Slab Concrete

The structure of a building consists of essential elements that offer stability to the building, ensuring a safe environment for occupants. Stability is ensured through components like slabs, columns, beams, and others. This article will focus on slabs, detailing their role in construction and the different types available. Continue reading to gain further insight.

What is Slab in Construction?

A slab is a level, horizontal structural element of a structure. Various forms of concrete slabs are utilized to construct roofs, floors, and ceilings. Ground-bearing slabs refer to thick concrete slabs that are supported by foundations. On the other hand, suspended slabs are those that are not in direct contact with the ground.

How are Slabs Made?

Now that you have acquired an understanding of the concept of slabs, let us delve into the process of their creation. Slabs can either be prefabricated or constructed on-site. In the case of prefabricated slabs, they are manufactured in a factory and subsequently transported to the construction site. Once at the site, these pre-made slabs are inserted between concrete or steel beams.

Alternatively, concrete slabs can be constructed directly at the construction site. In this method, wet concrete is poured into formwork, which is essentially a framework made of wooden planks, plastic, or steel. If reinforcement is desired, metal bars are strategically placed within the formwork, ensuring they do not come into contact with the bottom or sides. This ensures that no metal bars protrude from the concrete once it sets.

For ground-bearing slabs, the side walls of the formwork are embedded into the ground, eliminating the need for a base. These side walls serve to hold the concrete in place. On the other hand, suspended slabs involve pouring the concrete into a tray-like structure, which is temporarily supported by scaffolding.

Types of Slabs ?

There are various types of slabs available . But i am Explain few only

Conventional Slab

Conventional slabs are concrete slabs that are supported by beams and columns. In this case, the thickness of the slab is minimal, whereas the depth of the beam is substantial. The weight from the slabs is conveyed to the foundation through the beams and columns. When conventional rectangular slabs are upheld by beams positioned across from each other, they are referred to as one-way slabs. Two-way slabs are rectangular slabs that are supported by beams on all four sides. One-way slabs are typically utilized in verandas, whereas two-way slabs are commonly found in multi-storey buildings.

Flat Slab

Flat slabs, also referred to as beam-less slabs, are reinforced concrete slabs that transfer loads directly to the columns. This type of construction is often used in parking lots and commercial buildings where beams are not necessary. To improve the shear strength of the flat slab, drop panels or column heads, or both, are incorporated between the slab and the column.

Hollow Core Slab

Hollow core slabs are concrete slabs that contain voids or cores running through them. These voids can serve as service ducts, providing a functional space within the slabs. Additionally, the cores contribute to reducing the amount of concrete required for the slabs. Typically, hollow core slabs have four to six cores running along their length. To enhance their strength, these slabs are reinforced with steel, compensating for the hollow space in the middle. Hollow core slabs are commonly prefabricated and offer ease of installation. They are frequently utilized in the construction of bridges and wall panels.

Waffle Slab

Waffle slabs feature evenly distributed hollows in a grid pattern on their underside or soffit. These hollows serve the purpose of reducing both the weight and volume of concrete used. Waffle slabs are constructed using reinforced concrete and are commonly employed in various settings such as auditoriums, cinema halls, museums, and airports. The concrete space between the grids can be considered as a beam, providing support for the load from above and reinforced accordingly.

Bubble Deck Slab

Bubble deck slabs represent an innovative approach to slab construction, as they incorporate high-density polyethylene plastic balls in place of concrete in the middle section. By eliminating concrete from the tension zone, these slabs effectively decrease the structural dead weight. This reduction in concrete usage not only lowers costs associated with formwork but also contributes to a lighter overall weight of the slab without sacrificing strength. Bubble deck slabs are commonly employed in public and high-rise buildings.

Dome Slab

Dome slabs, resembling hemispheres, find their application in monumental buildings, galleries, museums, religious structures, and more. These architectural elements have been utilized since ancient times to ensure that only compressive forces are exerted on the structure. The dome shape itself emerged due to a limited understanding of tensile materials during that era. In dome slabs, the load is commonly transmitted through axial compression, effectively distributing the forces. Moreover, domes eliminate the necessity for structural columns, thereby enhancing the versatility and functionality of the space.

Pretensioned Slab

Pretensioned slabs are created by prestressing the concrete before it sets and hardens. This process strengthens the concrete against the tensile forces that occur once the structure is completed. The prestressing is done by stretching wires or strands between two anchorages before the concrete is poured. Once the slab has hardened, the prestressed strands are released by cutting them loose.

Post-tensioned Slab

Post-tensioned slabs are slabs where tension is applied after the construction process. These slabs are equipped with high strength steel tendons in addition to conventional reinforcements. By enhancing the concrete’s strength during compression, post-tensioned slabs contribute to thinner structural members. Moreover, they effectively minimize shrinkage, leading to a reduced number of joints.

Functions of Slab

Slabs have various purposes:

• They provide insulation against heat, fire, and sound.
• They distribute weight by flexing in multiple orientations.
• They offer protection from the elements.
• The top slab acts as the floor for the level below it.

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