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REBAR MARKINGS
There are a number of ways to identify reinforcing bar (rebar) from the production mill to the fabrication shop to the jobsite. This documentation and marking system helps provide a wealth of useful information about the manufacturing and composition of each bar of reinforcing steel.
American Society for Testing and Materials (ASTM) range of individual markings reveal the identification of each individual rebar:
1. The first letter or symbol means producing mill and deformation pattern.
2. The second marking means the bar size.
3. The third letter represents the type of steel as follow:
a. S: Carbon-steel (A615).
b. W: Low-alloy steel (A706).
c. R: Rail-steel (A996).
d. I: Axle-steel (A996).
e. A: Rail-steel (A996).
4. The last marking shows the grade of reinforcing bar.
a. 40: grade 40.
b. 60: grade 60.
c. 75: grade 75.
d. 4: grade 420, also grade 60.
e. 5: grade 520, also grade 75.
According to the Philippine Standards, The Bureau of Product Standards of the Department of Trade and Industry of the Philippines now requires all rebar manufacturers to put identifying marks on their bars.
TYPES OF REBAR
Choosing the suitable rebar for your project will depend on the size and grade needed to add the necessary support and strength. It will also largely depend on the material used to make the rebar, as well as what’s used to coat it.
Carbon Steel Rebar
The most common type of rebar used in residential and commercial projects. This alloy steel is exceptionally cost-effective and durable, but the carbon steel may not hold up well to projects with high moisture exposure. Using carbon steel rebar may be risky if you work with high moisture content or in high-humidity areas.
2. Stainless Steel Rebar
Although not as cheap as carbon steel rebar, stainless steel rebar can be a viable alternative. These steel reinforcing bars are used for bridges, roads, piers, and other weight-supporting structures. Unlike carbon steel rebar, stainless steel rebar can help prevent corrosion, giving you added protection.
3. Galvanized Rebar
One of the more expensive options, galvanized rebar, is an alloy steel rebar dipped in a zinc solution to add a special water coating that can deter corrosion. This material is an excellent alternative to epoxy-coated rebar. Galvanized rebar is 40 times more resistant to corrosion and holds up better during shipping and installation.
4. Glass Fiber Reinforced polymer(GFRP) Rebar
Also known as fiberglass rebar, this material is perfect for projects that are exposed to water. Glass fiber rebar will never corrode and boasts a much greater tensile strength than traditional steel rebar. Plus, it’s 75% lighter than steel, which means you can save on costly shipping expenses. This specialized material also has non-conductive electrical properties.
5. Epoxy Coated Rebar
Works well in high-humidity and high-moisture construction projects. The rebar is coated with a thick epoxy, which helps to slow corrosion. Unfortunately, the delicate epoxy coating can become scratched and damaged during shipping, rendering the rebar much less effective against corrosion.
6. Welded Wire Fabric(WWF) Rebar
Although this type of material has a different kind of name than other standard rebar types, WWF rebar is actually a grid pattern made of welded low-carbon steel wire. The grid can help reinforce concrete slabs to improve the overall tensile strength of the concrete.
7. Expanded Metal Rebar
Similar to WWF rebar, expanded metal creates a metal mesh that is detailed in diamond-shaped lines. The mesh is made from a single steel sheet that is expertly cut and expanded. This material is commonly used when extremely thick plaster is needed to support the concrete. Expanded metal rebar is often used for sidewalks or walking surfaces, but it is not strong enough to withstand heavy vehicle traffic or heavy weights.
CONCLUSION
Rebar is an essential material for reinforced concrete. Choosing the proper size, grade, and type of reinforcement bars are crucial to the success of any project. Proper and even spacing is also important. Fully understanding each rebar grade’s tensile and yield strength, as well as the benefits, disadvantages, and overall cost difference between your rebar options will allow you to create a safe, cost-effective, and durable project.
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