Cellular Lightweight Concrete (CLC) also known as Foamed concrete is one of the most significant type of concrete used for construction purposes due to its various advantages and usages over traditionally produced concrete.
Foamed concrete is manufactured by mixing Portland cement, sand, fly ash, water and preformed foam in varied proportions. Cellular lightweight concrete can be produced at building sites using machines and molds devised for normal concrete at ambivalent conditions.
One of profound characteristics of specially formulated foamed concrete is the self compacting property wherein no compaction is required and it steadily flows out of a pump outlet to fill mould. Due to this property, it can be pumped over major height and distances
Constituents of Cellular Lightweight Concrete
Important constituents of cellular lightweight concrete are:
- Fly ash, and
Foam: The foam generator is employed to produce stable foam by using an appropriate agent. The air content is maintained at 40 to 80 percent of the total volume. The size of the bubbles differs from around 0.1 to 1.5 mm in diameter. The main raw material for foaming is Genfil and its organic substance.
Fly ash: Generally considered as an industrial waste, it’s not easy to dispose of fly-ash easily. Since Fly-ash is one of the key ingredients of cellular lightweight concrete, it resolves the issue of disposal and at the same time it’s very economical. For same reason, foamed concrete is considered environment friendly.
Cement: Cellular lightweight concrete is homogenous combination of Portland cement, cement-silica, cement-pozzolana, lime-pozzolana; lime-silica pastes having identical cell structure obtained using gas-forming chemicals of foaming agents at measured levels.
Production of Cellular Lightweight Concrete
1. Batches of cellular lightweight concrete is manufactured by combining key elements in an ordinary concrete mixer. The strength and dry density of the ingredients differ based on its composition and air pocket content.
2. Continuous Cellular Lightweight Concrete is produced by mixing light mortar and preformed foam under pressure in a special static mixer.
Density of Cellular Lightweight Concrete
The variable density is described in terms of kg per m³. The density of regular concrete is normally measured at 2400 kg/m³ whereas the density of the foamed concrete ranges from 400 kg/m3 to 1,800 kg/m3
The density of cellular lightweight concrete can be effectively determined by introducing foam formed utilizing a foam-generator. Using fly-ash based CLC lowers the density but it has absolutely no effect on the overall strength of the structures. Large volume is notably realized even with low quantity of concrete.
Density Ranges and their Significance
Foamed concrete is produced in varied ranges for different purposes:
1. The lower densities (400 –600 kg/m3): CLC at this range of density are ideal for thermal and sound insulations. They act as resistance against fire accidents, termite and moisture absorbent. They have also proved to be better substitute than glass wool, wood wool and thermocol.
2. The medium densities (800-1000 kg/m3): This density of foamed concrete in attained for manufacturing pre- cast blocks for non-load-bearing brickwork. The size of blocks may vary based on the design and construction requirements.
3. The high densities (1200kg/m3 to 1800 kg/m3). This is structural- grade material used for:
- Construction of load-bearing walls and ceilings of low rise structures.
- Formation of partitioning walls
- Production of pre-cast blocks for load -bearing brickwork.
Advantages of Cellular Lightweight concrete
Cellular lightweight concrete has several advantages associated with their applications:
- Fire resistant
- Thermal insulation
- Sound absorption and Acoustical Insulation
- Environmental Friendly
- Termite proof and resistant towards freezing issues.
1. Lightweight: Cellular lightweight concrete is low on weight and thus it has a positive impact on weight management of building material and craning work. Normal concrete on the other hand is very dense and it’s difficult to work on it especially once it sets into a form.
2. Fire resistance: In CLC, the air pockets in its structure are responsible for high resistance to fire breakout. Irrespective of density range CLC walls are non-combustible and can endure fire breakout for hours.
3. Thermal insulation: At reduced density foamed concrete acts as a perfect thermal insulator. Although at this density it has absolutely no structural reliability in terms of strength.
4. Sound absorption and Acoustical Insulation: The low density increases acoustical insulation.
5. Environmental Friendly: Fly ash based cellular lightweight concrete is suitable for surrounding because fly-ash is one of the by-products of industrial waste.
6. Cost-efficient: Apart from fruitful application of industrial waste addition of fly ash also saves considerable amount of investment on cement products. Hence it substantially diminishes cost of construction.
7. Cellular light weight concrete is also termite proof and resistant towards freezing issues.
Applications of Cellular Lightweight Concrete
- Cellular lightweight concrete is utilized as thermal insulation in the form of bricks and blocks over flat roofs or non-loading walls.
- Bulk filling by applying relatively low strength material for old sewer pipes, wells, unused cellars and basements, storage tanks, tunnels and subways.
- Production of heat-insulated light wall panel.
- Maintain Acoustical balance of concrete.
- Manufacture cement and plaster-based light plate.
- Production of special of light heat resistant ceramic tiles.
- For soil water drainage purposes.
- Application in the bridge to prevent freezing.
- Utilized for tunnel and shaft filling and lightweight concrete manufacturing.
- Production of Perlite plaster and Perlite lightweight concrete.
Difference between Light weight concrete and Aerated Concrete:
Foamed concrete is often confused with gas or aerated concrete. In aerated concrete the bubbles are chemically formed due to reaction of aluminum powder with calcium hydro oxide and other alkaline compounds.
The aerated concrete is produced by the mixing of an air-entraining agent to the concrete. Foam Concrete on the other hand is manufactured using completely different technique.
Cellular lightweight concrete because of its special and versatile properties and application, it is widely produced and used for building projects around the world now. It has special importance in the light of growing awareness related to pollution control like air, water and noise.
Together with it’s easy to handle characteristics and profitability, its fire-resistant features make it one of the most endorsed construction material by builders and architects around the globe.
Read More: Fly Ash Based Cellular Light Weight Concrete