September 2010 – Civil Engineering Projects

Design of Roads and Road Junctions

September 29, 2010 by Designer

Means of Vehicular Access – Roads

The general term in which we describe the means of Vehicular Access in one word is “Roads.” In this article, we are going to discuss in detail different types of roads for different purposes. We will also deal with the design factors that are to be considered while designing roads and Road Junctions.

Lets study the design of roads in a systematic way:

Means of Access and Design factors to be considered for the design of roads
Important elements to be considered in Road Design
Types of Road Junctions
Parking Methods

Here are the names of different types of roads for different types of vehicles and which depend on its width and purpose of construction:

Highways
Streets
Lanes
Pathways
Alley
Passageway
Carriageway
Footways
Square ways
Bridge ways

Testing for Hardened Concrete | Building Construction

September 25, 2010 by Designer

In my earlier article, we discussed “Tests for Fresh Concrete” in detail which will reduce the probability of failure that a building undergoes after the concrete hardens. In this article, we are going to discuss the “Tests for Hardened Concrete in Detail”.

Main objective of tests is to ensure properties of concrete vis-a-vis control quality and to adhere to the specifications. Properties of concrete are a function of time and ambient humidity.

Compression tests

Specimens used – Cube, cylinders and prisms.

Cube test

Tested normal (perpendicular) to the position of cart steel moulds of 150mm x 150mm x 150mm. Apply oil inside. Mould to be filled in 3 layers. Cone is filled to overflow and then it is compacted. Steel scale rule is used to chop off surplus (gives homogeneity)

Each layer is compacted with 35 strokes of 25 diameter steel squares pinner.

The specimen is stored for 24 hours at 18 to 22 degrees at relative humidity not less than 90%.

Mould is the removed and cured (simulating field conditions)

In compression test, cube is in contact with platens of the testing machine load is applied at constant rate of stern (15Mpa/minute)

Crushing strength is reported nearest to 0.5Mpa.

Remedial Measures to prevent failure of Concrete

September 24, 2010 by Designer

Remedies adopted to prevent failure of Concrete

Prevention of failure of Concrete will help preventing the building from failure. Good quality concreting strengthens the building and keeps it standing. Failure of Concrete results in structural failure of the building. Therefore, to prevent this from happening, measures have to be taken in order to strengthen the building and prevent it from structural failure.

Remedial Measures to prevent failure of Concrete

Capping

It does not affect the strength adversely and reduces scatter compared with uncapped specimens.

Grinding

Very good, expensive, very satisfactory results; it is done using silicon carbide abrasion. Specimens give same strength as cast face results.

Ideal capping shall have stress-strain properties similar to concrete, so that no splitting can take place and to achieve uniform stress distribution, it shall be 1.5mm to 3mm thick. A strong capping can increase the strength of the specimen.

Influence of capping is higher on high and medium strength concretes.

Capping can be done with neat cement after 2 hours of casting (to allow for plastic shrinkage of concrete). Dental plaster also can be used for capping due to its early strength gain and smooth finish it is viscous too. Do not use plaster of paris due to its low strength.

Tests for Fresh Concrete | Building Construction

September 22, 2010 by Designer

Tests for Concrete to be performed on site

Tests are held at 28 days, 7 days and 3 days. Constituent of mix should be such that concrete can be transported, placed and finished easily without segregation.

Workability – it is a property of fresh concrete and affects the finished product as it affects compaction.
Need for workability – Imparted by the amount of useful internal work necessary to provide full compaction.

Optimum water varies for different methods of compaction

i.e., more water – hand compaction – lower density
less water – mechanized compaction – higher density

If we add more water, the workability may increase may increase but core has more voids

5% of more voids – reduces strength by 30%
2% of more voids – reduces strength by 10%

The voids result due to –

The entrapped air voids are caused by grading of fine aggregate.

Excess water evaporating later excess – (water) voids are due to increase in workability

Aim should be to have maximum density – therefore for maximum compaction, you will have to have optimum water cement ratio, at which both the type voids are at minimum.

Classification of Cracks | Treatment of Cracks in a Building

September 9, 2010 by Designer

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.

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:

Direction of the cracks
Extent of the cracks
Width of the cracks (if tapers)
Width of the cracks
Depth of the cracks
Alignment of the cracks
Sharpness of the edges
Cleanliness
General

Structures and Classification of Structures | Design of Steel Structures

September 7, 2010 by Designer

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.

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.

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

Read more

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

September 5, 2010 by Designer

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.

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%.

Specifications for Coursed Rubble Stone (CRS) Masonry

September 3, 2010 by Designer

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.

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.

Specifications for Brick masonry in Cement Mortar

September 1, 2010 by Designer

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”.

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.