Comparision between light weight concrete and conventional concrete

Light weight concrete

One of the main advantages of conventional concrete is the self weight of concrete. Density of normal concrete is of the order of 2200 to 2600. This self weight will make it to some extend an uneconomical structural material.

1. Self weight of light weight concrete varies from 300 to 1850 kg/m3.
2. It helps reduce the dead load, increase the progress of building and lowers the hauling and handling cost.
3. The weight of building on foundation is an important factor in the design , particularly in case of weak soil and tall structures. In framed structure , the beam and column have to carry load of wall and floor. If these wall and floor are made of light weight concrete it will result in considerable economy.
4. Light weight concrete have low thermal conductivity.( In extreme climatic condition where air condition is to installed the use of light weight concrete with low thermal conductivity is advantageous from the point of thermal comfort and low power consumption.
5. Only method for making concrete light by inclusion of air. This is achieved by a) replacing original mineral aggregate by light weight aggregate, b) By introducing gas or air bubble in mortar c) By omitting sand fraction from concrete. This is called no – fine concrete.
6. Light weight aggregate include pumice, saw dust rice husk, thermocole beads, formed slag. Etc
7. Light weight concrete aggregate exhibit high fire resistance.
8. Structural lightweight aggregate’s cellular structure provides internal curing through water entrainment which is especially beneficial for high-performance concrete

9.  lightweight aggregate has better thermal properties, better fire ratings, reduced shrinkage, excellent freezing and thawing durability, improved contact between aggregate and cement matrix, less micro-cracking as a result of better elastic compatibility, more blast resistant, and has better shock and sound absorption, High-Performance lightweight aggregate concrete also has less cracking, improved skid resistance and is readily placed by the concrete pumping method

1. Aerated concrete is made by introducing air or gas into a slurry composed of Portland cement.
2. No fine concrete is made up of only coarse aggregate , cement and water.These type of concrete is used for load bearing cast in situ external walls for building. They are also used for temporary structures because of low initial cost and can be reused as aggregate.

High density concrete

1. The density of high density concrete varies from 3360 kg/m3 to 3840 kg/m3.They can however be produced with density upto 5820 kg/m3 using iron as both fine and coarse aggregate.

2. Heavyweight concrete uses heavy natural aggregates such as barites or magnetite or manufactured aggregates such as iron or lead shot. The density achieved will depend on the type of aggregate used. Typically using barites the density will be in the region of 3,500kg/m³, which is 45% greater than that of normal concrete, while with magnetite the density will be 3,900kg/m³, or 60% greater than normal concrete. Very heavy concretes can be achieved with iron or lead shot as aggregate, is 5,900kg/m³ and 8,900kg/m³ respectively.

1. They are mainly used in the construction of radiation shields (medical or nuclear). Offshore, heavyweight concrete is used for ballasting for pipelines and similar structures
2. The ideal property of normal and high density concrete are high modulus of elasticity , low thermal expansion , and creep deformation
3. Because of high density of concrete there will be tendency for segregation. To avoid this pre placed aggregate method of concreting is adopted.
4. High Modulus of Elasticity, Low thermal Expansion ,Low elasticity and creep deformation are ideal properties.
5. The high density. Concrete is used in construction of radiation shields. They are effective and economic construction material for permanent shielding purpose.
6. Most of the aggregate specific gravity is more than 3.5

Types of admixtures to use in construction

Admixtures  are  sometimes  used  in  concrete  mixtures to  improve  certain  qualities,  such  as  workability, strength,   

durability,   water tightness,   and   wear resistance. 

They   may   also   be   added   to   reduce segregation, reduce
  the  heat  of  hydration,  entrain  air, and accelerate or retard  
setting and hardening. We should note that the same results 
can often be obtained  by  changing  the  mix  proportions 
 or  by selecting  other  suitable  materials  without  

resorting  to the  use  of  admixtures 
 (except  air-entraining  admixtures when  necessary).

Whenever  possible,  comparison should be made 
between these alternatives to determine which  is 
 more  economical  or  convenient. Any admixture
 should be  added  according  to  current specifications 
and under the direction of the crew leader.

