System of Units and Measurement

Measurement 

Measurement is defined as the action of associating numerical with their possible physical quantities and phenomena. Measurement is a technique in which the properties of an object are determined by comparing them to a standard quantity. Also, measurement is the essential metric to express any quantity of objects, things and events. 

Unit 

Unit is defined as the physical quantity which is measured in terms of the chosen standards of measurement. The unit of a specified physical quantity can be considered as an arbitrarily chosen standard that can be used to estimate the quantities belonging to similar measurements. The units are well accepted and recognized by the people and well within all guidelines. 

System of Units 

The system of units is the complete set of units, both fundamental units and derived units, for all kinds of physical quantities. Each system is named with reference to fundamental units on which it is based. The common system of units utilized in mechanics is as follows. 

1) F.P.S or Foot-Pound System 

The F.P.S. system is a variant of the non-metric system, widely used in the states of the U.S. before the global audience universally accepted the S.I system. It uses the foot as the unit of measurement of length, and pound as the unit of mass and second as the unit of time. 

2) C.G.S or Centimeter-Gram-Second System 

The C.G.S. system is a metric system of measurement. This system uses centimeter, gram and second as the three basic units for length, mass and time respectively. 

3) M.K.S or Meter-Kilogram-Second System 

The fundamental units of length, mass and time are meter, kilogram and second respectively.

Fundamental Units

Every quantity is measured in terms of some internationally accepted units, called fundamental units. All the physical quantities in mechanics are expressed in terms of three fundamental quantities, i.e. Length, Mass and Time. 

1) Mass 

The fundamental property of all material things to resist any change in momentum is referred to as mass. It is independent of the object’s temperature, pressure or position in space. The downward force produced when a mass is in a gravitational field is referred to as weight. The metric units of mass are grams and kilograms, and both are mass units. The mass of an object can also include the total number of electrons, protons and neutrons, which an object contains.

2) Length 

Length is defined as the measurement or extent of something from end to end. The length of any object can be found in either way such as using a scale (i.e., ruler) or measuring tape. 

3) Time 

It is a concept for ordering the flow of events. Time is the change or the interval over which change occurs. It is impossible to know that time has passed unless something changes. It can be measured in terms of seconds, minutes, hours, days, weeks, months and years.

S.I. System of Units

In the year 1960, the Eleventh General Conference of Weights and Measures introduced the International System of Units. The International Standard Organization (ISO) and the International Electrochemical Commission endorsed the system in 1962. In October 1971 a replacement of the metric system of units was done with a new system called Systeme Internationale d’ Unites, International System of Units (S.I. Units).

Fundamental SI Units

Fundamental Quantity	SI Unit	Symbol
Length	Meter	M
Mass	Kilogram	kg
Time	Second	s
Electric Current	Ampere	A
Temperature	Kelvin	K
Luminous Intensity	Candela	cd
Amount of Substance	Mole	mol

Two supplementary units on the SI system are Radian and Steradian.

Quantity	SI Unit	Symbol
Plane Angle	Radian	rad
Solid Angle	Steradian	sr

1) Radian 

It is the unit of a plane angle. One radian is equivalent to an angle subtended at the center of a circle by an arc of length equal to the radius of the circle. 

Fig. 1 Radian

2) Steradian 

It is the unit of solid angle. One steradian is the solid angle subtended at the centre of a sphere, by the surface of a sphere which is equal in area to the square of its radius.

Fig. 2 Steradian

Properties of Fundamental Units 

Any standard unit should have the following properties. 

• Consistency or invariability 
• Availability or reproducibility 
• Imperishability or permanency 
• Convenience and acceptability

Derived Units

The units which are derived from the basic fundamental units are said to be derived units. These units are used to measure the physical quantities but the fact that these can be further resolved into simpler units or the fundamental units.

Quantity	Derived Unit	Symbol
Force	Newton	N
Moment	Newton-meter	Nm
Work	Joule	J
Power	Watt	W
Velocity	Meter per second	m/s
Pressure	Pascal or Newton per square meter	Pa or N/m2

Definition of Fundamental Units

1) Meter (m)

It is the unit of length. One meter is the distance traveled by light through a vacuum in 1/299,792,458 (3.33564095 x 10^-9) of a second. The meter was originally defined as one ten-millionth (0.0000001 or 10^-7) of the distance around the earth's surface, as measured in a great circle passing through Paris, France, from the geographic North Pole to the equator.

