Monthly ArchivesJuly 2020 - Q Green Techon PVT. LTD.

The common defects of brick masonry are described below.

Sulphate

The sulphate salt is present in the brickwork and it reacts with alumina content of cement and hydraulic lime in lime mortar and it causes a noticeable increase in the volume of the mortar. The result of this is the chipping and spalling of the bricks and form cracks in joints and rendering.

This defect occurs in where brickwork is exposed to boundary walls, parapets, etc. or it is in contact with the moisture like manholes, retaining walls, etc.

This problem is solved by using suitable construction and choosing materials that stop the moisture to enter in the brick work.

Crystallization of Salts in Bricks

The defects occur in the masonry made from bricks having excessive soluble salts. When the brick comes in contact with the water the soluble salts are dissolved and it appears in the form crystals on the brick surface. This is also called efflorescence.

This defect causes the disfigured the brickwork and makes look ugly of the brick. The efflorescence is solved by brushing and washing of surface repeatedly.

Corrosion of Iron or Steel

The iron and steel used in brickwork get corroded in the presence of dampness. With corrosion the metal expands in volume and also it can crack the brickwork.

The problem can be solved by encasing the reinforcement or iron in dense cement mortar and provides a cover of 15 to 25 mm around the embedded of steel.

Shrinkage on Drying

The brickwork is swelling with water absorption and shrinks when the water evaporates. The cracks are formed in the masonry joints when it shrinks. If there is a lean mortar is used the cracks are distributed over a large number of joints and if there is a rich mortar there are few cracks but they are wider. These cracks do not affect the structural strength of brickwork and it is easily improved.

All these problems can be solved with excellent quality bricks and protect it from the moisture.

The strength of the brick masonry is highly dependent on the strength of the bricks used in construction of a structure. Also, the strength of brick is depending on the soil used for making bricks, method, process, and burning of the bricks. As the nature of the soil is different in various regions the average strength of the bricks is also different in various regions.

Also, the permissible compressive stress of brick masonry depends upon several factors like

1. Types of Bricks (1^st Class, 2^nd Class, 3^rd Class)

2. Strength of Bricks

3. Size and Shape of construction

4. Mixing of Mortar

5. Uniformity of Bricks

6. Workmanship

7. Method used for laying bricks

There are various checklists which are applied for increasing strength of brick masonry

1. Visual Check

The brick used for masonry has to be good quality, burnt well with uniform shape, size, and color

2. The metallic sound should be produced by striking two bricks with each other

3. A high-quality brick should not break if it is dropped from one-meter height

4. The good quality brick should not absorb water more than 20% (by its weight) as it submerged in water for 24 hours