HAND MIXING OF CONCRETE -- PROCEDURE AND PRECAUTIONS

 Concrete is mixed by any two methods based on requirement as per quality and quantity of concrete required, Normally for mass concrete where good quality of concrete is required, where mechanical mixture is used.

Carrying out hand mixing of concrete required special skills and care during the process of quality control of fresh concrete. The precaution and the correct way to performing hand mixing of concrete is to undergo the mixing process as recommended by stander procedure.

Mixing  by hand is employed only to specific cases where quality control is not of much important and quantity of concrete is less.  Stone aggregate is washed with water to remove dust or any other forign material before mixing.

The main purpose is mixing the concrete is to finally obtain a uniformly mixture that shows uniformity in term of color or consistency.

Procedure of Hand mixing of Concrete

1. Measured quantity of sand evenly.

2. Required quantity of cement spread evenly upon the sand

3. The sand and cement is then mixed immedietly, turning the mixing over and over again. untill it is an even color.

4. The sand cement mixture is spread throughout, Then coarse aggregate spread on his top . Then mixing over and over again. 

5. A hollow is made in the middle of mixed pile.

6. Three quater of  middle of quantity of water is added while the materials turns towards centre of spread , last the remaining quantity of water is added over the fitted with rose head then slowly turning the whole mixture over and over again untill the uniformly color consistency is obtained throughout the pile.

7. 5 percent extra cement is added then the specific the machine mixing, when hand mix cement is produced. 

8. The required personal protective equipment shale be worn by the labour and masson while mixing and handling the concrete. The mixing platform should be washed at the end of the day.

Precautions during Hand mixing of Concrete

1. The hand mixing procedure have to be carried out only for small or minimum concrete.

2. The handmixing procedure the employes only for work that will give adequate interval of mixing.

3. The mixing procedure have to be conducted on a water tight platforms.

4. The floor must have one bag of cement at a time in there respective materials.

5. Initially the measured accurate quantity of cement is mixed properly over the water tight platforms.

6. The coarse aggregate have to be placed over this bed of uniform mixture.

7. The addition of water must be done in interval or not in a single streach.

8. The whole mixing must be done unoformly without a hurry.

9. A good and clean showel should be done withmixing procedure.

10. Over mixing of the concrete mixture have to be avoided.

ELECTRO KINETIC ROAD RAMP

Introduction

Among the all form of energy the electricity is most widelyused from of energy. There is great lack of electricity in today's world, which we can overcome. As we know the vehicle on road are increasing very fastest n the world. Vehicle are moving on the road they process some kinetic energy. Which can be used generating rotational motion for generator and then we can produced considerable amount of electricity. As we know that the resources to generator the electricity are lasting very rapidely. And there is great increase in population which used the electricity for their day to day requirements. These has generater the probleam of energy crisis in the world. So we need to brings such ideas which can generate electricity from the things which we can used in daily life. So form the vehicle we can generate the electricity by using their kinetic energy as these vehicle passes over the ramp. This generated energy can be utilised for many purpose like street light, toll plaza villages , lighting of signals where the lack of electricity is more.

Roads in India

The India has second largest road network in the world , which conduced of over 5000000 km. Among which 1450 km of expressway are operational now a day in India.

The 145000 km of a state highway are operational in India and the maharastra state has over 30000 km of state highway which is largest of state highway as compared to others state.

And additional over 18000 km of expressway is aim to ber constructed by Govt. of In dia by the year 2022, National Highway Authority of India which is responsible for developments managements of the network of over 50000 km of a national highway out of 115000 km in India. So using these road network and vehicle we can generate electricity using Electro Kinetic Road installed on road.

Methodology

• First moving car pass over the road. Due to vehicle road pressure plate presents on the road will be pressed down.
• All pressure plates are connected to shaft using racks and pinion mechanism.
• Rack and pinion mechanism convert the linier motion of pressure plates into angular motion and rotates shaft.
• All shaft is connected to Gearbox. And the Gearbox is connected to flywheel and DC alternator.
• Alternator convert the rotational energy to electricity energy.
• As a results it produced electricity and it stored in batteries.
• When ever needed DC energy id convert to the AC energy with the help of inverter.

Advantages

1. Emits no pollutants.
2. Generate no hazared waste because most of the materials can be recycled.
3. Connection of storage and energy are simple and easy.
4. Easy to adapt or impliment if any location.
5. Very Durable.
6. Efficiency is more compared to conventional methods.

