OCTAVO:
Ah?

whats ah? Abi na space you wan book?

This slab cast design as most experts in the house has rightly put is waffle type slab. To save concrete mix, to reduce weight, to sound proof and heatproof a structure, but takes more expertise in construction of these slabs and more rods are needed than usual.

Hey, octavo, you no longer visit cartalk, why?

@AbdulWastecx, weren't you proposing something similar?

Ebubeslym:
It is called a bubble deck or bubble slab....

It makes floors thinner and reduces concrete weight.
This type of slab is believed to save cost because the amount of concrete needed is a lot more less than the normal heavy all concrete slabs.

The areas between columns in a solid slab more or less have limited structural effect beyond adding extra weight to the structure, so those blue balls you see are placed between layers of reinforced welded steel and an internal lattice girder which when casted produces a slab that is 35% lighter...

Cheers.

u r on point... I guess dis will now take d place of claypot in concrete designs to enable for high-rise possibilities.

I thought na slap I see that make me to open the tread o........... which one come be slab

Informative

The slab u see is similar to the normal clay pot slabs we do here in Nigeria. where by claypots are arranged in similar manner with adequate reinforcement on all sides. However, against most comments above, this method of slabbling doesn't reduce the thickness of the slab, in fact, slabs of this type has thickness ranging from 200mm-250mm, however, concrete volumes are greatly reduced thereby saving cost. Another advantage of this slab over the solid slab is temperature control and sound damping. The calculations are not out of this world, similar calculations involving clay pot hollow slab can still be applied

Ask buhari

surely this is anti-Nigerian engineers/contractors

ahhh you want to reduce concentrate/ cost hmm na if una building collapse now una go dey blame supervisors Oga H'add money make ur house fine well well like dasuki own

true2home:
The above explanations covered the idea for its use. I will not recommend it in Nigeria because the method requires close supervision and clear structural mathematical calculation. Less me just say there is less room for mistake when building such deck. The iron used has to be the right Fy and the concrete right Fc as well. Concrete characteristic is compression strength, while iron's is tension. Tension is experience in the bottom of a slab while compression is exact on the top section of a slab. if the bottom section does not deform excessively, then the concrete at the bottom area of a slab do not serve much engineering purpose other then composition for the iron rod. Anyways, i have to stop here before i loss non-engineering NL

As if I'm not lost already, abeg where I fit get Oshodi bus.


In simple words; its a floating concrete slab made of Iron, rubber and concrete with reduced weight. The aim is to reduce the overall load on the beams. Hope I'm correct.

[quote author=EVILFOREST post=45478565]Please, stop posting such because i don't know when We may get there

we are there already, construction companies on the island had been using hollow pot for decking since and it serves the same purpose as that of the waffle balls

true2home:
The above explanations covered the idea for its use. I will not recommend it in Nigeria because the method requires close supervision and clear structural mathematical calculation. Less me just say there is less room for mistake when building such deck. The iron used has to be the right Fy and the concrete right Fc as well. Concrete characteristic is compression strength, while iron's is tension. Tension is experience in the bottom of a slab while compression is exact on the top section of a slab. if the bottom section does not deform excessively, then the concrete at the bottom area of a slab do not serve much engineering purpose other then composition for the iron rod. Anyways, i have to stop here before i loss non-engineering NL

Please stop. Go to Yabatech library. You will find the waffle slab there. The structure has been standing for many yrs. In all forms of slab construction, we all focus on using the right Fy iron and Fc for concrete. We are aware of tensile strength and tensile strain. All this is what a civil engineer takes into consideration before putting together his structural design. Stop underrating the nigerian construction industry. Many of us take our jobs seriously.

