Flaking is usually caused by capillary moisture or freeze-thaw cycles which occur within the masonry. The problem can also occur due to sub-florescence, so that if flaking occurs, the area should be examined to determine if salt crystallization is occurring in the flaked areas.
Peeling is the flaking away of the stone surface from the substrate in strips or layers. It may also result from a defect in the stone, or from weathering. Encrustations of the surface caused by chemical reactions with environmental elements may also peel or flake along the bedding plane. Rising damp is the suction of ground water into the base of masonry through capillary action.
During active wet periods, rising damp may be visible as a darkening of the stone along the base at ground level. Due to the continuous changing of the moisture level due to varying exposure conditions, staining or efflorescence may be visible at a range of several feet up from the ground. Spalling is the separation and breaking away of pieces of stone due to sub-florescence, freeze-thaw, improper repointing withtoo hard a mortar mixcontaining too much portland cement, or structural overloading of the stone.
Spalling is less frequent with limestone than with sedimentary stones which are also less hard. Limestone is hard enough to resist internal forces which would cause spalling in other natural stones or fabricated masonry.
This is a potentially harmful internal accumulation of soluble salts deposited under or just beneath the masonry surface as moisture in the wall evaporates. The build-up of salts and their crystallization can create substantial pressures within the masonry, causing pieces to break off along the planes of deposition.
Efflorescence at the surface is an indication that sub-florescence is possible. Techniques for mitigating the problem include poulticing, removal of identified salt sources, elimination of moisture in the stone and damp- proofing. Please try again later. No results could be found for the location you've entered.
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Introduction Limestone is a sedimentary rock composed principally of calcium carbonate calcite or the double carbonate of calcium and magnesium dolomite.
Some calcarenites contain oolites and if the oolites are present in sufficient quantity, the stone is called oolite limestone. Oolite limestone is a sub-category of calcarenite. Coquina:Coquina consists of raw, unaltered shell fragments, often quite large, loosely cemented by calcite.
It is generally very coarse and porous, frequently consisting of oyster and sea shells and fragments. Dolomite: Dolomite is a sedimentary carbonate rock composed of calcium and magnesium carbonate. Microcrystalline limestone: This is a limestone structure of crystals too small to be seen without magnification.
Oolitic limestone: Oolitic limestone is a calcite cemented calcareous stone composed of shell fragments, practically non- crystalline in character. Generally without cleavage, and extremely uniform in composition and texture, oolitic limestone adjusts to temperature changes. Travertine:A calcium carbonate, usually light in color, travertine can be extremely porous or cellular. It is usually deposited from solids in groundwater. Typical Uses Limestone is widely used in architectural applications for walls, decorative trim and veneer.
Problems and Deterioration Weathering may have a degrading effect on the appearance and structural soundness of limestone. Natural or Inherent Limestone Problems Weathering: Limestone subjected to exterior exposures deteriorates due to weathering or the natural effects of wind, rain, and thermal change. Erosion: Erosion can be the result of general weathering described above, or it can be a more localized phenomenon based upon handling or exposure. Staining: Discoloration of the limestone, whether general or localized, is staining.
A variety of organic or inorganic oils may be absorbed into the stone upon contact. Dyes and inks: The staining could be any color depending on the type and source of the dye. This type of stain is likely to be extremely localized around the area of contact. The liquid containing the coloration may be absorbed into the stone and during the normal process of evaporation, the coloring pigment is deposited in the stone.
For specific guidance on removing ink and dye stains from limestone, see R. Organic stains: Organic stains are caused by direct contact with decomposing organic matter, such as leaves, bird or animal droppings, flowers, tea or coffee. Regardless of the source these stains tend to be a slight reddish-brown in color. They also frequently disappear after the source has been removed.
These stains may be left to weather and bleach or oxidize out after the removal of the organic source, however a residue may still remain on the stone. For specific guidance on removing organic stains from limestone, see R. Metallic stains: Two major categories of metallic staining occur, they tend to be based on either iron or copper. The source of the staining may be internal structural components or elements. A major source is the water wash, or run-off, from adjacent metallic elements, especially bronze and copper.
Rust stains: These stains are reddish-orange and are caused by the oxidation rusting of iron. The source of iron staining is usually the structural or connecting components. Some of the oolites may be of algal origin. When the grains formed by the process are more than two millimeters in diameter about the size of the head of a pin , they are called pisolites. Many limestones in Kansas particularly of Pennsylvanian age contain oolites. Most outcrops of oolitic limestone are found in the eastern one-third of the state.
Kansas rocks of Permian and younger ages do not contain many oolites. Pure chalk is white, but it may be stained with iron oxide or other impurities. It is a soft porous rock that crumbles easily. In the Cretaceous rocks of western Kansas the Niobrara Chalk also contains some shale outcrops in an irregular belt from Smith and Jewell counties on the northeast to Finney and Logan counties on the southwest.
The rock is gray to cream color, but weathers white, yellow or orange. The average thickness of the entire formation is about feet. Kansas chalk beds are known worldwide for the reptilian and other vertebrate fossils found. They are equally famous for the pinnacles, spires and odd-shaped masses formed.
Diatomaceous Marl - This rock is important because of the calcium carbonate content and the silica content from the diatoms which are tiny, single-celled creatures that have characteristics of both plants and animals.
The deposits can been seen from a distance where they outcrop along the south side on a valley for about four miles. Outcrops are also found in Meade, Seward counties and elsewhere in western Kansas. The rock can be mined and used for filtering water or other solutions and as a filler in paints and other products. Travertine is a banded, compact variety of limestone. It is formed along streams, particularly where there are waterfalls and around hot or cold springs. Calcium carbonate is deposited, where evaporation of the water leaves a solution that is supersaturated with chemical constituents of calcite.