Fig. 3 A bar of platinum - iridium metre kept at a temperature of 0º C

2) Kilogram (kg)

It is the unit of mass. The value of the kilogram is now based on the Planck constant, which is 6.62607015 × 10^-34 Js. Prior to 2018, the kilogram was defined as the mass of a specific international prototype made of platinum-iridium and kept at BIPM (The International Bureau of Weights and Measures (Bureau International des Poids et Mesures)) headquarters. Before that, the kilogram was defined as the mass of one liter (10^-3 cubic meters) of pure water.

Fig. 4 The standard platinum - iridium is kept at the International Bureau of Weights and Measures in France

3) Second (s)

It is the unit of time. One second is the time that elapses during 9.192631770 periods of the radiation produced by the transition between two hyperfine levels of the Cesium-133 atom in an unperturbed ground state. It is also the time required for light to travel 299,792,458 (2.99792458 x 10^8) meters through a vacuum.

4) Kelvin (K)

It is the unit of thermodynamic temperature. The value of the Kelvin is now based on the Boltzmann constant, which is 1.380649 × 10^-23 J/K-1. Prior to 2018, a Kelvin was considered equal to 1/273.16 (3.6609 x 10^-3) of the thermodynamic temperature of the triple point of pure water (H2O).

5) Ampere (A)

It is the unit of electric current. The value of the ampere is now based on the elementary charge, which is 1/1.602176634 × 10^-19 times the elementary charge per second. Prior to 2018, the ampere was based on the force between two current carrying conductors that fixed the value of vacuum magnetic permeability at 4π × 10^−7 H m−1.

6) Candela (cd)

It is the unit of luminous intensity. The value of the candela is now based on the luminous efficacy of monochromatic radiation of frequency 540 × 1014 Hz, which is 683 lm/W. Prior to 2018, the candela was the measure of electromagnetic radiation, in a specified direction, that had an intensity of 1/683 (1.46 x 10^-3) watt per steradian at a frequency of 540 terahertz (5.40 x 10^14 hertz).

7) Mole (mol)

It is the unit of an amount of substance. The value of the mole is based on the Avogadro constant, which is 6.02214076 x 10^23 mol−1. One mole has exactly 6.022169 x 10^23 elementary entities.

Read More

Common Applications of Fluids

Fluids are used in a wide range of applications, often playing a vital role, without which, these applications will just cease to exist. The important thing to note is that most of the crucial applications of fluids are for generation of electricity or power. In hydroelectric power plants and automobiles, fluids are directly used to generate power or electricity. In thermal and nuclear power plants, fluids are indirectly used for generation of power, and still they are the dominant parts of these applications. It is not an overstatement to say that without fluids, the progress of the human race would stop. Some of the major applications are:

1) Hydroelectric Power Plants

In hydroelectric power plants, water is used to generate electricity on a large-scale basis. Water stored in the dam possesses potential energy, which is converted into the electrical energy in the power generation unit of the plant. Hydroelectric power plants are one of the major suppliers of power throughout the world. In some countries power requirements are fulfilled entirely by these plants. The discharged water from dams can be used for irrigation purpose also.

2) Hydraulic machines

Machines that operate on a fluid like water and oil are called hydraulic machines. The fluid has the capacity to lift heavy loads and exert extremely high pressures. Some hydraulic machines are used to perform various machining operations. In most of these machines, oil is used as the fluid. The oil is passed through the hydraulic motor which transfers large amounts of energy to the fluid. This high energy fluid enters the piston and cylinder arrangement where it can be used to lift heavy loads or apply large forces.

3) Automobiles

No automobile can run without fluid. Fluids perform three crucial operations in automobiles: generation of power, lubrication and cooling of the engine. Petrol or diesel generates provide power to combustion in the engine. This is commonly referred to as fuel. Oil is used for the lubrication of the engine and the gearbox and also various other moving parts of the vehicle. In larger automobiles like cars, busses and trucks, water is used for cooling the engine.

