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4  FM quick reads on concrete

1. Concrete Inspections for Long-Term Performance


Concrete sidewalks, ramps, parking lots and garages around institutional and commercial facilities can perform reliably for years. But they can do so only if maintenance managers implement a comprehensive concrete-maintenance program that identifies small problems early and addresses them before they become larger and more costly.

By developing inspection guidelines focused on common causes of problems, combining them with effective repair procedures, materials and equipment, and specifying coatings to protect surfaces, managers can extend concrete performance life and minimize trip-and-fall hazards.

Managers tackling the challenges of concrete maintenance must accept two contradictory facts: Water is a necessary ingredient in concrete, as well as its single most destructive enemy. Without a vapor retarder to keep water out, concrete coatings on below-grade inside floors or walls soon will fail.

Water expands by 9 percent when it freezes, causing spalling and cracking in exterior concrete walkways, floors, walls, and roofs. Concrete is alkaline and normally protects rebar from rusting, but water mixed with chlorides in de-icing compounds can penetrate to rebar and rust it, causing expansion and cracking. Water also can penetrate structural concrete beams and cause cracking, rusting the rebar and weakening the structure.

The first thing technicians must determine when inspecting concrete is whether the problem is structural or superficial. The start of a structural failure — for example, a deep crack in a structural concrete beam — requires immediate attention and documentation. A concrete engineer using non-destructive evaluation, such as ground-penetrating radar, infrared thermography, and impact-echo technology, can discover hidden problems.


2.  Concrete and Asphalt: Effective Maintenance

I'm Dan Hounsell, editor of Maintenance Solutions magazine. Today's topic is, effective concrete and asphalt maintenance.

Exterior concrete and asphalt surfaces create a visitor's first impression of a facility. If drives, parking lots, and sidewalks deteriorate because they are not maintained properly, they can create problems that include poor appearance, tripping hazards, and costly repairs.

The causes of concrete and asphalt problems generally fall into three categories: design, use, and maintenance.

Design problems result from errors in material makeup, the placement of reinforcing materials, and poor support structure. One common design problem is excess water in the concrete mix. Managers need to properly specify concrete and asphalt mixes for each application and inspect them during application to ensure workers take test specimens and place the materials properly.

Another common problem is surface spalling, which results from imbedded metal around windows and other locations that strengthens concrete. Structural settling causes cracks that allow water intrusion, freezing and more cracking.

Even properly applied asphalt can develop problems that result from the effects of ultraviolet rays, water, petroleum products, and traffic. New asphalt combines asphalt-cement binder, sand and stone, and it is black. As the surface dries, asphalt turns gray from the absence of binder, and the elements begin to deteriorate it.

Managers also must be aware of unintended traffic, which can lead to premature degradation. For example, parking lots feature lanes for cars and those for trucks, which have much thicker bases.

If the design does not provide truck lanes or if trucks wander off designated lanes, they will crush the car-parking surfaces. The resulting depressions will collect standing water, and the water will turn to ice. Cracking and spalling can occur, causing damage that requires major repairs.

3.  Effective Concrete Maintenance Strategies

I'm Dan Hounsell, editor of Maintenance Solutions magazine. Today's topic is, effective concrete maintenance strategies.

Managers seeking to effectively maintain concrete parking lots around their facilities are constantly looking for the right mix of preventive maintenance and major restoration. The longer problems such as potholes remain unattended, the larger they become and the deeper into the base they penetrate, resulting in safety issues and costly repairs.

One key to effective concrete repairs is selecting the most appropriate repair method, which includes specifying the proper material based on the surface and on conditions at the repair site.

For example, managers need to select concrete sealants and coatings that are formulated for either wet or dry conditions. Extensive independent testing has shown that epoxies, siloxane/silane materials, and high-molecular-weight methacrylates are the best types of material for controlling the deterioration of concrete where freezing and thawing occur repeatedly and water is present.

Workers should inspect sections of concrete that most often deteriorate from freezing weather. These sections include exposed surfaces, such as posts, handrails, piers, parapets, and the top 2 feet of walls.

As with any other asset, concrete and asphalt surfaces need periodic inspection and preventive maintenance to ensure sustainability and lower life-cycle costs. Annual inspections are the most economical way to retain and improve the value of the asset.

The best preventive maintenance for asphalt is applying a sealant. Workers should reseal new asphalt between 90 days and one year after placement. This practice locks in the binder, keeps the pavement flexible, and prevents cracks and further degradation, which can destroy the surface and the base.

4.  Paints and Coatings: Match Substrate and Surface

This is Chris Matt, Managing Editor — Print & E-Media with Maintenance Solutions magazine. Today's tip is matching the right substrate to the proper surface.

The type of surface and condition determine the best paint and coatings option. Is the surface concrete or masonry? Wood? Drywall? Metal? Is the surface bare? Is it previously painted? Is the project a touch-up involving color-matching?

The key to ensuring an effective match between the paint and the substrate is understanding label and material safety data sheet information, which is available from the vendor. The paint must protect the substrate while meeting a facility's need for proper air quality and sustainability. Products with high pigment percentages are more costly but offer greater surface protection and better hiding qualities.

Managers might have other objectives, though. For example, with the emphasis on energy efficiency, the goal might be to use paint with a ceramic additive, which provides insulation by adding an invisible, radiant-heat-reflecting barrier. For a high-visibility reception area, managers might need to specify a surfactant to reduce surface tension and smooth out brush marks.

New rheology modifier additives that are free of volatile organic compounds are formulated to improve pigment dispersal, provide good leveling, and resist sagging. They also prevent misting and paint scatter during application.

Biocides — preservatives and fungicides — are additives to latex paints used for exterior or high-moisture interior applications. Manufacturers add defoamers to prevent air entrapment so the surface is free of pinholes. They also are developing multi-tasking additives, such as defoaming-coalescing agents.

Matching the texture of the surface to be painted requires using the same application method — brush, spray or roller — as used originally. Another technique is using clear spray-on sand or orange-peel coating before applying the final coat.


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