Cellular Light Weight Concrete (CLC) is a lightweight concrete that is produced by mixing cement and fly ash slurry with pre-formed foam. CLC is also known by the names as foam concrete, aircrete, foamcrete or reduced density concrete.
We will find out the main principles, constituent materials, manufacturing, properties, advantages and disadvantages of CLC in the blog.
Let’s start from the principles.
Cellular lightweight concrete technology
- Cellular lightweight concrete is prepared by introducing air bubbles into the concrete using a foaming agent.
- Amount of air-entrained determines the density of the material.
- Use of coarse aggregates is eliminated in CLC.
We will see the constituent materials in the next sections.
Ordinary Portland Cement is used.
The water used in the manufacture of CLC Blocks is potable water.
3. Fly-Ash :
Class F Fly-ash conforming to IS 3812 (part-1) is used .
4. Sand :
Sand passing through 2.36 mm IS sieve is used.
5. Foaming Agent :
Hydrolyzed protein-based foaming agent or synthetic-based foaming agent is used. Protein-based foaming agents are prepared with raw material in presence of Ca(OH)2 and a small portion of NaHSO3.
Time to look into the classification of cellular light weight concrete.
Classification of cellular light weight concrete
The cellular light-weight concrete blocks confirms to the following grades :
- Grade-A: These are used as load-bearing units and shall have a block density in the range of 1200 kg/m3 to 1800 kg/m3.
- Grade-B: These are used as non-load bearing units and shall have a block density in the range of 800 kg/m3 to 1000 kg/m3.
- Grade-C: These are used for providing thermal insulation and shall have a block density in the range of 400 kg/m3 to 600 kg/m3.
How about the manufacturing process?
Cellular light weight concrete manufacturing process
|CEMENT (%)||FLY ASH (%)||SAND (%)|
- Cement, sand and fly ash are dry mixed in proportion
- The slurry is made by wet mixing with water.
- Foaming agent about an amount of 1.5% of the total weight of cement, fly ash and sand is taken.
- The foaming agent is diluted with water in the dilution ratio is 1:35.
- The above solution is fed into the foam generator.
- the foam is mixed thoroughly with the cement-based slurry.
- After mixing is completed check that the wet density of the foamed concrete is close to what is required.
- The slurry form of foamed cellular concrete is pumped into assembled moulds of blocks of dimensions 600mm x 250mm x 200mm.
- The blocks are then cured and this curing is done by Water for 2 to 3 weeks.
We will find out the properties of fresh and hard cellular light weight concrete now.
Fresh CLC properties
- Workability of foamed concrete is very high and have a slump value of 150mm to collapse
- Reduces tendencies of segregation, bleeding and laitance
- Reduced alkali-aggregate reaction
- Freely flowing consistency and self-compacting property
Hardened cellular light weight concrete properties
- Physical properties of the foam concrete are clearly related to the dry density (400 to 1400kg/m3)
- Thermal conductivity of foam concrete ranges from 0.1W/m.K to 0.7 W/m.K
- Better acoustical insulation
- Good resistance against freezing and thawing
- Reduced permeability
I will show you the comparison of various technical parameters of cellular light weight concrete in the next section.
Comparison of technical parameters of clc blocks and burnt clay bricks
|1||Dry Density (Kg/m3)||800||900||1000||1100|
|2||Compressive Strength (N/mm2)||2.6||3.2||3.8||5.4|
|3||Drying Shrinkage||No Shrinkage||No Shrinkage||No Shrinkage||No Shrinkage|
|4||Thermal Conductivity (W/m.K)||0.32||0.34||0.36||0.37|
|5||Water Absorption (%)||11.87||11.51||11.37||10.96|
Now comes the the mandatory section on advantages and disadvantages of cellular light weight concrete.
Advantages of CLC
- reduces dead load of the building
- easy to handle and hence reduce the cost of transportation
- low thermal conductivity and good acoustical insulation
- good resistance to freezing and thawing action
- disposal of harmful industrial wastes like fly ash
- better placeability
- lower water absorption
- Fire resistant
Disadvantages of cellular lightweight concrete
- Difficulty in finishing
- Time of mixing longer
- With the decrease in density, the compressive strength and flexural strength also decreases
Let’s wrap up with the conclusion.
- 68% of our country’s electricity demand is fulfilled by coal-based thermal power plants and so the harmful fly ash produced can be used in CLC.
- CLC blocks are environment friendly and thus we can reduce environmental pollution and global warming.
- Technical properties of CLC are far more superior than conventional burnt clay bricks and so the use of burnt clay bricks can be replaced with CLC.
That’s it about cellular light weight concrete. Do you have any doubts? Did I miss out anything? Please help yourself to the comment box.