Disadvantages

1. Epensive to build a kinetic road.
2. The road was damaged when road has flooding.

Modular Constructions

MODULAR CONSTRUCTION

• Modular construction is a concept of coordination of diamension and space in which building are dimensioned and positions in term of basic unit of module

• Modular construction is a pre engineered process of making any structure a factory that is offsite  and are deliverd to the site and assembled as large volumetric component.

• With increasing istallation to the building industry stadily large part of building are made up to prerfabricated component. Delivered of the building site from factories.

• It can also be defined A modular building pre engineered structure that is flexible enough to satisfy vertuality any requiremets toughfs than standerd drywell constructions , its is canbe relocated and reuses.

• Instdustrial building system is one of the improve buildings system that are being introduce to achive the target and faster cpmpletetion with mass a productions of the building elements in placed out of its final locations in a building.

• Industrial building system can be defined as building system in which structure component in a manufacture of the factory, on or off site. Trnasport and assembled in structure with minimum additional site work.

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  Characteristics of Modular Constructions

• Reduce labour during prefabrications of component and site works.

• Open building concept permission hybrid applications and adabltable to standeriazation and modular construction.

• Modern design and manufacturing involving information technology like usas and computer aided (CAD) nad othets.

• One of the major characteristics of industrialised building construction is the industrial production of components thtough pre febrications.

   Why Modular Constructions

• It provides a practicle method of coordinating, the position and diamension of elements in the planning design of a building.

• To permit standerization which enough the use of standered building component for the constructions of different type of building.

• One of the major tension to adopt modular construction is that not only can one save upto 35% of the initial construction cost like labour and materials.

• For mass production of building component and factories which ensure good and consist workmenship and quality.

• Another major reason is the quyality as one can attened a suitable quiality of the elements of any structure that any prefabricated in the construction factory.

• Sustanabily in modular construction can be achived through the factory production of the modular units.

      For more information 

Classification of Modular Construction

1. Basic Module : It is the fundamental size in modular constructions and its generally application in building and components. The size of basic module taken 100mm denoted by M.

2. Sub Module :  Certain submultiples of basic module which are whole simple fractons shall be choosen absolutely necessary for an increments smaller then thye basic modules. 

3. Multi Module : Certain whole multiples of basic module usally expressed is an M with prefix as 2M, 3M, 4M etc arerefered to as multi modules.

Advantage of Modular Constructions

• Lower total construction costs 

• Reduction of site labour

• Safer site

• Cleaner enviroments

• Minimum wastage 

• Faster project complention.

• Less site materials

                                                                                                                                                                                                 

Solar Building

Passive solar building usas solar energy for its energy needs in different season. The concept of passive solar building , performance and benefits are discussed.

Concept of a Solar Building 

The rate of increasing  population groth with increasing innovations in the field of industries and technologies have all together results in the increasing energy consumption normally. This high consumption is a concern for sustanability. This has a negetive impact on the enviromental and energy consumptions. So, an innovation in building construction that would perform with the existing energy, withoutexploting any additional mechanicalk and electical energy sources is called as solar building. design concept. These bulking take the advantage of the climates where it must be constructed. A proper site analysis would judge the performance of the building. The concept of solar bulding is adopted in new building But already existing building can be behave passively. The building is named  solar building because we dont make use of any mechanical or electrical device with in the bulding to bring the concepts.

                                                         Solar Panel

Concept of solar building works base don the following principles:

• The first principle base don the route of the sun in different season. The sun is winter travellingf in a lower based route compared to summer time.
• Proper insulation enable warmth in winter and coolless in summer.
• The direct sun can be resisted by the over hanging elements.
• The location of thermal mass in a positions enabilling with absoption of solar energy would helps in the easy release of the same during evening time.
• In winter the south direction faced glasses will help in energy absorption and storage in the building

Elements consider for solar building construction:

• Room type, internal doors, wall and furniture in building and their placements.
• Building dismension extension in east west direction.
• The equator faced oriantation for the building.
• Use of thermal mass like floor and wall.
• Windows in the west are avoided.
• Window sized fixed to get adequete in solar in winter and shade of summer.

Performance of Solar Building

• The site climatic conditions.
• The solar building design criteria.
• The building size.
• The passive solar building is adopted.

