Steel is a common construction material mainly due to its durability and high strength. Steel’s relatively low cost, coupled with its high tensile strength, has made it a popular material for civil and structural engineers.
The types of steel used in construction often vary depending on the nature of the construction project. However, the main types include structural steel, rebar steel, alloy steel, carbon steel, light gauge steel, tool steel, and weathering steel.
Are you curious to learn more about the main types of steel used in construction? Read on as we discuss all you need to know about steel and its various usage in construction projects.
1. Steel Rebar
Also known as reinforcing steel, rebar is a mesh of steel wires or a steel bar. This type of steel is used in masonry structures and reinforced concrete to provide extra strength to withstand load pressure. Rebar’s surface is often patterned to enhance the quality of the bond made with concrete.
Rebar is popularly used in construction to add positive properties to concrete. For instance, despite being strong in compression, concrete is usually weak in tension. Therefore, by carefully casting rebar into the concrete, the overall tensile strength increases, thus making it possible to carry heavy tensile loads.
Steel is usually preferred as rebar when dealing with concrete due to their almost similar thermal expansion coefficient, which means the structure won’t buckle or weaken when the overall temperature levels increase.
Uses of Steel Rebar
- Primary reinforcement: Rebar is a crucial construction material used to provide support and resistance to design loads. There are different types of rebar steel, each of which adds unique features depending on the nature of construction.
- Secondary reinforcement: Rebar is also vital in reducing the chances of cracking and neutralizing the risks of temperature-induced stresses. This allows the structure to remain firm while also increasing its overall lifespan.
- Provide resistance: Rebar functions by spreading concentrated loads across a wider area, which helps maintain a building or bridge’s structural integrity. Structures with greater dead and dynamic loads need more rebar compared to smaller structures with reduced weights.
- Reinforced masonry: Some masonry bricks and blocks include strategically measured voids designed to accommodate rebar. Once secured in place through the use of grout, the rebar allows the blocks and bricks to manage greater tensile loads.
Advantages of Steel Rebar
Great in Crack Prevention
Rebar steel is a crucial component in structures in need of great tensile strength. When concrete is poured without adequate support down the middle, it is highly likely to develop cracks due to enhanced stress. Placing rebar helps to absorb and distribute tension stress, thus reducing the chances of cracks or breaking.
Ideal for Projects That Require Medium to Small Thickness
Although rebar steel can be used in large structures, it can also come in handy when used in minor projects like driveways or garage floors. Thick concrete isn’t preferred in minor construction projects, which explains why rebars are often used to provide additional support to the reduced quantity of concrete poured in such projects.
Therefore, by placing rebar steel, the resulting concrete can withstand increased compression and tensile loads while still maintaining a thin profile. This also allows for increased savings since the total amount of concrete needed reduces significantly when using rebar.
Durable and Strong
Stainless steel rebar is among the most durable types of steel and can withstand repeated abuse and abrasion during construction work. Rebar’s ability to make strong and smooth bonds with concrete makes it perfect for use in reinforcement.
Rebar steel is reusable but can also be melted down, re-purposed, and recycled, thus promoting green construction.
2. Alloy Steel
Alloy steels are made when carbon steel is combined with one or more alloying elements like manganese, nickel, copper, titanium, aluminum, and chromium. The alloying elements are usually added to produce favorable properties that increase the construction value of carbon steel.
When producing alloy steel, the elements are usually added in varied combinations or proportions depending on the nature of construction. Some alloys help increase the hardness, corrosion resistance, overall strength, ductility, and weldability of steel.
For construction projects, alloy steels are mostly preferred for their increased corrosion resistance and hardenability. Also, alloy steels are perfectly capable of retaining their overall strength and hardness over time.
The Main Alloying Elements and Their Effects
- Chromium: One of the most popular alloying elements. Chromium is preferred due to its ability to increase the hardness, toughness, and wear resistance of steel.
- Manganese: When used as an alloying element, manganese improves overall resistance to strain, shocks, and hammering.
- Nickel: Known to increase steel’s overall corrosion resistance. Nickel is also used to increase the toughness and strength of steel.
- Tungsten: Another alloying element known to increase the grain structure and hardness of steel while also providing increased heat resistance.
- Chromium-vanadium: This alloying element is ideal for improving steel’s overall tensile strength. It makes the final product hard but easy to cut and bend.
Advantages of Alloy Steel
- High tensile strength: Compared to mild steel, alloy steel bars have a high tensile strength and compressibility rating. Alloy steel is usually smaller in size than most steel types, which increases its versatility when used in construction projects.
