Gas-block

The gas-block in Astana

The gas-block (cellular concrete) on density and appointment is shared on heat-insulating with Z00 density... 600 kg/m3 and with the durability of 0,4... 1,2 MPas and constructive with a density of 600... 1200 kg/m3 (most often about 800 kg/m3) and with the durability of 2,5... 15 MPas.

Gazoobrazovatel apply to formation of cellular structure of concrete. As a gazoobrazovatel apply aluminum powder which is let out four brands.

For production of a gas concrete use powder of the PAK-3 or PAK-4 brand with the content of active aluminum – 82% and a subtlety of a grinding 5000... 6000 quarter see the Consumption of aluminum powder depend on density of the received gas concrete and makes 0,25 - 0,6 kg/m3.

Physicomechanical properties of cellular concrete (gas concretes and foam concretes) depend on ways of formation of porosity, uniformity of distribution of a time, their character (opened, reported or closed), the type knitting of conditions of curing and some other factors.

Properties of cellular concrete are interconnected among themselves. So, the heat conductivity coefficient in a dry state depends generally on the size of average density. Insignificant impact on size is exerted by a look knitting, conditions of curing and other factors. This results from the fact that material of the walls forming a time consists of a cement stone or a hydrosilicate framework, close to it. Therefore, the size of porosity and according to average density mainly defines heat conductivity of cellular concrete. Porosity of material with cellular structure is formed of air porosity (macroporosity) and porosity of mezhporovy partitions (microporosity).

Nature of cellular porosity is determined by a spatial arrangement of a time (packing), distribution of a time by the sizes (a combination of a time of various sizes), the maximum and average size of a time, their form, thickness of mezhporovy partitions.

Form of a time – the parameter characterizing extent of deformation of a spherical time in regular polyhedrons. Increase of cellular porosity of system, decrease in a superficial tension, increase of stability of weight, fast fixing of structure by hardening leads to formation of a time – polyhedrons. About extent of deformation of a time it is possible to judge by the volume of cellular porosity: if its value exceeds 75-80%, it indicates a possibility of transition of a spherical time to polyhedrons. Than porosity is higher, especially the correct form there have to be polyhedrons.

Increase of porosity is reached when a time has the different size and is characterized by an asheric form. Polydisperse nature of distribution of a time by the sizes provides high probability of uniform placement of a time of the smaller sizes between a time of big diameters. The size of a time mainly is defined by viscosity of suspension and a type of frother.

Drying of cellular concrete (humidity reduction) to an equilibrium state with environment is followed by shrinkage deformations. The size of damp shrinkage makes from 0,2 to 3,0 mm/m and depends mainly on initial moisture content, equilibrium humidity, average density and the look knitting. Both at humidity change, and at carbonization foam concrete less treshchinostoyek, than an autoclave gas concrete.

Quality of cellular concrete is estimated in coefficient of constructional quality(qualities) which represents private from division of durability at compression (Rszh, MPa) at a size of a square of average density (? 0, kg/m3). Size A gives the chance to compare properties of the materials differing on structure and structure.

Heatphysical properties of cellular concrete depend in many respects on their humidity. Water absorption of cellular concrete depends on the type knitting of nature of porosity and some other factors. The size of a gain of heat conductivity of cellular concrete for each percent of increase in humidity makes from 6 to 8%. Decrease in heat conductivity of cellular concrete increase of the general porosity is decisive factor. So, decrease in average density by 100 kg/m3 leads to reduction of heat conductivity by 20%. In this regard decrease in average density of cellular concrete to 200 kg/m3 provides reduction of heat conductivity to 0,06 W / (m a hail) and below that corresponds to heat conductivity of highly effective heat-insulating materials, such as mineral wool and porous plastic.

Durability of cellular concrete depends on its density, a look and properties of initial materials, the mode of thermal treatment, humidity and other factors. For constructional and heat-insulating cellular concrete the following classes on durability on compression (State standard specification 25485-89) are established: B0,5; B0,75; B1; B1,5; B2,5. Heat-insulating not autoclave concrete with an average density of D400 has to have a class on durability on compression of B0,5 or B0,75. At brands of not autoclave D350 and D300 concrete a class on durability on compression and brand on frost resistance are not normalized.

Frost resistance of constructional and heat-insulating cellular concrete, as a rule, exceeds 25 cycles. The structure of mezhporovy partitions and a type of knitting has significant effect on frost resistance.

The low density and the high heat-insulating properties of cellular concrete allow to reduce the mass of walls by 25-55% in comparison with designs from light concrete:

• the protecting designs from cellular concrete of 3 times easier brick;
• the minimum quantity of solution is spent for construction of walls from them;
• labor costs are considerably reduced;
• cellular concrete is easily sawn, moves out, cut, drilled, nailed, pasted over with wall-paper and painted;
• the fine soundproofing properties;
• ecological purity.