Bubble deck slab

CONTENTS
INTRODUCTION
MATERIALS USED
SCHEMATIC DESIGN
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STRUCTURAL PROPERTIES

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BUBBLE DECK SLAB
INTRODUCTION
 In building, the slab is very important structural member to make a space and it
is one of the largest member consuming concrete.
 As the people getting interest of long span buildings the slab thickness is on the
increase. The increasing of slab thickness makes slab heavier, and it leads to
increase column and base size.
 Thus, it makes building consume more materials such as concrete and steel.
 For decades, several attempts have been made to create biaxial slabs with
hollow cavities in order to reduce the weight.
 Most attempts have consisted of laying blocks of a less heavy material like
expanded polystyrene between the bottom and top reinforcement, while other
types including waffle slabs / grid slabs.

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BUBBLE DECK SLAB
INTRODUCTION (Contd..)
 Of these types, only waffle slabs can be regarded to have a certain use in the
market. But the use will always be very limited due to reduced resistances
towards shear, local punching and fire.
 The revolutionary technology of flat slab construction by using hollow sphere
to replace the ineffective concrete in the centre of the slab has many advantages,
beside it is reduce the material, the load, lower the cost and increasing the span
length it is also a green technology.

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BUBBLE DECK SLAB
TYPES OF HOLLOW SLAB SYSTEMS
• AIR DECK SLAB
• COBIAX SLAB

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BUBBLE DECK SLAB
• U-BOOT BETON
• POLYSTYRENE
VOIDED BLOCKS

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BUBBLE DECK SLAB
BUBBLE DECK SLAB

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BUBBLE DECK SLAB
BUBBLE DECK SLAB ???
 Bubble deck slab is a biaxial hollow core slab invented in Denmark, by Jorgen
Breuning who invented a way to link air space and steel within a voided biaxial
concrete slab.
 Bubble deck slab is based on a new patented technique which involves the
direct way of linking air and steel.
 It is a new innovative and sustainable floor system to be used as a self
supporting concrete floor.
 Void forms in the middle of a flat slab by means of plastic spheres eliminate
35% of a slab's self- weight.
 The spheres made of recycled industrial plastic create air voids, while providing
strength through arch action.

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BUBBLE DECK SLAB
BUBBLE DECK SLAB (Contd..)
 The system allows for the realization of longer spans, more rapid and less
expensive erection, as well as the elimination of down-stand beams.
 According to the manufacturer, Bubble deck slab can reduce total project costs
by three percent.
 Through the tests, models and analysis from variety of institution, bubble deck
was proven to be superior to the traditional solid concrete slab.
 The reduced dead load makes the long-term response more economical for the
building while offsetting the slightly increased deflection of the slab.
 However, the shear and punching shear resistance of the bubble deck floor is
significantly less than a solid deck since resistance is directly related to the
depth of concrete.

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BUBBLE DECK SLAB
BUBBLE DECK SLAB (Contd..)
 The ratio of the diameter of the plastic spheres to the thickness of the floor is
such that a 35% saving is achieved on the material or concrete consumption.
 This leads to a further advantage, resulting in a saving of 40 to 50% of the
material consumption in the floor construction.
 Because of the lower weight of the floor system itself, the supporting
constructions such as columns and foundations can be less heavy.
 A Bubble deck slab floor is a flat slab floor, therefore without beams and
column heads.
 Currently, this innovative technology has only been applied to a few hundred
residential, high- rise, and industrial floor slabs due to limited understanding

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BUBBLE DECK SLAB
MATERIALS USED
 HOLLOW BUBBLES
 The bubbles are made using high density polypropylene materials. These are
usually made with nonporous material that does not react chemically with
the concrete or reinforcement bars.
 The bubbles have enough strength and stiffness to support safely the applied
loads in the phases before and during concrete pouring.
 Bubble diameter varies between 180mm to 450mm. Depending on this; the
slab depth is 230mm to 600mm.
 The distance between bubbles must be greater than 1/9th of bubble diameter.
 The nominal diameter of the gaps may be of: 180, 225, 270, 315 or 360 mm.
 The bubbles may be of spherical or ellipsoidal in shape.

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BUBBLE DECK SLAB
MATERIALS USED
 HOLLOW BUBBLES

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BUBBLE DECK SLAB
MATERIALS USED(Contd..)
 CONCRETE
 The concrete used for joint filling in the Bubble Deck floor system must be
above class 20/25.
 Usually self-compacting concrete is used, either for the casting of
prefabricated filigree slab, or for the joint filling on the site.
 Self compacting concrete can be poured into the slab forms; it flows around
congested areas of reinforcement and into tight sections.
 Thereby it allows air to escape and resist segregation.
 The nominal maximum size of the aggregate is the function of thickness of
the slab.
 The size should be less than 15mm.

