Brick Work

Brick is very commonly used construction material in Sri Lanka. But it was seen that the quality of bricks varies to a larger extend. Bricks are molded either by machinery or by hand. The size of the brick is often smaller than the standard size of 225×112.5×75 mm in size.

1:5, cement: sand mortar was used in the site. English bond & Stretched bond were used in the walls construction with 10mm thick cement mortar joint. Before the construction, bricks should be immersed in water. If they are not soaked in water, the bricks would absorb water from cement mixture and this leads to a reduction in hydration reaction in cement and a reduction in the strength of wall. The courses are to be kept perfectly horizontal & every fourth course shall be checked for level & plumb. All walls are to be carried up uniformly & as regularly as possible.

English bond was used in partition wall construction (225mm thickness).

RULES FOR BONDING

1. The lap should be one-fourth of the brick.
2. The bricks should be uniform in shape and size.
3. The vertical joints should lie vertically above each other in the alternate courses.
4. Least number of bats should be used.

BONDING

The walls can be constructed in different bounds according to the thickness of the wall. If the long face of the brick is exposed, this is termed a ‘stretcher’ and if the end face is exposed, this is a ‘header’. The bond pattern is depending on the arrangement of headers and stretchers visible in the face of the wall. There are many types of brick bonds commonly used. In the site we used two types of bonds.

1. English bond
2. Stretched bond

English bond

The English bond was used for 225 mm brick wall. It have stretched layer and headed layer.

Stretcher bond

The stretcher bond have only stretcher course by shifting half of a brick. (Half brick thick wall)

MORTAR FOR BRICK WORK

Mortar is a mixture of cement, sand, and water. The primary function of the mortar is to bind the individual bricks together, so that the wall will act as large single unit. Mortar is used in all masonry units. So it is important to have an adequate consideration about mortar. The mortar is used not only as binding material, but also seal against air and moisture penetration. It also has responsible for the strength of the masonry. The mortar should be able to spread easily and remain plastically to long time for bricks or blocks to be adjusted to the required alignment and level. And also harden without unnecessary delay. It should have enough compressive strength.

The most commonly used cement in mortar is Ordinary Portland Cement and the sand is river sand. The sand, which contains approximately same size coarser particles, will be preferable. The water for mortar should be free from impurities to reduce adverse effects. Drinking water will be satisfactory.

The cracks in wall can be due to less water content in mortar, effects of applied loads and inadequate foundation condition. The unsatisfactory foundation conditions are a common course of cracking in masonry walls due to settlement or uplift of soil.

The overlapping arrangement of bricks in order to tie them together in a mass of brick work is known as “bonding”. Good bonding should have a minimum of vertical joints in any part of the work and it should not be continuous in two successive courses since it is a source of weakness.

Sand and cement measuring.

Sand: Cement ration is important factor that conceder when mixing the mortar. To measure sand, we used gauge box. Gauge box is 12”×12”×15” size box that can contain 1 bag (50kg) of cement.

Quantity of mortar and brick needed to area of 1m²

Bricks,

For 9” thick brick wall            = 59.25×2

                                                = 118.5 Nos.

Volume of mortar,

Volume of mortar       = (1×0.225) – (0.215×0.065×0.1025×118.5)

                                    = 0.06m³

Ratio,  1:5

Cement            = 0.06×                                                          Sand    = 0.06×

                        = 0.01m³                                                                      = 0.05m³

1m³                  = 1420kg

                        = 0.01×1420

Cement            =14.2kg (For 1m²)

CONSTRUCTION METHOD OF BRICK WORK

In constructing the walls strength is very important. Also careful handling in the construction stage is very important. To ensure the proper bonding all the bricks must be wetted before use.

In construction of wall, first of all two end corners were carefully laid, and then in between portion of wall were built. A cord stretched along the header & it helps in keeping the alignment of bricks & maintaining them in one level. Each corner was set vertical by plumb bob and bricks were adjusted until wall is true. Then the other bricks of that layer must be completed. For that, firstly mortar (1:5 cement: sand) was placed on the last completed course in uniformly. Then the bricks were pressed in to the mortar leaving space for vertical mortar joints. Then the vertical joint was filled with mortar. By repeating the above procedure the walls were constructed up to soffit level.

The each horizontal joint was raked out to minimum depth of 12mm by raking tool when the mortar is still green. The height of wall constructed per day must not exceed 1.5m.

When brick wall was constructed between columns, it was essential proper bonding between column and brick wall. 10mm diameter reinforcements call dowel were used to this purpose. While constructing the brick wall, reinforcements were inserted to those holes. The strength of the wall was improved using this dowels.

TERMS USED IN MASONRY

Course

The layer of brick laid on the same bed is known as a course. The thickness of the course is equal to actual thickness of the brick plus the thickness of one mortar joint.

Stretcher

The side of the brick when laid longitudinally and visible in elevation is called stretcher.

Header

The side surface of the brick when lay transversely and visible in elevation is called header.

Bond

Bonds are an arrangement of courses of blocks which no continuous vertical joints. In this arrangements blocks in wall are laid in each course in such a way that they over lap the block of the course laid immediately below.

MASONRY TOOLS

Trowel

It is available in varies size of trowel. Trowels are used for lifting and spreading mortar, for cutting block construction of joint.

Plumb bob

This helps in checking vertically of the block work.

Square

A wooden section. This is employed for checking perpendicular during construction.

Sprit level

This helps in checking the horizontality of the floors.

Measurement tape

For measuring purposes.