Autoclaved cellular concrete (HCCA)
Introduction
Cellular concrete also known as Lightweight cellular concrete (CCL), Low density cellular concrete (CCBD) is a cement-based suspension, with a minimum of 20% (by volume) of foam entrained in the mortar. As coarse aggregate is mostly not used for the production of cellular concrete, the correct term would be called mortar rather than concrete; It can also be called "foamed cement." The density of cellular concrete generally varies from 400 kg/m³ to 1600 kg/m³ (for comparison, common concrete has densities from 2200 to 2400 kg/m³). Density is normally controlled by replacing all or part of the fine aggregate with foam.[1].
It is a construction material intended for heavy work. It is produced exclusively from natural raw materials, so it is composed of water, sand, cement and air.
If it is processed only with water, cement and additives, it is known as cellular concrete. If sand is also added, the result is lightweight concrete.
Aerated concrete can be made on site or in factories where cellular concrete blocks are produced. On construction sites, it is ideal for counter-floors, carpets, fillings and injections; It is also usable on walls or partitions with suitable molds. For its production, a mixer, foam generator for cellular concrete, air compressor, water pump and worm drive pump (rotor/stator) are used to transport it to upper floors.
Foam generator for cellular concrete
It is equipment that uses a foaming agent, water and compressed air to produce foam of variable density according to the components of the mixture. In general, the density that the foam must have to obtain a creamy and fluid consistency in pumpable malt is 75 g/L. Both the foam concentrate and the foam generator must be of proven quality, otherwise the walls of the air cells can break during excessive pumping or generate unstable foam that does not contain inert materials (cement, sand) and clogs the pumping hoses. The stability and homogeneity of the foam is also an essential factor to avoid cracks in the finished subfloor (or in the cellular concrete blocks).[2].
Another important characteristic is that it has a contained structure to allow easy transportation and location on site, as well as its productive capacity. The good quality of the final malt depends on the production speed; it must produce no less than 500 L of foam/min, since the mixing time in the mixer (concrete mixer) must be short so as not to compromise the structure of the micro-air cells that will undergo further compression during the pumping process.