What is one way concrete slab? 

The article aims to answer the question, “What is one way concrete slab?”. It will also discuss how you can pour your concrete slab. Read on to know more:

What is one way concrete slab? 

Due to their geometry, one-way slabs transmit loads from two parallel walls or beams and only bend in one direction (the spanning direction). Simply put, it spans just one direction and curves in that way.

Load is transmitted along the span or the shorter side of the slab. A one-way slab can only be bent in one direction, making it ideal for use in the spanning direction. Therefore, the primary tension reinforcing bars run parallel (with regular spacing) to the shorter span and are often situated at the base of the slab.

The effects of warmth and shrinkage are taken care of by providing minimal reinforcement in the transverse direction (the longer one). Distribution steel, sometimes known as secondary reinforcement, is the name of this kind of reinforcement steel.

The use of this steel also aids in weight distribution. What I mean is the point load that tends to punch through the slab. The local impact, such as plastic shrinkage fractures caused by temperature and shrinkage, is mitigated by the distribution steel’s ability to distribute the load transversely across a wider breadth.

Frames made of reinforced concrete columns (RCC) are widely used in modern construction. The building’s slabs, beams, columns, and foundations are all crucial components that ensure the structure will hold up to various loads and function optimally for the duration of the building’s useful life. 

The one-way slab is the topic at hand. Two-way slabs are the two most common types of slab designs. Familiarizing with the RCC slab is necessary to fully grasp the one-way slab. The slab is often employed as the primary horizontal structural element when constructing a floor, ceiling, or roof. 

It may be continuously supported, cantilever, or just supported. The slab is a structural component that links the floor’s various loads to the building’s joists. The slab is the structural component whose thickness D is relatively low about its span L and width b.

It is also possible to categorise slabs depending on how they were built, including precast, prestressed, and cast-in-place varieties. One-way slabs, two-way slabs, flat plates, flat slabs, waffle slabs, and ribbed (joist) slabs are some other types of slabs.

How to pour a concrete slab?

To pour a concrete slab:

  • In the designated area, make rough markings using the tape measure, rope, or hose to indicate where the concrete slab will go. Use a carpenter’s square or speed square to establish the straight lines.
  • Use the hammer to drive a stake into the ground at each of the four corners of the slab. To create a border around the slab’s perimeter, thread the twine tightly between the posts.
  • Just shovel or trim the grass a few inches above the marked area. The goal is to provide more room for oneself to move about while working.
  • Empty the opened bags of multi-use gravel onto the area where the slab will be laid. The gravel may be compacted and levelled with the help of a tamper.
  • Mark off four pieces of 24 at 3 feet, 3 inches each, then cut them using the circular or electric mitre saw. Nail the boards together using 16d galvanised nails to create the desired form. Spread the shape out on the bottom foundation.
  • The ends of four pieces of two-by-four are trimmed to a length of about 12 inches and honed into points (one end only). All stakes must be pushed into the ground within a few feet of a form corner.
  • Each stake has to be screwed into a side of the form using the cordless drill to provide support. The inside of the form should be coated with vegetable oil or a concrete form release agent, such as Kleen Kote’s water-based release agent.
  • Use the garden hose to spray the sub-base lightly. Use the wheelbarrow, hoe, and hose to blend the ready-mix concrete as the manufacturer directs. Once the consistency is that of peanut butter, pour it into the mould.
  • Move the concrete around the form using a hoe and your gloved hands. Concrete is easier to work with when a little more water is utilized than is ideal. Too much water during the mixing process can diminish the final concrete strength.
  • Only increase the water content if necessary. Adding water in 2-ounce increments won’t make a difference. Use a scrap piece of two-by-four lumber four feet in length to screed the surface of the concrete footing.
  • The concrete is smoothed out, and excess is removed by sawing back and forth with the screed. You may throw away the surplus when it has fallen to the side.
  • Screed the outside of the mould and then pounded it repeatedly with a hammer. This will prevent the “honeycombing” effect at the margins caused by air and empty spaces.
  • Wait until the surface water has evaporated to allow the concrete to settle. Concrete hand floats are then used to compress and smooth the slab’s surface.
  • Wait for 10 to 20 minutes after floating before smoothing the surface with a metal concrete trowel. Any surface may be left smooth or given texture with a light sweep of a broom.
  • An edging trowel may give the perimeter’s edges a more finished, professional look. The curing time for concrete is 48 hours. Maintain a moist plastic sheet over the slab and often shower it with water from the garden hose throughout this period.
  • Walking on it after the two days is recommended, although full strength often develops after 28 days. It is recommended to wait 7-10 days before putting patio furniture on the concrete.

Conclusion

Because two walls are held together on opposing sides, a one-way slab can only be stressed in one direction. The direction perpendicular to the beam is the one that bears the brunt of the weight. Only one direction receives significant reinforcement. 

Cross-directional reinforcement of the nominal distribution is given. The ratio of a length to a shorter span must be more than two for a slab to be classified as a one-way slab, even if it is supported on all four sides. Load is not transmitted in the longer path because of the drastic length difference.

Frequently asked questions (FAQS): What is one way concrete slab? 

What is one way concrete slab? 

One-way slabs transmit loads from two parallel walls or beams and only bend in one direction (the spanning direction) due to their geometry. Simply put, it spans just one direction and curves in that way.

Load is transmitted along the span or the shorter side of the slab. A one-way slab can only be bent in one direction, making it ideal for use in the spanning direction. Therefore, the primary tension reinforcing bars run parallel (with regular spacing) to the shorter span and are often situated at the base of the slab.

Is a one-way slab better than a two-way slab?

Yes. In creating a two-way slab, we include more steel, which causes the slab’s depth to reduce; as a consequence, the two-way slab is thinner than the one-way slab. Up to a length of 3.6 meters, the one-way slab is the most cost-effective option. Alternatively, the two-way slab is the most cost-effective option for panels no larger than 6m x 6m.

Why is a one-way slab used?

Load is transmitted along the span or the shorter side of the slab. A one-way slab can only be bent in one direction, making it ideal for use in the spanning direction. Therefore, the primary tension reinforcing bars run parallel (with regular spacing) to the shorter span and are often situated at the base of the slab.

Bibliography

Krishna. Difference between One Way Slab and Two Way Slab. retrieved from: https://civilread.com/differences-one-way-slab-two-way-slab/

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