What is Mortar? Definition, Types, Properties and Uses

What is Mortar?

Mortar is a paste made by cement sand and water or by lime, surkhi and water. lime and cement are binding material in the mortar. sand and surkhi give the strength to the mortar. the strength of mortar decreases as the proportion of sand increases. a mix of 1 cement and 3 sand (1:3) is better mix the water required for a better result is 20 to 25 % as it gives the greatest strength of mortar.

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Types of Mortar

Accordingly, as the material used in mortar,

1. Lime Mortar                  A paste of lime and sand
2. Cement mortar              A paste of cement and sand
3. Surkhi Mortar               A  paste of lime and surkhi
4. Mud Mortar                  A clay of good consistency

1. Lime mortar - A lime mortar should be made of hydraulic lime, as none hydraulic lime sets very poorly. Mortar made of fat lime and sand cannot withstand the action of water. Therefore, fat lime mortar should not be used in wet places and in a soil that is constantly wet. Also, it should not be used for masonry construction underwater. Lime mortar is of two types.
1. Hydraulic Lime Mortar    2. Hydraulic Lime surkhi Mortar

2. Cement Mortar - It is prepared by mixing cement and sand in suitable proportion with an adequate quantity of water to bring the required consistency. The usual proportion of mix is one part of cement to two to six part of sand. The mortar should be used within 30 minutes after mixing i.e. prior to the initial setting of mortar.

3. Surkhi Mortar - This type of mortar is prepared by using fully surkhi instead of sand or by replacing half of sand in case of fat lime mortar. The powder of surkhi should be fine enough to pass BIS No. 9 sieve and the residue should not be more than 10% by weight. The surkhi mortar is used for ordinary masonry work of all kinds in foundation and superstructure. But it cannot be used for plastering or pointing since surkhi is likely to disintegrate after some time.

4. Mud Mortar - Mud mortar is made from clay nodules or lumps and are meant for cheap constructions and are commonly used in rural areas. Mud mortar is used for masonry works, floors and for plastering walls in low-cost house construction. In order to provide resistance to rain attack, the plastered surface is some times coated with bituminous material by spraying.

Properties of Mortar

1. It should be easily workable.
2. It should develop adequate strength in tension and compression.
3. It should be set quickly.
4. It should bind the brick or building stone properly.
5. It should be cheap.
6. It should be durable.
7. It should maintain the appearance for quite a long period.
8. It should be capable of resisting the penetration of rainwater.
9. It should not affect the durability of materials with which it comes in to contact.
10. It should have a good consistency.
11. It should possess the ability to retain adequate humidity during transportation and laying over a porous bed.

Uses of Mortar

1. Mortar is used to form a soft layer for bricks and stone in masonry work.
2. It is also used to distribute uniformly load over the lower brick or stone.
3. It is also used to bind the bricks and stones with each other.
4. It also provides water-tightness against the weather.
5. It is used as plaster or impermeable covering for walls and roofs.
6. It is also used as paint, which protects the joints of bricks or stones.
7. It is used to fill up the voids which remain in the structure.
8. It is used to repair cracks of any structure.
9. It is also used for various ornamental works to improve the general appearance of a building or structure.

Also, read - Tests on Bricks

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