                                            Solar Panel at Roof Space 

Benefits of passive Solar Building

• The interior of the building would be filled with sufficient light. This is due to the transmission of visible lights frequencies.
• The directultraviolet rays are harmful. The passive solar building Has the advantages of blocking almost 99.99%of the ultra violet radiation energy.
• Summer is made cooler and comfortable , it keep the interior cool during the hot season .
• Winner made warmer.

Problems Faced by Solar Building

In hot climateds building with large glass area can overheat. Be sure the minimize east and west facing window and size shade device properly . For large building With high internal heat gain, solar heat gain is a liability because it increase cooling cost more than the amount saved in spaced heating.

                                                 

                                                Solar Building

Fiber Reinforced Concrete, Transparent Concrete , Bacterial Concrete

Fiber Reinforced Concrete(FRC)

Fiber Reinforced Concrete(FRC) is that type of concrete which containning fibrous materials which increase its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers.

Fiber is a small pices of reinforcing material processing certain characteristic properties. They can be circular or flat, the fiber is obtain describe by a convenient parameter called aspects ratio. The aspect ratio of the fiber is the ratio of its length to its diameter. Typically aspect ratio range from 30 to 150.

Use

It is mainly used in shotcrete , but can also be used in normal concrete. Fiber Reinforced normal  concrete are mostly used for on ground floors and pavements. Concrete reinforced with fiber is less expensive then conventional reinforcement, while steel increasing the tensile sterngth many times. Shape , diamension and length of fiber is important. A thin and short fiber, for example short hair shaped glass fiber, will only be effective the first hours after pouring of concrete but will not increase the concrete tensile strength.

Benefits

1. It ibncrease the durability of the concrete.
2. It incease the tensile strength of the concrete.
3. It reduce the air voids and water voids. 

 Transparent Concrete

Transparent concrete is a concrete based building material with light transmissive properties due to embaded light optical element usally optical fibers. Light is conducted through the store from one end to other end. There fore the fibers have go through the whole objects. Transparentr concrete is also known as the translucent concerete  and light transmitting concrete because of its properties. It is used in fine architecture as a facade materials and for cladding of interior walls. In this paper the intigrate the meriets of concrete and optical fibers, for developping transparent arrenging the light numerical apperatus for the plastic optical fibers or big diameter  glass optical fibers into concrete. The main purpose is to used sunlight as a light sources to reduce the power consption of illumination and to use the optical fiber to sence the stress of structure asnd also user this concrete as an architectural purpose for good ahesthetical view of the building.

Application

• Illuminate your wall
• Watch your pavement shine at sunset
• Get ceative with design.
• Transparent concrete blocks suitable for floors
• Pvement and load bearing walls
• In furniture for the decorative and aesthetic 
• Light fixtures
• Light sidewalks at night
• Increasing visibility in dark subway stations.

Bacterial Concrete

Concrete is the fore most building material bradly used in building construction, but crack in concrete are concrete are inivatble and are one of the inhernet weakness of concrete. The major downside of concrete its is low tensile stress due to which micro cracks occureswhen the load applied is more than its limit and this pave way of the seepage of water and other salts. The innitiate corrotion make the whole structure vulnerble and leads to the faliure the structure. To remidiatethis type of faliure due to cracks and fissures  an approach of  using of bio minaralisation in concrete has evolved in simple in recent years . In this methods , of enhancing the performance of concrete , the calcite pricipitating spor facting bacteria its introduce to concrete. When water entire through the cracks, its reacts with bacteria and forms precipiating the calcium carbonate , as a by products, which fill the cracks and make crack free concrete. This type of concrete prepared with bacteria is called as bacterial concrete.

Advantages

• Self repairing of cracks without any external aide.
• Resistance toward freeze-thaw attacks
• Reduction of permiability of concrete
• Reduce the corrosion of steel due to the cracks formation.

Disadvantage

• Cost of bacterial concrete is double than conventional concrete
• Groth of bacteria is not good any atmosphere and media.
• Investigation of calcite precipitate is costly.
• Design of mis concrete with bacteria here is not available any IS Code or other code.

Straw Bale Construction

Straw Bale Construction

In this mordern day we primarily construct building with materials that retain a single life use, Meanning at the end of its course the materials remain unstablke and unrecycled. Example of said materialsare concrete, Various naterialsand asphalts. If you look back far enough the industrial revolution, you would find house with walls builts out from straw bales, Though straw today is used as a biofuel and confactionning verious subjects, it can also be used to be as a very ecologhycal and effective construction materials.