Workability Agents

           Materials, such as hydrated lime and bentonite,  are  used  to  improve  workability.  These  materials 
increase   the   fines   in   a   concrete   mix   when  
 an aggregate  is  tested  deficient  in  fines 
 (that  is,  lacks sufficient  fine  material).

Air-Entraining Agents

            The   deliberate   adding   of   millions   of  
 minute disconnected air bubbles to cement paste, 
if evenly diffused,  changes  the  basic  concrete 
 mix  and increases durability, workability, and strength. 

The acceptable  amount  of  entrained  air  in  
a  concrete  mix, by volume, is 3 to 7 percent. 
Air-entraining agents, used with types I, II,
 or III cement, are derivatives of natural  
wood  resins,  animal  or  vegetable  fats, 
 oils, alkali   salts   of   sulfated   organic   

compounds,   and water-soluble soaps. 
Most air-entraining agents are in liquid 
form for use in the mixing water. 

Accelerator 

                 The  only  accepted  accelerator 
 for  general concrete work is calcium chloride 
with not more than2 percent by weight of 

the cement being used. This accelerator is 
added as a solution to the mix water and is
 used to speed up the strength gain. 

Although the final strength is not affected,
 the strength gain for the first 7 days is greatly
 affected. The strength gain for the first 7 days

 can be as high as 1,000 pounds per square 
 inch  (psi)  over  that  of  normal  concrete 
 mixes.

Retarders

             The accepted use for retarders is to reduce
 the rate hydration.This   permits   the   placement 
  and consolidation  of  concrete  before  initial  set.
  Agentsnormally used are fatty acids, sugar, and 
starches

Types of flooring

Types of Flooring

The following are commonly used types of flooring.

• Cement Concrete flooring
• Terrazzo flooring
• Crazy Marble flooring
• Brick flooring
• Ceramic Tile flooring
• Marble flooring
• White Marble Flooring
• Kota Stone flooring
• Wooden flooring

Cement Concrete Flooring

Cement and concrete are main components of both commercial and residential flooring. Cement is key ingredient in concrete products. It is binding agent that holds sand and other aggregate together in a hard, stone-like mass. Concrete is produced by mixing cement with fine aggregate (sand), coarse aggregate (gravel or crushed stone), water, and often small amounts of various chemicals called admixtures which control such properties as setting time and plasticity. When the water is added to cement, it forms a slurry (thin semi-liquid cement) or gel that coats surfaces of the aggregate and fills the voids to form solid concrete.
The ratio of water and cement is the key that determines the strength of concrete whereas aggregates provide thickness, and decoration in some cases. Cement concrete flooring consists of cement concrete in the ratio of 1:2:4 (1 part of cement, 2 parts of coarse sand, and 4 parts of graded stone aggregate). Its thickness varies from 25mm to 50mm. The base concrete should be provided with slopes.
Flooring in veranda, courtyard, kitchens, and baths should have slope ranging from 1:48 to 1:60 depending on the location. Floors in water closet should have slope of 1:30.

Concrete Cement flooring... back in trend

Terrazzo Flooring

It is popular flooring for residential as well as public buildings. Terrazzo tiles have a smooth shine and are designed with marble or granite chips which add attractive designs to them. It’s available in an excellent range of colors and textures. This flooring is usually not slippery when wet because this has many grout lines. Terrazzo flooring consists of an under layer of cement concrete in ratio of 1:2:4 (1 part of cement, 2 parts of coarse sand, 4 parts of graded stone aggregate, 12.5 nominal size). Its thickness varies from 34mm to 28mm. Thickness of top layer of marble chips varies from 6mm to 12mm whereas the thickness of terrazzo flooring depends on the size of marble chips used.


 

 

Terrazzo floor

 

A blue white blend of color in kitchen with perfect terrazo floor

(This Picture is Contributed by "Apurva Sharma")

Crazy Marble Flooring

It is little different from mosaic flooring for its casting. The cement concrete under layer of crazy marble should be 25mm thick. Marble stone pieces are laid on cement concrete base. The usual thickness of marble stone pieces is 20 mm to 30 mm. The mix of cement chips 4:7 is laid around stone pieces.
The mix of crazy marble stone flooring consists of white cement-marble powder mixture (ratio 3:1) by weight in proportion of 4:7(4 cement-marble powder mixes: 7 marble chips).  