4) Refrigerators and Air Conditioners

This is another important area where fluids play a crucial role. In refrigerators and air-conditioners, the fluids are known as refrigerants. The refrigerant absorbs the heat from whatever is being kept in the chiller or evaporator, which is at a low temperature, and delivers that heat to the atmosphere, which is at a high temperature. In air conditioners, the refrigerant absorbs room heat and throws it in to the atmosphere, thereby keeping the room cool. The entire operation of refrigerators and air-conditioners depends on the use of a refrigerant.

5) Thermal Power Plants

In thermal power plants, water is used as the working fluid. After getting heated in a boiler, water is converted into superheated steam which is passes through the blades of turbines, thus rotating them. The shaft of the turbine rotates in the generator, where electricity is produced. Thermal power plants are one of the major suppliers of power in various parts of the world, and water working as the fluid is their most important component.

6) Nuclear power plants

Water is again a crucial power plant component. Here it is both the working fluid and a coolant. In some nuclear power plants, heat produced within the nuclear reactor is used to directly heat water, which is converted into steam. This steam is passed through the turbines similar to thermal power plants, rotating turbine blades to generate power. This is an application of water as the working fluid.

In other nuclear power plants, the heat from nuclear reactors is not used to generate steam directly. Heat is first used to heat the water, which acts as the coolant. This coolant then transfers the heat to a secondary coolant or the working fluid, which is again water and it is passed through the turbine to generate electricity.

7) Fluids as a Renewable Energy Source

There are number of fluids that are being used as a renewable energy source. Air or wind is one of the most popular sources of renewable energy. Wind is used for generation of electricity on a small as well as large scale basis. Water is used in tidal power plants to generate electricity on a small scale basis. Ocean waves are used to rotate turbine blades within the power generation unit. Bio diesel, a type of the vegetable oil, is used as a fuel for vehicles along with traditional diesel.

8) Operating Various Instruments

Compressed air is used for the operation of various types of instruments and automatic valves. These valves can be activated and deactivated by applying the pressure of compressed air. The pneumatic tools which work on compressed air are used for various applications like grinding, screwing and unscrewing various machinery parts etc.

Read More

Ingredients of Ordinary Concrete

Concrete is a heterogeneous composite material consisting of cement, water, fine aggregates and coarse aggregates. Aggregates occupy about 60 to 80 percent of the volume of concrete. The paste which is formed from cement and water constitutes 20 to 40 percent of the total volume. Concrete is one of the most frequently used building materials. The quality of the concrete is greatly depending upon the quality of paste, which in turn, is dependent upon the ratio of water to cement content used. To get quality concrete due attention should be paid in choosing the constituents, in mixing them in correct proportions, in mixing the concrete in correct manner and finally in using it properly followed by proper curing.

The ingredient of concrete can be classified in to two groups active group such as cement and water, inactive group such as fine and coarse aggregate.

Fine Aggregate

The particle that passes through 4.75 mm sieve and retain on 0.075 mm sieve is known as fine aggregate. The surface area of fine aggregates is higher. The voids between the coarse aggregate are filled up by fine aggregate. It reduces the cost of the concrete and increase the workability of concrete. The main characteristics of fine aggregate which affect in the properties of concrete is bulking. The phenomenon of increase in sand volume due to the increase of moisture content i.e. called Bulking of sand. The main causes of bulking of sand are the moisture content in the sand and it makes thin films around sand particles. Hence, each particle exerts pressure. Thus they move away from each other causing increasing in volume.

The bulking of the aggregates are dependent on two factors; the fineness of the aggregates and percentage moisture content. A fully saturated fine aggregate does not show any bulking. Thus when the sand contains sufficient moisture 12-20%, it occupies the same volume as when it was dry. The percentage of bulking is inversely proportional to the size of the fine aggregates. Hence, finer the sand more is bulking.