DisGuy:
surely this is anti-Nigerian engineers/contractors

ahhh you want to reduce concentrate/ cost hmm na if una building collapse now una go dey blame supervisors Oga H'add money make ur house fine well well like dasuki own

Acrually, excess concrete load manytimes result into collapse. Concrete is dead load. All engineering designs are supposed to ensure the optimal use of concrete so that it will not eventually pull down the structure. And the costliest building is not the strongest. It is the strutural design and attention to details and quality that produce a well standing building

EVILFOREST:
Please, stop posting such because i don't know when We may get there

You dont even know where we are right now.

true2home:
The above explanations covered the idea for its use. I will not recommend it in Nigeria because the method requires close supervision and clear structural mathematical calculation. Less me just say there is less room for mistake when building such deck. The iron used has to be the right Fy and the concrete right Fc as well. Concrete characteristic is compression strength, while iron's is tension. Tension is experience in the bottom of a slab while compression is exact on the top section of a slab. if the bottom section does not deform excessively, then the concrete at the bottom area of a slab do not serve much engineering purpose other then composition for the iron rod. Anyways, i have to stop here before i loss non-engineering NL

You would not recommend it in Nigeria...just like the steel structures. Lol...this Oga don see naija finish.

Sir, you know naija very well but you are surely far from the reality on ground.

I'm enjoying all these answers I have bin receiving dis morning

dododawa1:
easy answer =bubble slab and to save concrete money,BUT to try this in water lodged area

What do u mean? This is a suspended slab design type not foundation slab

HOLAROCKDAY:
To the civil Engineers, Builders in the forum.
Base on my pictures below, A friend of mine sent me this pic asking me what type of slab it is. And where can it be use, the reason of putting the waffles ball in between the reinforcement. To cut the story short, an explanation on the slab. I believe you will help me out with these.

This is a waffle slab with permanent shuttering (former). Waffle slab is a slab with rib beam in two direction (different from ribbed slab with rib only in one direction.
The ribbed are space at a regular distance between each other based on formers, life load and code specifications.

Waffles slab is made up of
1. Topping
2. Series of rib beam accros both the short and long span of the slab.
3. Former ( the bubble above, hollow block, clay block, plastic pod, polystyrene pod etc) which remain part of the construction after the Formwork is removed.

In most cases the waffle slab is designed in such a way that the topping is not consider to contribute to structural strength but only to linked the rib beams together. The topping can also be made of concrete of not necessarily of the same strength as that used in ribs.

The former (polystyrene pod, bubble or clay block) are not consider to contribute to the slab strength in the design calculation most time.

The major advantage of these floor is the reduction in weight achieved by removing part of the concrete section below the neutral axis and replacing that with lighter weight materials. These types of construction are economical for building where there are long spans, over between 5m to 6m with light to moderate life load (1.5 - 3kN/m2), such as residential houses, schools, hospital, hotels etc. They would not be suitable for floors having heavy load like warehouse, production facilities, garage etc

talk2riel:
It increases the head room in floor by eliminating drop beams in slabs.


modified one of the site am currently working on.

I think the use of Hollow Block is wayy to risky.

Dieumerci:

You would not recommend it in Nigeria...just like the steel structures. Lol...this Oga don see naija finish.

Sir, you know naija very well but you are surely far from the reality on ground.

Dont mind him. He needs someone to take him on site expeditions. He thinks nigerian construction is still defined by those ''baba kudi '' constructions he is used to seeing...

IMO

Sound Proof - Agree
Heat Insulant - Agree
Ligth Weight - Agree

Cost Less - err... errrrr... Agr... mbanu! DISAGREE!

Yes, less concrete volume but the reinforcement is doubled if not quadrupled. The (Waffles, Foams, etc) fillings would not cost so cheap either!

***NOTE : Not a Civil Eng/Construction Personnel, just using my common sense!

EgunMogaji:
@AbdulWastecx, weren't you proposing something similar?

Yes sir, I have designed a couple before. The one I was proposing is using polystyrene as the former instead of this bubble they have here.

Most Nigeria home owner are not too comfortable with it because they perceived the material to be too light weight.

Our conservative mentality about what can work and what cannot. People don't know that the polystyrene is just occupying concrete space below neutral axis at places where they are not useful. The major structural component is the ribbed beam which is closely spaced. The ribbed beam in waffle slab do all the structural work while the polystyrene pod help to reduce unwanted concrete section thereby reducing weight and cost of not only the slab but also other dependent structural members like beams, columns and foundation footings since the load transfered to these members will be significantly lower than that from an equivalent solid slab

ewizard1:
IMO

Sound Proof - Agree
Heat Insulant - Agree
Ligth Weight - Agree

Cost Less - err... errrrr... Agr... mbanu! DISAGREE!

