do you have questions
Yes - very easily of course! Steel's unique magnetic properties make it an easy material to recover from the waste stream, so it can be recycled. The properties of steel remain unchanged no matter how many times the steel is recycled. Steel is the world's most recycled material. The electric furnace method of steel production can use recycled steel exclusively!
Most steel is made via one of two basic routes:
- Integrated (blast furnace and basic oxygen furnace).
- Electric arc furnace (EAF).
The integrated route uses raw materials (that is, iron ore, limestone and coke) and scrap to create steel. The EAF method uses scrap as its principal input.
The EAF method is much easier and faster since it only requires scrap steel. Recycled steel is introduced into a furnace and re-melted along with some other additions to produce the end product.
Steel can be produced by other methods such as open hearth. However, the amount of steel produced by these methods decreases every year.
Steel is not a single product. There are currently more than 3,500 different grades of steel with many different physical, chemical, and environmental properties.
Approximately 75% of modern steels have been developed in the last 20 years. If the Eiffel Tower were to be rebuilt today the engineers would only need one-third of the amount of steel. Modern cars are built with new steels that are stronger, but up to 25% lighter than in the past.
Steel is very friendly to the environment. It is completely recyclable, possesses great durability, and, compared to other materials, requires relatively low amounts of energy to produce. Innovative lightweight steel construction (such as in automobile and rail vehicle construction) help to save energy and resources. The steel industry has made immense efforts to limit environmental pollution in the last decades. Energy consumption and carbon dioxide emissions have decreased by one-half of what they were in the 1960s. Dust emissions have been reduced by even more.
Finished steel products are forged from semi-finished products. They are classified as follows:
- Cold-finished bars and flats (bright bars)
- Cold-finished sections including forged and cold-formed sections
- Cold-rolled narrow strip
- Cold-rolled plate and sheet in coil and lengths
- Deformed reinforcing bars
- Drawn wire
- Forged bars
- Forgings (un-worked)
- Heavy sections, piling and welded structural sections
- Hot-rolled bars and flats in lengths
- Hot-rolled light sections
- Hot-rolled narrow strip including universal plates
- Hot-rolled rod in a coil (including reinforcement bar in a coil)
- Hot-rolled wide strip, plate and sheet
- Points, switches, crossings, tires, wheels and axles
- Rails and rolled accessories
- Silicon electrical sheet and strip
- Steel castings (un-worked)
- Steel tubes (seamless and welded, and steel tube fittings)
- Tin mill products
- Zinc- and other coated sheet etc.
A flat steel product is typically made by rolling steel through sets of rollers to produce the final thickness. There are two types of flat steel products:
- Plate products: Vary in thickness from 10 mm to 200 mm. Plate products are used for ship building, construction, large diameter welded pipes and boiler applications.
- Strip products: Can be hot or cold rolled and vary in thickness from 1 mm to 10 mm. Thin flat products are used in automotive body panels, domestic white goods (for example, refrigerators and washing machines), steel (or tin) cans, and a number of other products from office furniture to heart pacemakers.
A long product is a rod, a bar or a section. Typical rod products are the reinforcing rods used in concrete, engineering products, gears, tools etc. are typical of bar products and. Sections are the large rolled steel joists (RSJ) that are used in building projects. Wire-drawn products and seamless pipes are also part of the long products group.
A mini-mill is a molten steel producing process that feeds scrap steel into an electric arc furnace to re-process the material into finished steel for new applications.
Semi-finished products are solid blocks of steel, usually with a square or rectangular cross section. At a steel mill, the crude steel production process turns molten steel into ingots, blooms, billets or slabs. These are called semi-finished products.
Steel is an alloy of iron and carbon containing less than 2% carbon and 1.65% manganese and small amounts of silicon, phosphorus, sulphur and oxygen. Steel is the world's most important engineering and construction material. It is used in every aspect of our lives; in cars and construction products, refrigerators and washing machines, cargo ships and surgical scalpels.
It is not known who produced the first steel. Since 200 BC, many cultures have produced steel in one form or another. A British inventor, Henry Bessemer, is generally credited with the invention of the first technique to mass produce steel in the mid 1850s. Steel is still produced using technology based on the Bessemer Process of blowing air through molten pig iron to oxidize the material and separate impurities.
Many elements and materials go through chemical reactions with other elements. When steel comes into contact with water and oxygen there is a chemical reaction and the steel begins to change to its original form - iron oxide. In most modern steel applications this problem is easily overcome by coating. Many different coating materials can be applied to steel. Paint is used to coat automobiles, and enamel is used on refrigerators and other domestic appliances. In other cases, elements such as nickel and chromium are added to make stainless steel, which can help prevent rust.
