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Classification of Cracks | Treatment of Cracks in a Building

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Importance of Classification of Cracks

Cracks in a building are like ailments in human body. The building gets weaker and weaker if the cracks are not treated properly. The cracks give an impression of faulty and poor quality work. Moisture penetrates through the cracks and deteriorates the external facade as well as the internal facade. For determining a treatment procedure for the cracks, cracks have to be classified depending on its cause and nature. Different types of cracks have to be treated in different ways depending on its nature of occurrence.

Cracks in Buildings
Cracks in Buildings

In my earlier articles, I have discussed major and minor causes of cracks. Studying these causes also help in the classification of cracks.

Minor causes of Cracks

Major causes of Cracks

The classification of cracks is based on various factors:

  1. Direction of the cracks
  2. Extent of the cracks
  3. Width of the cracks (if tapers)
  4. Width of the cracks
  5. Depth of the cracks
  6. Alignment of the cracks
  7. Sharpness of the edges
  8. Cleanliness
  9. General

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Structures and Classification of Structures | Design of Steel Structures

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What is a Structure?

When any body is subjected to a system of loads and deformation takes place and the resistance is set up against the deformation, then, the body is known as structure. The structure are means of transferring forces and moments. The structures may be classified as statistically determinate structures and statistically indeterminate structures. When the equations of statistics are enough to determine all the forces acting on the structures, in the structures, then, the structures are known as statistically determinate structures.

Design of Steel Structures
Design of Steel Structures

When the equations of statistical equilibrium are not sufficient to determine all forces acting on the structure and in the structures, then the structures are known as Statistically Indeterminate Structures. The equations of consistent deformations are added to the equations of equilibrium inorder to analyse the Statistically Indeterminate Structures.

Classification of Structures

The structures are categorised by their supporting systems. There are one dimensional, two dimensional and three dimensional supporting systems.

  1. When a supporting system is subjected to only one type of stresses, then, it is known as basic system.
  2. When a system is subjected to simultaneously several types of stresses, then it is known as mixed system.

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Specifications for Plain Cement Concrete (PCC) | Building Estimation and Costing

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Plain Cement Concrete (PCC) is a construction material generally used as a binding materials and is composed of cement, (commonly Portland Cement) and other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate made of gravels or crushed rocks such as limestone or granite, plus a fine aggregate such as sand), water, and chemical admixtures.

Cement mixing with sand
Cement mixing with sand

In my earlier articles, I discussed types of specifications, purpose of specifications, RCC specifications, Specifications for Brick masonry in Cement Mortar, Coursed Rubble Masonry Specifications. In this article, we are going to discuss in detail various specifications that are to be given before the initiation of PCC work.

Specifications for Plain Cement Concrete (PCC)

Materials Specifications

Aggregate shall be of invert materials and should be clean, dense, hard, sound, durable, non-absorbent and capable of developing good bond with mortar.

Coarse aggregate shall be of hard broken stone of granite or similar stone, free from dust, dirt and other foreign matters. The stone ballast shall be of 20mm size and smaller. All the coarse material should be retained in a 5mm square mesh and should be well graded such that the voids do not exceed 42%.

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Specifications for Coursed Rubble Stone (CRS) Masonry

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Coursed Rubble Masonry

Masonry is affected by the use of low grade materials that is in case of stone masonry, use of low grade stones, improperly cut stones, chipped off stones etc. The mortar mix should follow a specific standard for the proper bonding between the joints of Course Rubble Masonry. Therefore, specifications have to be given for the materials used, the laying technique, Bond or Through stones, Quoins and curing – for the ultimate strengthening of the final masonry work.

Coursed Rubble Masonry
Coursed Rubble Masonry

In our earlier articles, we studied different types of specifications, purpose of specifications, RCC specifications, Specifications for Brick Masonry in Cement Mortar. We will be discussing Specifications for Plain cement concrete in our next articles. In this article, we are going to discuss in detail all the necessary specifications that are to be given for the construction of Coursed Rubble Masonry.

Specifications for Coursed Rubble Stone (CRS) Masonry

Material Specifications

Stone shall be hard, sound, free from decay and weathering. Stones with porous matter or with boulder skin shall be rejected. The size of stones shall not be less than 15cm in any direction.

Cement and sand for cement mortar or lime and surkhi for lime mortar shall be of standard specification.

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Specifications for Brick masonry in Cement Mortar

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Brick Masonry with Cement Mortar

Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone such as marble, granite, travertine, limestone, concrete block, glass block and tile. Masonry is generally a highly durable form of construction. Brick masonry construction involves use of high quality materials in construction. Use of low grade materials in construction or mortar mix in inappropriate ratio can affect the quality of construction.

In our earlier articles, we discussed different types of specifications and purpose of specifications, RCC specifications in detail. We will be discussing specifications for Coursed Rubble Masonry (CRS) and Specifications for Plain Cement Concrete (PCC) in our further articles. In this article, we are going discuss or rather list out all the specifications that are to be given for “Brick Masonry in Cement Mortar”.

