Defects in Buildings | Building Materials used in Construction
In my previous article, we began with a discussion on Building Materials used for Construction. We have already discussed the two major building materials such as Sand and Mud. Now we will go on and discuss the role of water, Cement and Cement Mortar in Construction.
Water in Construction
Salt free water should be used on the construction site for the mixing of cement. If salty water is used in the construction, it will result in formation of cracks in the building.
For example: Vishakhapatnam in Andhra Pradesh, India has brine water below 100’. That is why, the bore cannot be dug to more than 80’ feet for water to be used on the construction site.
Cement in Construction
There are various grades of cement available for the purpose of construction.
For example: M15, M20, M25 etc
The grade of cement to be used for construction is decided on the basis of the kind of construction and the structural design.
Cement is always used along with steel, that is RCC (Reinforced Cement Concrete) construction. Only cement cannot be used because it develops cracks.
Grooves are made over the layer of cement mortar.
For example: When cement flooring is done, a thin layer of cement is laid and grooves are made on the cement layer to prevent cracks.
Ratios of cement and sand in Mortar, RCC, Plastering and flooring
Cement +sand = Mortar
1 cement + 2 sand +4 steel = RCC
1 cement +6 sand = Plastering
1 cement + 8 sand = flooring
Role of Cement Mortar in Construction
Reasons for the development of cracks in cement mortar used in construction:
- Too much cement
- Too much water
- Too much sand
- Too less water
- No curing or less curing
- Vast expanses of plaster
Expansion co-efficient is different for different materials
For example, the co-efficient of expansion of wood is different from that of cement concrete.
That is why when cement concrete is used to along with wood, the bonding is not very strong.
Taking note of expansion co-efficient of various materials for the strength of the construction and proper bonding of materials to be used on site.