Coarse Aggregate

The particles that are retained on the 4.75 mm sieve are called coarse aggregate. Use of the largest maximum size of coarse aggregate permits a reduction in cement and water requirements. Using aggregates larger than the maximum size of coarse aggregates permitted can result in interlock and form arches or obstructions within a concrete form. That allows the area below to become a void, or at best, to become filled with finer particles of sand and cement only and results in a weakened area. Size of aggregate shall depend upon the type of work and the reinforcement. Size of aggregate should be less than the distance between two consecutive steel bars in RCC.

The main characteristics of fine aggregate which affect in the properties of concrete is crushing strength of aggregate. The crushing strength of aggregate defines as the resistance of aggregate to the compressive load. The compressive strength of concrete is depending on the strength of aggregate.

Cement

Cement is the most important ingredient of concrete act as a binding material having both adhesive and cohesive properties. Cement binds the coarse and fine aggregate by filling the voids and chemically reacting with water. It contains about 10% of the volume of concrete mix. The type of cement to be selected for concrete is based on the factors like type of work, site condition, transportation time etc. The different types of cement are ordinary portland cement (OPC), portland slag cement, portland pozzolana cement, white cement, sulphate resisting cement, low heat cement, rapid hardening cement, quick setting cement, blast furnace slag cement, high alumina cement, colored cement, expansive cement etc.

Water

Water is an important ingredient of concrete without which concrete cannot be manufactured. Water in concrete making is used for mixing, washing aggregate and curing. In general, water which is acceptable for drinking purpose is suitable for making the concrete. The main harmful substance in water for concrete is salt which is present in sea water. The salts present in sea water reduce the strength of concrete, but sometimes it has to be used when there is no alternative. Sea water contains up to 3.5% salt and has tendency to decrease the strength 10% - 20% of the concrete. There is more chance of causes of dampness and surface efflorescence in building.

Admixtures 

Admixtures are optional in concrete. This is used for the special purposes like to increase or decrease the initial or final setting time of the concrete, workability of concrete etc. Admixtures are used in special cases only. Type of admixtures used in concrete includes accelerators, retarders, water-reducing agents, super plasticizers, air entraining agents etc. The proportion of all the ingredients of concrete is considered as per grade of the concrete or as per mix design of concrete.

Read More

Soil and Soil Mechanics

The word “Soil” is derived from the Latin word “solum” which, according to Webster’s dictionary, means ‘the upper layer of the earth that may be dug or plowed specifically, the loose surface material of the earth in which plants grow’. The term ‘Soil’ has different meanings in different scientific fields. To an agricultural scientist, it means ‘‘the loose material on the earth’s crust consisting of disintegrated rock with an admixture of organic matter, which supports plant life’’. To a geologist, it means the disintegrated rock material which has/has not been transported from the place of origin.

But, to a civil engineer, the term ‘soil’ means, the loose unconsolidated inorganic material on the earth’s crust produced by the disintegration of rocks, overlying hard rock with or without organic matter. Foundations of all structures have to be placed on or in such soil, which is the primary reason for its engineering behaviour.

In general, soils are formed by weathering of rocks. The formation of soil happens over a very long period of time. The physical properties of soil are dictated primarily by the minerals that constitute the soil particles and, hence, the rock from which it is derived. The mineral grains that form the solid phase of a soil aggregate are the product of rock weathering. The size of the individual grains varies over a wide range. Many of the physical properties of soil are dictated by the size, shape and chemical composition of the grains.

Soils are formed over thousands of years through the weathering of parent rocks, which can be igneous, sedimentary or metamorphic rocks. Igneous rocks (e.g., granite) are formed by the cooling of magma (underground) or lava (above the ground). Sedimentary rocks (e.g., limestone, shale) are formed by gradual deposition of fine soil grains over a long period. Metamorphic rocks (e.g., marble) are formed by altering igneous or sedimentary rocks by pressure or temperature or both. Soils are quite different from other engineering materials, which makes them interesting and at the same time challenging.

Soil Mechanics

Karl Terzaghi (an Austrian geotechnical engineer, and geologist known as the "father of soil mechanics and geotechnical engineering) defined Soil Mechanics as follows:

“Soil Mechanics is the application of the laws of mechanics and hydraulics to engineering problems dealing with sediments and other unconsolidated accumulations of solid particles produced by the mechanical and chemical disintegration of rocks regardless of whether or not they contain an admixture of organic constituents.”