Yes, less concrete volume but the reinforcement is doubled if not quadrupled. The (Waffles, Foams, etc) fillings would not cost so cheap either!

***NOTE : Not a Civil Eng/Construction Personnel, just using my common sense!

It cost less.
The reinforcement is much less because you only reinforced the rib beam with 2y 12 down and nominal top reinforcement and use y8 spaced @ 300mm center to center in most cases ( though reinforcement details depend on your structural designs) . The topping is provided with Iron mesh or light mat reinforcement preferably y8 spaced at 300mm center at the middle of the topping to control temperature shrinkage and cracking.

The concrete section of the beam is smaller (150mm x 250mm for a simple residential building) with a topping around 50-75mm the remaining section of the slab is replaced with polystyrene pod which is cheaper

NOTE: I am an agriculturist not an engineer but I am asking my question on basic physics knowledge.
You have listed advantages. Good. But what exactly are the waffle balls made of? If they do not allow sound thru and are good in places with high temparatures, I figure that the balls are hollowed out with air spaces inside to trap sound and heat. IF they are thus hollow, how can they support decking? They'd be too light na. How durable are they sef?
At least the waffle slabs look dense enough to me. The material is packed tight and should be strong.

SilvanusII:
NOTE: I am an agriculturist not an engineer but I am asking my question on basic physics knowledge.
You have listed advantages. Good. But what exactly are the waffle balls made of? If they do not allow sound thru and are good in places with high temparatures, I figure that the balls are hollowed out with air spaces inside to trap sound and heat. IF they are thus hollow, how can they support decking? They'd be too light na. How durable are they sef?
At least the waffle slabs look dense enough to me. The material is packed tight and should be strong.

Question like '' how can they support decking '' is the misconception people havd with these materials. They are not designed to support decking, they are designed to replace some concrete section that are useless in the slab section in the first place.
The ribbed beam with reinforcement support the slab or decking load. The slab is designed with these grid beam spaced at mostly 600 center to center in the case of polystyrene slab, the beam carries the floor load while the 600mm square spaced between these beam is occupied by poly slab.

EVILFOREST:
Please, stop posting such because i don't know when We may get there

When we may get there?
The SEET Complex in FUTO was designed and constructed in this manner. The only difference from the above picture and that of FUTO is the material used. That of FUTO was done with blocks. Some also use clay pots as the required material - like where I did my six months IT. Though the project was halted before the slab was introduced. It's very commendable and cost wise. But considerations are made before going for such type of slab.





PS: You can also run a combination of this type with solid slab at difference floors of your building.

true2home:
The above explanations covered the idea for its use. I will not recommend it in Nigeria because the method requires close supervision and clear structural mathematical calculation. Less me just say there is less room for mistake when building such deck. The iron used has to be the right Fy and the concrete right Fc as well. Concrete characteristic is compression strength, while iron's is tension. Tension is experience in the bottom of a slab while compression is exact on the top section of a slab. if the bottom section does not deform excessively, then the concrete at the bottom area of a slab do not serve much engineering purpose other then composition for the iron rod. Anyways, i have to stop here before i loss non-engineering NL

with this kind knowledge you have,you still went ahead to underate us

following

abdulwastecx:


It cost less.
The reinforcement is much less because you only reinforced the rib beam with 2y 12 down and nominal top reinforcement and use y8 spaced @ 300mm center to center in most cases ( though reinforcement details depend on your structural designs) . The topping is provided with Iron mesh or light mat reinforcement preferably y8 spaced at 300mm center at the middle of the topping to control temperature shrinkage and cracking.

The concrete section of the beam is smaller (150mm x 250mm for a simple residential building) with a topping around 50-75mm the remaining section of the slab is replaced with polystyrene pod which is cheaper

Ok then... You know better!

