Recently, something really funny was asked by a new Trilogy Pool Builder. With a very serious tone he asked, "Now, are your pools Composite or Fiberglass?" After a brief pause, we replied, "technically all pools are composite pools, but ours just happen to be fiberglass composite pools." Generally speaking, if one talks about a "composite" part, they are referring to a part with fiberglass or other synthetic fiber reinforcement encased within a polymer matrix. To read a more detailed explanation about how composites structures are revolutionizing entire industries, click here. The best single source for information concerning composites is the American Composite Manufacturing Association (ACMA).

Although this question was generated through misinformation in an advertisment from another fiberglass pool manufacturer, it is actually cause for an extremely interesting discussion. Technically a composite structure is two or more dissimilar materials that when combined are stronger than the individual components. So if one considers the three general types of pool construction: vinyl liner, fiberglass, and concrete, then all of them fit this definition. There are even fiberglass wall/concrete bottom pools that are not only built of two different composite materials but in fact are a combination of both. Since a vinyl liner pool fits this composite definition the least, we will focus on simply concrete and fiberglass pool structures.

The interesting result that this question yielded is that composite pools comprise the majority of swimming pools installed every year. As a fiberglass manufacturer, we like the sound of that statement. For nearly 40 years, fiberglass pools have struggled to gain wide acceptance in the market place. Some of this struggle was due to the early raw material failures seen in both swimming pool and marine industries, but that was long ago solved. There is no doubt that in terms of longevity and maintenance, today's fiberglass pools are absolutely superior. From a simple perspective of material science, fiberglass is an amazingly durable construction material.

Why has the pool industry and the consumer been so slow to accept a fiberglass pool if it has such superior performance qualities? The answer is actually buried in the question asked by our new Trilogy Pool Builder. Trilogy pools has really focused in on how similar our product is to a concrete pool. In fact, the majority of the objections to owning a fiberglass pool shell are brought on by the very industry manufacturing and promoting these shells. If a fiberglass shell is installed in exactly the same way as a concrete shell, then you can't tell the difference (ok, except the maintenance - but that is a different topic). The same plumbing, the same water turnover, same filtration, and the same concrete deck is required on both fiberglass composite pools and concrete composite pools.

Composite Pools: more familiar than you may think...

Let's take a closer look at the construction of the two shells: Fiberglass Composite Pools and Concrete Composite Pools. We will see there are many more similarities than differences. In most composite structures there are two basic components: reinforcement and a matrix. The reinforcement carries the load of the structure. Somewhat like the trusses under your roof, the reinforcement is what makes the composite material (concrete or fiberglass) strong. The matrix transfers the load from one reinforcement to another. The matrix encases and protects the reinforcement from the environment. Together, these two components create a synergistic stucture that out performs either in their individual state. Below is a comparison of the composite components in both concrete and fiberglass structures.

As it turns out, the reason a boat floats is simply that it displaces a volume of water, equal to its own weight. There is a real great set of experiments put together by the Army Corp of Engineers and can be found by clicking here.

Even the Titanic can sink

What you learned is that as long as the boat doesn't have water inside, it will float and displaces a volume of water equal to its own weight. Now what happens if one puts a hole in it? Yes, even the mighty Titanic sinks if it has water inside. At that point it becomes a big hunk of steel and plunges to the ocean floor.

With that refresher under your belt, lets return to what you heard in the pool store, this time armed with a little science fact on your side. "Yes, I don't carry those fiberglass pools. You know, they'll pop out of the ground, " you may hear. Next time consider asking what is special about a fiberglass pool that causes it to spontaneously "pop out of the ground" even when full of water? It will be great fun to actually listen to the answer. The answer should be, just like the Titanic, if it is full of water, it simply can't float. So what is the truth? All three pool shells: concrete, vinyl liner, and fiberglass may heave due to the buoyancy of water, when they are 1) empty and there is 2) a high ground water table. The weight of the shell has nothing to do with the problem.

