249399169 bubble deck technology
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1. Introduction
1.1Concrete Floor Systems
Reinforced concrete slabs are components commonly used in floors, ceilings, garages,
and outdoor wearing surfaces. There are several types of concrete floor systems in use today,
and are shown in Figure 11!
• Twoway flat plate "bia#ial slab$ There are no beams supporting the floor between the
columns. %nstead, the slab is heavily reinforced with steel in both directions and
connected to the columns in order to transfer the loads.
• Twoway flat slab with drop panels This system differs from the twoway flat plate
system by the drop panel used to provide e#tra thickness around the columns. This
strengthens the column to floor connection in consideration of punching shear.
• &neway beam and slab This is the most typical floor system used in construction.
The slab loads are transferred to the beams, which are then transferred to the columns.
• &neway 'oist slab The 'oists act like small beams to support the slab. This floor system
is economical since the formwork is readily available and less reinforcement is re(uired.
• &neway wide module 'oist slab This system is a variation on the oneway 'oist slab with
wider spaces between the 'oists.
• Twoway 'oist slab "waffle slab$ This floor system is the stiffest and has the least
deflection of those mentioned since the 'oists run in two directions ")oncrete Reinforcing
*teel %nstitute$
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.
Figure 1-1: Types of Reinforced Concrete Floor Systems (Concrete Reinforcing Steel Institute)
Reinforced concrete has many advantages for floor systems it provides resistance to
high compressive stresses and to bending stresses it is relatively cheap to produce and
construct and it can be molded into virtually any shape and si-e. Disadvantages include a
high weightto strength ratio and difficulty in structural health monitoring "Reinforced
)ement )oncrete Design$.
1.2Hollo-Core Sl!"s
%n the mid/th )entury, the voided or hollow core floor system was created to reduce
the high weighttostrength ratio of typical concrete systems. This concept removes and0or
replaces concrete from the center of the slab, where it is less useful, with a lighter material in
order to decrease the dead weight of the concrete floor. owever, these hollow cavities
significantly decrease the slabs resistance to shear and fire, thus reducing its structural
integrity.
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This floor system typically comes in the form of precast planks that run from 2 ft to
1 ft wide and consist of strips of hollow coring with prestressed steel strands in between.
Figure 1 illustrates several types of hollowcore planks used in the industry. They are
combined on site to form a oneway spanning slab and topped with a thin layer of surfacing.
Figure 1-2: Types of Hollo-Core #l!n$s
Bubble Deck Technology
%n the 133/4s, 5orgen Breuning invented a way to link the air space and steel within a
voided bia#ial concrete slab. The BubbleDeck technology uses spheres made of recycled
industrial plastic to create air voids while providing strength through arch action. 6s a result,
this allows the hollow slab to act as a normal monolithic twoway spanning concrete slab.
These bubbles can decrease the dead weight up to 789 and can increase the capacity by
almost 1//9 with the same thickness. 6s a result, BubbleDeck slabs can be lighter, stronger,
and thinner than regular reinforced concrete slabs "BubbleDeck:;$.
)urrently, this innovative technology has only been applied to a few hundred
residential, highrise, and industrial floor slabs due to limited understanding. For this
investigation, the structural behavior of BubbleDeck under various conditions will be studied
in order to gain an understanding on this new techni(ue and to compare it to the current slab
systems. This technology will then be applied to create lightweight bridge decks since a
significant portion of the stress applied to a bridge comes from its own selfweight. By
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applying the knowledge gathered during the behavioral analysis, a modular deck component
for pedestrian bridges that is notably lighter but comparable in strength to typical reinforced
concrete sections will be designed.
2. %&%%' C*
2.1+!teri!ls
BubbleDeck is composed of three main materials steel, plastic spheres and concrete,
as see in Figure 1.
• *teel The steel reinforcement is of higher o plastici-ers are necessary for the concrete mi#ture. "BubbleDeck
%nternational$.