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BUBBLE DECK SLAB
MATERIALS USED(Contd..)
 REINFORCEMENT BARS
 The reinforcement of the plates is made of two
meshes, one at the bottom part and one at the upper
part that can be tied or welded.
 The steel is fabricated in two forms - the meshed
layers for lateral support and diagonal girders for
vertical support of the bubbles.
 The distance between the bars are corresponding to
the dimensions of the bubbles that are to be used.
 Grade 500 strength or higher is used.

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BUBBLE DECK SLAB
TYPES OF BUBBLE DECK SLAB
TYPE A (FILIGREE ELEMENTS)
TYPE B (REINFORCEMENT
MODULE)
TYPE C (FINISHED PLANKS)

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BUBBLE DECK SLAB
TYPE A (FILIGREE ELEMENTS)
 Bubble Deck type A is a combination of constructed and
unconstructed elements.
 A 60mm thick concrete layer that acts as both the formwork
and part of the finished depth is precast and brought on site
with the bubbles and steel reinforcement unattached.
 The bubbles are then supported by temporary stands on top
of the precast layer and held in place by a honeycomb of
interconnected steel mesh.

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BUBBLE DECK SLAB
TYPE B (REINFORCEMENT MODULE)
 Bubble Deck type B is a reinforcement module that consists of a pre-
assembled sandwich of steel mesh and plastic bubbles, or bubble lattice.
 These components are brought to the site, laid on traditional formwork,
connected with any additional shear or edge reinforcement, and then
concreted in 2 stages to the full slab depth by traditional methods.
 This category of Bubble Deck is optimal for construction areas with tight
spaces such as suspended ground floor slabs and alteration/ refurbishment
projects.
 Since these modules can be stacked on top of one another for storage
until needed. This can be manually lifted into position.

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BUBBLE DECK SLAB
TYPE B (REINFORCEMENT MODULE)

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BUBBLE DECK SLAB
TYPE C (FINISHED PLANKS)
 The Bubble Deck type C is a shop
fabricated module that includes the plastic
spheres, reinforcement mesh, and concrete
in its form.
 This module is manufactured to the final
depth in the form of a plank and is brought
to site.
 This class of bubble deck slab is best for
shorter spans and limited construction areas
such as balconies or staircases.

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BUBBLE DECK SLAB
SCHEMATIC DESIGN
 Bubble Deck is intended to be a flat, two way spanning slab supported directly
by columns.
 The design of this system is generally regulated by the allowed maximum
deflection during service loading.
 The dimensions are controlled by the span (L) to effective depth (d) ratio, as
stated by BS8110 or EC2.
 The criterion can be modified by a factor of 1.5 that takes into account the
significantly decreased dead weight of the Bubble Deck as compared to a solid
concrete slab.
 In addition, larger spans can be achieved with the use of post tensioning as the
L/d ratio can be increased up to 30%.

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BUBBLE DECK SLAB
SCHEMATIC DESIGN
 L/d < 30 for simply supported, single spans
 L/d < 41 for continuously supported, multiple spans
 L/d < 10.5 for cantilevers
Version
Bubble Diameter
(mm)
Minimum slab
thickness (mm)
Minimum c/c
spacing (mm)
BD230 180 230 200
BD280 225 280 250
BD340 270 340 300
BD390 315 390 350
BD450 360 450 400
BD510 405 510 450

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BUBBLE DECK SLAB
STRUCTURAL PROPERTIES
 FLEXURAL STRENGTH
 In terms of flexural strength, the moments of resistance are the same as for
solid slabs, provided this compression depth is checked during design so that it
does not encroach significantly into the ball.
 Solid slab can carry only about one-third of its own weight and have problems
with long spans due to its heavy weight.
 Bubble Deck slab with same load carrying capacity can be used only 50% of
the concrete required for a solid slab or with the same thickness of Bubble
Deck slab the load carrying capacity can be increased up to two times by using
65% of concrete.

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BUBBLE DECK SLAB
Item Solid Slab Bubble Deck Slab
Strength 100 150
Bending Stiffness 100 300
Volume of concrete for
same strength 100 67
Comparison of bending strength in bubble deck slab and solid slab for
same volume of concrete (in %)
 The Bubble Deck slabs have much larger capacity than the theoretical
values for the solid slabs and have considerable smaller deflections under
service load than solid slabs with the same amount of concrete and the
same reinforcement ratio.
 The flexural rigidity will be more than six times greater than the
calculated value.

