Different Types of Slabs in Construction

What Is a Slab?

Slabs are structural elements manufactured from concrete constructed to produce flat surfaces, usually horizontal, in building floors, roofs, bridges.

The slab is usually several inches hefty & is additionally supported by walls, by concrete beams usually cast monolithically with the slab, by steel beams, by columns, or anchored by the bottom.

If reinforcement is required, slabs could also be pre-stressed or the concrete will be spilled over rebar positioned within the framework.

Types of Slabs

 

19 Different types of slabs in construction are as follows.

1. Flat Slab

Flat slab doesn’t possess beams, & are supported by concrete columns or caps itself, & hence it is additionally known as a beam-less slab. Loads are directly conveyed to columns. The flat slab is effortless to develop & requires smaller formwork.

Thickness of Flat Slab =  8″ or 0.2 m.

Where Flat Slabs are Used?

1. To supply plain ceiling surface giving preferable diffusion of sunlight.
2. Effortless constructability of the economy within the formwork.
3. Flat slabs are utilized in parking decks, commercial buildings, hotels.

Advantages of Flat Slab 

1. It diminishes floor-to-floor lofts when there’s no requirement for a deep false ceiling& hence building loftiness may be diminished.
2. Auto sprinkler is less complicated.
3. Less construction time is required.
4. It surges the shear strength of the slab.
5. It helps to diminish the instant within the slab by diminishing the clear or effective time span.

Disadvantages of Flat Slab 

1. Utilized during a flat plate system, it’s impossible to possess a sizeable span.
2. Not suitable to hold up fragile partitions.
3. Higher slab bulkiness.

2. Conventional Slab

These square-shaped slabs which are held up on beams & columns are termed a traditional slab. The soupiness of this slab is bijou but the depth of the beam is sizeable & load is conveyed from beams to columns. It requires greater formwork when with respect to the flat slab.

Main Reinforcement Bars– Horizontal

Distribution bars– Vertical

Based on the length and breadth it’s categorized into 2 types:

1. One-way: Supported by beams on opposite sides, carrying a load in one direction.
   • Longer Span / Short Span ≥ 2
2. Two-way: Supported by beams on four sides, carrying load in both directions.
   • Longer Span / Short Span =< 2

Thickness of Conventional Slab : 4″ or 10”& Length- 4m.

Where Conventional Slab are Used?

1. Cantilever slabs are utilized for a one-way slab.
2. Utilized in developing floors of a multi-storeyed building.

Advantages of Conventional Slab

Conventional slab has got features like more stiffness, higher load-carrying capacity, safe and economical also. Conventional Reinforced Concrete (RC) frame buildings are commonly used for construction.

Disadvantages of Conventional Slab

Conventional concrete slabs are limited in length and thickness. They require a specific level of thickness to maintain their strength – usually at least 4 inches for a slab-on-grade foundation. Long concrete slabs elevated above the ground are limited in length due to the danger of cracking.

3. Hollow Core Ribbed Slab or Hollow Core Slab

Hollowcore ribbed slabs gain their name from the longitudinal voids or barren cores which run through the modules.

The cores can act as service ducts & can conveniently diminish the self-weight of the slabs, bumping up the structural efficiency. The cores have a satisfaction in sustainability terms diminishing the amount of concrete utilized.

Width : 1200 mm

Depth : 110mm to 400 mm.

Where Hollow Core Ribbed Slab are Used?

Using a hollow-core ribbed slab not only reduces building costs it also reduces the overall weight of the structure. Excellent fire resistance and sound insulation are the other attributes of a hollow core slab due to its thickness. It eliminates the need to drill in slabs for an electrical and plumbing unit.

Advantages of Hollow Core Ribbed Slab

1. It diminishes building costs & general weight of the structure.
2. Excellent fireproof capability & sound insulation.
3. It eliminates the necessity to drill in slabs for electrical and plumbing units.
4. Effortless to put in and requires less drudgery.
5. Quick to develop.
6. No special machinery is required for reinforcing.

Disadvantages of Hollow Core Ribbed Slab

1. The hollow core ribbed slab modules are also impaired during transport.
2. It becomes strenuous to supply satisfactory connections between the precast members.
3. It’s essential to rearrange for special equipment for lifting up & moving of the precast modules.
4. Not economic for bijou spans.
5. Strenuous to renovate & strengthen.

4. Hardy Slab

Hardy slab is a type of concrete slab constructed by hardy bricks. Hardy bricks are hollow bricks and it is made up of concrete hollow blocks.

These blocks are used to fill portions of the slab. Hardy slabs reduce the amount of concrete in the slab and also its own weight of the slab is also reduced. This type of slab has a more thickness of 2.27 m when compared with the conventional ones.