Figure 2-1: Components of ! %u""leec$ (Stu""s)
2.2Sc,em!tic esign
BubbleDeck is intended to be a flat, twoway spanning slab supported directly by
columns. The design of this system is generally regulated by the allowed ma#imum
deflection during service loading. The dimensions are controlled by the span "?$ to effectivedepth "d$ ratio "?0d$ as stated by B*@ 11/ or =). This criterion can be modified by applying
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a factor of 1.8 that takes into account the significantly decreased dead weight of the
BubbleDeck slab as compared to a solid concrete slab.
%n addition, larger spans can be achieved with the use of post tensioning as the L/d
ratio can be increased up to 7/9. "BubbleDeck:;$
L/d A 7/ for simply supported, single spans
L/d A 21 for continuously supported, multiple spans
L/d A 1/.8 for cantilevers
There are five standard thicknesses for BubbleDeck, which vary from 7/ mm to 28/
mm, and up to 510 mm and // mm for specific designs pending ;&C& certification. The
varieties of BubbleDeck can be found in Table 1.
T!"le -1: ersions of %u""leec$/ (T,e %i!0i!l Hollo dec$- T,e !y to ne solutions)
2.Types of %u""leec$
6ll of the BubbleDeck versions come in three forms filigree elements, reinforcement
modules, and finished planks. They are depicted in Figure . For all types of BubbleDeck,
the ma#imum element si-e for transportation reasons is 7 m. &nce the sections are connected
on site however, there is no difference in the capacity.
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2..1 Type - Filigree lements
BubbleDeck Type 6 is a combination of constructed and unconstructed elements. 6
/ mm 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. 6dditional steel may be inserted according to the
reinforcement re(uirements of the design. The full depth of the slab is reached by common
concreting techni(ues and finished as necessary. This type of BubbleDeck is optimal for new
construction pro'ects where the designer can determine the bubble positions and steel mesh
layout.
2..2 Type %- Reinforcement +odules
BubbleDeck Type B is a reinforcement module that consists of a preassembled
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
reinforcement, and then concreted in place by traditional methods. This category of
BubbleDeck is optimal for construction areas with tight spaces since these modules can be
stacked on top of one another for storage until needed
2.. Type C- Finis,ed #l!n$s
BubbleDeck Type ) is a shopfabricated module that includes the plastic spheres,
reinforcement mesh and concrete in its finished form. The module is manufactured to the
final depth in the form of a plank and is delivered on site. :nlike Type 6 and B, it is a one
way spanning design that re(uires the use of support beams or load bearing walls. This class
of BubbleDeck is best for shorter spans and limited construction schedules "BubbleDeckE
:;$.
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Figure 2-2: T,ree Types of %u""leec$- Type % 3 C
2.4d5!nt!ges of %u""leec$
2.4.1 +!teri!l !nd 6eig,t Reduction
The dominant advantage of a BubbleDeck slab is that it uses 7/8/9 less concrete
than normal solid slabs. The bubbles replace the noneffective concrete in the center of the
section, thus reducing the dead load of the structure by removing unused, heavy material.
Decreased concrete material and weight also leads to less structural steel since the
need for reinforcement diminishes. The building foundations can be designed for smaller
dead loads as well. &verall, due to the lighter floor slabs, the several downstream components
can be engineered for lower loads and thus save additional material "rap$.
2.4.2 Structur!l #roperties
Due to the lower dead weight of the slab and its twoway spanning action, load
bearing walls become unnecessary. BubbleDeck is also designed as a flat slab, which
eliminates the need for support beams and girder members. 6s a result, these features
decrease some of the structural re(uirements for the columns and foundations.
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6dditionally, BubbleDeck slabs can be designed and analy-ed as a standard concrete
flat slab according to research performed on its strength and ductility. 6s summari-ed by
Table , the dead loadtocarrying capacity of a solid slab is 7!1 while a BubbleDeck of the
same thickness has a 1!1 dead loadtocarrying capacity ratio "rap$.
