Last updated: April 9, 2018

What Does Limestone Mean?

Limestone is a sedimentary rock mainly composed of calcium carbonate (CaCO3), usually in the form of calcite and aragonite. It may be crystalline, elastic, granular or dense, depending on the method of formation.

Limestone is commonly used as:

  • Building material
  • Aggregate for the base of roads
  • White pigment or filler in products such as toothpaste or paints
  • Chemical feedstock

Corrosionpedia Explains Limestone

Limestone is a sedimentary rock in the class known as chemical sedimentary rocks. Limestone is formed partly by chemical processes and partly biological process. Most limestone is composed of skeletal fragments of marine organisms such as coral. Pure limestone is white or almost white, but because of impurities, such as clay, sand, organic remains, iron oxide and other materials, many limestones exhibit different colors, especially on weathered surfaces.

Acids have a corrosive effect on limestone or marble buildings or sculptures. It is well established that either wet or dry deposition of sulfur dioxide significantly increases the rate of corrosion on limestone, sandstone and marble.

Limestone deposits can be found in:

  • Water pipes
  • Water heaters
  • Hot water tanks
  • Heat exchangers
  • Hot water reservoirs
  • Cooling systems

Limestone deposits lead to narrowing of the inside diameter of water pipes, and in extreme cases may cause complete blockage. Limestone deposits have been found in larger boilers that can measure up to several centimeters thick. They can cause serious technical problems for heating and water supply systems.

The buildup of limestone deposits inside heating systems and hot water reservoirs leads to the reduction of heat exchanged between the heating water or industrial water and the heat source. A 1mm thick deposit of limestone on the surface of heating coils may result in an energy loss of 10%.

Corrosion and limestone deposits in plumbing systems lead to broken pipes, blockages and eventual flooding. Increased energy and water consumption as well as all other related costs are results of diminished performance of heating installations.


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