Economic Construction of Slabs using Bubble Deck Technology

Last Updated on March 5, 2024 by Admin

In today’s building sector, the economy is extremely crucial. Reinforced concrete slabs are a common building component in today’s construction. Concrete is widely used in the building sector, and it plays a vital role in the industry. Because more concrete is required in the construction of a floor system, the structure’s economy suffers.

The greatest answer to this problem is the bubble deck slab system. Plastic waste material is used to make polypropylene balls. This polypropylene ball is used in the middle of the slab to assist reduce the amount of concrete utilized. A portion of the concrete is replaced with polypropylene balls. Because bubble deck slabs are small in weight, they help to reduce slab dead load and increase efficiency.

The bubble deck slab is a slab in which a portion of the concrete is replaced by plastic hollow bubbles created from waste plastic material, reducing the structure’s self-weight. The principal function of the plastic sphere is to reduce the deck’s dead load by a factor of two when compared to a solid slab of the same thickness with no influence on deflection behavior or bending strength.

The slab has the same capabilities as a solid slab, but it is significantly lighter due to the lack of surplus concrete. Even if the building is demolished or restored in the future, the spheres could be recycled. The hollow spheres’ dead air area provides insulation and can be filled with foam for added energy efficiency, as well as increased fire protection and sound insulation.

What is Bubble Deck?

Bubble Deck is a brilliant solution to this issue; it fills the slab with plastic balls that are held in place by prefabricated reinforcement assembly. Bubble deck is a biaxial technology that reduces weight while preserving the performance of reinforced concrete slabs, allowing for longer spans and thinner floors.

What is Bubble Deck? 

The idea is based on the reality that the space between the columns of a solid slab has little structural impact other than to add weight. A grid of voids placed between layers of reinforcing welded wire steel and an internal lattice girder replaces this area, resulting in a slab that is typically 35 percent lighter and functions like solid reinforced concrete.

The steel lattice/void sandwich is then precast into panels of various sizes and craned into place on the structure after it has been concreted. The bubble deck system effectively becomes and functions like a monolithic two-way slab that distributes force equally and continuously once the concrete is poured over the balls in the panels.

Properties of Bubble Deck Slab

The bubble deck slab is a novel self-supporting concrete floor design that is both innovative and sustainable. The following are some of the characteristics of the Bubble Deck slab:

• Flexural Strength

In comparison to a solid slab, a bubble deck slab is designed to omit a considerable volume of concrete in the central core, where the slab is primarily un-stressed in flexure. Because the depth of compressed concrete in slabs is typically a small proportion of the slab depth, it nearly always affects only the concrete between the ball and the surface, there is no discernible difference in behavior between a solid slab and a Bubble Deck. The outer ‘shell’ of concrete on the compression side and the steel on the tension side are the sole materials that work.

• Shear Strength

Design shear resistance near columns is usually crucial in any flat slab. The transverse and longitudinal shear stresses outside the column zones have been confirmed by testing and calculation to be within the capacity of the Bubble deck slab system. Bubbles are left out near the columns, so a Bubble deck slab is constructed exactly like a solid slab in these zones. Bubble deck slabs have a shear resistance of 0.6 times that of a solid slab of the same thickness.

• Durability

The durability of a bubble deck slab is similar to that of regular solid slabs. The concrete is standard structural grade concrete, which, when combined with proper bar cover, gives the best durability control for solid slabs. The reinforcement module and balls are vibrated into the concrete when the filigree slabs are formed, and the standard and consistency of compaction is such that a density of surface concrete is produced that is at least as impermeable and durable as that produced on-site, if not more so.

• Deflection

Span depth ratio estimates for deflections are quite rough and should only be used in the simplest or least critical circumstances in flat slabs with irregular layouts. The deflection is calculated using FE modeling, which includes non-linear cracked section analysis, and normal structural concrete with a Young’s Modulus (secant) Ecm multiplied by 0.9 and a tensile strength, fctm multiplied by 0.8.

• Sound insulation

Bubble Deck was compared to a one-way prefabricated hollow deck of comparable height. Bubble Deck reduced noise by 1 decibel more than a one-way prefabricated hollow deck. The weight of the deck is the primary criterion for decreasing noise, hence Bubble Deck will behave similarly to other deck types of the same weight. Every standard criterion is followed in the creation of the Bubble Deck slab, and it may be calculated using standard principles.

