Technology

The mineralization of the foam

The technology of the preparation of the aerated concrete by mineralization of the foam was one of the first to appear; it was this technology that gave rise to the production of the aerated concrete. In spite of some disadvantages exactly this technology is the most widespread on the territory of Russian Federation.

Two sorts of it - the method of "dry" and "wet" mineralization of the foam - differ in the fact that in the first case the ready foam is mixed with dry components (cement and filler), in the second case it is mixed with specially prepared mortar.

While preparing the aerated concrete mixture by mineralization of the foam, first of all the working mortar with the concentration of the frother - 2-5% is prepared from the concentrated mortar of the frother (25-40%) beforehand. Then it is brought to the foam generator by the water pump, where the foam is made. Foam generators can be different in construction and cost, but the essence of the process going in them is the same - it is the getting of the foam from the working mortar. Then an ordinary concrete mixer or specially prepared mixer (in this case it is called aerated concrete mixer) is filled with the foam. The main peculiarity of such mixer is the swiftness of the working organ - not more than 300 revolutions/min. The last stage in the process of preparation of the aerated concrete is to direct cement and sand ("dry" mineralization) or cement-sand mortar itself ("wet" mineralization) to the mixer (aerated concrete mixer) very carefully in order not to destroy the ready foam.

The peculiarities of the preparation of the aerated concrete by mineralization:

1. It is necessary to have quite difficult in operation additional equipment for the getting of the foam (a container with the mixer for the preparation of the working mortar of the frother, water pump, foam generator, the system of tubing, etc.). The result of it is the increase of capital investments in the production, additional costs of energy supply, the enlarged spaces for the allocation of the equipment. The latter is very important for the production of the aerated concrete on construction sites.
2. In case if the foam filling the aerated concrete mixer has destroyed, for example, because of non-uniform supply of the cement or sand, - such things happen very often, - it is impossible to correct the composition of the aerated concrete and it should be either thrown away or one should run risks selling the material, which does not correspond the declared characteristics.
3. It is extremely advisable to use different kinds of self-feeders for the supply of cement and sand into the mixer (aerated concrete mixer) because the non-uniform supply (for example, hand supply) of the raw materials to the mixer (aerated concrete mixer) leads exactly to the destruction of the foam.
4. The quality of the used pebble gravel (sand) has the decisive importance. The coarse grains of the sand can "break through" the foam and jump in the bottom layer of the aerated concrete.
5. High consumption of the frother is from 1,2kg up to 2kg per 1m³ of the finished aerated concrete. (We proved ourselves not once that real consumption of the frother can come up to even 3-4kg)
6. The correction of the composition of the aerated concrete is long and laborious and depends on the characteristics of the feedstock (the type of the cement, sand humidity, concentration of the frother).

Standard scheme of the production of the aerated concrete

The minimum of the equipment necessary for the organization of the production of the aerated concrete by mineralization:

1. Container for the preparation of the working mortar equipped with the mixer
2. Water pump for the supply of the working mortar of the frother to foam generator
3. Foam generator
4. Mixer (aerated concrete mixer) for mixing foam with cement or cement-sand mortar
5. Air compressor
6. Encasement