Expanded clay gravel is widely used in construction due to the reliability of structures formed from it. Building forms and structures are able to stand for decades without losing physical and aesthetic characteristics. The composition of cement mortar and expanded clay belongs to the light group of concrete. The claydite concrete composition contains coarse clay aggregate, fine sand aggregate and cement as a cementitious component. In addition to cement, plaster can be used for ligaments. Let us consider in detail what claydite concrete is, the proportions for mixtures of different densities, the scope and characteristics of the building material.
Material properties and characteristics
Visually, expanded clay concrete has a porous structure, the pore size depends on the firing mode of the main aggregate. There are three degrees of concrete porosity: large-porous, porous and dense. The performance characteristics of structures and structures are significantly affected by the uniformity of the concrete structure.
The normative strength of expanded clay concrete is determined by the proportion of expanded clay gravel of small and large fractions. The use of expanded clay concrete as the main element of building forms requires additional reinforcement, in order to increase the strength of structures, the installation of concrete elements is accompanied by reinforcement fasteners. The main role of expanded clay concrete is the formation of a protective heat-insulating layer in multilayer structures.
The strength and physical characteristics of expanded clay concrete depend on the ratio of components. It should be noted that the proportions of expanded clay concrete for the floor and the proportions of the mixture for the manufacture of building blocks are different.
Expanded clay: proportions and composition of the solution
For the construction of buildings, reinforced concrete slabs have been used for a long time , today this technology is not relevant. Reinforced concrete floors have a significant drawback - low thermal insulation. Expanded clay, which is used in the form of a screed, is a material that can successfully withstand loads and at the same time provide comfortable living conditions in the room.
When laying the screed, you need to pay attention to the type of surface on which its composition depends. The optimal proportions of expanded clay for screed: a height of 30 mm per 1 m2 requires 40 kg of a
mixture of sandstone M300 and 35 kg of expanded clay gravel.
Expanded clay: proportions for screed depending on the calculated density value per 1m3
| Density value | Expanded clay, bulk density | Cement | Sand | Water |
| kg / m3 | kg | m3 | kg | kg | l |
| 1000 | 700 | 720 | - | 250 | - | 140 |
| 1500 | 700 | - | 0.8 | 430 | 420 | - |
| 1600 | 700 | - | 0.72 | 400 | 640 | - |
| 1600 | 600 | - | 0.68 | 430 | 680 | - |
| 1700 | 700 | - | 0.62 | 380 | 830 | - |
| 1700 | 600 | - | 0.56 | 410 | 880 | - |
To prepare the concrete mixture , expanded clay is loaded into a suitable container, after which it is poured with water (a small amount). After dissolving the porous structure of the granules, binders — cement and sand concrete — are loaded into the container. Everything is mixed with a construction mixer to a thick consistency. Mixing of the solution stops after the expanded clay acquires the color of cement.
Advantages and disadvantages of expanded clay screed
Often, expanded clay screed is used when it is necessary to increase the floor level in the room. The formed surface has high strength, is resistant to moisture, does not allow air to pass through. Advantages of expanded clay screed:
- its costs depend on the area and thickness of the coating;
- affordable installation technology and a long service life;
- the ability to correct the plane, eliminating differences and irregularities;
- absolute compatibility with all types of floor coverings;
- high degree of moisture resistance and fire resistance, sound insulation;
- resistance to biological and chemical effects;
- in a process such as the preparation of expanded clay concrete, proportions control the density;
- ecological cleanliness.
Ceramsite concrete screed has the following disadvantages:
- installation is accompanied by a significant rise in floor level;
- After drying, surface grinding is required.
Availability of block production technology
When erecting a small residential or farm building in a country house or infield, owners often give preference to building blocks of expanded clay concrete. They are also used for the construction of houses built in areas with low soil bearing capacities. The reason for choosing is the high performance of the material and the affordable technology for the production of blocks. They can be made independently on a personal plot without the use of technological equipment.
The formation of blocks of expanded clay concrete
Expanded clay blocks are of two types: hollow and solid. Regardless of the shape of the blocks, the foundation is expanded clay gravel. Blocks, the shape of which has no voids, are used for laying foundations and cladding external walls. Hollow blocks are widely used as a soundproofing and heat-insulating enclosing layer of the internal walls of a building.
Through the use of porous blocks, the bearing characteristics of the foundation and walls of the building are increased. However, the main advantage of using expanded clay in construction is determined by the cost-effectiveness of the structures being constructed. Due to the porosity of the structure, a reduction in raw material costs and low weight of structural elements is achieved.
Expanded clay: composition and proportions of the mixture for forming blocks
Expanded clay blocks in their composition contain expanded clay, cement, fine sand and other additives. In other words, the mixture contains binders and expanded clay. As additives that increase the physical properties of building blocks, you can use saponified wood resin (SDO) to increase resistance to low temperatures. To increase the degree of binding, technical lignosulfonate powder (LSTP) is added.
Solution preparation
The bonding base of the mixture for forming the textured layer is slag cement (ShPC) or cement grade M400 (Portland cement). Keep in mind that the brand of cement cannot be less than M400. Then expanded clay and fine sand are added.
We make expanded clay concrete with our own hands, the proportions of the mixture are: 1 (cement), 8 (expanded clay gravel) and 3 (sand). This composition will give optimal characteristics of the future building material. To make expanded clay concrete, the proportions per 1m3 should be as follows: 230-250 liters of water. To give concrete plasticity, you can use the folk method: in the process of mixing the components, add a teaspoon of washing powder.
Mixing of all components should be carried out in a concrete mixer, the sequence of actions is as follows: loose components are loaded and mixed, then water is gradually added until a homogeneous mass resembling plasticine in consistency is obtained.
Block Forming and Final Stage
In place for forming blocks, a pallet is installed on which the formwork is placed. In the process of drying the blocks, direct exposure to moisture and direct sunlight is unacceptable, for this purpose a canopy is installed. Before laying the mortar, the inner walls of the molds are liberally coated with machine oil, and the base is sprinkled with sand. There are standard sizes of blocks made of expanded clay concrete: 190 × 190 × 140, as well as 390 × 190 × 140 mm. Standard dimensions should be adhered to, but for small cottage construction, dimensions can be changed at your discretion.
After completing all the preparatory steps, the forms are filled with solution. The mixture is compacted to eliminate voids until cement milk appears. Block surfaces are aligned with a trowel. The molds are taken apart after a day from the moment the mortar was laid, the blocks themselves do not move until they completely harden.
The drying period lasts up to 25-28 days, depending on climatic factors. The drying process should not be stimulated artificially and take place in a short time, a rapid loss of moisture can cause cracking and loss of strength of the blocks.
Expanded clay blocks produced at home, subject to all the above rules, are not inferior to blocks produced in an industrial technological area.