Crazy Marble Flooring

Brick Flooring

Bricks are very easy to install. As bricks are slip resistant you can avoid danger of slippery even when the floor is wet. This is the cheapest floor and is used in low category houses and temporary structures. Cement mortar in ratio 1:4 or 1:6 (1 part of cement, 4 or 6 parts of coarse sand by volume) is used in brick flooring. Brick flooring laid on base concrete consists of 75 mm thick lime concrete mix or cement concrete mix (ratio1:4:8 or 1:5:10).
 

Brick Floor on Terrace

 

Trendy Brick Floor

(This Picture is Contributed by "Sharmishtha")

Ceramic Tile Flooring

One of the most common uses of ceramic tiles is for flooring design in homes. Ceramic tiles are affordable, have low-maintenance, and can easily match with any room decor. These tiles come in various sizes, shapes, thicknesses, and colors, and are either glazed or unglazed.

Ceramic Tile Flooring with minimal designing  

Tiles are available in different sizes.

Length (mm)	Breadth (mm)	Thickness (mm)
200	200	5-6
250	250	5-6
300	300	5-6

The thickness of ceramic tiles for floor is 8 mm.

Marble Flooring

Marble is usually found as rectangular, square tiles or as whole slabs. One side is smooth and the edges are beveled (sloping). Marble tiles provide beauty for years and functionality to your home with low maintenance. These tiles are durable and available in varieties of colors such as white, pink, green, grey etc. these tiles come in plain as well as textured form. This flooring provides an elegant, royal and decorative look to the room. They are suitable for almost any place.

Royal villa with marble flooring

(This Picture is Contributed by "Ahmed")

White Marble Flooring

White marble stones of good quality are used. These stones have uniform veins and are spotless. This flooring is recommended for Hotels, Hospitals, Rest houses and Ban glows.  

White Marble Flooring with minimal designing  

Kota Stone Flooring

Kota stone is a flat rectangular limestone. It is available as rough natural  slab in natural blue, green and brown color. Kota stone is a natural stone which provides value for money to common man. It is hard and strong and remains undamaged for hundreds of years, yet it is cheap in prices. Kota  in its natural surface is useful for exteriors and high traffic areas like swimming pool etc. It offers non slippery surface and good look. Its polished surface finish is highly suitable for Interiors. It can be used in bedroom, dining room, guest room, particularly in circulation area. in fact in whole house, office etc.

Wooden flooring

Hardwood flooring is one of the most popular and beautiful flooring which has been in use for years. It has an elegance, charm, and durability that make it a popular choice in most of modern homes. The style of hardwood flooring you choose should be a decision based on your lifestyle, the construction of your house, and your budget. This flooring may be used for auditoriums, dance halls, gymnasium floors etc. The thickness of wooden blocks does not exceed 10 mm. The blocks are laid in desired patterns and they are fixed by means of hot glue. Then they are nailed with the help of panel pins. The heads of these pins are punched off and putty is filled in the holes.


  

Wooden Flooring

Wooden dine

( This Picture is Contributed by "Sharmishtha"

Earthquake: the end of the world here?  

Earthquake: THE END OF THE WORLD IS HERE?
Much is made about the life of the earth. Some argue that it forever, while others who lost the land in its current form and to demand a new country. Is it really End of the world is on 21 December 2012. IF end of the world is near then why science and technology try to protect. Are you prepared for end of the world?
The year was 1975, and it was rumored that the world is soon to end. For example in Nigeria, where he was born and lives, many young people have to get rid of their studies to the ground when the prediction that the world was at the end of this year, well, there is no need to continue their studies. This has led to so many drop out, although many of them have returned to school when the year rolled on the floor without fading. Do not ask me, but suffice it to say that a religious group is said with a flair for evangelization, has been the mastermind behind the fear of the forecast. IF end of the world exist then why GOD Created Life. The end of the world with the ultimate war between good and evil. SO many people are talking about the end of the world.
All that is history now that the world is undergoing unprecedented technological advances and other forms of development since then. 7 dozen past predictions of the end of the world has done till now. The current cycle of the end of the world is in December 2012.
But with the recent rise in natural disasters, especially since 2004 when the tsunami sent thousands of people to his early death, believes the time has come for us to get more people in this endless debate or the world, the world participate to an end. Is this really the end of the world of the 21st December 2012.
The debate is not over whether the formation of the Earth is not well understood and appreciated.
I read some books and religious literature in various shades of opinions about how the world really began. Although Darwin evolution is due, other schools of thought believe that the world is too complex and demanding as the man to stop his rise to the possibility of evolution.
Of all the books I've read that the Bible alone dared to say, he is the Lord God of Abraham and the children of Israel, the Christians, venerated really create the world.
On the other hand, God Almighty, Creator of heaven and earth actually said in the book of Isaiah in the Bible at his side, there is no God. Also clear in the Book of Genesis: "In the beginning God created heaven and earth."
Therefore, if we agree with the biblical story and believe it is the best decision, then you must also agree that since God is the Creator of heaven and earth, he is the only the power of the end of the world or not.

