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disadvantages filler slab
#1

INTRODUCTION TO RCC FILLER SLAB

Filler slab technology is a simple and a very innovative technology for a slab construction.

The reason why, concrete and steel are used together to construct RCC slab, is in their individual properties as separate building materials and their individual limitation. Concrete is good in taking compression and steel is good in tension. Thus RCC slab is a product which resists both compression as well as tensile.

Fig 1: Simply supported slab cross section

Knowing this much if we want to move further to understand the Filler slab technology, we will have to further study the cross section of a typical simply supported RCC Slab. Under its own load and applied load, the slab will try to bend as shown in the Figure 1.



Fig 2: showing unwanted tension concrete

If we refer Figure 2, which indicates the neutral axis and also tension concrete in the bottom fibers of the slab which is in tension but the top fibers will be in compression. Knowing this much is the key to understand the filler slab technology. Tension in a slab is on the bottom fiber and compression on the top fiber. That means if we want to optimise the structure we can remove concrete from the tension zone where it is not much needed. That s the key behind filler slab construction.

This is a very cost effective roofing technology. Knowing the way slab is constructed on site (w.r.t. Gujarat, India), it is not easy to remove, the concrete from the tension zone, hence we try and replace (partially); that part of concrete using light weight and low cost filler material. This method of construction is called filler slab.

Filler slab technology is being used across India, but substantial amount of work on the successful promotion and transfer of this technology was done by Ar. Laurie Baker in South India. It is one place where filler slab has crossed the boundary of research and controlled implementation to being one of the regular options of construction by both government and private sector and also architects and designers have been promoting this technology.

These filler materials are so placed as not to compromise the structural strength, stability and durability, resulting in replacing unwanted and non-functional tension concrete, from below and thus resulting in economy of high energy material consumption and respective cost savings and decreased dead load of the slab.

An internal cavity can be provided between the filler material which adds an extra advantage; other than cost savings and energy savings; improved thermal comfort for the interiors. Also an added advantage of lower dead weight transferred to the supporting elements and finally onto the foundation to further adds up cost saving in design of these elements.

These filler materials are so placed as not to compromise the structural strength, stability and durability, resulting in replacing unwanted and non-functional tension concrete, from below and thus resulting in economy of high energy material s, consumption and considerable cost saving and decreased dead load of the slab.
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#2
Introduction
Filler slab is a variation of conventional reinforced cement concrete slab in which part of the concrete is replaced with a filler material which can be a waste material to ensure economical advantage over an RCC slab.The basic principle in a filler slab is that, considering an RCC slab of a given thickness, the concrete in the bottom half of the slab is simply dead weight and does not play a role in taking up compressive load, which is normally taken up by concrete in an RCC slab. So, this concrete can be replaced by a suitable lightweight filler material which can be accommodated in the bottom half of the slab. Since it reduces the weight of the slab by replacing concrete, savings can also be achieved in quantity of steel reinforcement without any compromise on the quality and strength of the slab. The filler materials commonly used are burnt clay tiles (such as Mangalore tiles), bricks, coconut shells, terracotta pots etc. The filler slab was first popularized by architect Laurie Baker in India in the late 70s and subsequently promoted by HUDCO through its national network of building centers. It has been successfully tested for structural performance by the Research and Development laboratory by the Civil engineering department of Anna University, Chennai.
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#3
Filler Slab

Lightweight, inexpensive materials such as lowgrade Mangalore tiles, bricks, coconut shells, glass bottles, etc. are used as filler materials in filler slabs to replace the redundant concrete in tension zones.

These materials are laid in the grids of steel reinforcement rods (6mm or 8mm dia.), and concreting is done over them. The concrete mix used is 1:2:4. The grid size depends upon the design, span, and the material used. For Mangalore tiles (size 23cm by 40cm), the grid size is 33cm by 50cm. The slab thickness is 10 centimeters.

This technique saves energy-consuming concrete. Roofs and intermediate floors account for 20-25% of the total cost of the house. This roofing costs 30-35% less than conventionally used concrete roofing. Thus a considerable amount is saved in terms of materials, energy, and cost.

This technique also reduces the unwanted dead load of roofing. Compared to other roofing systems, it is thermally comfortable and has no health hazards. Galvanized iron and asbestos cement sheet roofs dissipate too much heat and are difficult to live under. Also, asbestos cement sheets are long associated with diseases such as lung cancer, hence must be avoided.
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#4
The concrete of superior quality is produced as it is possible to have better technical control on the production of concrete in factory.
It is not necessary to provide joints in the precast construction.
The labour required in the manufacturing process of the precast units can easily be trained.
The moulds employed for preparing the precast units are of steel with exact dimension in all directions. These moulds are more durable and they can be used several times.
The precast articles may be given the desired shape and finish with accuracy.
The precast structures can be dismantled, when required and they can then be suitably used elsewhere.
The transport and storage of various components of concrete for cast in situ work are eliminated when precast members are adopted.
The work can be completed in a short time, when precast units are adopted.
When precast structures are to be installed, it is evident that the amount of scaffolding and formwork is considerably reduced.
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#5

Dear Sir/Madam,
My house construction is started and I'm eager to know about the Filler slab concrete Pro's & Con's.

I need help on this.

please revert.

Thanks

Ashraf Sainuddeen

email:[email protected]
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