-Mortar is the term which is used to describe the paste obtained by the addition of water in the mixture of binding material like cement or lime and aggregate like sand in definite proportion.
-The binding material used may also be referred as matrix and the aggregate used may also be referred as adulterant. Hence, mortar is a mixture of matrix & adulterant.
Qualities of good sand to be used in preparation of mortar:-
(1) It should be free from the presence of organic and vegetative matter.
(2) it should be free from the presence of chemical salts.
(3) it should be comically inert. (should not react with binding material)
(4) it should be well graded.
Function of sand in Mortar:-
(1) To provide bulk: -sand in mortar does not gives strength to it but adds bulk or volume in the mortar. Thereby, helps in reducing its cost by increasing its volume.
(2) Strength: -Sand helps in adjusting the strength of the mortar that is achieved by increasing or decreasing its proportion in it.
(3) Surface area:-Sand subdivides the paste of binding material into numerous layers thereby, increases the surface area over which mortar can be spread or adhered. (4) shrinkage:- Sand in mortar prevents the shrinkage during its setting process.
Qualities of good mortar:-
(1) Mortar should not affect the durability of the construction unit in which it comes in contacts with.
(2) It should be capable of developing the design stresses.
(3) It should be capable of resisting the penetration of water through it.
(4) It should be cheap, durable and should posses high work ability (should not set early)
Types of mortar to be used for different construction activities
|Types of construction||Types of Mortar|
|(1) Pointing works||Cement mortar 1:1 maximum strength|
|(2) Damp proof course (DPC)||Cement mortar 1:2|
|(3) Concrete pavement||Cement mortar 1:2 (wear & tear)|
|(4) Plastering||Cement mortar 1:3 / lime mortar 1:2|
|(5) Masonary in super structure||Cement mortar 1:3 / lime mortar 1:2|
|(6) Masonary in fundation||Cement mortar 1:6 / lime mortar 1:3|