Shell limestone is a sedimentary rock and belongs to the so-called zoogenic formations. It consists of the remains of organisms that died millions of years ago: shells, carapaces, eggshells, etc.
🔍Limestone, as a stone, is characterized by high porosity (macroporosity), ranging from 21-60%; bulk density 1100-2240 kg/m³; thermal conductivity 0.29-0.99 W/(m•K); compressive strength 0.4-28 mN/m². Chemical analysis shows that limestone mainly consists of calcium carbonate and contains a small amount of impurities of magnesium salts and alumina compounds.
In 1986, the Soviet Union was developing 149 deposits of shell limestone, from which 9,585 thousand m³ of this limestone was extracted. In the treeless areas of the former Soviet Union, local natural stone materials were widely used, among which shell limestones occupied a significant place. In Moldova, Azerbaijan, southern Ukraine, Crimea, Kalmykia, and Kazakhstan, they are widely used in construction as wall and facing materials. Crushed stone and sand from shell limestone are of interest as excellent fillers for lightweight concrete.
"The Soviet Union was developing 149 deposits of shell limestone in 1986."
Building shell limestones are easily cut even with a hand saw, which is why they are called "sawable" limestones. The limit of sawability of limestones during manual cutting is considered to be the compressive strength limit of 35-50 kg/cm². Therefore, soft shell limestones are classified as sawable.
Limestone-shell stones are divided into grades: 4, 7, 10, 15, 25, 35, and 50. The strength of the stones is characterized by the compressive strength, determined by testing samples. The grade of the stone indicates the compressive strength in kg/cm².
Frost resistance of cut limestone is the ability of water-saturated stone to repeatedly withstand alternating freezing and thawing. The stone is considered frost-resistant if the average compressive strength limit of control cubes of the stone subjected to freezing and thawing is at least 75% of the average strength before the frost resistance test, and if no signs of destruction are found upon external inspection of the stone sample.
🔍It should be noted that the freshly extracted stone from most shell limestone quarries usually does not withstand frost resistance tests. This stone, after being exposed to air for 3 months, typically becomes frost-resistant. It can be assumed that the destruction of freshly extracted shell limestones occurs due to the filling of the naturally quarry moisture in the finest and deeply located capillaries of the stone. Complete water saturation of the stone is the reason for its destruction during freezing due to the increase in volume of the water freezing in the pores of the stone.
The pink, and less frequently light or yellowish-gray, medium and coarse-grained shell limestones of the Mangyshlak Peninsula in Kazakhstan have high decorative properties.
Limestone from Europe
In Europe, there are also many deposits of shell limestone. For example, in Germany (FRG) in Lower Franconia, Würzburg (Bavaria) and Jena (Thuringia), there are deposits of shell limestone with distinctly layered bedding.
🔍This stone was formed about 240 million years ago during the so-called Triassic period. This material has a color range from light gray shades to dark gray with a bluish tint. Depending on the layer of deposition, the material can have a coarse-pored structure or can be completely solid.
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🔍Currently, limestone is actively used as a finishing material, both in interiors and for the exterior decoration of buildings.
Characteristics of limestone
Due to its physicochemical characteristics, limestone can even be used as paving elements.
🔍Shell limestone facade
Some types of this stone can be polished well, which allows it to be used for making countertops in kitchen interiors.
🔍Given the limited annual extraction and processing of this stone, it is primarily used for the exclusive finishing of the exteriors and interiors of high-end real estate properties.
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