What Is Foam Concrete?
Foam concrete is a highly fluid, lightweight cellular concrete fill material made by combining a cement paste (slurry or mortar) with a prepared foam that has been generated separately.
The ratio of foam to slurry determines the density of foam concrete, which usually ranges from 300 to 1600 kg/m3. To further improve the qualities of foam concrete, sand, powdered fuel ash (PFA), quarry dust, or limestone dust can be used.
In general, it is a type of concrete that contains no big aggregates and just fine sand and cement, water, and foam. Because it does not include coarse material, it can be regarded as reasonably homogenous compared to ordinary concrete.
The microstructure and content of foamed concrete, on the other hand, are determined by the kind of binder employed, as well as pre-foaming and curing techniques.
Components Of Foamed Concrete
- Foaming agent,
- Additive, and
The amount of water needed for constituent material is determined by the mortar body’s composition, consistency, and stability. The lesser water content results in a hard combination, which readily bursts bubbles.
Because of the increasing water content, the mixture becomes too thin to accept bubbles, leading bubbles to separate from the mixture. According to the American Concrete Institute (ACI), mixed water should be fresh, clean, and drinkable.
If the strength of foam concrete could reach 90% within the stipulated curing period, the mixed water can be replaced with equivalent-performance water obtained from municipal areas.
The most often used binder is cement. Ordinary Portland cement, quick hardening Portland cement, calcium sulpho-aluminate cement, and high-alumina cement can be used in binder concentrations ranging from 25% to 100%.
3. Foaming Agent
The resin-based foam was one of the first foaming substances used in foaming concrete. The foaming agent controls the pace at which bubbles in cement paste form, hence determining foaming concrete density.
Surfactants generated and created thus far include synthetic, protein-based, composite, and synthetic surfactants, with synthetic and protein-based surfactants being the most utilized.
To improve foaming concrete mechanical performance, various fillers such as silica fume, fly ash, limestone powder, granulated blast furnace slag, and fly-ash ceramicite have been commonly used.
These fillers can aid with mix proportion design, long-term strength, and cost reduction. Furthermore, fine aggregates, including fine sand, recycled glass powder, and surface-modified chip, are frequently employed to create high-density foaming concrete.
Plasticizers are always considered while looking for solutions to improve compatibility. Actually, they’re classified as water reducers, and they’re used to enhance the performance of new concrete by lowering fluidity and plasticity, with no significant impact on segregation.
Water reducers, water-proofing additives, retarders, coagulation accelerators, and other commonly used additives are only a few examples
A variety of fibers are added to foaming concrete to increase strength and decrease shrinking properties. Polypropylene, glass and polypropylene, red ramie, palm oil, steel, coconut waste paper, cellulose, carbon, and polypropylene are the most common, accounting for between 0.2 and 1.5 percent of the total volume of the combination.
How To Prepare Foamed Concrete
The pre-foaming method and the mix-foaming method are two strategies that may be used to produce this concrete. Both methods manage the mixing process and quality of foamed concrete .
The pre-foaming course includes separately preparing the base mix and stabilizing the preformed aqueous foam. The foam is then thoroughly mixed into the foundation mix.
Either a dry or a wet process might be used to create the preformed foam. The dry foam is created by simultaneously forcing compressed air and a foam agent solution through a series of high-density restrictions inside a mixing chamber.
The dry foam is highly stable and produces bubbles smaller than 1 mm in diameter. The microscopic bubbles allow for a consistent and homogenous foam mix with the base material, resulting in pumpable foamed concrete.
Spraying the foam agent solution through a fine screen produces wet foam. The size of wet foam bubbles is usually between 2 and 5 mm, and the foam generated is less stable than dry foam.
During the mixing phase of the mixed foaming technique, the surface-active agent is practically combined with base-mix ingredients, notably cement slurry. The foamed concrete develops a cellular structure due to the produced foam.
The foam used should be firm and sturdy to withstand the mortar pressure until the cement sets. It aids in the formation of a sturdy concrete framework throughout the air-filled space.
Advantages Of Foam Concrete
- Foam concrete is light in weight. The adjacent sub-structure is not subjected to much vertical stress.
- It has minimal heat conductivity and excellent sound insulation qualities that regular concrete lacks.
- It is resistant to freezing and thawing.
- Foam concrete is free-flowing concrete that does not need to be compacted. Foam concrete adheres to any subgrade contour when used in foundations or excavations.
- This concrete can be easily pumped over a long distance with relatively little pressure.
- It is a substance that lasts a long time. It will not decay and will last as long as a rock.
- This concrete has a low permeability coefficient.
- The compressive and flexural strength of foam concrete decreases as its density decreases.
- Because foam concrete has a higher paste concentration and no coarse aggregate, it shrinks more than regular concrete.
- Because it contains more cement than ordinary concrete, as a result, it gets expensive.
- The linked pore to total pore ratio has a significant impact on foam concrete’s longevity.
- The time it takes to mix foam concrete is longer.
Foamed concrete can be used in various civil and structural constructions due to its unique qualities, such as density reduction, low thermal conductivity, high flowability, self-compacting concrete, simplicity of production, and comparatively low cost.
Low-density foamed concrete, for example, is used for cavity filling and insulation, whereas high-density foamed concrete has been employed in structural applications.
This concrete is also used to make lightweight blocks and pre-cast panels, fire insulation, thermal and acoustic insulation, road sub-base, trench restoration, soil stabilization, and shock absorption barriers for airports and regular traffic.
It is also an excellent material for voids like old sewers, storage tanks, basements, ducts, and voids under highways caused by a lot of strong rainfall because of its flowability.
The first findings indicate that foam concrete has sufficient strength to be used as an alternative construction material in the industrialized building system. For lower density mixtures, the strength of foam concrete is minimal.
Because of the significant reduction in overall weight, structural frames, footings, and piles may be saved, and construction can be completed quickly and easily.