Thickness– 0.27 m greater with respect to the standard one.

Where Hardy Slab are Used?

1. Hardy slab is utilized where temperatures are lofty.
2. To test the temperature flow from the loftiest of the slab, soupiness surges.
3. The warmth coming from walls are checked by using thermocol bricks. Thermocol is the finest insulator of sunlight.

Advantages of Hardy Slab

1. Reducing slab poundage by diminishing the quantity of concrete beneath the neutral axis.
2. Effortless construction, especially when all beams are concealed beams.
3. Improved insulation for sound & warmth.

Disadvantages of Hardy Slab

1. The hollow core ribbed brick units are also impaired during transport.
2. Not economic for bijou spans.
3. Strenuous to repair & strengthen.

5. Waffle Slab

A waffle slab may be a reinforced concrete roof or floor containing square grids with deep sides & it’s also known as grid slabs. This sort of slab is primarily utilized at the doorway of hotels, Malls, Restaurants, Commercial Buildings permanently graphic view & to put in artificial lighting.

Where Waffle Slab are Used?

1. It is utilized where brobdingnagian spans are required (e.g auditorium, cinema halls).
2. It is utilized for its brawny foundation features of crack & sagging resistance.
3. Waffle slab holds a brobdingnagian load with respect to conventional concrete slabs.

Advantages of Waffle Slab

1. Waffle slabs have a capacity to carry ponderous loads.
2. Waffle slabs are often utilized as both ceiling & floor slabs.
3. Suitable for spans of 7metres – 16metres; longer spans are additionally possible in case of post-tensioning.
4. These systems are light in weight & therefore considerable saving is ensured within the framework because a light framework is required.

Disadvantages of Waffle Slab

1. Waffle slab isn’t employed in typical construction projects.
2. The casting forms or moulds required for precast modules are very expensive & hence only economical when large-scale production of indistinguishable units are desired.
3. Construction requires strict supervision and skilled workers.

6. Dome Slab

This is developed in Temples, Mosques, Palaces, etc. Domes are in the semi-circle in shape and shuttering is done on a conventional slab in a dome shape and concrete is filled in shuttering forming dome shapes. This is one of the types of concrete slabs.  

Thickness- 0.15m.

Where Dome Slab are Used?

One major benefit of the dome-shaped system is the ability to provide structural carrying capacities equivalent to conventional slabs but requires less concrete to do so (up to a 20% reduction in concrete consumption).

Advantages of Dome Slab

Domes are extremely durable and strong. While the average building life is measured in decades, the Monolithic Dome can be measured in centuries. They are fire, water, and wind-resistant, making them impervious to hurricanes, tornadoes, fires, and other threatening natural disasters.

Disadvantages of Dome Slab

1. Unsustainable Materials. The three materials used in monolithic domes are not the most environmentally products.
2. Vulnerability of the Air Form. The airform is a delicate membrane which can easily become damaged by falling trees and.
3. Poor Ventilation. The monolithic dome creates a tight hermetic seal, which is not always desirable given that activities.
4. Permits and Property Value. Building a monolithic dome may require special permits depending on the type of structure.

7. Pitch Roof Slab

Pitch roof is a particularly lightweight inclined slab, generally developed on resorts for a natural look.  A pitched roof is a roof that slopes downwards, typically in two parts at an angle from a central ridge, but sometimes in one part, from one edge to another. The ‘pitch‘ of a roof is its vertical rise divided by its horizontal span and is a measure of its steepness

Thickness: 2″-8″.

Where Pitch Roof Slab are Used?

Pitched roofs allow natural ventilation between the outer layer and the building, preserving energy

Advantages of Pitched Roof Slab

1. Pitched roof sheds off rainwater comparatively better.
2. It’s less plausible to leak.
3. Roof coverings are comparatively cheaper.
4. If it’s a standard pitch, building materials are comparatively cheaper.
5. Thermal insulation.
6. Energy savings.
7. Protection against enviromental hazards.
8. Cost-effective additional space.
9. Longer lifespan.
10. Rainwater reuse.
11. Sustainability.

Disadvantages of Pitched Roof Slab

1. Pitched roofs place a greater burden on the foundations of the building and demand a greater depth of the footings. Replacing a flat roof with a pitched roof on an existing structure is not always feasible.
2. Not feasible for buildings with multiple levels or complex plans.
3. More expensive to install and maintain.

8. Arch Slab

Arch slab are adopted at a place where there is a need for redirecting wind load and if there is a long curve in direction of slab these slabs are adopted

Where Arch slab are Used?