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BUBBLE DECK SLAB
 SHEAR STRENGTH
 In any flat slab, design shear resistance is usually critical near columns.
 Shear strength of any concrete slab is chiefly dependent on the effective mass
of concrete.
 Due to the inclusion of plastic bubbles, the shear resistance of a Bubble Deck
slab is greatly reduced compared to a solid slab.
 From theoretical models, the shear strength of the Voided slab was determined
to be 60-80% of a solid slab with the same depth.
 Near the columns, bubbles are left out, so in these zones a Bubble deck slab is
designed exactly the same way as a solid slab.
 Shear resistance of Bubble deck slab is 0.6 times the shear resistance of a solid
slab of the same thickness.

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BUBBLE DECK SLAB
 SHEAR STRENGTH (Contd…)
 If this is exceeded by the applied shear, at a column for example, we leave
out the balls and use the full solid shear values.
 Using Euro code 2, we would calculate the applied shear at 2d and
subsequent perimeters from the column face as per the code requirements,
as well as at the column face itself.
 We would then compare this to our calculated resistance. If the applied
shear is less than the un-reinforced hollow slab resistance, no further check
is required.
 If the applied shear is greater than the hollow slab resistance we omit balls
and make it solid and then check the solid part.
 The shear capacity is measured for two ratios of a/d (distance from imposed
force to support divided by deck thickness).

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BUBBLE DECK SLAB
 SHEAR STRENGTH (Contd…)
 If the resistance is still greater than the solid slab resistance and less than the
maximum allowed, we provide shear reinforcement.
 Punching shear the average shear capacity is measured to 91 % compared to
the calculated values of a solid deck.
Shear Capacity in
% of Solid deck
a/d =2.15 a/d = 3
Solid Deck 100 100
Bubble Deck 91 78-81
Comparison of shear capacity in girders with solid deck and bubble deck

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BUBBLE DECK SLAB
 DURABILITY
 The durability of bubble deck slab is not fundamentally different from ordinary
solid slabs.
 The concrete is standard structural grade concrete and combined with adequate
bar cover determined in accordance with EC2 or BS8110 provides most control
of durability commensurate with normal standards for solid slabs.
 When the filigree slabs are manufactured, the reinforcement module and balls
are vibrated into the concrete and the standard and uniformity of compaction is
such that a density of surface concrete is produced which is at least as
impermeable and durable, arguably more so, to that normally produced on site.

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BUBBLE DECK SLAB
 DEFLECTION
 Span depth ratio calculations for deflections are very approximate and are not
appropriate in flat slabs of irregular layout except for the most simple or
unimportant cases.
 FE modelling, including non- linear cracked section analysis is used to
calculate the deflection using normal structural concrete with a Young's
Modulus,Ec multiplied by 0.9 and a tensile strength, fc multiplied by 0.8 to
reduce the crack moment.
Slab Type
Max. Load
(kN)
Max. Deflection (mm)
Solid Slab 190 7.95
Bubble Deck Slab 195 7.61

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BUBBLE DECK SLAB
 VIBRATION
 RC slab structures are generally less susceptible to vibration problems
compared to steel framed and light weight skeletal structures, especially using
thin slabs.
 Bubble deck slab is light and is not immune from vibration in all cases so this
must be checked just as it should be in appropriate solid slab applications.
 Where deflections are large, as indicated by the static design, it is often an
indication that the structure is Sensitive to vibration issues.
 The lighter weight of Bubble deck slab may be exploited if it can usefully alter
the modal frequencies of a slab - generally raising them compared to a solid
slab.

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BUBBLE DECK SLAB
 FIRE RESISTANCE
 The fire resistance of the slab is a complex matter but is chiefly dependent on
the ability of the steel to retain sufficient strength during a fire when it will be
heated and lose significant strength as the temperature rises.
 In an intense, prolonged fire, the ball would melt and eventually char without
significant or detectable effect.
 Fire resistance depends on concrete cover nearly 60-180 minutes.
 Smoke Resistance is about 1.5 times the fire resistance.
 Depth of smoke is less than 10 m on both sides.
 Balls simply carbonize. No toxic gasses will be released.