• Vibration

When compared to steel-framed and lightweight skeletal systems, RC slab constructions are less vulnerable to vibration concerns, especially when thin slabs are used. The bubble deck slab, on the other hand, is light and susceptible to vibration. For the same amount of concrete, a bubble deck slab can deliver over double the rigidity of a solid slab.

• Fire resistance

The slab’s fire resistance is complicated, but it is mostly determined by the steel’s capacity to retain sufficient strength during a fire when it will be burned and lose significant strength as the temperature rises. The fire and the steel’s insulation from the heat regulate the temperature of the steel. In any case, all concrete is broken, and in the event of a fire, the air would most likely escape and the pressure would decrease.

When the typical bubble material (HDPE) is utilized, the combustion products are rather innocuous, especially when compared to other materials that might be burning nearby. The ball would melt and finally scorch in an intense, long-term fire with no discernible consequence. Nearly 60-180 minutes of fire resistance is dependent on the concrete cover.

Types of Bubble Deck Slab

Mainly there are three types of Bubble Deck slabs and for all types, the maximum element size for transportation reasons is 3 meters.

• Type A – Filigree Elements

Type A bubble deck is made up of both constructed and unconstructed pieces. A 60 mm thick concrete layer and a portion of the finished depth are prefabricated and delivered to the job site without the bubbles or steel reinforcement.

The bubbles are then held in place by interconnected steel mesh and supported by temporary stands on top of the precast layer. This sort of bubble deck is ideal for new construction projects where the bubble placements and steel mesh pattern can be determined by the designer.

• Type B – Reinforcement Modules

The Type B bubble deck is a reinforcement module made up of a steel mesh and plastic bubbles that are pre-assembled. These components are delivered to the job site, laid out on typical formwork, joined to any additional reinforcement, and then concreted in place using traditional techniques.

Because these modules may be stacked on top of one another for storage until needed, this kind of Bubble Deck is ideal for construction sites with limited space.

• Type C – Finished Planks

The Type C bubble deck is a shop-fabricated module that comes complete with plastic spheres, reinforcement mesh, and concrete. The plank-shaped module is made to the final depth and supplied on-site.

It is a one-way spanning design that needs the use of support beams or load-bearing walls, unlike Type A and B. Shorter spans and a tight construction timetable are ideal for this type of Bubble Deck.

Materials used in the Bubble deck slab

The bubble deck slab is composed of three main materials:

• Concrete

The concrete used in the Bubble Deck floor system for joint filling must be above M20-25 grade. The nominal maximum size of the aggregate is determined by the slab thickness.

Self-compacting concrete is typically utilized for the casting of prefabricated filigree slabs or the site joint filling. Self-compacting concrete can be poured into forms, flow around congested reinforcing areas and into tight spaces, and avoid segregation by allowing air to escape.

• Reinforcement Bars

The plates’ reinforcement is made up of two meshes, one at the bottom and one at the top, that can be knotted or welded together. The steel is made up of two types of layers: meshed layers for lateral support and diagonal girders for bubble vertical support. The distance between the bars is determined by the size of the bubbles to be used and the amount of reinforcement from the slab’s transverse ribs. The strength of grade Fe-500 or above is used.

• Hollow Bubbles

High-density polypropylene materials are used to create bubbles. These are typically made of a non-porous substance that does not chemically react with the concrete or reinforcing bars. The bubbles are strong and sturdy enough to support objects ranging in size from 180mm to 450mm. The slab depth varies from 230mm to 600mm depending on this. The space between bubbles must be at least 1/9th of the diameter of the bubble. The gaps’ nominal diameters could be 180, 225, 270, 315, or 360 mm. The bubbles might be either spherical or ellipsoidal.

Installation of Bubble deck slab

This procedure is followed for the installation of the Bubble deck slab:

• The overall floor area is subdivided into a number of planned individual pieces that can be up to 3 meters wide depending on on-site access.
• The top and bottom reinforcement meshes, which are sized to suit the unique project, are connected together with vertical lattice girders, with the void formers trapped between the top and bottom mesh reinforcement to establish their ideal position, resulting in a bubble-reinforcement sandwich.
• To provide permanent formwork within part of the overall final slab depth, the bottom layer of 60 mm pre-cast concrete is cast, encasing the bottom mesh reinforcement.
• Individual elements are then ‘stitched’ together on-site using loose reinforcement that is simply put over the joints between elements.
• Concrete is poured and cured once the site is finished.
• This technique creates a seamless biaxial floor slab by providing structural continuity across the whole floor slab — the seams between sections are thus redundant without having any structural effect.