The term Soil Mechanics is now accepted quite generally to designate that discipline of engineering science which deals with the properties and behavior of soil as a structural material. All structures have to be built on soils. The application of the principles of soil mechanics to the design and construction of foundations for various structures is known as ‘‘Foundation Engineering’’. ‘‘Geotechnical Engineering’’ may be considered to include both soil mechanics and foundation engineering.

History and Development of Soil Mechanics

The use of soil for engineering purposes dates back to prehistoric times. Soil was used not only for foundations but also as construction material for embankments. The knowledge was empirical in nature and was based on trial and error, and experience. The hanging gardens of Babylon were supported by huge retaining walls, the construction of which should have required some knowledge of earth pressures. The large public buildings, harbours, aqueducts, bridges, roads and sanitary works of Romans certainly indicate some knowledge of the engineering behaviour of soil. This has been evident from the writings of Vitruvius, the Roman Engineer in the first century, B.C. Mansar and Viswakarma, in India, wrote books on ‘construction science’ during the medieval period.

The Leaning Tower of Pisa, Italy, built between 1174 and 1350 A.D., is a glaring example of a lack of sufficient knowledge of the behaviour of compressible soil, in those days. Coulomb, a French Engineer, published his wedge theory of earth pressure in 1776, which is the first major contribution to the scientific study of soil behaviour. He was the first to introduce the concept of shearing resistance of the soil as composed of the two components— cohesion and internal friction. Poncelet, Culmann and Rebhann were the other men who extended the work of Coulomb. D’ Arcy and Stokes were notable for their laws for the flow of water through soil and settlement of a solid particle in liquid medium, respectively. These laws are still valid and play an important role in soil mechanics.

Rankine gave his theory of earth pressure in 1857; he did not consider cohesion, although he knew of its existence. Boussinesq, in 1885, gave his theory of stress distribution in an elastic medium under a point load on the surface. Mohr, in 1871, gave a graphical representation of the state of stress at a point, called ‘Mohr’s Circle of Stress’. This has an extensive application in the strength theories applicable to soil. Atterberg, a Swedish soil scientist, gave in 1911 the concept of ‘consistency limits’ for a soil. This made possible the understanding of the physical properties of soil.

The Swedish method of slices for slope stability analysis was developed by Fellenius in 1926. He was the chairman of the Swedish Geotechnical Commission. Prandtl gave his theory of plastic equilibrium in 1920 which became the basis for the development of various theories of bearing capacity. Terzaghi gave his theory of consolidation in 1923 which became an important development in soil mechanics. He also published, in 1925, the first treatise on Soil Mechanics, a term coined by him. Thus, he is regarded as the Father of modern soil mechanics’. Later on, R.R. Proctor and A. Casagrande and a host of others were responsible for the development of the subject as a full-fledged discipline.

Application of Soil Mechanics

1) Foundations

The loads from any structure have to be ultimately transmitted to a soil through the foundation for the structure. Thus, the foundation is an important part of a structure, the type and details of which can be decided upon only with the knowledge and application of the principles of soil mechanics. A foundation is termed shallow foundation when it transmitted the load to upper strata of earth. A foundation is called deep foundation when the load is transmitted to strata at considerable depth below the ground surface. Pile foundation is a type of deep foundation.

Shallow Foundation

Deep Foundation

2) Earth-Retaining Structures

When sufficient space is not available for a mass of soil to spread and form a safe slope, a structure is required to retain the soil. An earth retaining structure is also required to keep the soil at different levels on its either side. The retaining structure may be rigid retaining wall or a sheet pile which is relatively flexible. Such as retaining walls can be designed and constructed only by using the principles of soil mechanics and the concept of ‘soil-structure interaction’.

Retaining Wall

Sheet Pile

3) Stability of Slopes

If soil surface is not horizontal, there is a component of weight of the soil which tends to move it downward and thus causes instability of slope. The slopes may be natural or man-made. Soil engineering provides the methods for checking the stability of slopes.

Embankment Slope

4) Underground structures

The design and construction of underground structures, such as tunnels and conduits, require evaluation of forces exerted by the soil on these structures.

