Indoor Air Quality
Due to its inert quality of not giving off any gases, stone has little direct impact on indoor air quality. Most stone is smooth and does not harbor bacteria; however, some stone used indoors will have a rough texture and hold dust or bacteria. In the case of lava rock or travertine, there are holes through the stone where organisms such as mold could live. Sealing or deep cleaning could solve these potential air-quality problems. When stone is set without the use of mortar, it is environmentally friendly. The use of mortar reduces the sustainability due to the absorption of carbon dioxide when the mortar is drying. Lime mortar is more sustainable than other mortars because it absorbs less carbon dioxide.
Before the time of recorded history (500 b.c.e.), stone was used for building in the post and lintel construction style, where vertical posts held up a horizontal lintel. This was a common building technique in Egypt, Greece, and Mesopotamia. Stone was good for the vertical posts or columns because of its high compressive strength. However, stone is low in tensile strength, which is needed for spanning distances. Column spacing was limited to the length of a stone, dictating that the vertical elements needed to be placed close together. Hand-carved stone columns replaced posts in more decorative architectural construction, becoming very important cultural icons.
Marble was plentiful in Greece and on the Aegean Islands close to Greece. The Minoans and later the Greeks used marble blocks held together by metal clamps (instead of mortar) for building. Classical Greek (500 b.c.e.) structures used marble and limestone for floors and fluted columns in temples. As stone working tools changed from bronze to iron, stone building techniques developed, allowing larger enclosed spaces to be constructed. Trusses were used extensively in ancient Greece. The truss, being a triangular shape, can span a long distance. This allowed the interior spaces to be more open, not requiring the closely spaced columns previously used.
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Romans gave more attention to interior spaces and used more materials than the Greeks did. Alabaster, lava, and travertine were used in addition to marble and limestone. Both Greeks and Romans used mosaics for decorating floors. Mosaics were made of tesserae, extremely tiny pieces of stone or glass set in mortar to form a design. Because of the weight of stone, it was used for ground floors over earth, but not used for upper floors.
By the fourth century b.c.e., Romans were using arches to transfer the horizontal load, which allowed columns to be spaced farther apart. An example of the use of arches is the Colosseum in Rome, built in the first century c.e. The exterior of the Colosseum consisted of 80 travertine arches. The basis of stone arch construction was to first construct a wood frame in the shape of an arch. The stone work was built up around the frame starting at the bottom of the arch with wedge-shaped stones. At the apex, a keystone in a wedge shape was set in to hold the other stones in position. Each wedge-shaped stone would thrust downward. Arches continued to be used into the early Christian era (313 to 476 c.e.) in Rome. Roman building technology was also used in Constantinople in the Byzantine era (482 to 1453 c.e.), including mosaics in tesserae and arches.