As history progressed, so did the materials. Many of
the most famous columns of the past were erected out
of various types of stone such as limestone. Architects
and designers found stone difficult to work with when
constructing large projects, so several different types
of materials have been used to build columns.
One of the materials used over the past hundred years
that has been used for producing architectural columns
is a fake limestone, or cast stone. A man-made rock,
cast stone tends to be considerably less expensive
than natural limestone as well as quicker to produce
products
in a timely manor. One of the disadvantages of this
material is that although it reflects a natural stone’s
appearance, it also reflects its weight.
Dating back even further than cast stone, are some of
the materials that we see hundreds of times a day, concrete
and cement. Concrete dates back over four-thousand years
ago to the ancient Egyptians. Around 300 BC, the Romans
added strength to the standard substance by mixing in
pink sand formed by volcanic ash. This allowed concrete
structures to bear more weight and deteriorate slower.
Since that time, many different mixtures of cement and
concrete have been discovered and hundreds of columns
have been erected.
Even though concrete is fairly easy to create a mold
for and reproduce quickly, it tends to be extremely heavy
and thus difficult to transport. Because of those reasons,
column manufacturers are always in search of a more advanced
material with the same load bearing capacities of stone
yet without the weight. About twenty years ago, column
manufacturers happened upon a material now known as FRP
that has revolutionized the column industry.
FRP, or Fiber Reinforced Polymer has been used in this
country since the early 1930s, but its origin has been
traced back to the Israelites of 800 BC who reinforced
bricks with straw to provide added strength. Beginning
in the 1930s, manufacturers began mixing fiberglass with
cement to increase strength and lifetime.
After World War Two, fiberglass materials were used
to construct boat hulls, and during the 50s the automotive
industry introduced fiber reinforced composites into
vehicle bodies. This effort led to en even more advanced
material called filament wound fiberglass, which is also
used to manufacture lightweight columns today.
Since that time, numerous composite materials have been
discovered and manufactured for different purposes. A
composite has basic elements that define the name. The
materials used fall into the following categories: resin,
fillers, additives, and fiber reinforcements. The fibers
are added in the manufacturing process to increase stiffness
and tensile capacity. They also offer a lower thermal
expansion coefficient than that of steel. To bind the
fibers into a firm matrix, a resin is added to offer
high compressive strength. Because resin tends to be
quite expensive, fillers are used to reduce cost and
shrinkage. The additives help to improve the mechanical,
physical and workability properties of the product. Over
all, composite materials tend to be a quicker and cheaper
way to manufacture products.
Within the last twenty years, column manufacturers have
adapted the composite known as FRP, fiberglass reinforced
polymer, into their process of producing columns. The
result is a lightweight, durable, and inexpensive way
to manufacture architectural columns.
To manufacture an FRP column, molds are made for every
architectural size column starting from six inches in
diameters growing larger to twenty-four inches in diameter
and from heights of anywhere between six feet to about
twenty-four feet high. Mixtures of fillers, such as marble
dust, polyresins, and four to six inch strands of fiberglass
are poured into a mold. Once the materials are in the
mold, it is spun so that the centrifical force pushes
the mixture to the outside of the cast. During this process
the mixture hardens so that by the time the mold is done
spinning, a column with the load bearing capacity of
twenty thousand pounds is formed.