Tunnel

5) Pavement Design

Pavement Design may consist of the design of flexible or rigid pavements. Flexible pavements depend more on the subgrade soil for transmitting the traffic loads. Problems peculiar to the design of pavements are the effect of repetitive loading, swelling and shrinkage of sub-soil and frost action. Consideration of these and other factors in the efficient design of a pavement is a must and one cannot do without the knowledge of soil mechanics.

Pavement

6) Excavations, Embankments and Dams

Excavations require the knowledge of slope stability analysis; deep excavations may need temporary supports such as ‘timbering’ or ‘bracing’, the design of which requires knowledge of soil mechanics. Likewise the construction of embankments and earth dams where soil itself is used as the construction material requires a thorough knowledge of the engineering behaviour of soil especially in the presence of water.

Earth Dam

7) Miscellaneous Soil

The geotechnical engineer has sometimes to tackle miscellaneous problems related with soil. Such as soil heave, soil subsidence, frost heave, shrinkage and swelling of soils.

Read More

Fine aggregate/Sand

Aggregate is the granular material used to produce concrete or mortar. Sand is a form of silica (quartz) and may be of argillaceous, siliceous or calcareous according to its composition. Natural sands are formed from weathering of rocks (mainly quartzite) and are of various size or grades depending on the intensity of weathering. The sand grains may be of sharp, angular or rounded. Aggregates passing through 4.75mm sieve and retained on 75micron sieve is termed as fine aggregate.

Fine aggregate sand is important ingredient of mortar and cement concrete. Sand particles consist of small grains of silica. It is formed by decomposition of sand stone due to various effects of weather. River sand is widely used as fine aggregate. Fine aggregates are classified as follows: 

1. Source of Origin 
2. Grain Size 
3. Composition

I) Classification according to Sources of Origin

Sand particles consist of small grains of silica (Si02). It is formed by the decomposition of sand stones due to various effects of weather. The following are the natural sources of sand.

1) Pit Sand

This sand is found as deposits in soil and it is obtained by forming pits to a depth of about 1m to 2m from ground level. Pit sand consists of sharp angular grains, which are free from salts for making mortar. Clean pit sand free from organic matter and clay should be used.

Pit Sand

2) River Sand

This sand is obtained from beds of rivers. River sand consists of fine rounded grains. Colour of river sand is almost white. As the river sand is usually available in clean condition, it is widely used for all purposes.

River Sand

3) Sea Sand

This sand is obtained from sea shores. Sea sand consists of rounded grains in light brown colour. Sea sand consists of salts which attract the moisture from the atmosphere and causes dampness, efflorescence and disintegration of work. Due to all such reasons, sea sand is not recommendable for engineering works. However be used as a local material after being thoroughly washed to remove the salts.

Sea Sand

The natural product which is obtained as river sand & pit sand is called sand.

II) Classification Fine Aggregate According to Grain Size

Fine aggregate	Size variation (mm)
Coarse Sand	0.5 – 2.0
Medium sand	0.25 –  0.5
Fine sand	0.060 – 0.25
Silt	0.0020 – 0.06
Clay	<0.002

III) Classification Fine Aggregate According to Composition 

1) Clean Sand 

These are well-graded sand containing quartz particles in a wide range of grain sizes. 

2) Silty Sand 

These are poorly graded, having a considerable proportion of silt and other non-plastic fines. 

3) Clayey Sand 

There is poorly graded sand that has a prominent clay fraction and also plastic fines.

Requirement of good sand

1. It should be hard
2. It should be chemically inert
3. It should be free from salts
4. It should free from organic matters
5. It should be well graded

Uses of sand

1. It is used in mortar
2. It is used in concrete
3. It is used for the filling the gaps between the building blocks
4. It is used as binding materials in the form of paste
5. It prevents the shrinkage of cementing materials.

