Technical characteristics and specific density of expanded clay

Expanded clay is a loose insulation material. It is lightweight porous balls or burnt with low-melting clay, this poet is distinguished by exceptional ecological purity and safety for man and the environment.

Production

To insulation was effective, the density of expanded clay should be small. This can be achieved by foaming the clay. It happens on the technological chain at the plant:

1. In special installations, low-melting clay is subjected to a powerful thermal shock. This ensures a high porosity of the raw materials.

2. Further, the raw porous granules are fused from the outside - this achieves high strength and tightness, necessary for the resistance of the balls to moisture and aggressive environmental influences.

Technical characteristics of claydite directly depend on the accuracy of production processes: deviation from the norms of manufacture can lead to insufficient porosity and tightness, the fragility of the insulation.

Properties

Like any building material, expanded clay possesses a certain set of characteristics, which are taken into account when designing the objects under construction. These include:

• Bulk density and specific gravity.
• Water resistance and humidity.
• Mark of strength.
• Thermal conductivity.
• Frost resistance.

Density of expanded clay is the primary parameter on which all other values depend. By the term means the ratio of mass to volume of production.

The true and specific gravity

The weight of the granules will tell you a lot about the material, primarily about the thermal insulation and the effectiveness of the material.

The density of expanded clay, as well as any bulk material, can be true and specific (bulk). These parameters are interrelated and depend on the method of production of the material - dry, wet, plastic and powder-plastic. Each method has its own technology of frothing raw, which is the determining factor in determining the value of weight.

The specific density of expanded clay is one of the most important characteristics of the material. It shows the ratio of the mass of the selected amount of material to its volume. As the expanded clay is a loose insulation with a porous structure, the shape of the balls is not constant, air gaps are present between them. Therefore, for the same volume of material, the specific (bulk density) will be different.

The true density of expanded clay (another common name is bulk) is determined in laboratory or factory conditions and shows the weight of the mass of the compacted material without air gaps.

Fractions and weight

The insulation is divided into groups according to the size of the granules. The fraction and density of expanded clay are related by an inverse proportion - the smaller the balls, the higher the mass-to-volume ratio:

There is another classification, which gives GOST 9757-90. According to the document, expanded clay is divided into grades according to the density of the material. It is denoted by the letter M followed by the numerical value of the maximum density for the category: M250 weighs 250 kg / m3, then in order to M600: M300, M350, M400, M450, M500.

Ratio of characteristics

Bulk density of expanded clay is inextricably linked with other important indicators - with moisture and thermal conductivity. This characteristic is always taken into account when choosing a material for the insulation of floors, ceilings and walls.

Knowing the normal value of bulk density and claydite fraction, we can determine its moisture content. If it is higher than permissible, then the porous granules must be dried before stacking in the structure. GOST 9757-90 "Gravel, rubble and sand artificial porous" regulates not more than 2% of excess moisture. Accordingly, when weighing claydite, take into account the mass of water in it, then it is subtracted.

The ratio of the density with the thermal conductivity is arbitrary, but still takes place. As is known from the physics course of the school curriculum, the lower the mass-to-volume ratio, the worse the material conducts heat. This rule applies to free-flowing expanded clay. The closer it is, the less it keeps the heat. When using such a material, it is necessary to carefully calculate the required layer size so that the structure does not freeze and does not conduct cold air.

Other technical specifications

The specific density does not affect the other performance characteristics, but it is worth talking about them.

The strength of expanded clay granules is reached at the stage of production at the second stage - reflow. Its size is determined by laboratory tests by squeezing the pellets in the cylinder. It should be noted that the method has a significant drawback: the result of measuring the strength depends on the shape of the grain and the distribution of pores inside it. To obtain relatively reliable information, I test up to 10 balls from one production lot of the material. The strength of claydite varies in perdelah 0,3 ... 6,0 MN / m ² , which is a good indicator, so the material as a filler is added to the concrete.

The thermal conductivity of loose insulating material averages 0.08 ... 0.12 W / m * K, which is 8-10 times higher than that of traditional plate heaters. Nevertheless, the use of the material is possible in determining and laying a sufficient thickness of the insulation layer.

The frost resistance of expanded clay must not be less than 15 full cycles. For external structures (walls, floors of the first floor), it is advisable to select up to 50 cycles.

The water absorption at the properly made insulation is almost zero due to the tightness of the pellet body due to the repeated roasting. If water is absorbed into the pellets, the material will cease to perform its functions and begin to break down. Therefore, GOST 9757-90 sets the maximum permissible threshold of 10-25% by weight, depending on the thickness of the layer.

To comply with all technical indicators, they are monitored at the production stage. After transportation, the insulation must be stored in conditions of low humidity without additional destructive effects of the environment. Preference should be given to closed deposits and hangars.

Claydite is not afraid of mildew, rodents and other biological pests, therefore its use in closed structures is completely safe.