- Corrosion resistance: Since alloy steel is made from integrating carbon steel with other alloying elements, it’s possible to increase its overall corrosion resistance. Elements like nickel and chromium help form strong and durable alloy steels.
- Increased toughness: Due to heat treating, alloying elements can make steel tougher and more resistant to heavy loads. Stronger steel translates to more structurally sound buildings.
3. Carbon Steel
As the name suggests, carbon steel is a type of steel with a higher carbon concentration than other steel types. The carbon content in this type of steel can reach up to 2.5%, which significantly increases the steel’s strength, therefore making it ideal for heavy constructions.
The Main Types of Carbon Steel
- Mild steel (low carbon steel): This type of carbon steel contains 0.04%-0.30% carbon content and comes in various shapes ranging from flat sheets to structural beams. Other elements can be added to mild steel depending on desired properties. Despite its strength, mild steel is also very flexible, which prevents it from cracking when bent. This can withstand great seismic movements, making it ideal for earthquake-prone areas.
- Medium carbon steel: This type of steel has more carbon content compared to mild steel. The higher carbon concentration makes this steel stronger than low carbon steel. However, it is more difficult to form, cut, and weld. Medium carbon steel is commonly used in making crankshafts, heat-treated parts of a machine, axles, and screws.
- High carbon steel: High carbon steel is also referred to as ‘carbon tool steel’ due to its hardness. The increased carbon content makes it hard to cut, bend and weld, hence its preferred usage in manufacturing tools like hammers, screwdrivers, rope wires, edge tools, and high-strength springs.
Advantages of Carbon Steel
- Availability in different forms: Carbon steel is available either as low carbon steel, medium carbon steel, and high carbon steel. The wide range of options makes carbon steel ideal for different types of construction projects.
- Strong and highly durable: As the type of steel with the highest carbon content, carbon steel is strong and durable. The high carbon content makes products made from carbon steel extra strong compared to those with low carbon.
- Weather-resistant: Carbon steel is a great material for constructing homes resistant to earthquakes, tornadoes, hurricanes, and fires.
- Economical: Not too many metals can compare to carbon steel when it comes to affordability and versatility. From being used in large structural members to making tools and even pipes, carbon steel is highly versatile and can be used in place of other costlier materials.
4. Stainless Steel
Stainless steel is a steel alloy with increased corrosion and weather resistance compared to alloy steel or carbon steel. Some of the common ingredients used in stainless steel include chromium, molybdenum, or nickel.
The high chromium content gives stainless steel its impressive corrosion-resisting properties. This is because the chromium allows for chromium oxide formation, a rough film that enhances steel’s corrosion-resisting properties.
Advantages of Stainless Steel
- Durable: Stainless steel is durable due to its anti-corrosive properties and its ability to resist rust even in acidic or alkaline environments. Chromium content plays an integral role in determining the corrosion-resistant properties of stainless steel. For alkaline or acidic environments, using stainless steel with high chromium content is advised.
- Heat-resistant: Stainless steel is resistant to extreme temperatures, making it a popular option for use in boilers, heat exchangers, and valves, among other applications requiring high heat levels.
- High strength-to-weight ratio: Using higher grades of stainless steel allows civil engineers to capitalize on steel’s strength-to-weight ratio, which translates to using less material than would be required with other metals.
- Ductility: Stainless steel is highly ductile and therefore responds better to seismic movements than other construction materials like concrete. Its overall strength and durability explain its usage in primary structural components like suspension systems and decks.
- Recyclable: Stainless steel is usually produced by melting scrap with relevant steel alloys. The ability to reuse and recycle steel makes it a green material for use in construction.
- Enhances overall beauty: In addition to resisting corrosion and rust, stainless steel has a shiny appearance that adds to the overall beauty of structures. Stainless steel is also easy to polish and maintain, making it ideal for usage in construction.
5. Structural Steel
Structural steel is a type of steel produced with a particular shape or cross-section and specific chemical composition and strength values. In most industrialized countries, the composition, strength, size, and shapes of structural steel is usually controlled.
Structural steel can be easily transformed into different shapes, including L shape, I-Beam, T shape, and Z shape, among other shapes. High rise buildings rely heavily on structural steel, but it also makes a great option for light construction work.
Advantages of Structural Steel
- Strength: Structural steel is known for its toughness, high strength, and ductility. Its favorable features make it one of the most commonly used construction materials for both large and small projects.
- Constructability: Structural steel stands out due to its high level of constructability. It can be welded or bolted together in construction and used immediately, unlike concrete, which must be cured for several days.