Alternatives to river sand

Sand is a vital ingredient in making two most used construction materials viz. cement concrete and mortar. Traditionally River sand, which is formed by natural weathering of rocks over many years, is preferred as fine aggregate. The economic development fuelling the growth of infrastructure and housing generates huge demand for building materials like sand. The indiscriminate mining of sand from riverbeds is posing a serious threat to environment such as erosion of riverbed and banks, triggering landslides, loss of vegetation on the bank of rivers, lowering the ground water table etc. Demand for sand is increasing day by day and at the same time mining threats cannot be ignored. Hence, sand mining from riverbeds is being restricted or banned by the authorities like National Green Tribunal, State Environmental Impact Assessment Authority and Pollution Control Board. Hence it is necessary to find and use the alternative for river sand.

Some of the Alternatives to River sand are:

• Manufactured sand
• Processed quarry dust
• Processed crushed rock fines
• Offshore sand
• Processed glass
• Aluminum saw mill waste
• Granite fines slurry
• Washed soil (filtered sand)
• Fly ash (bottom ash/ pond ash)
• Slag sand
• Copper slag sand
• Construction Demolition waste

Manufactured Sand (M-Sand)

Manufactured sand is an alternative for river sand. Due to fast growing construction industry, the demand for sand has increased tremendously, causing deficiency of suitable river sand in most part of the word. Due to the depletion of good quality river sand for the use of construction, the use of manufactured sand has been increased. Another reason for use of M-Sand is its availability and transportation cost. Since manufactured sand can be crushed from hard granite rocks, it can be readily available at the nearby place, reducing the cost of transportation from far-off river sand bed. Thus, the cost of construction can be controlled by the use of manufactured sand as an alternative material for construction. The other advantage of using M-Sand is, it can be dust free, the sizes of M sand can be controlled easily so that it meets the required grading for the given construction.

M-Sand

Advantages of Manufactured Sand

• It is well graded in the required proportion. It does not contain organic and soluble compound that affects the setting time and properties of cement, thus the required strength of concrete can be maintained. 
• It does not have the presence of impurities such as clay, dust and silt coatings, increase water requirement as in the case of river sand which impair bond between cement paste and aggregate. Thus, increased quality and durability of concrete.

Read More

Types of Drawings

Drawing

A drawing is a graphic representation of an object, or a part of it and is the result of creative thought by an engineer or technician. Graphic communication involves using visual materials to relate ideas. Drawings, photographs, slides, transparencies and sketches are all forms of graphic communication. One of the most widely used forms of graphic communication is the drawing.

Technically, it can be defined as “a graphic representation of an idea, a concept or an entity which actually or potentially exists in life”. Drawing is one of the oldest forms of communicating, dating back even farther than verbal communication. The drawing itself is a way of communicating all necessary information about an abstract, such as an idea or concept or a graphic representation of some real entity, such as a machine part, house or tools. There are two basic types of drawings: Artistic and Technical drawings.

1) Artistic Drawings

Artistic Drawings range in scope from the simplest line drawing to the most famous paintings. Regardless of their complexity, artistic drawings are used to express the feelings, beliefs, philosophies and ideas of the artist. In order to understand an artistic drawing, it is sometimes necessary to first understand the artist. Artists often take a subtle or abstract approach in communicating through their drawings, which in turn gives rise to various interpretations.

Artistic drawing

2) Technical Drawings

The technical drawing is not subtle, or abstract. It does not require an understanding of its creator, only an understanding of technical drawings. A technical drawing is a means of clearly and concisely communicating all of the information necessary to transform an idea or a concept in to reality. Therefore, a technical drawing often contains more than just a graphic representation of its subject. It also contains dimensions, notes and specifications.

                      Technical drawing

Purpose of Technical Drawings

To appreciate the need for technical drawings, one must understand the design process. The design process is an orderly, systematic procedure used in accomplishing a needed design. Any product that is to be manufactured, fabricated, assembled, constructed, built or subjected to any other types of conversion process must first be designed. For example, a house must be designed before it can be built.

Application of Technical Drawing

Technical drawings are used in many different applications. They are needed in any setting, which involves design and in any subsequent forms of conversion process. The most common applications of technical drawings can be found in the fields of manufacturing, engineering and construction. For instance, surveyors, civil engineers, sanitarians use technical drawings to document such works as the layout of a new subdivisions or the marking of the boundaries for a piece of property. Construction personnel use the technical drawings as their blue prints in converting architectural and engineering designs into reality.

Read More