Easy Ways to Get Healthy 

When you go to the grocery store, be smart about it. When you make good decisions at the grocery store, your meals will get healthier automatically. Think for a second: you don't want to go to a busy grocery store or sit in a long line at the drive thru at the end of your day. You want to go to your apartment and make a little something from your kitchen. Your home should be filled with healthy foods and ingredients. This makes it simple to have a great meal--even if you want something junky--because you'll be eating something that is obviously better for you than anything you'd buy in a hurry at the store or in the fast food joint.
Climb stairs. Walk up the stairs to where you live or work instead of using the elevator. Obviously this isn't as possible if you work on the 25th floor of a high rise, but if you work on the fourth, climbing the stairs is a excellent way to get some exercise in. Even if you do live or work on one of the top floors, you can still get out of the elevator early and climb up the stairs the rest of the way. Most people will decide to be idle and take an elevator instead of getting exercise on the stairs. Even just a sole flight of stairs, when walked up or down a few times a day--can be a great boost to your system.
Choose water over other products. Soda and coffee, when consumed in small amounts, aren't that bad. Getting all your hydration from them is a horrendous idea. Drinking water instead of other kinds of drinks is a good way to aid your body in its health and hydration. Doing this helps you cut hundreds of calories out of your diet without your having to suffer through a bunch of gross diet food. Water is usually one of the keys to really slimming down and getting healthy. Get a cheap trampoline. Here is a site about cheap trampolines.
There are all kinds of things that you can do to get healthy and balanced. An overpriced gym membership and very restrictive diets are not the only way to do it. It is the little things you choose on a daily basis that really help you with weight loss and becoming healthy. Make shrewd choices every day is a great start. Trying to get in as much physical activity as possible is another. Remember: being healthy and balanced isn't just about reducing your weight. You need to help make your body as strong it can be.

The Delightful Ways to Tie Your Laces.  

Kids and adults love to wear shoes for whatever season there is. It is enjoyable to show that you don't only have new shoes but you also know how you tie your laces with fashion. Since we were kids, our parents teach us how to lace our shoes. Finding the right beautiful style for your shoelaces isn't just for fun but it is an enjoyable pass time as well. What is the basic way to dress up your shoes? What are basic and beautiful ways to lace them - making the suitable for different types of activities?
Here are some faster and secure ways to tie your shoelaces:
1. The over-front style- You start to lace the shoes by taking first each end and pushing it through the first hole on each lace. After this, cross your laces over each other and pushing the laces to the second set of lace holes from the crown. Just continue doing this over and push the laces through the top of its eyelets.
2. The basic bow style- This style is good for those who are advanced in tying shoelaces. The knot is tied by starting with the basic style of knot and then making one bow. The other shoelace is wrapped around the loop and doubled up as being pulled through the hole creating a crossed shoelaces style and then pulled it tight. This style is good for going to school and in backyard activities.
3. The loopy style- Take your shoelace and pushed it through the bottom eyelets from it bottom up. Cross then the laces twice before you push it laces through the next hole-above the first of its same side, instead of criss-crossing it to its tongue.
4. The double loop bow style- This is a good style for beginners of how to tie their shoelaces. It is so easy to do and remember. You begin this with a basic knot and create two bows with the laces. These bows then be crossed and one bow is to be putted under the hole made by the crossed and pulled tight.
5. The XYZ cross style- Take the laces and lace it straight across its bottom, pushing its laces to the eyelets from the bottom up. You skip the two eyelets together with the tongue of the shoe, making it to cross and pushed it through the fourth eyelets from the bottom, from top up. Move downward one eyelet and feed the lace from its bottom up. Carry on this procedure by reaching to the fourth eyelets. Move down again to push your lace through the bottom up and finally, criss-cross it like before.
6. The secure bow style- This style is fitted for sport minded and athletes who need to be sure of the tightness of their shoelaces. You begin this style with knot, the double or the traditional method. When your bow is tied, you may now take both its loops and cross them like a double bow and then pull it through again. You pull it forcefully for its most secure knot so that the bow will not come undone. You may choose this style anytime you need your lace to be stay tied