While straw has been to creat housing in Africa since the paleothitic eRA, Its seaing a modern with the rise in popularity of straw bale construction. This affrodable and sustanable means of building being discovered by moderns builders and home ownsers accross the globe with some stand out land mark assisting its rise to prominance.

How to Build With Straw:--

The methode of building a straw house is very different to that of our own , from the bottom up a foundation the width of a bale must be poured in place to support the straw walls. When straw was baled , you obtain rectangular of veried diamensions between (915mmX455mmX355mm) These rectanguar are straw like lego block upto the desire height, are wood rod are inserted at each 5 to 6 layers of straw in order to anchore each bale together , because straw is a organic material containning air, the exterior and interior finished must albe composed of 100% organic materials to allow the wall to prespire, this said materialstypically a coconation of clay sand and straw , by adding water to all this material you create a mud li8ke mix that is easy manupulatable and smooth when dry. The roof it self typically roof truss construction because of the structural ingradient and high stability of the straw wall, the roof can simple rest on and be anchored to the walls.

History of Straw Bale Construction:--

The history od straw bale constructions has a strng foundation in the 1700's but date much further back in africa during the paleolithic era . Germany and France in the used straw as a mean of construction various buildingthat can even still be visited today, In century ago in Nabraska the rapiud evolution of farming equipment pushed the use of straw construction of building house, chuches and even museums, Today there are a modest amount of architects that specilized in straw bale constructions homes, pushing the boundary and what can be accompolished with the materials. 

    Advantages of Straw Bale Construction:--

• Straw bale are made from a low cost products.
• Straw bale are 100% biodegradable.
• With good maintance straw bale are very durable.
• Straw bvale have a low embodies energy.
• Insulation valve of R-30, R-35 can be achived.
• They are relatively easy and cost efficient to install.

    Disadvantages of Straw Bale Construction:--

• Moisture and mould are significant risks. 
• Wall thickness means that more of the building overal floor space is unusable.
• Bales must be kept dry to avoid compressive stress.
• As it is not a conventional building materials.
• Straw dust can cause difficult for people with allergies.
• Fire is also a risk , because of the density of bales , fire trends to smoulder rather than sprade when a igniations sourced is removed.

Green Building

What is Green Building?

The day and age you hear everyone talking about going green. Whether you want to admit it or not, at some point everyone will have to follow with the green movement. This is because at the rate we are going the earth is simple the sustanable , that means that over the years, we will begin to run out of certain natural resource that are needed in order for us to survive. That is alarming to some people, which is why there are so many people that focus on green building. But what exactly is green building? Lets take a closer look at what it is, why should consider it, and what the goals of a green building are. You are sure to find out that it is some thimng that you should take part in.

Defining a Green Building:-

We will take a look a what green building is, some people may think of a green or sustanable building as just a building does not really have as bad of an impact on the enviroment as another average or same building.Some other people find out the type of building and the actual surroundings of the building.

The ideal green building would be a building projects that would allow to preserve most of the natural enviroment around the projects site, while still being able to produce a building that is going to serve a purpose. The construction and operation will promote a healthy enviroment for all are involved , and it will not disrupt the land, water, resourceenergy in and around the building. This the actual defination of a Green Building.

Does Going Green Really Cost More ?

Some people feel that they just can't go green beacause it will cost them more money, but that is really a common conception. While it may cost you a bit moreto get started when you are going green, because green materials and products can be more costly. You really have to cosider the type of savings taht you will be able to reap. you will be able to save the energy costs, Because going green also means conserveing energy. You should really look at the green building as more of an investment then anything else. An investments that will be able to save you money, as well as an investment that will be able to help the enviroments it is a win situations for everyone.

Why Go Green?

Now let us take a look at why it is so important to go green , most people will find when going green that they are able to reduced carbon footprint and actually lend a helping hand to the enviroments. You can go green in a variety of diffenrence ways, But building and construction works must do their part as well , if you have not begun going green, then you will find that their are a variety of different that you can do to help you get started, you dont have to jump you in head first and you can actually take some baby step alongs the way. Green building are design in such a way to reduced overall impact on enviroment and human being.

• Protecting occupant health and improving productivity.
• Reducing trash pollution and degriation of enviroments.
• Efficiently using energy , water and other sources.

