Brick Masonry Walls
Brick masonry is the most commonly used masonry for Superstructure of buildings.
- Country bricks of size 230 x 110 x 70 mm, well burnt shall be used.
- Cement mortar 1:5 mix is to be used for bonding.
- Bricks are to be well soaked in water before use.
- For partition wall, 110mm thick bricks shall be used.
- For the main wall, 230 mm thick bricks shall be used.
Provision of Brick Pillars
The minimum size of brick pillars shall be of size by 340 mm x 340 mm. Brick pillar cannot restrain free movement of continuous RCC beams and hence such movement causes cracks at the end walls and also at the mid-height of brick pillars.
Slender brick pillars of size 230 mm x 230 mm should never be constructed as load-bearing masonry. Even in the case of larger sections of brick pillars, rich mix mass concrete (with nominal reinforcement) for 150mm height for the full cross-sectional dimension of brick pillar should be cast at mid-height of the pillar so as to eliminate shear cracks.
In coastal areas and in the areas where the structures will be subjected to high winds, independent brick pillars for supporting either RCC roof or tiled roof should not be constructed, as the masonry pillars will be subjected to tension. Only RCC columns should be adopted in these locations.
Inspection of Workmanship of Brick Masonry
Workmanship has a considerable effect on the strength of masonry and bad workmanship may reduce the strength of brick masonry to as low as half the intended strength. The basic compressive stress values for masonry would hold good for commercially obtainable standards of workmanship with a reasonable degree of supervision.
Close supervision, while the work is in progress, will ensure better quality with the material available for use. The following shall be observed at the time of inspection:
a) All loose materials, dirt, and lumps of mortar lying over the surface over which brickwork is to be removed with a wire brush.
b) All the bricks shall be thoroughly soaked in clean water immediately before use.
c) The surface over which the brickwork is to be started shall be slightly wetted.
d) The first course itself shall be made horizontal by providing enough mortar in the bed joint to fill up any undulations in the bed course.
e) Plastic mortar results in thorough bedding of the brick and more complete filling of the joints which ensure greater strength. Care shall be taken to see that the required quantity of water is added to the mortar at the mixing platform itself and not over the courses.
f) All the joints shall, as far as possible, be thin.
g) Care shall be taken to see that there is no through joints and the lap is not less than half the width of the brick and that all the vertical joints are properly filled with mortar.
h) The verticality of the walls and horizontality of the courses shall be checked very often with plumb bob and spirit level, respectively.
i) No portion of the work shall be left more than one lower than the other. Where the masonry of one part has to be delayed, it shall be ‘raked back’ suitably at an angle not exceeding 450 according to bond, and not toothed vertically.
j) Where plastering is required to be done, all the vertical, as well as horizontal joints, shall be raked to a depth of about 1 cm.
k) Care shall be taken to ensure that the brickwork is kept wet for seven days commencing from 24 hours after the course is laid.