Good Quality Designer furnishings for Decorating Your Home  

Furniture for home can be bought from various types of stores or shops. Styles of famed people like Hans Wegner, Ray Eames and Charles and Harry Bertoia can be seen in the new and typical fixtures stores. There are many stores which are offering reproductions of varied classic modern fixtures.
Some of the stores will be making the reproductions by following the design specifications of the original works while some people shall be simply approximating the design specifications of a piece of fixtures or will be adding their own spin on that piece. To know if fixtures is an exact replica or not, it is always recommended to search through the description manual and learn in detail before buying.
Even though many stores are offering new contemporary designs in furnitures, it will also be reproducing the classics or sometimes will be having a stock of the antique pieces of fixtures. There are many stores which are selling accessories, bedding, modern fixtures, decor and lighting at affordable rates.
Good quality, designed furnishings is offered in lots of modern furnishings stores in Toronto. Contemporary furnishings are stylish and these include adjustable beds making style statements, sofas for sleeping and several types of beds that are suitable for flats and houses where the central room can be combined to create both bedroom as well as living room.
Currently there are many Toronto contemporary furniture suppliers for condos along with homes. The contemporary fixtures in Toronto is offering high quality standard furnitures, paintings, contemporary mirrors etc at a very quite good price.
In a rush to make the interior of the home very attractive, many people are in look for where to purchase modern contemporary fixtures in Toronto. The contemporary furnitures are especially suitable for its easy usage in the common homes as well as for the better convenience. Smart coffee table that shines your lounge is one among the best examples coming under this group.
People tend to be more wanting modern and stylish fixtures in bedroom. The furnitures needs to be chosen in this type of way that it must go with with the design of the room. Generally a lot of misconceptions are associated with the area of contemporary fixtures, as people are always suspicious about anything that tis associated with the word modern.
There are a lot of modern furnitures which is having older varieties of fixtures works in it. At present, many older pieces of fixtures are being efficient. And above all the primary benefit with the contemporary fixtures is that they come in variety of styles and patterns.

Ways to maintain you're wigs   

Taking care of your wigs may well appear just a little daunting. You spend pretty much everything dollars on a lovely wig and also you do not want it to lose its healthy look or obtain it damaged by any means. It is really fairly effortless to take care of your wigs so long as you might be consistent in its care.
In as significantly given it feels as for anyone who is giving your personal hair a break, you still need to maintain and take care of your wigs. Prior to you undertake the task of fixing your wig it really is significant that you have the proper tools and accessories along with you.Obtain a hairpiece brush, comb, shampoo and conditioner from the beauty store towards you. It is quite crucial that you don't use regular hair shampoo as this tends to be incredibly harsh within the hair strands from the wigs.
Place your wigs on wig heads if offered and brush the right path by way of knots and tangles. Always work your way with the top as you head down to underneath. In this way you are able to stay clear of producing any tangles worse. While you brush your wig ensure that you spray a little conditioner on it also.
Shiny wigs are low-priced looking and for those who uncover your wigs have that excessive sheen apply a bit of baby powder and mud any excess particles off. In terms of the storage of the wigs be certain you store these wigs in a cool and dry location. Any damp areas could possibly offer breeding grounds for bacteria to nurture which of course could be harmful to your health must you want to wear your wig once more.
The place you store your wigs depends a whole lot over the type of hair your wigs are created of. If they are created of real human hair it would be crucial if you stored hair aloof from sunlight for the reason that rays can cause the head of hair strands to discolor. Synthetic wigs nonetheless will not change color having said that much they are confronted with sunlight. The sort of wig you obtain is determined by your own preference.
Whenever you wear your wigs and wish to style them it can be important that you simply use styling spray particularly for wigs. This will make sure that this hair strands are not weighed down by normal styling items.
Also you cannot use heat on synthetic wigs. The head of hair strands can not withstand such extreme temperatures and they are going to get damaged. Nonetheless with real hair it truly is really probable that you should style it employing heat as it would behave in the very same manner as your own hair.
Your wigs are a great investment in looking fabulous, so you must invest time to effectively take care of them. Your wigs must go to look wonderful every single day with the best loving care