Benefits of Green Building

With the technology constantly being developed the complements current practices in creating greener structure, the benifits of green bulding can range from enviroments to economic to social. Benefits of Green Building includes:--

      Enviromental Benefits:

• Reduced wastage of water.
• Protect biodivercity and ecosystem.
• Conserve natural resource.
• Improve air and water quality.

      Economic Benefits:

• Create market for green productsand services.
• Reduce operating costs.
• Improve occupant productivity.

Concrete Mix-Design

Defination--

Mix design can be defind as the process of selecting suitable ingradient of concrete and deternmine their relative proportion with the objects of producing concrete of certaiun minimum strength and durability as economical as possible.One of the ultimate aim of studing the verious properties of the materials of concrete, plastic concrete and hardent concrete is to enable a concrete technologiest to design a concrete mix for a particular strength.The design for concrete mis is not a normal task on account of the widely verying properties of the constituent materials, the conditions of the demanded for a particulars the exposure condition. and the condition that are demanded for a particular work of which the mix is designed.

Design of concrete mix required complete knowledge of verious properties of this materials. These make the task of mixdesign more complex and difficult. Design of concrete mix need not only the knowing the materials properties of concrete in plastic conditions , it also need wider experience of concrete and knowledge.Even the proportion of the material of the concrete found at the labrotory required modifications and adjustment of suit the field condition. With better understanding of the properties, the concrete is become more and more that exact material than in the past. The structural designer specific certain minimum strength  and the concrete technologydesighn the concrete mixwith the knowledge of the materirials, site exposure condition and standerds of supervison available at the site of work to the achive the minimum strength and durability. Further the site engineer is required to make the concrete at site, In some cases the site engineer may be required to slightly properties the mix design.He/She also make cube or cylinder sufficient in no and tested then to confirm the achivement with respectto the minimum specified strength. Mix-design earlier , may have make trial cube with representitive materials to arrive the value of standerd coefficient of variation to be used in the Mix-design.

Manufacturing of concrete include the following stages--

1. Batching                                    
2. Mixing
3. Transporting
4. Placing
5. Compacting
6. Curing
7. Finishing

Batching of materials for making concrete is known as batching.
Method of batching:--

• Volume Batching
• Weigh Batching

What is M20 grade concrete?

M denotes Mix-Design and After 28 days the characteristic strength of concrete ( size 15cm X 15cm X 15cm )  cube is 20Mpa.

                       

                     

              

 Concrete Cube (15cm X 15cm X 15cm)   

Benifits of Concrete Mix-Design:--

1. Reduce thermal peaks.
2. High workability for long periods.
3. Lower pumping Pressure.
4. Reristance of segregation even at high workability.
5. Extended setting with longer workability.
6. Reduced water content for a given workability.
7. Higher ultimate strength.
8. Reduce permiability and increase durability.
9. Reduce shrinkage and creep.
10. Better resistance to aggressive atmosphearic condition.
11. Increased ease in finishing concrete.

Point To Remember For Civil Construction Site

Following are the few general point to remember at civil construction site to make the construction work easy while maintaining quality of construction.

• Lapping is not allowed for the bar having diameters more then 36mm.
• For dowel rod minimum of 12mm diameter should be used.
• Chair specing maximum is 1000mm.
• Longitudional reinforcement not less than 0.8% and more than 6% of gross C/S.
• Chair minimum of 12mm dia meter bar to be used.
• Mainb bar in the slab shall not be less than 8mm to 10mm and distributor not less than 8mm and not more than 1/8 of slab thickness.
• Minimum bar of square column is 4nos and 6nos for circular column.
• Diamension tolerance for cube is +2mm.
• Minimum thickness of slab is 125mm.
• Free fall concrete is allowed maximum to 1.50m.
• Lap slice not be used for bar larger than 36mm.
• Water absoption of brick should not be more than 15%.
• Compressive strength of bricks is 3.5N/sqmm.
• PH value of water should not beless than 6.
• In soiol filling as per IS Code, 3 sample should be taken for core cutting test for every 100sqm.
• In steel reinforcement binding wire required is 8kg per MT.

Density of material

                    Material                                                                          Density

                     Bricks                                                                         1600-1920 kg/cubicmeter
                     Concrete Block                                                          1920 kg/cubicmeter
                     Reinforced Concrete                                                   2310 kg/cubicmeter

.
Curing time for RCC members for different type of cement

Super Sulphate Cement -- 7 Days.

Ordinary Portland Cement -- 10 Days.

