Filler Slabs: Material and Advantages

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Filler slab technology is an innovative and cost-effective technology where the dead load of the slab is reduced by replacing the concrete with filler material.

The fundamental concept behind the filler slab is that an RCC slab does not need concrete located in the slab's lower half for its construction. This is because the concrete functions as a compression material, which is only required in the upper half of the slab. As a result, a lightweight, inexpensive filler material like clay pots, Mangalore tiles, etc., is used to replace this concrete component.

The filler slab is based on the idea that for supported roofs, the lower part of the slab is subjected to tensile forces while the upper part is subjected to compressive forces. Bricks, cellular concrete blocks, and tiles are used as replacements.

Since steel can withstand greater tensile forces than concrete, the lower tensile region of the slab only needs steel reinforcements to keep the structure together.

The reinforcements are placed in a grid pattern when the shuttering is complete. The grid's size is determined by the filler material's size and the structure's design.

For instance, a grid of 35 cm x 50 cm is used as filler for Mangalore tiles, while a grid of 45 cm x 45 cm is used as filler for clay pots with a 40 cm diameter. To avoid absorbing water from the concrete, the filler material must be soaked in water before casting. The slab is then cast using cement concrete like conventional concrete slabs.  

Selection Criteria of Filler Materials

1. Filler materials should not react with other materials like rebars, cement, or water.
2. The filler's dimensions, size, and form must suit the reinforcement's spacing. All relevant stakeholders, including the client, the architect, and the structural engineer, must work together to ensure a smooth process. Any last-minute revelation might lead to a compromise, resulting in rusted rebars and leaks over time.
3. It is necessary to ensure that the filler material only absorbs a little amount of water, and it is better to check this before construction.
4. To keep expenses under control, local materials should be utilized.
5. Lightweight materials should be used.
6. The choice of materials is also influenced by the design of the ceiling and the room's purpose.

Materials used for Filler Slabs

To maintain an eco-friendly environment, the materials used as filler must be waste or discarded products that could be reused. After researching a wide range of resources, including mine waste and other waste, a short list of materials that fulfilled the requirements was formed. The following are the material used for filler slabs:

1. Mangalore tiles
2. Clay pans
3. Bricks
4. Waste bottles
5. Coconut shells
6. Thermocol
7. Cyber wastes like keyboard
8. Stabilized mud Blocks
9. Terracotta tiles

Advantages of Filler Slabs

1. It's 20% cheaper than a traditional RCC slab due to cheaper filler materials and less amount of steel and concrete.
2. It provides a great thermal insulation layer because of the air pocket formed by the contours of the tiles, and taking into consideration the negative zones and reinforcing regions, the design integrity of a filler slab requires careful planning for such a slab.
3. Filler slabs with better quality control are strong and durable.
4. The heat-resistant air spaces between filler slabs offer pleasant living room temperatures. In humid, hot climates, infill slabs give thermal comfort.
5. When items like keyboards, discarded plastic, and bottles are utilized as fillers, this technology automatically manages waste by reusing hazardous elements to the soil and earth.
6. The filler slab decreases carbon footprint by 20%.
7. Filler slabs with the right patterns improve the ceiling's appearance.

Disadvantages of Filler slabs

1. The filler slab technique requires expertise. There is a probability of errors made in its construction unless an expert is consulted for its design and construction.
2. If the rebars come in touch with filler products made of clay, they may rust. To avoid this. enough cover for reinforcement, sufficient care should be taken.
3. For the reasons stated above, the terrace slopes must be properly planned, and all rainwater downpipes must be clog free. Sufficient care must be made to ensure terrace maintenance.

FAQs

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