to a successful project.  In these cases, the expertise of a concrete repair specialist can be invaluable.

Repair in Action

Case in point is a recent project for a downtown Chicago hospital. Although boiler rooms are often topped by a roof membrane, which is problematic in itself, this room was located underneath another concrete slab that was coated with a waterproof urethane coating.  The coating trapped the vapor and moisture from the boiler and caused corrosion of the reinforcing steel that resulted in major spalling and delamination of the concrete, resulting in many areas where concrete had fallen off and landed on piping, equipment and the floor. 

Structural Preservation Systems (SPS), the nation's largest dedicated concrete repair contractor, was hired to handle the repairs, which included shoring up the existing ceiling, support of all piping, removal of four small pumps and two compressors in the chiller room, and removal of approximately 340 square feet of concrete with an estimated thickness of 9- to 11-inches. SPS shored up the existing chillers on the top of the slab to remove concrete around the area.  SPS then replaced reinforcing steel and concrete, reinstalled all pipe supports and then reinstalled the compressors and pumps.

Because of the structure's age, the hospital had experienced a few expansions and the boiler room was located in an area that was only accessible via a pedestrian hallway for personnel and a courtyard for materials and equipment. The room was extremely congested with equipment and piping. Demolished concrete was removed from the area and new concrete was placed with a crane and pump respectively. Additionally, many large pieces of equipment were needed to facilitate the construction project. As such, major coordination with hospital staff was necessary to ensure the safety of personnel and the public.

Shoring of the equipment also was a challenge. Although the operation of the systems could not be affected, it was essential to remove all of the concrete below the equipment.  SPS utilized specially designed shore jacks in conjunction with shoring towers to support the operational equipment while removing the concrete. Although little room was left for movement of personnel and materials, SPS was able to install the essential shoring equipment and the project was a success.

Upping the Ante

Facility maintenance budgets are typically well-funded for repair of equipment and process systems, but structural repair budgets are given a much lower priority - until a problematic structural condition deteriorates to the point where the facilities operations are jeopardized. As in any decision-making process, knowledge is power. Effective concrete repair solutions include a commitment to learning from past lessons and addressing problems with the goal of ensuring the long-term integrity and service life of a facility's infrastructure. "Value-added" services relating to concrete repair should be no different than those provided by equipment suppliers. Education of personnel concerning concrete material basics, deterioration mechanisms, repair strategies and construction techniques enable repair teams to make better repair strategy decisions and prevent costly repairs. Failure to take preventative maintenance steps or properly address signs of deterioration can have a dramatic impact on the operations of a facility. Degrading concrete is a lurking threat that facility owners and management teams cannot afford to ignore.

Author

Mark Sitar is Branch Manager/Industrial Division Operations Manager for Structural Preservation Systems (SPS).