Cellular concrete is a special engineered concrete manufactured by mixing Portland cement, sand, fly ash, water and pre-formed foam in varied proportions to form a hardened material having an oven-dry density of 50 pounds per cubic foot (PCF) or less.
As per the definition by ACI, the density of the cellular concrete must be lesser than 50 pounds per cubic foot. Anyhow, cellular concrete can range in density from 20 PCF to 120 PCF.
One of the important characteristics of specially formulated cellular concrete is the self-compacting property wherein no compaction is required and it steadily flows out of a pump outlet to fill the mould. Due to this property, it can be pumped over major height and distances.
Fig 1: Difference between Cellular concrete and Aerated concrete.
This ly engineered concrete is also known as foam cement, foamed concrete, or lightweight flow-able fill.
Contents:
Material Used in Cellular Concrete
The materials used in cellular concrete which reduce the density of concrete are :
1. Cement
Cellular lightweight concrete is a 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.
2. Fly Ash
As fly ash is a by-product and its disposal is very expensive. It is used in the preparation of cellular light-weight concrete. It is one of the key ingredients which resolves the issue of disposal and at the same time, it’s very economical making it environmentally friendly.
3. Foam
The main constituent of the raw material of foam that is used in the production of cellular concrete is Genfil and its organic substance. The size of the bubbles differs from around 0.1 to 1.5 mm in diameter. The foam generator is employed to produce stable foam using an appropriate agent.
Reference Codes on Cellular Concrete
- ASTM C 869 - “Standard Specification for Foaming Agents Used in Making Preformed Foam for Cellular Concrete”
- ASTM C 796 - “Standard Test Method for Foaming Agents for use in Producing Cellular Concrete Preformed Foam”
- ASTM C 495 - “Standard Test Method for Compressive Strength of Lightweight Insulating Concrete”
Types of Cellular Concrete based on Density
Cellular concrete is differentiated into 3 types based on the range of density, which is produced for different purpose.
1. High Density Cellular Concrete
This is a structural grade concrete having the ranging from 1200kg/m3 to 1800 kg/m3. It is used in the construction of load-bearing walls, partition walls and in the production of pre-cast blocks for load-bearing brickwork.
2. Medium Density Cellular Concrete
The density range of this cellular concrete is 800-1000 kg/m3. The major use of this type of cellular concrete is found in the manufacturing pre-cast blocks for non-load-bearing brickwork.
3. Light Density Cellular Concrete
Light density cellular concrete has a density in the range of 400 –600 kg/m3. LDCC is ideal for thermal and sound insulations. They act as a resistance against fire accidents, termite and moisture absorbent. They have also proved to be a substitute than glass wool, wood wool and .
Advantages of Cellular Concrete
1. Lightweight
The low weight property of cellular concrete has a great advantage on building dead loads and craning works.
2. Fire Resistance
The air pockets formed acts as a barrier for fire. The structure made of cellular concrete is non-combustible and can endure fire breakout for hours.
3. Thermal Insulation
Cellular concrete acts a perfect thermal insulator.
4. 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
Cost of the material used is concrete is reduced as the foam is introduced into the concrete. Secondly, the use of industrial waste such as fly-ash saves a considerable amount of investment on cement products.
7. Other Advantages
Cellular light-weight concrete is also termite-proof and resistant towards freezing issues.
Applications of Cellular 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.