Brick Masonry in Cement Mortar
Brick Masonry in Cement Mortar

Specifications for Brick masonry in Cement Mortar

  • The bricks shall be of first class, regular in shape, size and colour.
  • The bricks should be free from flaws, cracks and lumps of any kind.
  • Shall have minimum crushing strength 10.5N/mm2.
  • The bricks shall not absorb the water more than one sixth of the weight of the brick.

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Purpose of Specifications and types of Specifications

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What are Specifications?

Specifications describe the nature and the class of the work, materials to be used in the work, workmanship etc. and is very important for the execution of the work. The cost of a work depends much on the specifications. Specifications should be clear.

Types of Specifications
Types of Specifications

Purpose of giving Specifications

  • The cost of an unit quantity of work is governed by its specifications.
  • Specification of a work is required to describe the quality and quantity of different materials required for a construction work and is one of the essential contract documents.
  • This also specifies the workmanship and the method of doing the work. Thus specification of a work serves as a guide to a supervising staff of a contractor as well as to the owner to execute the work to their satisfaction.
  • A work is carried out according to its specification and the contractor is paid for the same. Any change in specification changes the tendered rate.
  • As the rate of work is based on the specification, a contractor can calculate the rates of various items of works in tender with his procurement rates of materials and labour. Thus tender rate without specification of works is baseless, incomplete and invalid.

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Methods to calculate Property Depreciation | Building Costing and Estimation

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Depreciation is the gradual exhaustion of the usefulness of a property. This may be defined as the decrease or loss in the value of a property due to structural deterioration, life wear and tear, decay and obsolescence.

Methods of Depreciation
Methods of Depreciation

Four Methods for calculating depreciation

  1. Straight line Method
  2. Constant percentage method
  3. Sinking Fund Method
  4. Quantity Survey Method

Straight Line Method

In this method, it is assumed that the property losses its value by the same amount every year. A fixed amount of the original cost is deducted every year, so that at the end of the utility period, only the scrap value is left.

Annual Depreciation, D = (original cost of the asset – Scrap Value)/life in years

For example, a vehicle that depreciates over 5 years, is purchased at a cost of US$17,000, and will have a salvage value of US$2000, will depreciate at US$3,000 per year: ($17,000 ? $2,000)/ 5 years = $3,000 annual straight-line depreciation expense. In other words, it is the depreciable cost of the asset divided by the number of years of its useful life.

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Major causes of Cracks in Buildings | Building Construction

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Causes of cracks in Buildings

In the previous article, we discussed the occurrence of cracks in buildings due to climatic factors and cracks occurred due to problem at the time of construction of the building. These fall under the category of Minor causes of Cracks in Buildings.

Now we will go ahead with our discussion on “Major causes of Cracks in a Building”.

Major causes of cracks in a building

  1. Movements of the ground
  2. Over loading
  3. Effect of gases, liquids and solids
  4. Effect of changes of temperature
  5. General causes such as vibrations etc
Unrestrained Movement of Building Materials
Unrestrained Movement of Building Materials

Movements of the ground

Mining subsidence, land slips, earthquakes, moisture changes due to clay shrinkable soils (for example, Black cotton soil).

Cracks occur because a part of the building is displaced from the rest without any change in the actual size of the material.

Overloading

  • Overloading of the ground
  • Overloading of the building itself
  • Overloading of the building parts result in cracks

For example; Cracks under a floor due to overloading of slab.

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Cracks in Buildings | Building Construction

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Cracks in Buildings

Cracks result in applied forces greater than those which the building or its part can withstand. These forces may have emerged externally to the building or internally within the building or have been developed in the materials of the building as a result of Chemical changes. There may be a single force or a combination of forces having a single cause or several causes.

Building at San Francisco
Building at San Francisco

This is a residential building at San Francisco. Major cracks have developed on the external facade of the building. The cracks running across the entire facade of the building are diagonally directed and diagonal cracks are generally structural cracks. They occur due to structural problems in the buildings. Structural cracks could be due to major or minor problem in the structural design. Intensity of structural problem is determined on the basis of the intensity of cracks developed.

Most cracks occur due to drying of construction water.

  • These are generally superficial
  • Do not affect the serviceability of the building
  • Can be easily repaired

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Design of India Habitat Centre, New Delhi, India

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Design of India Habitat Centre

Indian Habitat Centre is located in New Delhi, India. It was conceived to be a catalyst relationship between individuals and institutions that is, NGO’s working in habitat related areas to increase their effectiveness.

Architect of the India Habitat Centre

Joseph Allen Stein

India Habitat Centre, New Delhi, India
India Habitat Centre, New Delhi, India

Purpose of the Construction of Indian Habitat Centre

Indian Habitat Centre has been constructed for various activities apart for commercial purposes. It is a centre for cultural, economic and social activities. Dramas, plays are also organized at the centre. There is banquet hall and party lawn and also a Restaurant. Basically, it is open for public use also. . The Habitat Centre would be a home not only to those offices and research organizations but in order to facilitate their interaction, the centre provides a range of facilities like conference venues, exhibition halls, seminar rooms, restaurants and performance venues for cultural activities.

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