Composite Matrix: encases and protects the reinforcement. Transfers the load from one reinforcement to another.

Fiberglass Composite Various polyester resins are used for creating the matrix in Fiberglass Reinforced Plastic (FRP) materials. Like cement, polyester resins have good compressive strength, but are weak in tensile strength. The polyester matrix functions to transfer the load from one fiberglass reinforcement to another. Individual resin formulations are selected based on particular application requirements such as flexibility, corrosion resistance, or strength.

Concrete Composite
Portland cement, sand, and aggregate combine to form the matrix for concrete. This mixture is good in compressive strength, but weak in tensile strength. The concrete matrix functions to transfer the load from one reinforcement to another. Aggregate size distribution, add mixtures, and air entrainment can be varied for workability and overall concrete performance.

Composite Reinforcement: Carries the structural load. Ultimately it is the strength of the reinforcement that determines how strong the composite part will be. More reinforcement equals greater strength.

Fiberglass Composite Fiberglass reinforcement is used to carry tensile loads in FRP structures. The fiberglass is protected by the polyester matrix. The glass fiber is composed of many filaments (5 to 25 microns) and is available in a variety of forms. The fiber roving can be woven into a cloth or chopped depending on application and desired structural performance. Fiberglass structures have high specific strength, a term that relates strength to weight. For a given weight, fiberglass is stronger than steel.

Concrete Composite Steel Reinforcement Bar (rebar) is used to carry the tensile load of the concrete structure. The concrete acts to both protect the steel and transfer loads to the steel rebar structure. Various structural applications demand different diameter and spacing of steel rebar.

Surface Finish: The surface finish creates the final look of the pool and is a key factor in determining the pool’s maintenance requirements. Some finishes interact with the pool water chemistry and some are chemically inert.

Fiberglass Composite Fiberglass composite pools are typically covered with a colored polyester resin called gel coat. Trilogy Pools offers a patented solid surface finish called Granicoat. This surface is identical to what is used in kitchen countertop and bathroom applications. It is a permanent and chemically inert surface finish. It is more durable than gel coat and is much easier to repair. Granicoat offers pool builders the opportunity to create the same visual appearance found in cementitious pebble finishes, but with a low porosity and easy to maintain surface.

Concrete Composite Concrete pools are made water tight through the addition of paint, tile or various cementitious surface coatings. Quartz, polished aggregate, and exposed pebble finishes are becoming very popular. Each of these finishes is affected by water chemistry and must be reapplied after some time.

Changing the way you think about fiberglass pools

In summary, there are a many more similarities between concrete pool and fiberglass pool structures. Certainly there isn't any difference between a "composite pool" and a "fiberglass pool." To say we make composite pools and the others make fiberglass pools is like saying we sell fuel and they sell unleaded gasoline. Most of the differences existing within a concrete pool builder's perspective regarding a fiberglass pool are created largely by how fiberglass pools have been traditionally sold and installed. The ease of installation has been taken too far and has attracted individuals to the industry, that simply do not care about quality features like tile, cantilever decks, stone coping or brick pavers. This has led to the "bathtub in the ground" image of a solid white fiberglass pool with concrete poured just up to the edge of the pool coping. Sometimes "the bathtub-look" can be “upgraded” with factory installed tile, but that is an entirely different discussion.

Bathtub or swimming pool? ...it's your choice!.

Trilogy Pools is changing the fiberglass pool image by promoting that the fiberglass shell should be installed exactly like a concrete pool. Today, there are many more surface finishes, sizes, and shapes available for fiberglass pools. Once installed properly, there is virtually no difference between the two aesthetically; however, the fiberglass shell is non porous and chemically inert, so there will be less maintenance. Trilogy Pools is committed to quality engineering and science and is actively working to promote fiberglass pools as a complement to a concrete builder’s existing line. At the same time, we are insisting that all fiberglass pool manufacturers stop promoting substandard installations and the use of misleading information to advertise their product.