Advantages of Bubble Deck slab

These are the few advantages of the Bubble deck slab:

• Superior Statics

Bubble deck slabs are superior to traditional slabs because they are lighter, stronger, have fewer columns, and have no beams or ribs under the roof.

• Production and Execution

The automated manufacture of prefabricated units improves the quality of the product. The lightweight of the slab aids in easier erection with light and inexpensive lifting equipment by reducing the amount of effort required on site.

• Transportation

Material transportation is significantly minimized. As a result, costs are lower, and the environment is better.
Financial Savings

Up to 50% savings can be obtained in materials (slabs, pillars, and foundations). Transportation costs are significantly decreased due to their small weight.

• Safety

The bubble deck slab is fireproof, and the seismic resistance is much improved. Fire – Because of the weight savings, the building is fireproof.

• Improvement of the Environment

1 kg of plastic replaces more than 100 tonnes of concrete when the bubble is used. The amount of energy used in production, transportation, and execution is extremely low. As a result, CO2 emissions are reduced.

• Explosions

The biaxial flat slab system and columns of Safe Bubble Deck are appropriate for structures that must withstand explosions. To eliminate heavy facades and inflexible walls, which suppress air pressure and, in the worst-case scenario, cause the structure to collapse.

• WEIGHT REDUCTION-

Because the amount of concrete required for the bubble deck slab is less, the slab’s dead load is also reduced. There is less load transfer to the column, wall, and foundation. The foundation of the building can be designed to support a lower dead load. There is no need for a beam. There is a reduction in the number of columns necessary.

• GREEN DESIGN 

Polypropylene balls are made from recycled plastic waste, which helps to tackle the plastic waste disposal problem. 100kg of concrete is replaced by 1kg of plastic. Emissions from production and transportation, particularly CO2, are reduced.

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Disadvantages of Bubble Deck slab

Further, this technology is not that common there are a few disadvantages of the Bubble deck slab:

• The slab’s thickness is restricted.
• Skilled labor is required
• The conventional slab is less deflecting than the Bubble deck slab
• The conventional slab has a lower load-carrying capacity than the Bubble deck slab
• During transportation, the thin concrete section may be fractured.
• The capacity of the punching share is limited.

Conclusion

Bubble deck slab failure is a critical concern in structural engineering, highlighting the importance of thorough design, precise manufacturing, and correct installation processes. These failures can arise from inadequate reinforcement, improper handling of the hollow plastic balls during construction, or errors in the structural analysis, leading to compromised integrity and safety of the entire structure.

Discussing bubble deck slab disadvantages, one notable aspect is the complexity of the design and construction process compared to traditional solid slabs. This complexity can lead to increased initial costs and the need for specialized labor. Moreover, if not properly designed or installed, issues such as reduced fire resistance and difficulties in integrating building services might occur.

Despite these challenges, bubble deck slab advantages and disadvantages must be weighed to understand their suitability for a project. Advantages include significant weight reduction, leading to less material use and lower foundation costs, as well as improved thermal and acoustic insulation properties. However, the disadvantages mentioned earlier, such as design complexity and potential for specific structural vulnerabilities, must be carefully managed.

Bubble deck slab design involves the strategic placement of hollow plastic balls within a lattice of steel, creating voids within the slab. This innovative design reduces weight without compromising strength, enabling longer spans and thinner floors, thus offering architects and engineers increased design flexibility.

The bubble deck slab price can vary depending on factors such as slab thickness, the density of the bubbles, and the project’s geographic location. While the initial material and construction costs may be higher than traditional concrete slabs, the overall project costs could be reduced through savings in foundation and support structure requirements.

Why bubble deck slab is used reflects its numerous benefits, such as material efficiency, reduced construction time, and enhanced building performance in terms of energy efficiency and load distribution. Its use is particularly beneficial in large-span constructions like commercial buildings, parking garages, and residential developments where its advantages can be fully realized.

In summary, while bubble deck slabs present an innovative approach to modern construction challenges, offering several structural and environmental benefits, it is crucial to carefully consider their design, application, and potential disadvantages. Proper implementation and expertise are key to leveraging the advantages of bubble deck slabs while minimizing the risks associated with their use.

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