Steel reinforcements are used, generally, in the form of bars of circular cross section in concrete structure. They are like a skeleton in human body. Plain concrete without steel or any other reinforcement is strong in compression but weak in tension. Steel is one of the best forms of reinforcements, to take care of those stresses and to strengthen concrete to bear all kinds of loads.
Bar-bending-schedule is the schedule of reinforcement bars prepared in advance before cutting and bending of rebars. This schedule contains all details of size, shape and dimension of rebars to be cut.
Mild steel bars conforming to ASTM A 615 grade 40 and Grade 60 where 40 and 60 indicate yield stresses 40,000 psi and 60.000 psi respectively are commonly used. Grade 60 is being used most commonly nowadays. This has limited the use of plain mild steel bars because of higher yield stress and bond strength resulting in saving of steel quantity.
Some companies have brought thermo-mechanically treated (TMT) steel bars which are not as easy as grade 40 and grade 60 bars to use.
Bars range in diameter from 6 to 50 mm. Hot-worked steel high strength deformed bars start from 8 mm diameter. For general house constructions, bars of diameter 6 to 20 mm are used.
Cover blocks are placed to prevent the steel rods from getting exposed to the atmosphere, and to place and fix the reinforcements as per the design drawings. Once the steel is exposed to the atmosphere, corrosion starts. Sometimes it is commonly seen that the cover gets misplaced during the concreting activity. To prevent this, tying of cover with steel bars using thin steel wires called binding wires (projected from cover surface and placed during making or casting of cover blocks) is recommended. Covers should be made of cement sand mortar (1:3). Ideally, cover should have strength similar to the surrounding concrete, with the least perimeter so that chances of water to penetrate through periphery will be minimized.
Shape of the cover blocks could be cubical or cylindrical. However, cover indicates thickness of the cover block. Normally, cubical cover blocks are used. As a thumb rule, minimum cover of 2” in footings, 1.5” in columns and 1” for other structures may be ensured.
How important are transverse reinforcements like links and stirrups? What precautions should be taken while tying them?
Transverse reinforcements are very important. They not only take care of structural requirements but also help main reinforcements to remain in desired position. They play a very significant role while abrupt changes or reversal of stresses like earthquake etc.
They should be closely spaced as per the drawing and properly tied to the main/longitudinal reinforcement.
This is the additional length of steel of one structure required to be inserted in other at the junction. For example, main bars of beam in column at beam column junction, column bars in footing etc. The length requirement is similar to the lap length mentioned in previous question or as per the design instructions.
Reinforcement should be free from loose rust, oil paints, mud etc. it should be cut, bent and fixed properly. The reinforcement shall be placed and maintained in position by providing proper cover blocks, spacers, supporting bars, laps etc. Reinforcements shall be placed and tied such that concrete placement is possible without segregation, and compaction possible by an immersion vibrator.
For a given diameter, how do we calculate the weight of steel per meter length of the steel bar and vice versa?
For any steel reinforcement bar, weight per running meter is equal to d2/162 Kg, where d is diameter of the bar in mm. For example, 10 mm diameter bar will weigh 10x10/162 = 0.617 Kg/m.
Yes. We can receive the test certificate of the batch of materials supplied at our site. The certificate will confirm the compliance of quality of supplied materials as per the requirement of relevant Indian standard code.
If you have been involved in the construction industry for any time at all, indeed even if you are involved in some manner in your first building project, you must come to a keen understanding and appreciation of the importance of quality deformed steel bars. With this in mind, this article is presented to provide you with the guidelines that you must keep in mind when it comes to selecting and purchasing quality deformed steel bars for your construction project.
Perhaps the most important guideline that you do need to keep in mind when it comes to seeking, selecting and purchasing deformed steel bars is the track record of the manufacturer. In the final analysis, not all manufacturers of deformed steel bars turn out the same quality product. Obviously, you must have the best quality product at a reasonable price. And, the best way to make this determination is to review the track record and history of any given manufacturer and the deformed steel bars that it historically has produced.
Another crucial guideline that you will want to follow when you are in need to quality deformed steel bars is to be able inspect personally actual representative samples (from a batch or lot of bars you are considering purchasing). The fact is that your investment in deformed steel bars simply is far too important to take on blindly. By undertaking hands on, personal inspection of representative deformed steel bars you will be in the best possible position to select a quality product when all is said and done.
