Limestone, a sedimentary rock widely distributed on the earth’s surface, occupies a pivotal position in the development process of human civilization and modern architectural system. It seems ordinary, but with its unique formation process, rich characteristics and wide application, it has become a precious resource given to human beings by nature.

Limestone is mainly composed of calcium carbonate (CaCO₃), and its formation originates from a long period of geological history. In the ancient oceans, a large number of Marine organisms such as corals and shellfish, their bones and shells are rich in calcium carbonate. When these creatures died, their remains sank to the sea floor, where they accumulated, compacted, and geological processes over a long period of time, forming thick layers of calcium carbonate deposits. With the movement of the crust, some of the sedimentary layers emerged from the sea surface, continued to undergo wind and rain erosion, transport and other processes in the terrestrial environment, and eventually consolidated into the limestone we see today under the right geological conditions. Limestone is widely distributed throughout the world. From the White Cliffs of Dover in Europe, where pure white limestone cliffs stretch majestically along the English Channel, to the landscapes of Guilin in China’s Guangxi Province, limestone has been carved by water and time, creating a karst landscape of extraordinary peaks and caves. In addition, the United States, India, Brazil and other countries also have rich limestone resources, providing a solid foundation for the development of local and global related industries.

What are the properties of limestone?

Chemical stability: at normal temperature and pressure, the chemical properties of limestone are relatively stable. However, it can react with acids, such as reacting with hydrochloric acid to produce calcium chloride, water and carbon dioxide, which makes it have many applications in the chemical industry, such as for the preparation of carbon dioxide gas, and as an alkaline neutralizer in industrial wastewater treatment to regulate the pH of wastewater.

Hardness and texture: Limestone has a Mohs hardness of about 3 and a relatively soft texture, which makes it easy to mine and process. In the construction industry, limestone can be made into various shapes of building materials, such as SLATE, stone columns, etc., for building decoration through cutting, grinding and other processes. At the same time, because of its moderate hardness, in road construction, crushed limestone is often used as a road base material to provide a stable support structure.

Thermal decomposition characteristics: When heated to about 900℃ -1000 ℃, limestone will undergo a thermal decomposition reaction to generate calcium oxide (CaO, commonly known as quicklime) and carbon dioxide. This reaction is the core principle of lime production, and quicklime has a wide range of uses in construction, metallurgy, chemical and other industries, such as the manufacture of cement, as a slag forming agent in the process of steelmaking.