Why is reinforced concrete better than normal concrete?

+46 votes
asked Sep 18, 2015 in Science by FelipeCarone (240 points)
Is it because steel has higher elasticity? What other factors are involved?

3 Answers

+25 votes
answered Sep 20, 2015 by PhilomenaW13 (380 points)

Reinforced concrete contains a support of steel, which is created by joining the steel together and enclosing it in a mold.  Concrete is then poured into the mold, filling the spaces in the steel network and setting into a solid state. Reinforced concrete is an instance of a composite material.

Reinforced concrete is a combination of steel and concrete. It’s more effective as a construction material than concrete alone because:

  1. Concrete is solid and strong when compressed, but weak when stretched.
  2. Steel is malleable and resilient when stretched.

The combination of concrete and steel engages the properties of both materials, so it remains solid and resilient whether it is squashed or stretched. Because of this, it is incredibly useful for building bridges.

Reference:

https://en.wikipedia.org/wiki/Reinforced_concrete

+7 votes
answered Sep 19, 2015 by VilmaSladen (430 points)
Why is reinforced concrete better than normal concrete? Reinforced concrete consists of normal concrete and steel. Concrete is robust when compressed, but doesn’t do well with extension, so it isn’t very effective at supporting stretching or bending forces. However, steel is a more flexible material and much more capable and handling these types of forces. Combining the two materials creates a composite structure that is able to handle both compression and bending.

In many cases, the steel is held under pressure while the concrete is setting. The result is pre-stressed concrete. This type of concrete is more flexible because it is already under compression, even when not bearing any load. Because of this, it is often implemented for structures such as beams that are subjected to bending forces.
+4 votes
answered Sep 21, 2015 by AntonCasteel (260 points)

Let’s examine the different forces a concrete beam or column endures:

  1. Compression, from weight applied directly to the structure.
  2. Bending, from tensile loads.

Concrete can handle compression very well, because it’s basically made of sand and gravel. It can withstand compressive loads of 3000 - 6000 psi.

However, concrete doesn’t handle tensile loads as well. Concrete’s malleable strength is a mere tenth of its compressive strength.

When you examine the bend, the inner part has visible compressive strain, but the outer area has tensile strains, which means that a concrete beam is pretty ineffective when it comes to bending.

However, steel has much more tensile strength, and embedding a steel support into a concrete beam distributes the tensile load and increases the flexibility of the structure as a whole.

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