Humorous Jokes In The Workplace Is Advantageous Depending On Measured Conditions   

April fool's day is an admired day since there are distinctive humorous jokes that can be displayed. But, the office can lead to a controversial place for comical jokes, because what is funny to one man can be considered as an insult by another. Building jokes at one more person's expense could cause several lawsuits or even voluminous exhausting days at work.
Harmful jokes or humor should never be acceptable in the office. With the condition that the joke isintended to harm another or proves a racial or gender bias in nature or could result in a person to be createdmade to look terrible primarily in the eyes of their superiors, line requirements to be drawn on building jokes. Each person should be accountable for their actions and accumulate measures to apprehend what has become legitimate and will besettled as a hilarious joke. If a joke has become vague, you should recognize that certain kind of humor should be refrained from.
Voluminous companies conserve educational session to discuss non-practicing of office humor, because they do not desire any of their workers to be offended. Yet, at times, organizations can cross the line on what is permissable jokes and what is not. Asking a person not to put into action harmful jokes at the workplace might cause the individual to feel sad and unwelcome at the office. As such, the firm must strike the evenness between the staff feelings in addition to ethics at the workplace.
A business has the responsibility to educate its staff on reasonable jokes furthermore what would be taken a not so humorous jokes. Yet, organizations should too aggregate precautions to permit their staff a pleasing office. Humor in addition to jokes should be allowed in the workplace to permit a more cheerful and more joyful working environment. A funny joke could cheer up an individual's day and a little humor could relieve physical or mental pressure. A vital exercise would inset allowing a personnel to consume email to forward jokes to public they apprehend. One idea for the workplace might be to have a 'no joke' list and if people do not wish to receive humor through email, they can place themselves on the record.
As an example, have a look on a show called 'Night Court'. Such affairs was a sitcom that appeared on quite a some years back. On the program, the judge was regularly having jest, nonetheless making direct humor at random which lead to trouble to him. Nevertheless, regularly, the judge's antics made possible to him to review a broader notion of the people he met. As such, he managed to help them to provide report for betterment of their lives.
Allowing staff the opportunity to forward jokes through email and detect jokes in some of the horrible things that may pass in the office can help to steer restlessness and bring a greater friendship between the workers.

 

howtodrawalion.com

How to draw a lion

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How to draw a lion step by step

Posted on May 21, 2011 by Knuckles


1-8 Easy Steps to Draw a Lion
In this lesson today I’m going to explain to everyone how to simply draw a beautiful lion, in few easy steps, we will start from the very beginning from the first line, to the very end when you will have a lion almost roaring lion in your painting papers.
This lesson is designed for beginners and kids, who are looking forward to improve their painting skill through a very simple and practical lesson, it will be also much better for you to print this page, and use it as future guide for your friends in the class, and for sons at home, I hope this is going to be useful.
Before I start the lion drawing steps I would like to give some few facts about lions, it will help you a lot in your drawing experience.
1-      Lions are considered to be the largest one of cat families, it lives in groups and it’s very powerful
2-      It’s also known as the king of the jungle.
3-      Male lions have a bushy fur on front of its head called Mane.
4-      Lions are different in appearance depending on the environment they live at ( Africa – Asia)
5-      The Lioness or Female lion is responsible for feeding the baby lions.

Now it’s time to start the drawing steps so, let’s go!
1-      We will begin drawing our lion by drawing the nose

2-      Then, we will add the lion’s mane to the top of the head, it’s very simple till now.


3-      Now you will need to add more to the lion’s mane.

