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Type of portland cement

portland cement
Portland cement is widely used building material in construction industry. As per ASTM, portland cements are five types. These types are based on their rate of hydration and sulfate resistant properties.
The cement types are:
Type I
Type II
Type III
Type IV
Type V

A short description of every types are given below-

Type I: This is the general purpose cement. Normally this type of cement is used for general construction purpose such as bridge, building and precast construction.

Type II: Moderate sulfate resisting cement. This type of cement used where there is a possibility of sulfate attack to concrete. Such as sub structure. Type I and Type II almost same based on their properties.

Type III: This type of cement is high early strength cement and useful during cold weather concreting where quick strength gain is factor. This Type produce more heat than type I.

Type IV: Low heat of hydration. The name of this type of cement clears that it produce less heat during hydration process thus useful for hot weather concreting. This type of cement is also useful for producing large quantity of concrete.

Type V: High sulfate resistance cement. This type of cement is used where there is a possibility to contact high sulfate with concrete. The rate of hydration of this type of cement is slower than Type I.

These types of portland cement is produced by controlling percentage of constituents of cement. I will discuss about the constituents of various types of cement someday on this blog.

There are also other three type of cement which are produced by mixing air entraining agent with particular type of cement. Such as Type IA, Type IIA and Type IIIA.

You may like to read: Common problems of concreting and how to avoid them.


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Painting procedure on plastered surface inside room

painting procedure
Wall is being painted
Photo by joshwept
Plastic emulson paint is normally used for painting plastered wall surface inside room. Painting is done in four steps-
Surface preparation
Applying primer
Applying putty
Applying paint

Surface preparation:

Surface should be minimum 45 days old, well cured and completely dry. If there is any defect repair that with cement-sand mortar that is called patch work. Cure and dry the patch work. Apply a coat of lime-wash then allow it to completely dry. Then remove loose mortar, dirt or any other foreign material by applying sand paper on the surface.

Applying primer:

The main job of primer is to provide adhesion between the surface and the paint film. It also make the surface smooth, less absorbent and and increases the spreading ability of paint. Normally primer is applied by brush or roller. Before applying primer it is thinned with water. The coverage area of primer is 45 sqm/gallon.

Applying putty:

Putty is applied to repair cracks and to make smooth & level the surface. After applying putty the surface should be allowed to dry for 4 days. And then scrap off the surplus putty with sand paper.
Preparation of putty: Putty is prepared by mixing 1 gallon plastic paint, 1 litre enamel paint and 25 kg chalk powder with water.

Applying paint:

Paint is applied two or three coat on the surface. After completely drying up the putty the first coat of paint is applied by roller. The paint is thinned by mixing water. The water should be maximum 20% for 1st coat and maximum 15% for subsequent coats. After applying 1st coat surface should be allowed to dry for minimum 7 days before applying 2nd coat. And then 2nd coat of paint is applied on the surface. In this stage, if the surface is not smooth, luster, good opacity and spotless then the 3rd coat should be applied.
Before starting painting work some precautions should be taken.
Precaution: Don't paint during damp, hot and dry weather. Relative humidity should be above 20% and below 50%. Also avoid painting on surface having direct sun contact.

Photo by joshwept

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Overview of structural parts of building

A building is consists of many structural components. Generally, structural components are divided into two categories-
 
i) Sub structure and 
ii) Super structure

 

Sub structure:

The structure below ground level is called sub structureSub structure can also be divided into two parts- a) Foundation and b) Plinth

 

Foundation:

The most lower part of the building. The main function of the foundation is to transfer load to sub soil. It is the most important part of structure. Most of the failure of a structure may happen due to foundation failure. Foundation should be strong enough to meet the following requirements-
 
It should be strong enough to distribute the load to sub soil.
It is capable to support structure.

Read More: Types of Foundation
 

Plinth:

The part between surrounding ground level and ground floor of the building  is called plinth. The purposes of the plinth are-
  • Transfer the incoming load from super structure to the foundation.
  • Provide damp proof to the building
  • Support the back filling as a retaining wall.
  • Plinth also increases the esthetical look of the building.
Keep in mind that, sometimes, plinth isn't considered as sub structure and count it as an individual part of a structure.

 

Super structure:

The part above plinth level is called super structure. Super structure contains many other structural components. Such as-
 
Wall
Floor/Slab
Lintel and sunshade
Step and stair
Roof
 
Wall: Wall is used to separate the usable area of floor for different purpose. Such as bedroom, bathroom, kitchen, living etc. Other prime purpose of wall is to provide privacy and security.
 
Floor: The main purpose of floor is to provide better living space and support of occupants, furniture and other equipment of a building. The purpose of making different floor in different level of a building is to create more accommodation within limited space. Floor should be strong, durable, damp prove and heat protected.
 
Lintel and Sunshade: Lintel is provided for the purpose of supporting wall above door or window opening. Sunshade is generally combined with lintel above window opening to protect rain and sun.

Read More: Types of RCC Lintel
 
Step and Stair: Stair is made for easy communication among various floors of a building. Stair consists of steps. steps height should be comfortable enough for vertical movement.
 
Roof: The top most part of a building is the roof. Roof is build for the purpose of enclosing and protect the living area/floor area from weather effect. Roof should be stable, durable and weather resistant.
 
There are also others structural parts of a building. Such as water tank, septic tank and parapet etc. Septic tank and under ground water tank is completely separate structural part and not included in building structure. But, parapet and overhead water tank are parts of building structure.


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Quality assessment of some basic building materials on site

As we all know that it is essential to use quality building materials for sustainable structure. Testing for knowing quality of materials is done in laboratory. But most of the time it is not possible to do laboratory test physically on site. Then, when we receive materials on project how we test the quality of materials. In this situation we depend on our experience to visually justify the quality of materials. Below are some processes for justifying quality of some basic building materials on site-
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