Arch, in architecture and civil engineering, a curved member that is used to span an opening and to support loads from above. The arch formed the basis for the evolution of the vault.

Advantages of Arch Slab

1. It offers higher levels of resistance compared to other designs.
2. It offers the option to span a greater distance.
3. It can be construction from almost any material.
4. It provides an advantage when carrying loads.
5. It continues to provide support without distortion over time.

Disadvantages of Arch Slab

1. It offers a finite span length to use.
2. It is a time-consuming project to complete.
3. It is a structure which requires careful maintenance.
4. It is a bridge option that cannot be built in some locations.
5. It requires more side support to complete a successful span

9. Post Tension Slab

Post–tensioned (PT) slabs are typically flat slabs, band beam and slabs or ribbed slabs. Post–tensioned slabs use high-strength tensioned steel strands to compress the slabs, keeping the majority of the concrete in compression.

The slab, tensioned after developing a slab is referred to as Post tension slab. Reinforcement is provided to check the compression force.

Where Post Tension Slab are Used?

Post–tensioning, which is a form of prestressing, has several advantages over standard reinforcing steel (rebars): It reduces or eliminates shrinkage cracking-therefore no joints, or fewer joints, are needed. Cracks that do form are held tightly together. It allows slabs and other structural members to be thinner.

Advantages of Post Tension Slab

1. It gives permission to slabs to be skinnier.
2. It allows to create of slabs on soft soils.
3. Cracks are packed tightly.
4. Post tension slabs are eximious ways to construct stronger structures at a reasonable price.
5. It eradicates shrinkage cracking.

Disadvantages of Post Tension Slab

1. The Post tension slab are often manufactured by skillful professionals.
2. The most ordinary problem with utilizing Post tension slab is that if care isn’t taken while manufacturing it, it can cause serious misfortunes.

10. Pre Tension Slab

Prestressed concrete is concrete that has had internal stresses introduced to counteract, to the degree desired, the tensile stresses that will be imposed in service.

The stress is usually imposed by tendons of individual hard-drawn wires, cables of hard-drawn wires, or bars of high-strength alloy steel.

Where Pre-Tension Slab are Used?

Pre–tensioning is generally done in precasting plants in permanent beds, which are used to produce Pre–tensioned precast concrete elements for the building industry.

Advantages of Pre Tension Slab

Longer span length increases untroubled floor space and parking facilities. Longer spans results in fewer joints, as a result, less maintenance is needed. Possibility of steel corrosion and subsequent concrete deterioration is declined because concrete is crack-free

Disadvantages of Pre Tension Slab

1. Pre Tension Slab requires high-quality dense concrete of high strength.
2. It requires high tensile steel, which is 2.5 to 3.5 times costlier than mild steel.
3. Prestressing process requires complicated tensioning equipment and anchoring devices.

11. Cable Suspension Slab

Suspended slabs are slabs that are not in direct contact with the ground. They form roofs or floors above ground level. Suspended slabs are grouped into two types: one-way slabs which are supported on two sides. two-way slabs which are supported on all four sides.

Where Cable Suspension Slabs are Used?

This kind of slab is provided where the length of the span is more and difficult in building columns. The slabs are tied with cables and these cables are joined to columns.

Advantages of Cable Suspension Slab

1. Long spans are achievable.
2. It has a simple construction method.
3. It has flexibility due to the cable system.
4. Less materials are required in construction.

Disadvantages of Cable Suspension Slab

1. Cable–stayed bridges do have a maximum length to consider.
2. This design option can become unstable in specific environments.
3. Cable–stayed bridges can be challenging to inspect and repair.
4. It is a design that can sometimes be susceptible to rust or corrosion.

12. Low Roof Slab

The slab given above the door for storage purposes known as a low roof slab. This slab is closed at all ends and open at one end, it is below the actual slab and above the level of the door cob. These concrete slabs is used in homes.

Advantages of Low Roof Slab

1. Enhanced Cooling And Heating Level.
2. Helpful For Maintaining Requirements.
3. Low Installation Costs.
4. You Can Install New Technology.

Disadvantages of Low Roof Slab

Low slope roofs change how water flows off of the structure. High pitched roofs don’t let water sit, so asphalt shingles and other materials that overlap work well. On a roof with a lower pitch, standing water soaks between these materials.

13. Projected Slab

The slab with one side fixed & other side free is thought of as a Projected Slab or Cantilever Slab. These slabs are developed in Hotels, Universities, Function halls, and so on.

Where Projected Slab are Used?

These types of slabs are generally constructed in hotels, Universities, function halls, etc. to use that area for dropping or picking up zone and for loading and unloading area.

