DIFFERENT TYPES OF MORTAR AND ITS FUNCTIONS
A paste obtained by adding water to a mixture of fine aggregates such as sand and binding material. The pyramids of the have been built with clay-gypsum, gypsum-lime and lime mortar.
The safety, strength and durability of resulting wall or any structure depends upon quality of mortar used as a binding medium.
The main functions of mortar are:
- Mortar acts as adhesive, binding the bricks or stones together in the solid mass.
- To protect the joints of the structure.
- To protect the surfaces of brick and stone masonry.
- To create an even bedding layer in between the different courses of masonry works and distribute the loads evenly on the lower layers.
- To form a matrix to hold the pieces of the stone together and form the mass of concrete.
- To fill the joints between the bricks or stones for making then water tight and to mould.
- To improve the appearance of the structure.
Types of Mortar:-
Cement mortar is a type of mortar where cement is used as binding material and sand is used as fine aggregate. Depending upon the desired strength, the cement to the sand proportion of cement mortar varies from 1:2 to 1:6.
Lime mortar is a type of mortar where lime (fat lime or hydraulic lime) is used as binding material and sand is used as fine aggregate. The lime to the sand proportion of cement mortar is kept 1:2. The pyramids at Giza are plastered with lime mortar.
Gauged mortar is a type of mortar where cement and lime both are used as binding material and sand is used as fine aggregate. Basically, it is a lime mortar where cement is added to gain higher strength. The process is known as gauging. The cement to the lime proportion varies from 1:6 to 1:9. Gauged mortar is economical than cement concrete and also possess higher strength than lime mortar.
Surki mortar is a type of mortar where lime is used as binding material and surki is used as fine aggregate. Surki mortar is economic.
Mud mortar is a type of mortar where mud is used as binding material and sawdust, rice husk or cow-dung is used as fine aggregate. Mud mortar is useful where lime or cement is not available.
Qualities or properties of mortar:-
- The mortar mix should be workable- easily transported to the place of application.
- It should develop adequate strength in tension, compression and bond for the work for it is used.
- It should capable of retaining sufficient water during it’s application.
- It should be sufficiently plastic easily placed on the bed is construction in the form of thin, smooth and uniform layer.
- It should be durable and strong in itself on drying and hardening at the same time. It should not react in anyway with construction units.
- It should set and garden quickly construction could be done with speed.
- It should not develop any cracks on drying and should be able to maintain their appearance for quite long period.
- It should capable of developing the designed stresses.
- It should be economical to make without compromising on any of the qualities.