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Mortar (masonry)

technology Maturity 11-13 Next article →

Mortar is a thick, workable paste used in building.

Three old bricks held together with mortar
Three old bricks held together with mortar

It serves a very important job in masonry. Builders use it to fill the irregular gaps between stones or bricks. This helps spread the heavy weight of the blocks evenly. It also seals the spaces to keep the structure tight. Sometimes, people even add colors to create pretty patterns on walls. While it is strong, mortar is often softer than the bricks it holds. This makes it a sacrificial element. This means it is easier and cheaper to fix than the building blocks themselves.

Making mortar is a simple process of mixing ingredients.

Most bricklayers mix sand, water, and a binder together. The binder is the special ingredient that makes everything stick. Since the early 20th century, the most common binder has been Portland cement. This type of mortar sets very hard and very quickly. However, builders still use older binders for special jobs. They might use lime or gypsum, which is used in plaster of Paris. These older materials are helpful when repairing very old, historic buildings.

Humans have been using mortar for thousands of years.

Qorogho Barelief (3)
Qorogho Barelief (3)

The first mortars were made of simple mud and clay. Evidence shows people used these in Jericho during the 10th millennium BC. Some evidence suggests humans in Baluchistan used sun-dried bricks and mortar in 6500 BC. In ancient Egypt, builders used mud and clay for early pyramids. Later pyramids used gypsum or lime instead. In China, builders around 500 CE even mixed sticky rice soup with lime. This created a very strong mortar that could resist water.

Different cultures found clever ways to make mortar work better.

Chetham's Library 2015 56
Chetham's Library 2015 56

The Greeks used a special kind called pozzolanic mortar. This was a lime-based mix that included volcanic ash. This ash allowed the mortar to harden even while underwater. The Romans later improved these methods to build their huge empires. They even made a version using crushed terra cotta. This version was very dense and kept water out well. These ancient discoveries helped create lasting structures like aqueducts and reservoirs.

Today, we use many different types of mortar for different needs.

Brick and block laying
Brick and block laying

In the United States, there are five standard types. They are named M, S, N, O, and K. Type M is the strongest, while Type K is the weakest. Scientists can even study old mortar to learn about history. As mortar hardens, it traps bits of the air from that time. This allows researchers to use radiocarbon dating to find out how old a building is. It is amazing how a simple paste can tell such big stories.

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🖼️ Images & Media (5)
File:Three old bricks held together with mortar.jpg
Three old bricks held together with mortar.jpg
File:Chetham's Library 2015 56.jpg
Chetham's Library 2015 56.jpg
File:Qorogho Barelief (3).jpg
Qorogho Barelief (3).jpg
File:Brick and block laying.jpg
Brick and block laying.jpg
File:Mortar mixed inside bucket.jpg
Mortar mixed inside bucket.jpg
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