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BUBBLE DECK SLAB
PRODUCTION AND CARRYING OUT
STAGE 1:
PRODUCTION
OF PLASTIC
BUBBLES
STAGE 2:
PRODUCTIONOF
THE BUBBLE-
LATTICE
STAGE 3:
INSTALLING
DIAGONAL
GIRDERS

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BUBBLE DECK SLAB
STAGE 4:
PREPARATION
OF CONCRETE
FOR FILIGREE
STAGE 5:
THE BUBBLE-
LATTICE IS
LOWERED INTO
THE CONCRETE
STAGE 6:
VIBRATION
OF THE
CONCRETE

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BUBBLE DECK SLAB
STAGE 7:
FINISHING OF
A FILIGREE-
ELEMENT
STAGE 8:
TRANSPORTATION
OF BUBBLE DECK
FILIGREE
ELEMENTS
STAGE 9:
CONCRETING,
COMPACTING
AND SURFACE
FINISHING

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BUBBLE DECK SLAB
ADVANTAGES
 MATERIALAND WEIGHT REDUCTION
Bubble Deck slab uses 30-50% less concrete than normal solid slabs
 STRUCTURAL PROPERTIES
The dead load to carrying capacity of a solid slab is 3:1 while a Bubble deck of
the same thickness has a 1:1 dead load to carrying capacity ratio.
 CONSTRUCTION AND TIME SAVINGS
Onsite constructions can be minimized since Bubble Deck slabs can be
precasted.
 COST SAVINGS
 GREEN DESIGN

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BUBBLE DECK SLAB
DISADVANTAGES
 Costing much money for transport these structures to construction sites.
 Sometimes the thin concrete layer may be broken during transportation.
 It is essential to use huge capacity crane to lift these structure to the planned
position and it is also very difficult for crane to access the desired position.
 Costing more steel used to fabricate stiffeners which are used to move and
lift deck structure.

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BUBBLE DECK SLAB
MILLENIUM TOWER
 Located at Rotterdam, Netherlands
 The first high rise building erected with Bubble
Deck filigree-elements
 The second highest building in Netherlands
 34 stories and 131 meter high
 Bubble Deck was chosen, in spite of being a
completely new product, because of its advantages
in cost, construction time and flexibility and
because of environmental issues.
 Built in 1998-2000.

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BUBBLE DECK SLAB
APPLICATIONS
 The Construction applications include:
 Commercial offices including high rise buildings, Hotels
 Buildings for storing retail and bulky goods, Industrial - warehouses and
factories
 Multi- unit residential buildings
 Airports, Car parks
 Special structures (marine, stadiums, rail platforms, etc.)
 Every component can be recycled. Easy demolition
 Substantial reduction in materials and transportation;
 Less emission and energy consumption

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BUBBLE DECK SLAB
CONCLUSIONS
 As per studies, the Bubble Deck configuration gives much improved flexural
capacity, stiffness and shear capacity of at least 70% when the same amount of
concrete and the same reinforcement is used as in the solid slab, realizing 30-
50% concrete economy, in comparison with the solid slab.
 Another advantage of Bubble Deck system is the significant cost saving,
because of the possibility of obtaining great spans with less support elements.
 By using the hollow elliptical balls, the better load-bearing capacity in Bubble
Deck can be achieved.
 Numerous applications in various countries, highlights the viability and the
efficiency of this system.
 Concrete usage is reduced as 1kg of recycled plastic replaces 100kg of concrete.

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BUBBLE DECK SLAB
CONCLUSIONS (Contd..)
 This avoids the cement production and allows reduction in global CO2
emissions. Hence this technology is environmentally green and sustainable.
 Reducing material consumption made it possible to make the construction time
faster, to reduce the overall costs.
 Besides that, it has led to reduce dead weight up to 50%, which allow creating
foundation sizes smaller.
 Therefore, this technology is very prospective in modern construction and
perhaps future of civil engineering belongs to this new kind of hollow slab if it
is applied effectively.
 In the last years, more than 1,000,000m² were built in several countries in the
world by using the Bubble Deck system.

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BUBBLE DECK SLAB
REFERENCES
 Churakov A,(2014) Biaxial hollow slab with innovative types of voids, Technical paper-
sciencedirect, 6 (21), 70-88.
 David A, Fanella Mustafa Mahamid and Michael Mota,(2017), Flat plate–voided
concrete slab systems, design, serviceability, fire resistance, and construction,
ascelibrary.org, 3(22), 1943-5546.
 Ashish Kumar Dwivedi, Prof. H. J Joshi, Rohit Raj, Prem Prakash Mishra, Mamta
Kadhane and Bharati Mohabey,(2016) Voided slab design, Review Paper, International
Journal of Research and Scientific Innovation, 1(4), 2321-2705.
 Bhagyashri G, Bhade and S.M Barelikar, (2016), An experimental study on two way
bubble deck slab with spherical hollow slab, International Journal of Recent Scientific
Research, 7(6), 11621-11626.

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