Marble Tile Flooring

Marble is the most ancient of all finished materials currently in use today. Egyptians used onyx marble, Parian marble was found in the Ancient ruins of Troy. Pentelic marble was used in the Parthenon in Athens. Makrana marble, a white marble, was used in the Taj Mahal in India. Marble tile floors were used in the European Baroque and Rococco periods. The French classic black and white marble squares remain a popular pattern for marble floors today. Marble is quarried in many countries, including Belgium, France, Great Britain, Greece, India, Italy, Spain and even the United States. Vermont and Georgia are the two principal states for marble production.

Marble is a metamorphic rock derived from limestone. Heat and pressure created the metamorphic change that turned limestone into marble. Today, all rocks that are capable of taking a polish come under the heading marble. Dolomitic limestone, although technically limestone, is known commercially as marble. Travertine and onyx are related stones; travertine being the more important for flooring purposes because it is easier to work. Onyx is brittle and is mostly relegated to decorations. Serpentine is of a different chemical makeup but because it can be polished it is classified as marble.

The colors of marble are as varied and numerous as the areas from which it is quarried. One of the famous Carrara marbles is pure white. Michelangelo used marble form many of his sculptures. Other Carrara marble many have black, gray, or brownish veinings. The name verd antiques is applied to marbles of prevailing green color, consisting chiefly of serpentine, a hydrous magnesium silicate. Verd antiques are highly decorative stones, the green being interspersed at times with streaks or veins of red and white. The pinks, reds, yellows, and browns are caused by the presence of iron oxides, whereas the blacks, grays and blue-grays result from bituminous deposits. Silicate, chlorite, and mica provide the green colors.

Marble does not come in sheets of equal size and must be mined with care. Blocks of marble are mined by drilling holes outlining the block and then wedges are driven into the holes and the blocks are split from the surrounding rock. Diamond blades are used to cut the blocks into the sizes required. Marble tiles are usually the ‘leftovers’ from the cutting of larger slabs, since the largest possible sizes are given preference in the cutting and grading processes. This being so, finding a set of visually and texturally compatible tiles large enough for one’s purpose can be quite a chore. Marble chips are used in the production of terrazzo and agglomerated marble tiles.

Marble is a relatively heavy and expensive material for use on floors due to the necessity of using the conventional, thick-bed installation method. One method of cutting down weight and cost is to use a layer of fiberglass and/or epoxy resins as a backing for thin layers of marble. Another method uses a ¼ inch layer of marble backed by a 1-inch thick piece of Styrofoam. This latter method also provides a marble floor that is warmer to the touch that one made of a thicker material.

The agglomerated marble tile consist of 90 to 95 percent marble chips combined with 5 to 10 percent resins and formed into blocks in a vacuum chamber, and are available as floor tile or marble wall veneers. Agglomerated marble may be classified as cast marble but the term “cast” is also used to describe a polyester product containing ground marble. Cast marble tile is a perfect balance of eye appeal and performance. Stronger and more abrasion-resistant than quarried stone products, it is ideal for high-traffic commercial installations.

The following properties need to be considered for marble floors:

• Density. Averages 0.1 pound per cubic inch. This figure may be used to calculate the weight of the marble.
• Water absorption. Measured by total immersion of a 2-inch cube for 48 hours and varies from 0.1 to 0.2 percent, which is less than other natural stones. The maximum absorption as established by ASTM C503 is 0.20 percent.
• Abrason resistance. Measured by a scuffing method that removes surface particles in a manner somewhat similar to the action of foot traffic. Abrasion resistance for commercial flooring should be at least a hardness value of 10 as measured by ASTM C241. The Marble Institute of America recommends a hardness of 12. This value is not necessary for one family homes.

Marble is also classified A through C, according to what methods of fabrication are considered necessary and acceptable in each instance, as based on standard trade practice.

A polished or glossy finish may be used in a residential installation but not for commercial installations. Smooth satin or honed ( a velvety, smooth surface with little or not gloss) or sand-rubbed ( a flat non-reflective surface with little or no gloss) should be specified for commercial floors.

When using marble or any other of the natural stones, it is necessary to calculate the weight of these materials and be sure the sub-floor is strong enough to support the extra weight. This, of course, is where the 3/8 inch materials come into use, especially for remodeling, where the floor was probably not constructed to bear these heavy stones. Any deflection in the floor will result in cracks in the marble.