Mineral and Admixture Added Cement -- 14 Days.


De-Shuttering Time of Difference RCC Member

Fore Columns, Walls, Verticle Formworks:-- 1Day.

Soffit Formworks to Slabs :-- 3Days.

Soffit to Beam Props :-- 7 Days.

Beam spanning over 4.5m :-- 14 Days.

Beam spanning upto 4.5m :-- 14 Days.

Arches spanning over 6m :-- 21 Days.

Arches spenning upto 6m :-- 14Days.

Concrete Sample Required for Different Quantity of Concrete


Quantity of concrete                                                             No of cube required

1-5 cum                                                                                          1No
6-15 cum                                                                                        2Nos
16-30 cum                                                                                      3Nos
31-50 cum                                                                                      4Nos
Above 50cum                                                                       4+1 Nos of addition of each 50cum

    

                                       

Various Type of Footing and Its Application in construction building

The foundation of your house is critical part of its structure as it helps distribute the load and minimised distress against the foundation soil movement , there by keeping the building and secure. Hense, foundation are critical to the structural safety of a building. 

Depending on the depth of the soil in which the foundation is made , there are two types of foundation used in construction building:

01. Shallow Foundation :-- These are use to small and light building. They are commonly reffered to as spread footing or open footings. There are four types of shallow foundation:

1. Individual footing is isolated footing.
2. Combined footing.
3. Strip foundation.
4. Raft or Mat foundation.

02. Deep Foundation :-- These are used for large structure. There are two main type of deep foundation:

1. Pile Foundation.
2. Drilled Shafts or Caissons

The foundation should be study enough to bear the load of the structure. Therefore lkarge area footings are needed to spread the vertical load, improving the stability of the building. Different kind of footings are design based on the soil type , the type of structure, and other local requirements arising during the design process.

The different type of footing are use in construction are described below:--

01. Continuous Wall Footing:-- 

The footing which supported a long mesonary or RCC wall is known as a continuous footing. It can be either simple or stepped.

Generally width of the footing should be at least equal to twice the width of wall that is rested on it. In this case , the width of the footing is smaller than length of the footing, offering continious vertical support to the structure. Basically it runs throughout the length of the wall. This type of footing is not economical.

Use of continious Wall Footing: Continious wall footings are used to support the foundation walls and load-bearing walls.

02. Isolated Footing:--

A footing that supports an individual column is known as Isolated footing. This kind of footing can be Pad, stepped, sloped and with isolated beam and slab, where good soil is available. this footing are economical.

Use of Isolated Footing: Isolated footing are used as shallow foundation in order totransfer concentrated load to the ground.

03. Combined Footing:--

A footing that support two or more columns is known as combined footings. It is used two or more column are close to each other or two or more individual footings of a column would overlap. Combined footing may be trapezoidal or rectangular of a plan. A trapezoidal footing is provide when the load of one column is greater than the other.

Use of Combined footing: Combined footing are used to transfer bload to closely spaced column to the ground or when the column place the boundary of plot.

04. Strip Footing:--

A footing which support a number of column in a line has to be a combined footing is known as Strip footing. It is used when the row of a column is closely space and there spread footings overlap the each other. Astrip footing is also known as a continuous footings.

Use of Strip footing: Strip footing are used to transfer the loads to closely row of column to the ground.

05. Strap Footing:--

W hen a distance between the two columns supported on combined footing become large, the cost increase rapidly. The strap footing is an economical option in such cases.

Use of Strap Footing: Generally, strap footings are used to conjuction with column of adjoining property.

06. Raft Footing:--

If load transmitted by the column in a structure are heavy and the soil pressure is smaller than the footing requires more area. In such a case it maybe better to provides continuous footing under all columns and wall. Such kind of footing is called a Raft footing.

Use of Raft Footing: It is widely used when soil has low load bearing capacity. 

07. Pile Footing:--

When the soil has a low beariung capacity or the ground water level is high, pile footings are applied. Piles are common while building foundation for btidge , Dam etc. And when a load is gradually applied on a foundation , sattlement occures,  which is almost elastic, to begain with the ultimate load, Share failure occurs when a plastic yeild of surface develop under the footing. Extending down ward and upward to the ground surface, and catastrophic settlement or rotation of the foundation occures. Which may fall the foundationof the building.

Use of Pile Footing: Piles are used as deep foundation where the soil is very week and has higher ground water level.

                                       Pile Footing