T!"le 2-2: %u""leec$ 5s. Solid Sl!" (!d!pted from %u""leec$/-&*)
2.4. Construction !nd Time S!5ings
&n site construction time can be shortened since BubbleDeck slabs can be precast.
Type 6 includes a / mm precast concrete plate as the base and formwork for the slab. This
type of slab would eliminate the need for on site erection of formwork, thus significantly
cutting down construction time. *imilar to modem precast concrete flooring modules,
BubbleDeck can be fully shop fabricated and transported on site for installation as well.
Time savings can also be achieved through the faster erection of walls, columns and
C=+s due to the lack of support beams and load bearing walls for this innovative flat slab.
6ddition time may be saved from the (uicker curing time since there is less concrete in the
slab.
2.4.4 Cost S!5ings
%n relation to the savings in material and time, cost reductions are also typical with the
BubbleDeck system. The decreased weight and materials mean lower transportation costs,
and would by more economical to lift the components. ith less onsite construction from
the full and semiprecast modules, labor costs will decrease as well. %n addition, money can
be saved downstream in the design and construction of the building frame elements "columns
and walls$ for lower loads.
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There is a slight rise in production costs for the BubbleDeck slab due to the
manufacturing and assembly of the D+= spheres. owever, the other savings in material,
time, transportation and labor will offset this manufacturing price increase "*tubbs$.
2.4.7 8reen esign
The number of owners, designers and engineers who desire green alternatives is
growing e#ponentially. BubbleDeck is a fitting solution for lowering the embodied carbon in
new buildings. 6ccording to the BubbleDeck )ompany, 1 kg of recycled plastic replaces 1//
kg of concrete. By using less concrete, designers can save up to 2/9 on embodied carbon in
the slab, resulting in significant savings downstream in the design of other structural
members. )arbon emissions from transportation and e(uipment usage will also decrease with
the use of fewer materials. 6dditionally, the bubbles can be salvaged and reused for other
pro'ects, or can be recycled.
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. STR&CT&R' #R9#RTIS SI8
.18ener!l
Research has been performed at several institutions in Denmark, etherlands on the mechanical and structural behavior of BubbleDeck. *tudies include
bending strength, deflection, shear strength, punching shear, fire resistance, and sound
testing.
.2%ending Strengt,:
Bubble Deck where compared to a solid decks both practically and theoretically. The
results showed that for the same deck thickness the bending strength is the same for
BubbleDeck and for a solid deck and that the stiffness of the Bubble Deck is slightly lower.
.S,e!r Strengt, !nd #unc,ing S,e!r:
The results of a number of practical tests confirm that the shear strength depends on
the effective mass of the concrete. The shear capacity is measured to be in the range of G
319 of the shear capacity of a solid deck. %n calculations, a factor of /. is used on the shear
capacity for a solid deck of identical height. This guarantees a large safety margin. 6reas with
high shear loads need therefore a special attention, e.g. around columns. That is solved by
omitting a few balls in the critical area around the columns, therefore giving full shear
capacity.
.4Sound
6 comparison was made between Bubble Deck and oneway prefabricated hollow
deck of similar height. The noise reduction with Bubble Deck was 1 db higher than the one
way prefabricated hollow deck. The main criterion for reducing noise is the weight of the
deck and therefore Bubble Deck will not act otherwise than other deck types with e(ual
weight.
The Bubble Deck construction is following every usual criteria, and can be calculated
according to usual principles. The construction is not deviating, in any way, from what is
already known and used. The construction is analogous to an e(uivalent solid deck.
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.7eflection:
Due to the bubbles a Bubble Deck slab is not as stiff as a solid slab H but this effect is
small. *tudies and tests have shown that Bubble Deck has appro#imately @G9 of the fle#ural
stiffness of a solid slab. %f no other measures were taken, this would mean marginally higher deflections at *?* than in an e(uivalent solid slab in direct proportion to this ratio. owever,
the effect can be compensated for by adding a modest amount of steel even though the
deflection is significantly mitigated by the fact that Bubble Deck is lighter and in long term
*?*, where fre(uently the load combination comprises 1//9 permanent load and a
proportion such as 779 imposed load, the permanent weight saving ma#imi-es Bubble
DeckIs effect. ?ong term *?* is fre(uently the governing criteria for flat slab designs.
