There are different types of concrete are used in construction for different purposes, foam concrete is one of them. Foamed concrete sounds like a contradictory sound, but it can be used extensively in do-it-yourself home projects regardless of size. Fire-resistant and insulating foamed concrete is a multifunctional product that can be both decorative and beneficial for construction projects.
What is Foam Concrete?
Foam concrete is a lightweight composition of cement, water, foam agent and, fine aggregates or sand (with no coarse aggregate) other names are Lightweight Cellular Concrete (LCC), Low-Density Cellular Concrete (LDCC), and other terms are defined as a cement-based slurry.
The Density of Foam Concrete
The density of foam concrete usually ranges from 400 kg/m3 to 1600 kg/m3 the density is normally controlled by replacement fully or some part of the fine aggregate with foam. The compressive strength of foam concrete at 28 days, ranges from 0.2 to 10N/mm2 or can go higher.
Its cellular microstructure makes it a highly air-entrained system with typical physical and mechanical properties. The air content is more than 50% as compared to air-entrained concrete with 5%.
How to Make Foamed Concrete?
Foamed concrete” is made by mixing foaming agent with mortar in truck mixer. Foamed concrete is a nonstructural void filler that can be dug out with excavators. It is used for various purposes like trench filling.
In recent years, its use has increased because of low cost and low energy consumption as compared to other lightweight materials used for the same purpose. Foamed concrete is used in many sectors of infrastructure mostly as engineered nonstructural fill, in precast panels, as thermal material, and more specifically in parts of construction buildings.
Fine sand+Binder+water + stabilizing foam=FOAM CONCRETE
Ingredients of Foam Concrete
ingredients of foam concrete are:
- Binder
- Foam agent
- Water
- Fine Sand
Binder
cement is the most used binder ingredient in foamed concrete. The types of cement used in the foamed concrete are mostly ordinary Portland cement, rapid hardening Portland cement, calcium sulfoaluminate cement, and high alumina cement.
It can be used in ranges between 25% and 100% of the binder content. Sometimes supplementary materials such as silica fume, fly ash, lime, incinerator bottom ash, and Lytag can also be replaced with cement in a percentage between the two values 10% and 75%.
Foam Agent
The foamed agent controls the concrete density through a rate of air bubbles created in the cement mixture. Foam bubbles are enclosed air-voids formed due to the addition of foam agent. The foam agents are commonly synthetic, protein-based, detergents, glue resins, hydrolyzed protein, resin, and soap, etc.
The most commonly used foam agents are synthetic and protein-based. The protein-based foam agents result in a stronger and more closed-cell bubble structure which permits the inclusion of greater amounts of air and also provides a more stable air void network and is thus superior while the synthetic ones yield greater expansion and thus lower density.
The amount of the foaming agent has a significant effect on the properties of both fresh and hardened concrete. The foam quantity determines the properties of foam concrete such as:
Lightness
Strength
Insulation
Fire resistance
Impermeability
Water
Admixtures and Constituents determine the quantity of water requirement. Consistency and uniformity also gets effected with water.
Fine Sand
The strength of low-density foam concrete is affected by the filler type. Foam concrete with fine aggregates has a greater tendency of shrinkage, and in this case, good curing is critical. Foam stability is effected by greater sand quantity, which usually causes strength reduction in foam concrete.
Properties of Foam Concrete
Foam concrete properties are given below:
- Low Density: Due to the absence of coarse aggregate it has a low density as compared to ordinary concrete.
- . Drying Shrinkage: Lack of coarse aggregates leads to higher shrinkage of the Foam Concrete than that observed in ordinary concrete. Drying shrinkage is affected by many factors, such as density, foaming agent, filler, additive, and moisture contents.
- High strength to weight ratio: Low density leads to high strength to weight ratio.
- Fire resistance: Due to the porous structure of foam concrete it has excellent thermal and insulation properties and reduces with decreasing densities. Aggregates type and admixtures have a significant effect on thermal conductivity. Similarly density, mix proportion, temperature, etc. have also very much effect on thermal conductivity.
- Compressive strength: Cement dosage, mix proportion, water-cement ratio, foam volume, foaming agent, curing method, additive, etc. Effect the compressive strength of foam concrete.
- Sound insulation: Compared to “normal” concrete, Foam concrete absorbs more sound energy, this means there is less sound reflecting off the surface, and less sound transmitted through the material and more sound absorption. This is one of the most important properties that is why it is such good building material. It also depends upon the density.
- Permeability: Due to the presence of foam the water absorption of foam concrete is higher than ordinary concrete. The lesser density value can increase the permeability. The water-cement ratio has also affected the permeability; a lower cement ratio means it will have lower permeability.
- High flowability: Due to high paste content and no coarse aggregate it has high flowability as compared to ordinary concrete.
- Corrosion: The resistance capacity of Foam Concrete to corrosion depends on its cellular structure.
- Self-compacting: High paste content and no coarse aggregates leads to the property of self-compacting.
- High resistance to aggressive environments such as freeze and thaw.
- Using Foamed concrete reduces dead loads on the structure and foundation which, contributes to energy conservation, and lowers the labor cost during construction. It also reduces the cost of production and transportation of building components compared to normal concrete.
Application of Foamed Concrete
- Screeds(insulation floor screeds and insulation roof screeds)
- Floors
- Roof fillings
- Walls fillings
- Walls cast on site
- Making Block
- For making Panels
- Bridge abutments
- Ground stabilization (Road Sub bases)
- Precast blocks
Advantages of Foamed Concrete
- It has no negative effect on the environment
- Good Thermal insulation
- Sound insulation (it is highly energy absorbent )
- Fire resistance(safety)
- Ideal in seismic areas:
- FC forms a solid matrix; the material is not so vulnerable to seismic shock waves, thus ideal for building structures in areas with seismic activity.
- 100% recyclable
- Reduced time and cost of labor
- Easier in transportation
- Cost-effective and less maintenance
Disadvantages of Foamed concrete
- Decreased compressive and flexure strength due to low density.
- Even though FC has been widely used in nonstructural components, the applications in structural members are still limited due to its strength issue. It is reported that the insufficient strength of Foam Concrete is mainly because of the uneven distribution of internal pore size. It is easy to lead to stress concentration in small pores under the action of the loads, resulting in the destruction of Foam Concrete
- Due to water presence, the foam becomes very sensitive
- Takes a lot of time in mixing
- Difficulty in finishing