A good deposit was found near Waconda Spring in Mitchell County, where the minerals in the spring water built a hill of travertine 42 feet high and feet in diameter. This deposit is now covered by the Glen Elder Reservoir. Starting at a microscopic scale, the calcium carbonate in the rock begins to crystallize or recrystallize into fine-grained calcite crystals. As the duration and intensity of metamorphism continues, the calcite crystals increase in size.
When the calcite crystals are large enough to be visible to the eye, the rock can then be recognized as marble - a metamorphic rock. Marble is the name of the metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed of calcium carbonate CaCO 3 and usually contains other minerals that might include clay minerals, micas, quartz, pyrite, iron oxide, and graphite.
At this location, and many other locations, the Kaibab Limestone is fossiliferous and dolomitic. Photograph by the United States Geological Survey. Dolomitic limestone is a rock composed mainly of calcite, but some of that calcite has been altered to dolomite.
Dolomite is thought to form when the calcite CaCO 3 in carbonate sediments or in limestone is modified by magnesium-rich groundwater. The available magnesium facilitates the conversion of calcite into dolomite CaMg CO 3 2. This chemical change is known as "dolomitization. Dolomitization can completely alter a limestone into a dolomite, or it can partially alter the rock to form a "dolomitic limestone.
Fossiliferous Limestone: Ammonite fossils found in limestone quarry in Germany. Ammonite fossils are abundant in the area around Nuremberg and Stuttgart. Fossiliferous limestone is a limestone that contains obvious and abundant fossils.
They are usually marine invertebrates such as brachiopods, crinoids, mollusks, gastropods, and coral. These are the normal shell and skeletal fossils found in many types of limestone. Fossiliferous limestone often contains information about the environment of deposition, and where the organisms lived or were deposited. Paleontologists can often examine the fossils and determine the geologic age of the rock. Lithographic Limestone: In , workers at NOAA's printing shop ink a slab of lithographic limestone that contains an image of a nautical chart.
In , NOAA produced approximately , lithographic prints using this method. A crop from an image in the NOAA archive. Lithographic limestone is a dense rock with a very fine and very uniform grain size. It occurs in thin beds which separate easily to form a very smooth surface.
In the late s, a printing process known as lithography named after the stones used was developed to reproduce images by drawing them on the stone with an oil-based ink, then using that stone to press multiple copies of the image. Lithographic printing developed into an art form that produced many of the finest maps, navigational charts, posters, and bookplates of the 18th and 19th century.
Printing with large stones weighing hundreds of pounds to over one ton was cumbersome work. Eventually lithographic printing was done using high-speed presses in which the image was inked on metal rollers and transferred onto sheets or rolls of paper as they streamed through the press. Oolitic Limestone: A specimen of limestone composed almost entirely of oolites. Photograph by James St. John, displayed here under a Creative Commons attribution license.
Oolites or ooliths are small, sand-size clasts of calcium carbonate with a spherical to ovate shape. They form by the concentric accumulation of calcium carbonate layers around a nucleus that might be a sand grain, a shell fragment, a coral fragment, or a particle of fecal debris.
They are thought to form by inorganic precipitation of material around a nucleus while the clast is transported in wave-agitated waters or rolling across sediment surfaces. In some parts of the Bahamas Platform, oolites are one of the most abundant clasts found in the sediment.
In areas where currents from deep water ascend onto the platform, broad areas are covered by great thicknesses of sediment that is almost entirely oolitic. Oolitic limestone is found in many parts of the world. Oolitic sediment is found in Great Salt Lake, Utah.
Some sedimentary rocks are composed almost entirely of ooids and the calcium carbonate cement that binds them together. Travertine used as flooring tile and wall panels in a modern home interior. Travertine is a variety of limestone that forms where geothermally heated alkaline water, supercharged with dissolved gases and minerals, emerges at the surface. There, calcium carbonate and other minerals precipitate as the water degases and begins to evaporate.
Travertine can also form where these waters emerge into subsurface caverns. There, it can precipitate as cave formations such as stalactites, stalagmites, and flowstone.
When pure, travertine is white, but it is often stained by the presence of other minerals to cream, tan, greenish, brownish, and other colors.
Because the precipitation is rapid and forms as encrustations on younger materials, travertine is often a banded rock with numerous voids and cavities. It sometimes contains inclusions of organic and mineral debris from the cave or surface environment.
Travertine was mined and used as an architectural stone in ancient Egypt and ancient Rome. Today, Egypt and Italy are famous sources of travertine that is exported throughout the world. It is sawn or sheared into floor tiles, window sills, wall panels, stair treads, and other shapes, mainly for interior use. High-quality material can sometimes accept a polish.
The material can be recognized by its low hardness 3 on the Mohs scale , banded appearance, and porous texture. Tufa is a porous rock that forms from the precipitation of calcium carbonate, often at a hot spring or along the shoreline of an alkaline lake where waters are saturated with calcium carbonate.
Tufa is a porous limestone produced by precipitation of calcium carbonate from the waters of a hot spring or other body of surface water that has the ability to precipitate volumes of calcium carbonate. The pore space in tufa often results when plant material is trapped in precipitating calcium carbonate. One of the most famous locations where tufa is actively forming is at Mono Lake, Yosemite National Park. The most spectacular tufa features at the lake are known as "tufa towers".
They form by the interaction of freshwater springs and alkaline lake water. In spite of its gnarly appearance as a rock, tufa actually has numerous architectural uses.
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