4-      Now we’ve finished the mane, let’s draw the back

5-      Now we will make the lion’s legs, so he can start walking

6-      Now we are going to finish the body by drawing the lion’s under belly, add the tail and some face details.

7-      Now our lion needs his other two legs so he doesn’t get mad at us!

8-      Now we will give our lion the final touch so it may look real as we expected by adding the tail and facial details to complete the King.

Now we have completed our beautiful lion, I’m going now to leave you all to have the choice of colors, I have given here the most basic lines, to make you able to draw your first perfect lion, I really hope my article has been useful to everyone, wish you all best of luck.

civil techniques based on quality: Bamboo Reinforced Structures A Positive Green Opti...

civil techniques based on quality: Bamboo Reinforced Structures A Positive Green Opti...: "Introduction Bamboo is gaining worldwide interest as an eco-friendly material, and thus there is developing interest towards bamboo buildin..."

Bamboo Reinforced Structures A Positive Green Option

Introduction

Bamboo is gaining worldwide interest as an eco-friendly material, and thus there is developing interest towards bamboo building technology based on recognized engineering principles. Bamboo construction has always been considered temporary and not surprisingly bamboo is replaced almost every year in many of the rural buildings.

Bamboo building techniques as they currently exist are mostly traditional in nature and based on knowledge gained over the years. In India, numerous studies have been carried out relating to the preservation of bamboo with a goal of enhancing its service life and understanding the mechanical properties of bamboo in order to assist engineers in selecting and designing. Factors such as its high strength to weight ratio, ease of construction, and particularly its rapid growth make it a green and sustainable building material.

In the modern context when forest cover is fast depleting and availability of wood is increasingly becoming scarce, the research and development undertaken in past few decades have established and amply demonstrated that bamboo could be a viable substitute of wood and several other traditional materials for housing and building construction sector and several infrastructure works. Its use through industrial processing have shown a high potential for production of composite materials and components which are cost-effective and can be successfully utilized for structural and non-structural applications in construction of housing and buildings.

In India, although bamboo is widely used in some regions, it must be emphasized that its use has been secondary as a semi load bearing element or as infill material in timber framed houses. It is in this context that the bamboo housing technology developed at IPIRTI is of greater significance.

The IPIRTI–TRADA Bamboo Housing system differs significantly from conventional bamboo constr- uction practices in many ways viz.–

(a) Use of round bamboo as columns, rafters and trusses as main load bearing element,

(b) Use of split bamboo grids/chicken mesh and plastered with cement mortar to act as shear walls for transmitting wind loads and to provide overall stability to the structure,

(c) Application of appropriate preservative treatment to bamboo depending on the degree of hazard and service conditions,

(d) Use of Bamboo Mat Board(BMB) as gussets in combination with mild steel bolts for load bearing joints in roofing structure, and

(e) Use of Bamboo Mat Corrugated Sheet (BMCS) as a roofing material.

Bamboo based housing system has very high potential for mass housing, housing in disaster prone areas and for earthquake resistant structures/houses and other applications. The low mass of the bamboo based building is an advantage under earthquake condition as compared to masonry structures. The buildings constructed in bamboo using this method are able to withstand the highest level of earthquake loading likely to be experienced in India. Bamboo has the potential of being used in sophisticated urban house construction and also for reinforcement in concrete. But due to absence of any standard building code for bamboo so far apart from method of test, it has not been officially recognized as a building material in house construction activity.

Steel Fibre Concrete Composites for Special Applications

Normal and High Volume Steel Fibre Concrete Composites for Special Applications

Steel Fibre Reinforced Concrete (SFRC)

Concrete is the most widely used structural material in the world with an annual production of over seven billion tons. For a variety of reasons, much of this concrete is cracked. The reason for concrete to suffer cracking may be attributed to structural, environmental or economic factors, but most of the cracks are formed due to the inherent weakness of the material to resist tensile forces. Again, concrete shrinks and will again crack, when it is restrained. It is now well established that steel fibre reinforcement offers a solution to the problem of cracking by making concrete tougher and more ductile. It has also been proved by extensive research and field trials carried out over the past three decades, that addition of steel fibres to conventional plain or reinforced and prestressed concrete members at the time of mixing/production imparts improvements to several properties of concrete, particularly those related to strength, performance and durability.

