How Does Steel Fibre Improve the Strength of Concrete?

The Breakthrough in Civil Engineering

In the 1970s, it was predicted that the limit of compressive strength would stay around 11,000 psi (pounds per square inch). That prediction was wrong, as technology can now make buildings with compressive strength up to 19,000 psi. Some of the first buildings that exceeded this compressive strength were Seattle's two Union Square buildings. It was a real shocker for most people and the news was spreading like wildfire with news headlines like ‘’Concrete strength record jumps to 36%!’’. This was surely an impressive feat, especially for architects that understood the math. It meant that you have safer buildings that won’t be easily compressed. The findings of tensile strength, which is the resistance something has to being pulled apart, was that concrete’s tensile strength is quite weak, but steel’s tensile strength is strong at about 53,700 psi. As shown in the figures, it’s easy to conclude that the amalgamation of these two building materials seemed advantageous, since they’ll both complement each other in their weaknesses. 

What’s the Difference Between Cement, Concrete, and Cement Concrete?

Cement is the liquid form. Concrete is the solid form. Cement concrete is the cement that gets mixed with concrete to create a higher flexural strength.

What’s the tension stress rate?

The tension stress rate is the rate at which tension opens up cracks in a wall. This tension can be lessened by using reinforced steel designs. For example, a beam reinforced steel design would carry the tension to the bottom of the beam and thereby reduce the tension stress rate.

What Does the Example of How to Lessen the Tension Rate Tell Us?

We can apply that concept to any wall on a building. For example, what if we used mini rebar across each crack? This would dramatically improve the wall's crack strength. And this is exactly what scientists did. They made concrete available that includes steel fibres as well as structural synthetic fibres!

So How Do They Physically Make This New and Improved Concrete?

They add hooked or crimped steel fibres to their concrete mixing and it gets mixed thoroughly into the concrete from 10kg to 40kgs per cubic metre. The mixture will leave the distribution of steel fibres in concrete randomized in the concrete and this, in turn, will allow tension loads to develop as they stay spread out amongst each other. So you're probably thinking, ‘’What’s the outcomes of using hooked or crimped fibre?’’. Well, the capacity strength is improved by a remarkable 50% or more, hence it improves the flexural strength. We call the end-product fibre reinforced concrete.

What Are Concrete Composites and Coarse Aggregate?

Concrete composites are made of gravel and sand in Portland cement because Portland cement usually uses civil engineering to improve the compression strength of the cement.

Civil engineers use point loading, this is when a load acts over a small distance. The objective of point loading is to test the structure's flexural strength and the overall strength of the concrete. Coarse aggregate contains rocks retrieved from a deep pit. It’s not so refined and is rough around the edges. It’s used as a filler material for concrete and to distribute the load evenly. It’s super cost-effective since the weight of the rocks increases the amount of cement. 

Conclusion

If you’d like to build a structurally safe building that won’t tear down easily, it’s best to talk to civil engineers who are knowledgeable on the subject, since it’s a very important matter. 

Bisley Co provides raw materials used for concrete admixture. To find out more gve us a call on +61 2 8905 4200.

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