Thanks!

true2home:
The above explanations covered the idea for its use. I will not recommend it in Nigeria because the method requires close supervision and clear structural mathematical calculation. Less me just say there is less room for mistake when building such deck. The iron used has to be the right Fy and the concrete right Fc as well. Concrete characteristic is compression strength, while iron's is tension. Tension is experience in the bottom of a slab while compression is exact on the top section of a slab. if the bottom section does not deform excessively, then the concrete at the bottom area of a slab do not serve much engineering purpose other then composition for the iron rod. Anyways, i have to stop here before i loss non-engineering NL

All method of slab construction requires close supervision and clear mathematical calculations.
Waffle slab is as straight forward as one - way solid slab or two - way solid slab, I think flat slab is more technical than even this waffle slab.

For all type of slab you need the right steel strength and concrete strength.
A one way slab behave like a continuous beam where the span is sagging ( bottom Fibre is in tension) while the continuous support is in hogging (top Fibre at the support is tenaion).

A two way slab behavior is dependent on the end conditions and for this type of slab we have about 9 different end Conditions, namely
1. Interior panel
2. All edges discontinuous
3. One short edge discontinuous
4. One long edges discontinuous
5. Two short edges discontinuous
6. Two long edges discontinuous
7. Adjacent edges discontinuous
8. One short edge continuous
9. One long edge continuous.

For these two way slab design code is use to determine both the positive and negative moment for design purpose.

For ribbed and waffle slab.
Ribbed slab is like a one way slab where the solid concrete section is replaced with series of ribbed parallel to one another at a reasonable space based on the life load, span of slab and the type or former to be use. It is made up of topping, rib beam and former which can either be temporary or permanent. The analysis of the rib is carried out like that of one way slab where the span and support moment and shear is gotten through beam analysis or using appropriate formulas from bs codes.

Waffle slab is like two way slab where the rib beam is in both directions. The ribbed intersect each other to form a box that is either filled using polystyrene, clay block or sancrete block.

it's done to cut cost by reducing the volume of concrete which consequently would result to reduction in the dead loads from the slap on the structure.

tossen:


Actually, excess concrete load many times result into collapse. Concrete is dead load. All engineering designs are supposed to ensure the optimal use of concrete so that it will not eventually pull down the structure. And the costliest building is not the strongest. It is the strutural design and attention to details and quality that produce a well standing building

Wow! Nice one, would be a pleasure to get to relate with you I must say.
Before I get distracted, the slab you've seen are all modifications of ribbed/ waffle slabs with essentially the same background principle underlying it's design n construction.
To a lay man, what those balls,styrofoam, pots or whatever else you see do is just take up space,basically to reduce the volume of concrete used in the slab. Now the logic is simple, if I can create many supports(beams), my slab need not be solid/big / thick. This is based on the premise that the higher the design load the thicker the slab has to be, also like someone mentioned, any concrete u have below the neutral zone is a waste( study civil engineering to understand this) ie anything below the reinforcement of a slab is just cover. Its like the 'ay' you have in the word OKAY, absolutely useless.
The beams provided are spaced at less than 500mm spacing along the shorter span in a one way slab(ribbed) or in both ways (waffle slab). This reduces the dead weight significantly without affecting the serviceability and ultimate limit state design considerations. Note that the materials used to fill the voids can be removed so it's not for soundproofing or insulation, those are just added benefits if you keep the material. The primary reason we engineers design ribbed/waffle slabs is when we have long spans panels exceeding 7metres along both axis, a drop beam and slab thickness of more than 200mm becomes excessive. Another reason is if the design load is high eg a library or hospital would have a live load consideration in excess of maybe 10KN/m2 which translates into plenty loadddddddd! That's why yabatech library that someone mentioned and most other such structures have waffle slabs.
This method has been perfected by Nigerian engineers, and we would continue to tweak it as more technological advance is made.
This building is somewhere in lagos, and it has a ribbed slab that had the void material removed, it's beautiful, lovely and it's still standing.
I don talk story sha, but it's like doctors talk, u have to belong to understand.
Kudos to the other quality and well informed engineers here! NICE,NIstructE.

lilzcee:
who u epp? Who u epp? Who u epp? U don baFf? Who u serve don't slam my door what is wrong with you

I believe that wat waffles slab is use for @ur who u epp

lilzcee:
who u epp? Who u epp? Who u epp? U don baFf? Who u serve don't slam my door what is wrong with you

I believe that wat waffles slab is use for @ur who u epp