Advantages of Projected Slab

1. This reduces the overall height of the structure.
2. Projected slabs are capable of lifting concentrated loads.
3. Since the reinforcement of projected slabs can be easily expanded, it is easy to place.
4. They also have better quality control.

Disadvantages of Projected Slab

1. In the projected plate system, construction of large spans is not possible.
2. The use of a drop panel can interfere with large mechanical ducting.
3. They are not suitable for masonry walls (brittle supports).
4. The thickness of the projected slab is greater than that of the typical RCC two-way slab.

14. Grounds Slab

Ground slabs are those slabs that are poured directly into excavated trenches in the ground. They rely entirely on the existing ground for support. The ground (more correctly known in the industry as the foundation) must be strong enough to support the concrete slab.

Where Ground Slab are Used?

Ground-bearing slabs, also known as “on-ground” or “slab-on-grade”, are commonly used for ground floors on domestic and some commercial applications. It is an economical and quick construction method for sites that have non-reactive soil and little slope.

Advantages of Ground Slab

Concrete slab foundations are more common in states with warm climates where the ground is less likely to freeze and cause the foundation to crack. There are good reasons for building or buying a house on a slab, such as cost savings and less risk of damage in certain instances.

Disadvantages of Ground Slab

There are good reasons for building or buying a house on a slab, such as cost savings and less risk of damage in certain instances. The disadvantages include that heating and cooling units may have to be installed on the ground floor, which takes up living space. There is also a potential for cracks.

15. Sunken Slab

unk slabs are slabs which are casted a certain depth (200 or 300 mm or any other depending on design) below normal floor level. This extra depth is used for placing pipes and utility ducts.

Where Sunken slab are Used?

This type of slab is used in bathrooms, toilets, washing places, or water closets. The purpose of providing a sunk slab is to prevent water from spilling over from the sunk slab area towards the surrounding slabs.

Advantages of Sunken Slab

1. In such slabs, all plumbing pipes are concealed inside the slab.
2. Special plumbing fixtures in sunken strips are not required to reduce noise in bathroom.
3. These slabs provide a good plumbing system, also used where the safety system is to be installed.

Disadvantages of Sunken Slab

1. Decrease in the height of the slab.
2. Slab, waterproofing, and brickbat takes more time to construct as compared to Sunken Slab.

16. Ribbed Slab

Ribbed slabs are made up of wide band beams running between columns with narrow ribs spanning the orthogonal direction. Normally the ribs and the beams are the same depth. A thin topping slab completes the system. Waffle slabs tend to be deeper than the equivalent ribbed slab.

Where Ribbed Slab Are Used?

Ribbed provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals

Advantages of Ribbed Slab

1. In this type of slab, the tension stress is eliminated in the tension side of the slab. The strength of concrete in tension is very small and so elimination of much of the tension concrete is done by the use of pan forms.
2. Economical where the live loads are fairly small such as apartment houses, hotels.
3. Long slab spans can be constructed through ribbed and waffle Slabs. In many cases, long spans are desirable in the building. Ribbed or waffle slabs.
4. Provide architectural advantages. All the Electrical appliances can be installed easily in the gap of the ribs which can be architecturally aesthetic.

Disadvantages of Ribbed Slab

1. Not suitable where the live loads are huge as heavy manufacturing buildings, warehouses.
2. The thickness of the slab is controlled as the requirement of fire resistance.
3. Formwork cost is high.
4. Sometimes difficult to install the electrical equipment.

17. Bubble Deck Slab

Bubble deck is a voided structural slab design that uses recycled plastic spheres sandwiched between layers of reinforcing steel lattice to introduce “voids” into the two-way slab.

Where Bubble Deck Slab Are Used?

Bubble Deck is a revolutionary method of virtually eliminating concrete from the middle of a floor slab not performing any structural function, thereby dramatically reducing structural dead weight. Bubble Deck is based on a new patented technique- the direct way of linking air and steel.

Advantages of Bubble Deck Slab

1. Superior Statics: Bubble deck slab has a superiority over the conventional slab as it has reduced weight, increased strength, fewer columns, and no beams or ribs under the ceiling.
2. Production and Carrying Out: The production is of higher quality through the automated production of prefabricated units. Minimum work at the site removes the possibility of errors and lightweight of the slab helps in easier erection with light and cheap lifting equipment.
3. Economic Savings: The major savings are found in materials (slabs, pillars, fundaments) up to 50 %. Due to its lightweight, transportation costs are heavily reduced.
4. Environmental Improvement: With the use of the bubble, 1 kg of plastic replaces more than 100 kg of concrete. Energy consumption for production, transport, and carrying out is very less. Thus, less emission of CO2.

