Mortar and their types

The term mortars is used to indicate a paste prepared by adding required Quantity of water to a mixture of binding material like cement or lime and fine aggregate like sand. There are different



types of mortars:-
  1. Bulk density
  2. Kind of binding material
  3. Nature of application
  4. Special mortars
  • Bulk density:- According to the bulk density there are two types of mortar:-
  1. Heavy mortars:- The mortars having bulk density of 15 Kn/m3 or more are known as the heavy mortars and they are prepared from heavy quartz's or other sands.
  2. Lightweight Mortars:- The mortars having bulk density less than 15kN/m3 are known as the lightweight mortars and they are prepared from light porous sands from pumice and other fine aggregates.
  • Kind of binding material:The kind of binding material foe a mortar is selected by keeping in mind several factors such as expected working conditions,hardening temperature,moisture conditions,etc.According to this kind of binding material,the mortars are classified into the following five categories:
  • Lime mortar
  • Surkhi mortar
  • Cement mortar
  • Gauged mortar
  • Gypsum mortar

  1. Lime mortar: In this type of mortar,the lime is used as binding material.The lime may be fat lime or hydraulic lime.The fat lime shrink to a great extent and hence it required about 2 to 3 times its volume of sand. The lime should be slaked before use. This mortar is unsuitable for water-logged areas or in damp situations.
  • 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.
  • Cement mortar: In this type of mortar,the cement is used as binding material.Depending upon the strength required and importance of work,the proportion of cement to sand by volume varies from 1:2 to 1:6 or more.It should be noted that surkhi and cinder are not chemically inert substances and hence they cannot be used as adulterants with matrix as cement.Thus the sand only can be used to form cement mortar.
  • Gauged mortar:To improve the quality of lime mortar and to achieve early strength,the cement is sometimes added to it.This process is known as the gauging.It makes a lime mortar economical,strong and dense.The usual proportion of cement to lime by volume is about 1:6 to 1:8 .It is also known as the composite mortar or lime-cement mortar and it can also be formed by the combination of cement and clay.This mortar may be used for bedding and for thick brick walls.
  • Gypsum mortar:These mortars are prepared from gypsum binding materials such as building gypsum and anhydrite binding materials
  • Nature of application:- According to this, there are two types of mortar:-
  1. Bricklaying mortars:- The mortars for bricklaying are intended to be used for brickwork and walls. Depending upon the working conditions and type of construction, the composition of masonry mortars with respect to the kind of binding material is decided.
  2. Finishing mortars:- These mortars include common plastering work and mortars for developing architectural or ornamental effects. The cement or lime is generally used as  binding material for ordinary plastering mortar.
  • Special mortars:-

  1. Fire-resistant mortar
  2. Lightweight mortar
  3. packing mortar
  4. sound-absorbing mortar
  5. X-ray shielding mortar.

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