The Ancient Craft of Stone Masonry: Lime Mortar

Mutianyu Great Wall, Huairou, Beijing, 6th century BC, Photo: David Henderson

Did you know that lime mortar made with sticky rice soup holds the stones and bricks of the Great Wall of China together? It is why the fortifications survive. The Chinese also used sticky rice mortar  for pagodas and tombs. While QuarryHouse forgoes the rice, it still relies on lime mortar to translate the ancient craft of stone masonry into a modern vernacular. Early builders first made mortar employing mud and clay, but these did not perform well. Burning limestone and combining it with water and an aggregate produced a breathable and flexible substance that hardened through carbonization. 

Ktisis Floor Mosaic, cubes of marble and limestone embedded in lime mortar, Excavation at Antioch, 5th century AD

The use of lime mortar in Western civilization dates back to the ancient Egyptians, Greeks, and Romans. Egyptians incorporated it into their great pyramids, and the Greco-Romans utilized it in their architectural endeavors. Marcus Vitruvius Pollio, a Roman architect during the 1st century BC, furnished detailed information about the construction material in his treatise on architecture, De architectura. He credited the Greeks with developing it and provided recipes for it, depending on its usage. One of these was "mix your mortar, if using pitsand, in the proportions of three parts of sand to one of lime."

Lime mortar being applied on a stone wall in France, Photo: Berrucomons

In the 19th century, Portland cement was developed in England and became a popular substitute for lime mortar worldwide. Its name derived from its resemblance to Portland stone, a white-grey limestone island in Dorset, England. Builders liked it because of its strength, setting speed, and price point. However, it was also not flexible, causing buildings to crack. Lime mortar is more pliant, durable, long-lasting, and environmentally friendly. The Great Wall and ancient Greco-Roman structures have lasted for centuries without crumbling. Master stone masons like QuarryHouse still use lime mortar for these reasons.