Limestone is a sedimentary rock that has been utilised by humankind for thousands of years. This timeline traces some of the key points in the history of limestone, from Egyptian pyramid building to modern day industries.
7000 – BCE Lime mortar floor
A lime mortar floor dating back to 7000 BCE is discovered in Yiftah El in modern Israel. It was apparently manufactured from hydrated lime produced by strongly heating limestone and then slaking the product.
2560 – BCE Limestone in pyramids and temples
Eocene limestone deposits flanking Egypt’s River Nile are extensively quarried to supply building materials to construct pyramids and temples. The Great Pyramid of Giza consists of about 2.3 million limestone blocks averaging 1 cubic metre with a mass of 2–3 tonnes.
300 – BCE Roman lime production technology
During the period 300 BCE to 200 CE, the Romans improve the technology of lime production and the making and use of lime mortar. Slaked lime mixed with volcanic ash found near Pozzouli at Naples Bay gave a type of cement that hardens both in air and under water.
10 CE – Lime cement in Roman roads
Towards the end of the reign of Emperor Augustus, the Roman Empire is divided into over 100 provinces connected by a network of over 350 roads. Lime cement serves as a base core as well as filler holding the blocks of roading stone together.
476 CE – Dark Ages – diminished use of lime
This is the traditional date for the end of the Roman Empire and, in Europe, the beginning of the Dark Ages. The use of limestone and lime in major construction work appears to have diminished in European societies during this time of political and social upheaval.
1240 – Great Tower of London whitened
During Henry III’s reign, an order is given to have the Great Tower of London “whitened both inside and out”. It is likely a slaked lime mixture (whitewash) was painted onto the stonework. Over time, calcium carbonate crystals form, giving a bright white appearance.
1368–1644 – Restoration of Great Wall of China
During the Ming Dynasty in China, restoration work is carried out on the Great Wall. This involves using huge amounts of lime mortar to cement the stonework in place.
16th century – Lime as agricultural fertiliser
The use of lime as an agricultural fertiliser becomes increasingly popular. Food production levels are greatly improved by crop rotation, the spreading of manure (both human and animal) and liming.
1756 – Hydraulic mortar
James Smeaton develops a type of cement that sets under water. By strongly heating a mixture of clay and limestone, the cement gives a more durable and stronger mortar. This new ‘hydraulic’ mortar is successfully used in construction of the third Eddystone lighthouse.
1824 – Portland cement
Joseph Aspdin patents a blend of limestone, clay and other minerals heated to a high temperature (calcined) and ground to a fine powder. It is called Portland cement as the concrete made from it looks like a widely used building stone known as Portland stone.
1926 – Plasticised PVC
Waldo Semen discovers a way of converting the plastic known as PVC into a more usable form. By blending PVC with additives like calcium carbonate, produced by grinding limestone, he finds a way to plasticise it, greatly increasing its commercial use.
1957 – Float glass method
Soda-lime glass is made by heating silica, sodium carbonate and lime to a very high temperature. Once formed, the molten glass can be made into plate glass by floating it on a bed of molten tin. Adrian Pilkington and Kenneth Bickerstaff invent this float glass method.
1980–90 – Paper manufacture and pcc
The paper-making industry undergoes a major change from acid to alkaline production methods, which involves replacing filler additives such as kaolin clay with a form of calcium carbonate known as pcc. The raw material used for the production of pcc is limestone.
21st century – 5000 million tonnes worldwide
Annual usage of limestone is 5000 million tonnes in building and construction, cement manufacture, agriculture and steel production. Many uses for calcium carbonate, directly sourced from limestone, have been found. Limestone is indeed a rock ‘fizzing' with applications.