Finally, in considering the guidelines associated with deformed steel bars, you will also want to obtain the most reasonable price for your purchase. Keep in mind that the cheapest product on the market really may not be your best choice. There could be a very good reason why certain bars are being sold for an extremely low price: they might not be quality bars. In the end, you must balance the cost factor against the need for quality deformed steel bars to arrive at the most reasonable price for your own project needs.
When it comes to construction and building projects there are various goals and objectives that need to be taken into consideration. In regard to any such project, two of these goals necessarily are affordability and safety. There are a variety of different components that can be utilized in a building project that can satisfy these primary, vital construction objectives. At the top of such a list are deformed reinforcing bars.
Time and time again we have all been able to witness – either first hand or through graphic media reports – what can happen when concrete or masonry buildings is constructed without the use of deformed reinforcing bars. The bottom line is that structures of this type that lack deformed reinforcing bars are very likely to collapse in the event of a number of different types of natural disasters, including earthquakes. The death toll in the aftermath of a number of different earthquakes has been significantly higher because men, women and children were inside buildings that lacked deformed reinforcing bars at the time an earthquake struck.
Perhaps there are still some contractors and builders in some places around the world that are balking at using deformed reinforcing bars because they are – wrongly – assuming that these materials or components will significantly increase the overall price of a particular construction project. The exact opposite actually is the case.
First, the use of deformed reinforcing bars actually makes it far easier to pour and place concrete or masonry. Therefore, you will save a great deal of time on any given construction project. And, in the end, time is money.
Second, the building will be more durable and will last far longer when deformed reinforcing bars are utilized in construction. There will be a sharply reduced need for repair and replacement when a building is constructed in this manner.
Finally, and most significantly as has been discussed, the costs associated with the unnecessary loss of human life in the event of a natural disaster will be tremendously reduced through the use of deformed reinforcing bars in the construction of a building.
While there are many considerations that come into play during the planning and construction of a building, safety definitely has to be a primary concern. Of course, a considerable number of buildings of all types – homes, schools and even hospitals – are constructed in whole or in part using concrete or masonry. Therefore, understanding how widely concrete and masonry is utilized in the construction of buildings of all types, it is crucial that the concrete and masonry used in this manner properly be reinforced. The best way – indeed, the only way – in which to properly reinforce concrete and masonry for safety and other considerations is through the use of deformed steel bars.
We have all witnessed what can (and will) happen when a building made of concrete (or masonry) is not reinforced properly and appropriately through the use of deformed steel bars. For example, in the event of what can be a minor earthquake, such a building that lacks proper reinforcement with deformed steel bars will collapse. Of course, the net result of this is the destruction of a costly building. However, even more significantly (and tragically) the loss of human life in such a situation can be tremendous.
In light of recent disasters that have resulted in the destruction of buildings that were not appropriately reinforced, in light of the massive number of people who have been killed and seriously injured as a result, an ever increasing number of governments are mandating that concrete and masonry buildings be reinforced appropriately with deformed steel bars. Experts universally agree that by taking the step to reinforce all concrete and masonry buildings with deformed steel bars the economic … and the human … loss associated with certain types of natural disasters (including earthquakes) will be reduced very substantially.
Over the course of the past several year`s there have been some significant earthquakes in a number of locations around the world. Unfortunately, the number of people who were killed or seriously injured as a result of these earthquakes ended up being very significant in some cases because concrete or masonry buildings were not properly strengthened through the proper utilization of rebar and construction rebar spacers.
Through this article you are provided an overview and a better understanding of the importance of construction rebar spacers. You are provided the information that you will require to better appreciate why construction rebar spacers are essential in earthquake zones.
For a number of reasons there remain some countries the world over in which concrete or masonry buildings are still being constructed without the insertion of rebar supports. These are precisely the same buildings that are collapsing under their own weight in the event of an earthquake. Sadly, even a minor earthquake can destroy these buildings with injury and kill the people inside.
Construction rebar spacers allows for the proper spacing and insertion of supportive steel rods (rebar) into the concrete or masonry being used in a building in the first instance. The properly spaced and inserted rebar in concrete or masonry provides two significant benefits in the event of an earthquake. First, it provides added strength to the concrete or masonry so that it will be less likely to collapse in the event of an earthquake. Second, the proper usage of construction rebar spacers renders the concrete more pliable and forgiving in the event of an earthquake. By this it is meant that the building will be able to “rock and flow” in response to earthquake rather than collapse and tumble.
Numerous countries around the world require rebar and construction rebar spacers in the construction of concrete or masonry structures. This includes most nations in Europe as well as in North America. The fact is that countries with lower rates of mortality from earthquakes are precisely the same nations that require or at least generally make use of construction rebar spacers in their construction projects.