.;ur!"ility
The durability of Bubble Deck slabs is not fundamentally different from ordinary
solid slabs. The concrete is standard structural grade concrete and combined with ade(uate
bar cover determined in accordance with =) or B*@11/ is what provides most control of
durability commensurate with normal standards for solid slabs. hen 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.
Bubble Deck 'oints have a chamfer on the inside to ensure that concrete surrounds
each bar and does not allow a direct route to air from the rebar surface. This is primarily a
function of the fire resistance but is also relevant to durability.
)racking in Bubble Deck slabs is not worse, and probably better, than solid slabs
designed to work at the same stress levels. %n fact Bubble Deck possesses a continuous mesh,
top and bottom, throughout the slab and this ensures shrinkage restraint is well provided for
and that cracking is kept to a minimum whether it is intrinsic or e#trinsic cracking.
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sway reversals should be properly considered as well as amplification of the punching shear
due to the vertical component of ground acceleration.
%n computing the buildingIs response, the seismic designer should be closely engaged
with determination of the mass and the effect of this on modal spectrum. :sing Bubble Deck
a significant reduction of mass in the floor plate may be reali-ed together with an increase in
modal fre(uency and reduction in the sway forces due to lateral acceleration.
.= 'o!d C!rrying C!p!city
6 solid slab can only carry load one third of its own weight, and have problems with
long spans due to its high weight. Bubble DeckIs bia#ial deck solves this problem by
eliminating 78 9 concrete, while maintaining strength. ence, a Bubble Deck slab has thesame applied load capacity with only 8/ 9 of the concrete re(uired for a solid slab, or with
the same slab thickness has twice the load capacity using 8 9 of the concrete.
*hear capacity is more than 8 9 of a solid deck with same height. %n calculations are
used a factor /.. %n critical areas "around columns$, balls can be omitted to achieve full
capacity
.>Cont!ct %eteen %u""les nd ReinforcementThe potential for any contact is only theoretical because the balls do not perfectly fit
between reinforcement bars and moves slightly during assembly 0 site concrete compaction so
that some grout surrounds it and provides a measure of passivation. owever, even if there
were contact between the ball and the steel, the environment inside the void is very dry and
protected there is also no breach "apart from micro cracking$ of the concrete to the outside
air. %t is a better situation than e#ists with inclusion of plastic rebar spacers within solid slabs
that create a discontinuity within the concrete between the outside air and the rebar in solid
R.). slabs. e therefore have a situation that is better than e#isting with plastic rebar spacers
and these have been permitted for many years. e have had balls cut open in olland and
Denmark and there has been no sign of significant corrosion.
.1?ffect of %u""le oids &pon Stiffness
:nlike hollow core units, Bubble Deck voids are discrete balls and not prismoidal
voids running the length of the span. This makes a huge difference to the performance
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compared to hollow core sections. Tests carried out in Denmark,
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4. SIT RCTI9 IST''TI9
4.1St!ge 1- rect Tempor!ry #ropping
During erection each slab must be placed on suitable temporary propping beams
arranged in parallel rows mounted on props sufficient to ade(uately support the weight of the
precast filigree elements plus the loose reinforcement fi#ed on site, concrete poured on site
and all other site construction loads applied during final pouring of the concrete topping and
curing of the slab.
Typic!l !rr!ngement of props !nd propping "e!ms
4.2St!ge 2@ eli5ery 'ifting !nd #l!cing lements
Site eli5ery: The elements are delivered on flatbed trailers typically between 1m to 17.m
long, e#cluding drivers cab. The filigree elements will be stacked on top of each other up to a
ma#imum .8 m overall height. For e#ample, with BD@/ slabs there will be ma#imum G
layers of slabs, with a transport height of 8/mm each plus wooden packers typically 8/mm
deep separating each element, making an overall height of .1m above the trailers bed. =ach
individual load will be planned so the weight of a load will be a ma#imum 3 Tonnes and you
must provide suitably hard and level access for our delivery transport to reach the offloading
position you have determined.
