Blog

Mar 16, 2023

Construction Concerns: Adhesives and Glues

Article and photos by Gregory Havel We are all familiar with adhesives and

Article and photos by Gregory Havel

We are all familiar with adhesives and glues: the materials used to make things stick to each other:

For the best results, the right glue must be used with each material and must be selected based on the amount of weight it will be expected to support.

For an adhesive to work properly, the surfaces to be joined must be clean and prepared for joining. Both surfaces must be compatible with the adhesive to be used. The adhesive must be allowed to cure under the proper conditions for at least the minimum amount of time to achieve full strength.

Some adhesives work best with two smooth surfaces; others require the surfaces to be roughened or coated with a primer. If the surfaces aren't properly prepared or aren't clean enough, the joint will not be strong and will fail under stress. If the adhesive cures at a temperature that is too hot or too cold or if the joint is stressed before it has cured long enough, the joint will also fail.

Firefighters must be aware that many of today's construction components are manufactured using adhesives or are assembled with adhesives during construction.

(1)

(2)

Failure of adhesives under fire conditions can lead to partial or total structural collapse.

Adhesives are known to fail without fire present. We have all opened a 50-plus-year-old photo album or scrapbook and watched as the glue or paste used to attach the photos or clippings disintegrated. Anyone who has renovated an older home knows that the old wallpaper must be removed before the new paper is hung or the new paint is applied. Old wallpaper tends to become loose and to peel easily. The adhesive used to attach vinyl floor tile and sheet flooring can loosen with age.

Adhesives can be said to achieve their maximum strength at the time they finish curing and to gradually begin to lose their strength as they age. This aging is a combined function of age, seasonal and daily temperature changes, seasonal changes in humidity, exposure to ultraviolet light (sunlight), vibration, flexing (loading and unloading), wetting and drying cycles, and other stresses and factors. The more factors that are involved at a location and the more frequently they change, the more rapidly the adhesive will age and weaken.

Perhaps we can say that adhesives have a "half-life," something like radioactive materials. After exposure to aging influences, adhesives will reach a point at which they will be only half as strong as they were at the time they finished curing, a point at which there no longer will be a safety factor. This half-life could be as short as a few minutes if the surfaces joined by the adhesive were not clean or properly prepared, if the adhesive was incompatible with either or both of the surfaces that were joined, or if the joint is severely overloaded. This half-life could be years or decades, depending on the strength of the adhesive bond and the aging influences present.

In any case, we need to be aware that today firefighters work inside structures that depend on adhesives for their stability and unity and that these adhesive bonds may not be as permanent as their manufacturers claim in advertisements.

Gregory Havel is a member of the Burlington (WI) Fire Department; a retired deputy chief and training officer; and a 30-year veteran of the fire service. He is a Wisconsin-certified fire instructor II and fire officer II, an adjunct instructor in fire service programs at Gateway Technical College, and safety director for Scherrer Construction Co., Inc. Havel has a bachelor's degree from St. Norbert College; has more than 30 years of experience in facilities management and building construction; and has presented classes at FDIC.

Subjects: Building construction for firefighters

FE Category: Prevention and Protection, Building Construction