What are the components of masonry mortar?

To fill and seal the irregular gaps between building blocks such as stones, bricks, and concrete masonry units, mortar is used to spread the weight of them evenly and sometimes to add decorative colors or patterns to masonry walls.As used between mud bricks, mortar includes pitch, asphalt, and soft mud or clay.Latin mortarium means crushed, and the word "mortar" comes from it.

Cement mortar becomes hard when it cures, resulting in a rigid aggregate structure, but it is easier and less expensive to repair than the building blocks.A mixture of sand, a binder, and water is used to make mortars.Portland cement is the most common binder since the early 20th century, but the ancient binder lime mortar is still used in some specialty new construction.Lime, lime mortar and gypsum in the form of plaster of Paris are used in historic buildings and structures so that the repair materials will be similar in performance and appearance to the original materials.There are several types of cement mortars.

The first mortars were made of mud and clay and were used in the 10th and 8th centuries BC.[2]

According to Roman Ghirshman, the first evidence of humans using a form of mortar was found in Pakistan.[3]

The plaster of Paris was used in the construction of many ancient structures.It requires a lower firing temperature to be made from gypsum.It is easier to make than lime mortar, which may be why it was used as the typical mortar in ancient, brick arch and vault construction.In damp conditions, gypsum mortar is not as durable as other mortars.[4]

There are multiple cement types found in the sites of the Indus Valley Civilization, with gypsum appearing at some of them.

In the construction of wells, drains, and on the exteriors of important looking buildings, gypsum cement was used that was light grey and contained sand, clay, traces of calcium carbonate and a high percentage of lime.Bitumen mortar was used in the Great Bath.[4][5]

The limestone blocks of the early Egyptian pyramids were bound by mud and clay.The mortar in Egyptian pyramids was made of gypsum or lime.The mixture of plaster and sand was soft.

Building with concrete and mortar was once common in Greece.A pozzolanic mortar 12mm thick was found in the underground aqueduct of Megara.The aqueduct was built around 500 BCE.Pozzolanic mortar is a lime based mortar that is made with volcanic ash that allows it to be hardened underwater.The Greeks obtained volcanic ash from the islands of Thira and Nisiros.The Romans improved their methods of making pozzolanic mortar and cement.The Romans introduced aluminum oxide and Silicon dioxide into the mix when they used a mortar without pozzolana.Because it was denser, this mortar was better able to resist penetration by water.[9]

There was a lack of volcanic ash in ancient China.The sticky rice soup was mixed with slaked lime to make a mortar that had more strength and water resistance than the lime mortar.[10][11]

It is not known how the art of making mortar and cement was lost for almost two centuries, despite the fact that it was widely used by both the Greeks and Romans.Lime was the only active ingredient in the mortar when Gothic cathedrals were being built.Many structures suffered over the centuries from wind-blown rain because cured lime mortar can be degraded by contact with water.

Ordinary Portland cement mortar is created by mixing powderedOrdinary Portland Cement, fine aggregate and water.

It was patented in 1824 due to efforts to develop stronger mortars.It became more popular than lime mortar as a construction material in the 1930's.Portland cement gives a faster pace of construction because it sets hard and quickly.Less skilled workers are needed to build a structure with Portland cement.

As a general rule, Portland cement should not be used for the repair or repointing of older buildings built in lime mortar, which require the flexibility, softness and breathability of lime if they are to function correctly.[13][12]

In the United States and other countries, five standard types of mortar are used for both new construction and repair.The mix ratio for each type of mortar is specified under the standards of the American Society for Testing and Materials.The strongest and weakest mortar products are designated by the letters M, S, N, O, and K.The mix ratio is always expressed by the volume of Portland cement.

The materials which are made by partially replacing the cement hydrate binders of conventional cement mortar with polymers are called PCM.There are latexes or emulsions, redispersible polymer powders, water-soluble polymers, liquid thermoset resins and monomers.When used to repair a brick, block or stone wall, the mortar may be bad for the environment because of its low permeability.It is designed to repair concrete structures.

The setting speed can be increased with the use of limestone in the kiln.It is necessary to store a lime as a dry powder.Adding pozzolanic material to the mortar mix is possible.The addition of pozzolanic material will make the mortar set quickly.

It would be difficult to use Portland cement mortars to repair older buildings.Lime mortar is softer than cement mortar, which makes it easier for brickwork to adapt to shifting ground or other changing conditions.Cement mortar is hard and inflexible.Where the two mortars are present in a single wall, the contrast can cause brickwork to crack.

Lime mortar can allow water to move through and evaporate from the surface.Walls that shift over time allow rain water to enter the structure.The lime mortar keeps the wall dry.Repointing or rendering an old wall with cement mortar can cause problems with water behind the cement.

Pozzolana is a volcanic ash.It was discovered and dug at the site of Mount Vesuvius in Italy.The Romans learned that adding pozzolana to lime mortar allowed it to set quickly.The Roman architect spoke of four types of pozzolana.It can be found in black, white, grey and red.The term Pozzolana has become a generic term for any siliceous or aluminous Additive to slaked lime.[15]

Finely ground and mixed with lime it is a strong mortar that can be set under water.

A firestop is a type of fire protection.Firestop mortars are used to stop large openings in walls and floors that need to have a fire-resistance rating.They can't be replaced with generic mortars without violating the listing and approval use and compliance.

Firestop mortar is a mixture of powder and water which forms a cementitious stone.It is sometimes mixed with lightweight materials.In an effort to prevent unlawful substitution and to enable verification of the certification listing, it is sometimes pigmented to distinguish it from generic materials.