Expanded clay is what? Production and application of expanded clay

Many people know that there is such a building material as expanded clay. This is well known. But few can give full answers to the questions, what is it, what properties it has, how it is made and where it is applied. We will try to eliminate this gap.

What is expanded clay?

Expanded clay is a light, porous material, produced in the form of gravel or crushed stone. Its production is based on roasting in special furnaces at a temperature of about 1200 ° C of special clayey light melting rocks. Due to firing, the structure of the clay acquires a fine-pored structure with a pronounced hard shell.

This structure of the material has determined the diversity of its application. This material is used both in construction work and planting.
The unique properties of expanded clay include water and frost resistance, excellent sound attenuating and heat insulation parameters. The material is practically not subject to the processes of decay and decomposition, it does not attract insects and rodents. In addition, it is durable and refractory, frost and acid resistant, light and durable, environmentally friendly and economical. Thanks to these qualities, expanded clay is widely used in construction and other branches of the economy.

Expanded clay as a heat insulator

The ability of claydite to be a heat insulator depends on the size of the granules, its strength and bulk density. By the size of the granules, claydite fractions are isolated 5-10, 10-20 and 20-40 mm. Each fraction allows 5% of granules of another size. According to the density of expanded clay, 10 grades are defined, starting from 250 to 800. This number indicates the number of kilograms in one cubic meter of material. The lower the density, the better the properties of expanded clay as a heat insulator. The claydite of a large fraction is stronger. It is suitable, for example, for warming the floor in a bath, and the insulation of the attic can be done with a fine fraction.

Manufacture of expanded clay

For the production of expanded clay, only certain clay rocks are suitable. The most suitable are montmorillonite and hydromica clays containing less than 30% quartz. The essence of the production of expanded clay is the preliminary treatment of raw clay, giving raw granules of a certain size, burning them in special furnaces-drums to obtain a specific structure and stage-by-stage cooling.

There are several technologies for preliminary processing of clay raw materials. This is dry processing, plastic, powder-plastic, as well as wet, or slip. The first (dry) technology - the simplest one - involves multi-stage crushing of pieces of clay rock with the screening out of suitable fractions for further processing. The second, the most common - plastic - consists in kneading with the aid of a clay mixer of raw clay, molding cylinders of granules and drying them. Powder-plastic technology differs from the previous one only in that before raw material is converted into a powder. Finally, with wet or slip technology, raw materials and water are first produced with the aid of clay beads by a so-called slip with a moisture content of about 50 percent, which is then pumped into the kilns characterized by the presence of veils from suspended chains. The latter heat up and break the slip into particles, which are then fired.

Rotating furnace in the form of a drum for baking is installed under a slight inclination. The raw material in the form of clay granules is poured into its upper end and gradually slides down to the burning nozzle. Under the influence of hot gases and a strong thermal shock when falling on a burning fuel from the nozzle (with a temperature of about 1200 degrees), the clay boils and swells, and its outer layer melts.

The entire firing process lasts no more than 45 minutes, forming a lightweight and strong gravel that is familiar to us. Other fractions of claydite production (crushed stone or sand) are obtained by crushing this gravel. Better products allow to obtain technology based on the use of two and three-drum furnaces, in which the drums rotate at different speeds, creating an optimal mode of heat treatment of raw materials.

The final stage of the production of expanded clay is cooling in several stages with a gradual decrease in temperature first in the furnace itself, then in drum and layer refrigerators and, finally, in the air chutes.

Where is expanded clay

This is only a small list of areas of application:
- thermal insulation of the roof, floors and floors;
- Sound insulation of floors and floors;
- Creation of the slope of the lawn surfaces;
- production of lightweight concrete, expanded clay blocks;
- thermal insulation of foundations and soil;
- drainage in road construction;
- growing plants (hydroponics).

Form of delivery of expanded clay

They deliver claydite in bags or loose in dump trucks. The material in the packaged form is much more convenient. It is easier to take into account (20 bags make up one cubicle of claydite), unload, store, and also transport to the place of work performance. Loose clay is cheaper, but it causes more trouble. Therefore it is better to use expanded clay in bags.

Warming of the floor with expanded clay

A significant part of the heat energy leaves the house through the floor. To avoid such losses, the floor is insulated. This is especially important in the case of making concrete floors. Among the many thermal insulation materials available on the market, keramzite is the most accessible. This application of this material (as a heater) is perhaps the most widely used in construction. And this is not surprising. After all, a layer of expanded clay 10 cm thick according to its insulation properties, a meter thick brickwork or 25 cm thick wood.
Apply keramzit for the floor (for its warming) by dry method (bulk method) or by pouring with expanded clay tie. The process of warming is fairly simple, it can be done on its own. It includes the following stages:

• Marking the level of filling claydite (for better insulation, the layer must be at least 10 cm);
• Waterproofing (high-strength polyethylene film);
• The setting of beacons to obtain a level surface;
• Filling and sealing the insulation layer;
• Leveling the surface by rule;
• Pouring a layer of cement-sand screed over the expanded clay.

Use the floor can only begin after the screed has dried.
Acceleration of floor insulation can be achieved using a dry method, when over the bulk layer of expanded clay lining floors Knauf. They can be used directly after the assembly of the floor from the elements, fastened together by glue PVA and self-tapping screws.