Foam concrete is not as same as conventional concrete and does not have the same characteristics. The properties of lightweight foam concrete can be classified into fresh state properties and hardened state properties. The fresh state property is stability. The hardened properties are classified into physical, mechanical, durability and functional characteristics
As foam concrete cannot be subjected to compaction or vibration, it should have flow ability and self-compact ability. These two properties are evaluated in terms of stability of foam concrete, which is affected by the water content in the base mix, amount of foam added along with the other solid ingredients in the mix.
Foam concrete possesses high drying shrinkage due to the absence of coarse aggregate, i.e., up to 10 times greater than those observed on normal weight concrete. The shrinkage of foam concrete reduces with density, which is attributed to the lower paste content affecting the shrinkage in low-density mixes. In a comparative study on the shrinkage behaviour with sand and quarry dust as filler, foam concrete with quarry dust exhibited smaller drying shrinkage which is attributed to the higher shrinkage restraining capacity of quarry dust as compared to sand.
The pore structure of cementation material, predetermined by its porosity, permeability and pore size distribution, is a very important characteristic as it influences the properties such as strength and durability.
Density can be either in a fresh or hardened state. Fresh density is required for mix design and casting control purposes. While specifying the density, the moisture condition needs to be indicated as the comparison of properties of foam concrete from different sources can have little meaning without a close definition of the degree of dryness.
The compressive strength decreases exponentially with a reduction in density of foam concrete. The specimen size and shape, the method of pore formation, direction of loading, age, water content, characteristics of ingredients used and the method of curing are reported to influence the strength of cellular concrete in total. Other parameters affecting the strength of foam concrete are cement–sand and water–cement ratios, curing regime, type and particle size distribution of sand and type of foaming agent used.
The ratio of flexural strength to compressive strength of cellular concrete is in the range of 0.25–0.35. Splitting tensile strengths of foam concrete are lower than those of equivalent normal weight and lightweight aggregate concrete with higher values observed for mixes with sand than those with quarry dust. This increase is attributed to the improved shear capacity between sand particles and the paste phase.
Low density foam concrete has a tensile strength of about 0.2 N/mm2; but higher densities approximately 1500 kg/m3, its tensile strength range is from 2-3 N/mm2. ASTM C869-91 recommends that foamed concrete should have a minimum tensile strength of 0.17 N/mm2.
Foam concrete is a highly porous material which is often assumed to be prone to rapid fluid ingress; however the interconnectivity of pores has not been established. Water is not easily absorbed into foam concrete if it is formed with hydrophobic surfactants.
The water absorption of foam concrete is mainly influenced by the paste phase and not all artificial pores are taking part in water absorption, as they are not interconnected. Expressing water absorption as percentage by mass can lead to misleading results when foam concrete is concerned because of larger differences in density. The oxygen and water vapour permeability of foam concrete have been observed to increase with increasing porosity and quarry dust content. Permeability coefficient of lightweight foamed concrete is proportional to unit weight and inversely proportional to pore ratio.
At high temperature the heat transfer through porous materials is influenced by radiation, which is an inverse function of the number of air–solid interfaces traversed. Hence along with its lower thermal conductivity and diffusivity, the foam concrete may result in better fire resistance properties.
|300 – 600||Used for roof and floor insulation against heat, Sound and also for interspaces filling between brickwork leaves in underground walls, insulation in hollow blocks and any other filling situation where high insulating properties are required.|
|600 – 900||Used for the production of precast blocks and panels for curtain and partition walls, slabs for false ceilings, Thermal insulation and soundproofing screeds in multi-level residential buildings.|
|900 – 1200||Used in concrete blocks and panels for outer leaves of buildings, architectural ornamentation as well as partition walls and floor screeds.|
|1200 – 1800||Used in precast panels of any dimension for commercial and industrial use, garden ornaments and other uses where structural concrete of light Weight is an advantage.|
Does not settle, hence requires no compaction.
Lightweight - does not impose large loadings.
Free flowing - spreads to fill all voids.
Excellent load spreading characteristics.
Once placed requires no maintenance.
Reliable quality control - batches are easy to reproduce.
Foam Concrete was low water absorption over time.
Excellent fire resistant properties.
Highly cost effective compared with other methods.
Enables fast work & Easy to re-excavate.
Sufficiently strong and durable for most applications.
Excellent sound and thermal insulation.
The foam concrete blocks brings so many advantages. Some of them are Tremendous weight reduction, high thermal insulation, optimum fire rating, substantial material savings, no gravel used, little cement, less steel in structure and foundation, easy and fast production, no primary energy and reduced transportation costs, boon for remote areas with only sand available.Get Quote