Disadvantages of Bubble Deck Slab

1. The thickness of the slab is limited.
2. Skilled labor required.
3. The conventional slab is less deflects than Bubble Deck Slab.
4. Load carrying capacity less than the conventional slab.
5. Sometimes the thin concrete portion may be broken during transportation.

18. Prefabricated Slab

Prefabricated granite is still granite. It’s just been cut to standard sizes before being shipped to the distributor. While they look and feel similar to custom granite slabs, they are available in a narrow range of sizes. They offer no customization options since they are prefabricated.

Where Prefabricated Slab Are Used?

1. Agricultural products.
2. Building and site amenities.
3. Retaining walls.
4. Sanitary and stormwater.
5. Utility structures.
6. Water and wastewater products.
7. Transportation and traffic-related products.
8. Modular paving.

Advantages of Prefabricated Slab

1. Saving in cost, material, time & manpower.
2. Shuttering and scaffolding are not necessary.
3. Installation of building services and finishes can be done immediately.
4. Independent of weather condition.
5. Components produced at close supervision .so quality is good
6. Clean and dry work at the site.
7.  Possibility of alterations and reuse
8. Correct shape and dimensions and sharp edges are maintained.
9. Very thin sections can be entirely precast with precision.

Disadvantages of Prefabricated Slab

1. Handling and transportation may cause breakages of members during the transit and extra provision is to be made.
2. High transport cost.
3. Need of erection equipment.
4.  Skilled labour and supervision are required.

19. Composite Slab

Composite slabs comprise reinforced concrete cast on top of profiled steel decking, which acts as formwork during construction and external reinforcement at the final stage. The decking may be either re-entrant or trapezoidal.

Where Composite Slab Are Used?

The composite slab is one of the essential floor systems used in the construction of steel structures.

Composite slabs comprise ferroconcrete sew the very best of profiled steel decking, which acts as formwork during construction and external reinforcement at the last word stage. The decking may be either re-entrant or trapezoidal.

Advantages of Composite Slab

1. Versatility; they can be adapted to many practical cases and a multitude of solutions.
2. Resistance/Weight ratio; greater resistance with less weight, thus enabling a global reduction of the structure’s weight.

Disadvantages of Composite Slab

1. Can not be used for load-bearing or structural work.
2. Expands and contracts at different rates than material needed to be used for structure/frame.
3. If damaged or faded the material must be replaced.
4. It is very temperature sensitive and expands and contracts with temperature change.

Frequently asked questions (FAQs) that could be included in your article about different types of slabs in construction:

What are slabs in construction?

Slabs are structural elements made of concrete that form flat, horizontal surfaces in buildings, bridges, and other structures.

What are the common types of slabs used in construction?

Common types include flat slabs, conventional slabs, hollow core ribbed slabs, waffle slabs, dome slabs, and more, each suited to specific structural and architectural requirements.

How do flat slabs differ from conventional slabs?

Flat slabs are beam-less and directly supported by columns, offering advantages in construction speed and ceiling height. Conventional slabs, on the other hand, are supported by beams and columns and are more suitable for longer spans.

What are the advantages of using pre-tensioned and post-tensioned slabs?

Pre-tensioned and post-tensioned slabs use high-strength steel to improve structural performance and reduce cracking, allowing for longer spans and thinner slabs compared to conventional reinforced concrete.

Where are ribbed and waffle slabs typically used?

Ribbed and waffle slabs are used where structural efficiency and aesthetic considerations are important, such as in large-span structures like auditoriums and commercial buildings.

What are the environmental benefits of using bubble deck slabs?

Bubble deck slabs reduce concrete usage and weight by incorporating recycled plastic spheres, offering environmental advantages such as reduced carbon emissions and energy consumption during construction.

What considerations should be made when choosing a slab type for a construction project?

Factors include span length, load-bearing requirements, architectural preferences, environmental impact, and cost-effectiveness in terms of materials and construction methods.

How do different types of slabs affect construction timelines and costs?

Slabs like precast and prefabricated slabs can accelerate construction timelines due to off-site fabrication, while complex designs like cable suspension slabs may require more time and specialized installation methods.

What are the challenges associated with installing and maintaining specific types of slabs?

Challenges may include transportation and handling issues for precast slabs, maintenance of cable systems in suspension slabs, and ensuring structural integrity over time in innovative designs like bubble deck slabs.

How can architects and engineers optimize slab design for specific building requirements?

Optimizations include choosing the appropriate slab type based on structural analysis, aesthetic goals, environmental impact, and long-term maintenance considerations to achieve efficient and sustainable construction outcomes.