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'o!ded tr!ilers !rri5ing on site
'ifting !nd #l!cing Filigree lements: The filigree elements must &>?K be lifted by the
lattice beam girder reinforcement. ?ifting hooks must 6?6K* be attached under the upper
angles of the girder reinforcement diagonal web bars. ?ifting hooks must >=L=R be attached
to the upper reinforcement mesh as this would be unsafe.
'ifting element into position 'ifting ,oo$s under girder di!gon!l e" "!rs
4.St!ge @ Fi0ing 'oose Site Reinforcement
*ite installation drawings are provided for loose site reinforcement "supplied by others$ fi#ed
at the bottom of the slab "directly on top of the precast concrete filigree permanent formwork
without spacers or on top of site shuttering on spacers$ and reinforcement fi#ed at the top of
the slab "directly onto top mesh reinforcement$, together with accompanying bar bending
schedules. These must be studied and closely followed at all times.
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4.4St!ge 4 @ Constructing S,uttering
&nce the perimeter loose reinforcement has been installed work on erecting perimeter
and construction 'oint shuttering can commence. Temporary works are our responsibility to
determine.
4.7St!ge 7 @ #rep!r!tion for Concreting
The precast concrete permanent formwork edges are manufactured to a high
accuracy and care taken to get a tight 'oint during laying the elements can render 'oint filling
unnecessary. hen 'oints between slab elements have not been closely butted they must be
filled to prevent grout seepage. *hould this be re(uired 'oint filling can be undertaken with
either mortar grout or a small bead of silicone sealant inserted at the bottom of the splay 'oint
between elements. This is most easily undertaken prior to installing the loose splicereinforcement.
4.;St!ge ; @ %u""le ec$ Site Inspection
The technical representative will visit the site and undertake a full inspection of the
BubbleDeck element and loose reinforcement installation. Following inspection, the technical
representative will issue you with an inspection record listing any work that needs to be
undertaken prior to site concreting, or confirming the installation is ready for concreting and
the work is to our approval.
4.
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#ouring i"r!ting 3 Flo!ting Site Concrete
4.=St!ge = @ Remo5ing Tempor!ry #ropping
During construction planning the minimum period for removal of propping before
backpropping is confirmed. This is usually between 7 to 8 days from pouring of the site
concrete as long as the early concrete test results have confirmed the site concrete has
reached at least /9 of its final design strength, but can vary dependant upon our floor slab
design, strength of site concrete, and ambient temperatures.
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7. A+#'S 9F %&%%' C* TCH9'98B
7.1+illennium Toer Rotterd!m
The first high rise building erected with BubbleDeck filigreeelements and the secondhighest building in >etherlands, 72 stories and 171 meter high. BubbleDeck was chosen, in
spite of being a completely new product, because of its advantages in cost, construction time
and fle#ibility and because of environmental issues. Beams could be e#cluded resulting in
two more stories than planned in the beginning for the same building height. Built in 133@
///.
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7.2C!r p!r$
)ar park built with BubbleDeck in Frankfurt
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;. C9C'&SI9
Bubble Deck will distribute the forces in a better way than any other hollow floor
structures.
Because of the threedimensional structure and the gentle graduated force flow the
hollow areas will have no negative influence and cause no loss of strength.
Bubble Deck behaves like a spatial structure as the only known hollow concrete
floor structure. The tests reveal that the shear strength is even higher than presupposed. This
indicates a positive influence of the balls.
Furthermore, the practical e#perience shows a positive effect in the process of
concreting H the balls cause an effect similar to plastici-er additives.6ll tests, statements and engineering e#perience confirm the fact that BubbleDeck in
any way acts as a solid deck H and therefore will follow the same rules0regulations as a solid
deck "with reduced mass$, and further,leads to considerable savings.
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