The weak matrix in concrete, when reinforced with steel fibres, uniformly distributed across its entire mass, gets strengthened enormously, thereby rendering the matrix to behave as a composite material with properties significantly different from conventional concrete.

The randomly-oriented steel fibres assist in controlling the propagation of micro-cracks present in the matrix, first by improving the overall cracking resistance of matrix itself, and later by bridging across even smaller cracks formed after the application of load on the member, thereby preventing their widening into major cracks (Fig. 1).

The idea that concrete can be strengthened by fibre inclusion was first put forward by Porter in 1910, but little progress was made in its development till 1963, when Roumaldi and Batson carried out extensive laboratory investigations and published their classical paper on the subject. Since then, there has been a great wave of interest in and applications of SFRC in many parts of the world. While steel fibres improve the compressive strength of concrete only marginally by about 10 to 30%, significant improvement is achieved in several other properties of concrete as listed in Table 1. Some popular shapes of fibres are given in Fig.2.

In general, SFRC is very ductile and particularly well suited for structures which are required to exhibit:

• 
  The behavior of SFRC under fatigue loading regime as compared to conventional concrete is shown in Fig. 3, while Fig. 4 illustrates the improvement in impact resistance of SFRC with the increase in the fibre content. The high ductility exhibited by normal SFRC and polymer-impregnated SFRC over conventional concrete is shown in Fig. 5.Resistance to impact, blast and shock loads and high fatigue
• Shrinkage control of concrete (fissuration)
• Very high flexural, shear and tensile strength
• Resistance to splitting/spalling, erosion and abrasion
• High thermal/ temperature resistance
• Resistance to seismic hazards.

The degree of improvement gained in any specific property exhibited by SFRC is dependent on a number of factors that include:

• Concrete mix and its age
• Steel fibre content
• Fibre shape, its aspect ratio (length to diameter ratio) and bond characteristics.

The efficiency of steel fibres as concrete macro-reinforcement is in proportion to increasing fibre content, fibre strength, aspect ratio and bonding efficiency of the fibres in the concrete matrix. The efficiency is further improved by deforming the fibres and by resorting to advanced production techniques. Any improvement in the mechanical bond ensures that the failure of a SFRC specimen is due mainly to fibres reaching their ultimate strength, and not due to their pull-out

Mix Design for SFRC

Just as different types of fibres have different characteristics, concrete made with steel fibres will also have different properties.

When developing an SFRC mix design, the fibre type and the application of the concrete must be considered. There must be sufficient quantity of mortar fraction in the concrete to adhere to the fibres and allow them to flow without tangling together, a phenomenon called ‘balling of fibres’ (Fig. 6). Cement content is, therefore, usually higher for SFRC than conventional mixes Aggregate shape and content is critical. Coarse aggregates of sizes ranging from 10 mm to 20 mm are commonly used with SFRC. Larger aggregate sizes usually require less volume of fibres per cubic meter.

Self Compacting Concrete

Self compacting concrete is a concrete which compacts itself, there is no further compaction required for self compacting concrete. Making concrete structures without vibration, have been done in the past. For examples, placement of concrete under water is done by the use of tremie without vibration. Mass concrete, and shaft concrete can be successfully placed without vibration. But the above examples of concrete are generally of lower strength and difficult to obtain consistent quality. Modern application of self-compacting concrete (SCC) is focussed on high performance, better and more reliable and uniform quality.

Recognising the lack of uniformity and complete compaction of concrete by vibration, researchers at the University of Tokyo, Japan, started in late 1980’s to develop Self compacting concrete. By the early 1990’s, Japan has developed and used SCC that does not require vibration to achieve full compaction. By the year 2000, the SCC has become popular in Japan for prefabricated products and ready mixed concrete. The utilisation of self compacting concrete started growing rapidly.

Self compacting concrete has been described as “the most revolutionary development in concrete construction for several decades”. Originally developed in Japan to offset a growing shortage of skilled labour, it has proved to be beneficial from the following points,

1. Faster construction,
2. Improved durability,
3. Reduction in site manpower,
4. Better surface finish,
5. Easier placing,
6. Safer working environment.