WHEN TO USE WHAT GRADE OF MASONRY MORTAR?

From durability point of view, the grade of masonry mortar to be used for a given work is primarily dependent upon the following two factors.

Loading condition
Exposure condition

Considering the above two factors the suitable grade of masonry mortar to be used for different works is given in the following table. Generally cement mortar is used for most of the cases, therefore corresponding to the grade, proportion of cement mortar (i.e. cement to sand ratio) is also shown in the below table for a quick reference.

TYPE OF WORK VS GRADE OF MASONRY

Type of Work	Grade of Masonry Mortar	Corresponding Cement : Sand ratio
Masonry exposed to rain but protected by plaster	MM 0.7 (minimum), MM 2 (preferable)	1.:8 to 1:7
Masonry exposed to rain but not protected by plaster	MM 2 (minimum)	1:7
Load bearing wall	MM 0.5 (minimum), MM 0.7 (preferable)	1:8
For foundation work laid below damp proof course (Soil having little moisture)	MM 0.7 (minimum)	1:8
For foundation work laid below damp proof course (Very damp soil)	MM 0.7 (minimum), MM 2 (preferable)	1:8 to 1:7
For foundation work laid below damp proof course (Saturated soil)	MM 2 (minimum) MM 3 (preferable)	1:7 to 1:6
Building subject to vibration of machine	MM 3 (minimum)	1:6
For parapet wall (where height is greater than thrice the thickness)	MM 3 (minimum)	1:6
For parapet wall (where height is less than thrice the thickness)	As used in the wall
Bedding joints with large concrete block	MM 3 (minimum)	1:6