BRICK MASONRY

As bricks are comparatively small in size, they can be handled easily. Further, brick being uniform in size can be arranged systematically and bonded together with mortar to form a homogeneous mass, which is called brick masonry. The materials used for brick masonry are bricks, mortar and specially shaped bricks. Mortar helps to bind the individual bricks and to form a cushion to take up the inequalities in the brick and to distribute the pressure evenly and also to fill up the interstices in the bricks.

Terminology

Some of the terms which are used in brick masonry are defined below.

1. Header

A brick laid with its breadth or width parallel to the face or direction of a wall.

2. Stretcher

A brick laid with its length parallel to the face or direction of the wall.

3. Bed

The lower surface of a brick when laid flat.

4. Bat

A portion of a brick cut across the width.

5. Closer

A part of brick that is used to close up the bond at the end of brick course. The different closers are: (i) king closer, (ii) queen closer and (iii) bevelled closer.

6. Quoin

A corner of the external angle on the face side of a wall.

7. Squint

A brick cut to a special shape and used at oblique quoins.

Figure 16.1 shows courses of brickwork and Fig. 16.2 shows types of special bricks.

Figure 16.1 Courses of brickwork

Figure 16.2 Types of bricks

16.2.2 Brick Laying Tools

Main tools used for brick laying are trowel, plumb bob, bolster, tri-square, lime and pins, sprit level, and brick hammer. Figure 16.3 shows the above tools and is explained below.

Figure 16.3 Common brick laying tools

1. Trowel

Brick trowel is usually about 30 cm long with a steel blade and a handle. The blade has one straight edge and one end curved edge.

2. Tri-square

It is used to set out a right-angled corner. It is like a large triangle having two legs. It should be used carefully to set the first course.

3. Plumb Bob

It consists of a piece of thick straight wood ruler with a piece of string which is fixed in the wood at one end and the metal plumb bob at the other end.

4. Line and Pins

The two pins used for brickwork have flattened and blunt point ends for inserting into the joints of brickwork as work proceeds.

5. Sprit Level

It is used to level the brickwork. It consists of a hardwood stock with anything from two to six bubbles. These bubbles are small, sealed inside a glass tube.

6. Brick Hammer and Bolster

Cutting of bricks to provide suitable shapes for the bonding is done with the club hammer and bolster.

16.2.3 Materials Used

Bricks and mortar are the materials used. Bricks may be of first, second, third or fourth class depending on the type of work.

As a general rule, the strength of a mortar need not be more than that of the bricks. Plasters should be more plastic and made of fine sand. Sand for mortar should pass through 64 mesh and for plaster 12 mesh. Table 16.1 gives the recommended mortars for different brick strengths.

Table 16.1 Recommended mortars for brickwork

Combination mortar is more plastic than cement mortar. For low-strength bricks, mortars of low strengths as given below may be used.

Cement and sand mortar 1:8; Lime, surki and sand mortar 1:2:6

Lime and sand mortar 1:3; Cement, lime, surki and sand mortar 1:2:4:20

Cement, lime and sand mortar 1:4:14

Bonds in Brickwork

It is the process of arranging bricks in courses to ensure that vertical joints do not come one over the other. A wall built without any continuous vertical joint shall distribute the load properly and shall also be more strong and durable.

1. Stretcher Band

In this type of bond, all courses are laid as stretchers. As only stretchers are visible in elevation, this bond is referred to as stretcher bond. This is used for partition walls (Fig. 16.4(a)).

2. Header Bond

In this type of bond, all courses are laid as headers. As only headers are visible in elevation, this bond is referred to as header bond. This is used for one brick and curved walls (Fig. 16.4(b)).

Figure 16.4 Bonds in brickwork

3. English Bond

This bond is produced by laying alternate courses of stretchers and headers. In order to break the joints vertically, it is essential to use a closer after the header quoin in the heading course. This is the most commonly used bond which is also the strongest. This type of bond is used for walls carrying heavy loads. Figure 16.4(c) shows formation of a wall adopting English bond.

4. Flemish Bond

This bond is produced by laying alternate stretchers and headers in each course. The headers and stretchers appear in the same course alternately on the front and the faces. The queen closer is used next to the quoin header in alternate courses in order to break the continuity of the vertical joints. A header in any course is in the centre of a stretcher in the course above or below it. This bond is also used for walls to carry moderate loads. Figure 16.4(d) shows formation of wall adopting Flemish bond.

16.2.5 Comparison of English and Flemish Bonds

Table 16.2 gives a comparison of English and Flemish bonds.

Table 16.2 Comparison of English and Flemish bond

16.2.6 General Principles of Construction of Brick Masonry

Brickwork should be systematically done keeping in view the bonding, jointing and finishing. The laying of brick masonry is practically the same for all types of constructions. But some special considerations have to be given to each case. Mortar of 10 cm thickness is first spread.

Bricks soaked in water (so as to prevent absorption of moisture from the mortar) are placed over the mortar and pressed to ensure adequate adhesion. Both the longitudinal and cross joints are packed well with mortar. Proper bond is adopted and the brickwork is to be constructed in uniform layers. It is essential to check frequently the verticality of the walls and perpendicularity between the walls. The joints which are exposed are carefully finished by jointing or painting. At the end of a day’s work, the brickwork is raked back by stepping the brickwork. After construction, brickwork should be kept wet for two weeks. The following points should be observed while supervising the construction of brick masonry:

1. Bricks should conform to the specification and requirements of the work.
2. Bricks should be saturated well with water before use.
3. Bricks should be laid with frog upwards, with mortar completely covering the bed.
4. A suitable bond has to be used to avoid continuous vertical joints anywhere in the work.
5. A good quality mortar has to be used and the thickness of mortar should not be more than 10 mm.
6. The brickwork should be raised uniformly.
7. Brickbats should be minimised and to be used only in the required places.
8. In no case the height of masonry should be greater than 1 m in a day’s work.
9. All vertical faces should be checked with a plumb bob and wall junctions should be checked for perpendicularity.
10. After the construction is over, the brickwork should be watered well for two weeks.