- Corrosion resistance: The main types of structural steel used in construction are usually resistant to water and corrosion, especially when set up in acidic or alkaline environments.
- Affordability: Since structural steel is naturally stronger, it’s likely to last longer than other materials, hence returning the initial investment (usually high).
- Recyclable and reusable: Structural steel promotes green construction as it can be reused and recycled with ease. Structural steel’s easily customizable properties mean it can be put to several uses when structures are brought down.
6. Tool Steel
Tool steel is another steel type used in construction. However, this type of steel is mostly used for tool manufacturing, which is still crucial in the construction business. Tool steel stands out due to its ability to retain shape at high temperatures, hardness, and abrasion resistance.
Due to its strength, tool steel is usually used in various tool applications, including knives, hammers, molds, and heavy cutting tools.
The Main Grades of Tool Steel
- Water hardening (W-Grades): This type of tool steel is usually high in carbon content. Despite its affordability, W-Grade tool steels aren’t ideal for use in high-temperature conditions. This grade of tool steel requires water quenching and is susceptible to warping and cracking. Typical applications of W-Grade tool steel include embossing, cutlery, reamers, and cutting tools and knives.
- Air hardening (A-Grades): Air hardening tool steels have increased chromium content that enhances corrosion resistance. Tool steels in this grade have great machinability and a unique balance of toughness and wear resistance. Applications of A-Grade tool steel include blanking, knife production, die bending, arbors, among other applications.
- D type (D-Grades): D type tool steels have high chromium and carbon content, making them strong and abrasion-resistant. These tool steels are commonly used to manufacture different types of knives, among other applications such as burnishing tools, blanking, die bending, cold trimming, and rotary slitters.
- Shock resisting types (S-Grades): This tool steel is designed to resist shock at high or low temperatures. It doesn’t have as much carbon content as other tool steels, but its impact toughness makes it ideal for battering tools, chisel blacksmiths, and clutch parts.
- Hot working (H-Grades): H-Grade steels are commonly used to cut materials at extra high temperatures. They are extra strong and hard, which allows for easy cutting of other metals. H-Grades are commonly used in applications such as hot forging, hot extrusion, and hot trimming.
7. Weathering Steel
This unique type of steel contains small amounts of phosphorus, copper, nickel, silicon, and chromium. The use of the above materials allows the weathered steel to form a protective rust layer once exposed to weather, consequently eliminating the need for paint.
The rust that forms once the weathered steel is exposed to oxygen and moisture acts as a protective layer that prevents further corrosion. Therefore, the rust layer acts as a shield protecting the weathered steel from the elements that caused rust.
Benefits of Weathering Steel
- High strength: Structures made from weathering steel are known to last long due to the properties of the main components. The durability and overall strength of weathering steel make it an ideal option for building bridges, open-framed structures, and roofing.
- Low maintenance: Weathering steel doesn’t require regular maintenance. Once the stable rust barrier is formed, the steel’s internal parts will be protected from gradual rust and corrosion. Bridges built from weathering steel require little maintenance and are usually strong enough to outlast concrete bridges.
- Cost-effective: The use of weathering steel allows for both short and long-term savings. Weathering steel is relatively cheaper than most types of steel, which makes it pocket-friendly in the short term. In addition to the low cost of purchase, weathering steel doesn’t need painting or regular maintenance, which reduces the overall costs of construction.
8. Light Gauge Steel
As the name suggests, this type of steel stands out due to its lightweight characteristics. Light gauge steel is produced when thin gauge materials are cold-formed into specific section profiles. The section sizes and profile shapes tend to vary but are usually strong enough to avoid local buckling and premature failure.
Advantages of Light Gauge Steel
- Light gauge steel is easy to handle: This type of steel can be molded or manipulated into different shapes and forms and allows for fast construction. The ease of handling also makes it a great option for health and education construction that usually have tight completion deadlines.
- Safe: Compared to the heavier types of steel, light gauge steel is lightweight and can be carried around the construction site without the risk of injury due to impact or carrying heavy loads.
- Cost-effective: Light gauge steel is easy to handle and highly sustainable due to its affordability. Using this type of steel allows for significant savings in terms of labor and materials.
The best type of steel to use in construction depends on the nature of the project. This is because each steel type has its unique properties that either add value or compromise the structural integrity of a building.
Therefore, to ensure the right type of steel is used, it’s crucial to examine the strength requirements of a structure and other needs such as corrosion resistance, tensile strength, and ductility. Considering these factors ensures the right type of steel is used in construction.