Expanded gravel is widely used in construction due to the reliability of structures formed from it. Building forms and structures can stand for decades without losing physical and aesthetic characteristics. The composition of cement mortar and expanded clay belongs to the light group of concretes. The composition of expanded clay concrete contains coarse expanded clay aggregate, fine aggregate sand and cement as a binder component. In addition to cement, building gypsum can be used for bonding. Let us consider in detail what claydite concrete is, the proportions for mixtures of various densities, the scope and characteristics of the building material.
Properties and characteristics of the material
Visually claydite concrete has a porous structure, the pore size depends on the firing mode of the main aggregate. There are three degrees of concrete porosity: coarse-porous, porous and dense. The performance of structures and structures is significantly affected by the uniformity of the concrete structure.
Normative strength of expanded clay concrete is determinedthe proportion of expanded clay gravel of fine and coarse 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 an enclosing heat-insulating layer in multilayer structures.
Strength and physical characteristics of expanded clay concrete depend on the ratio of components. It should be borne in mind 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 concrete: proportions and composition of the solution
Reinforced concrete slabs have been used as floors in the construction of buildings for a long time, today this technology is not relevant. Reinforced concrete floors have a significant drawback - low thermal insulation. A material that can successfully withstand loads and at the same time provide comfortable conditions for staying indoors is expanded clay concrete, which is used in the form of a screed.
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 concrete for screed: a height of 30 mm per 1 m2 requires 40 kg of a mixture of M300 sand concrete and 35 kg of expanded clay gravel.
Expanded concrete: proportions for screed depending on the calculated value of density 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 a concrete mixture, expanded clay is loaded into a suitable container, after which it is poured with water (a small amount). After dissolution of the porous structure of the granules, binders are loaded into the container - cement and sand concrete. Everything is mixed with a construction mixer to a thick consistency. Mixing of the mortar stops after the expanded clay acquires the color of cement.
Advantages and disadvantages of expanded clay concrete screed
Often, expanded clay concrete screed is used when it is necessary to increase the level of the floor in the room. The formed surface has high strength, is resistant to moisture, does not allow air to pass through. Advantages of the screedclaydite concrete:
- the cost of it depends on the area and thickness of the coating;
- affordable mounting technology and long service life;
- possibility of correcting the plane, eliminating drops and irregularities;
- absolute compatibility with all types of flooring;
- high moisture and fire resistance, sound insulation;
- biological and chemical resistance;
- in a process such as the preparation of expanded clay concrete, proportions control density;
- environmentally friendly.
Screed of expanded clay concrete has disadvantages:
- laying is accompanied by a significant rise in floor level;
- requires sanding after drying.
Availability of Block Production Technology
When building a small residential or outbuilding in a country house or garden plot, the owners often prefer building blocks made of expanded clay concrete. They are also used for the construction of houses built in areas with low soil bearing capacity. The reason for the choice lies in the high performance of the material and the available technology for the production of blocks. They can be made independently on a personal plot without the use of technological equipment.
Formation of blocks from expanded clay concrete
Expanded concrete blocks are of two types: hollow and solid. Regardless of the shape of the blocks, the basis is expanded claygravel. Blocks, the shape of which has no voids, are used for laying foundations and facing external walls. Hollow blocks are widely used as a soundproof and heat-insulating enclosing layer of the interior walls of a building.
Due to 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 concrete in construction is determined by the cost-effectiveness of the structures being built. Due to the porosity of the structure, a reduction in the cost of raw materials and a low weight of structural elements are achieved.
Expanded concrete: the composition and proportions of the mixture for molding blocks
Expanded concrete blocks 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, saponified wood resin (SDO) can be used to increase resistance to low temperatures. To increase the degree of binding, technical lingnosulfonate (LSTP) powder is added.
Preparation of mortar
The binding basis of the mixture for forming the textured layer is slag cement (ShPC) or M400 cement (Portland cement). It should be borne in mind that the brand of cement cannot be less than M400. Next, expanded clay and fine sand are added.
We make expanded clay concrete with our own hands, the proportions of the mixture: 1 (cement), 8 (expanded clay gravel) and 3 (sand). This composition will give optimal characteristics of the futurebuilding material. To make expanded clay concrete, the proportions per 1 m3 should be as follows: 230-250 liters of water. To give plasticity to concrete, you can use the folk method: in the process of mixing the components, add a teaspoon of washing powder.
Mixing of all components must be carried out in a concrete mixer, the sequence of actions is as follows: bulk components are loaded and mixed into the drum, then water is gradually added until a homogeneous mass is obtained, resembling plasticine in consistency.
Block forming and finishing step
In place for forming blocks, a pallet is installed on which the formwork is placed. In the process of drying the blocks, direct contact with moisture and direct sunlight is unacceptable; for this purpose, a canopy is installed. Before laying the mortar, the inner walls of the molds are abundantly 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 country construction, dimensions can be changed at your discretion.
After completing all the preparatory steps, the molds are filled with a solution. The mixture is compacted to eliminate voids until laitance appears. The surfaces of the blocks are leveled with a trowel. Forms are disassembled after a day from the moment of laying the mortar, while the blocks themselves do not move until they are completely hardened.
The drying period lasts up to 25-28days depending on climatic factors. The drying process should not be stimulated artificially and take place in a short time, rapid loss of moisture can cause cracking and loss of strength of the blocks.
Homemade claydite concrete blocks, subject to all the above rules, are not inferior to blocks produced in an industrial process area.
