Having decided on the project of the house, the developer proceeds to the choice of building material for the construction of walls. Polystyrene blocks are relatively recently actively used in low-rise construction, although they have been on the market for more than two decades. The reason is the conservatism of the industry and distrust of the foam used as a filler. Working with building materials implies knowledge of its features and rules of use.
What is polystyrene concrete
The considered building material belongs to an especially light class of concrete with a porous structure, made on a cement binder and a filler made of expanded polystyrene granules.
Depending on the strength grade, the ratio of the components changes. Washed river sand or quartz from quarries is introduced into the composition of products for masonry of load-bearing walls.
Scope of application
Products must comply with GOST R 51263-2012. “Polystyrene concrete. Technical conditions ".
The document defines the technical characteristics and methods of using monolithic or prefabricated products.
Main directions of use:
- erection of load-bearing walls in low-rise construction;
- insulation of external walls;
- thermal insulation of floors and ceilings with plates or by filling the screed;
- production of lintels for window and door openings;
- construction of interior partitions.
When building walls, the strength grade of the blocks must be taken into account.
Material properties
Technical parameters of finished products:
- density grade - from D150 to D600;
- compressive strength class - from M2 to B2.5;
- frost resistance grade - F35 – F300;
- thermal conductivity coefficient - 0.052-0.14 W / (m * oC).
Blocks reach their full strength 28 days after production.
Positive properties and disadvantages
Twenty years of experience of use has proven the positive qualities of plastic blocks:
- reduction of heating costs due to low thermal conductivity;
- fire safety;
- soundproofing ability;
- environmental friendliness;
- the material does not rot and does not support the spread of the fungus;
- facing blocks do not require finishing;
- high construction speed due to large prefabricated parts.
The revealed disadvantages of polystyrene concrete are mainly associated with the incorrect selection of building materials based on strength - the walls do not withstand the load, shrink, and cracks appear. The same problems are inherent with the wrong manufacturing technology.
Blocks are susceptible to destruction with frequent freeze-thaw cycles.
For fastening heavy structures to walls, it is necessary to use specialized hardware.
Varieties of polystyrene concrete
The positive result of construction and the durability of the building directly depends on the correct choice of materials.
GOST identifies four types of products.
Heat insulating polystyrene concrete is produced with an average density of D150 - D225 and a compressive strength of at least M2. Plates are used to insulate load-bearing walls, ceilings over cold driveways and basements. Liquid polystyrene concrete is poured in the form of a screed on the floors.
Heat-insulating and structural the variety must be D250 –D350 in density and correspond to a compressive strength class of at least B0.5. Blocks, lintels, additional elements are used to insulate load-bearing walls or build non-load-bearing structures. Overhead lintels are cast from polystyrene concrete.
Of cross-void elements they construct permanent formwork, which is filled with reinforced concrete, obtaining monolithic walls.
Structural and heat-insulating concrete is produced with a density of D400 - D600 and a compressive strength of at least B1.5. Blocks are made of it for load-bearing walls of one- or two-story buildings, used for the manufacture of lintels.
Dimensions of finished products
GOST does not establish the exact geometrical dimensions of polystyrene concrete products for manufacturers.
The sizes recommended by the document are collected in the table.
| Product type | Length, mm | Width, mm | Height / thickness mm |
| Polystyrene concrete slabs | 1000–2000 | 500–600 | 50–200 |
| Ordinary wall blocks | 590–1200 | 250–400 | 295–400 |
| Additional elements | 145–1200 | 250–400 | 60–200 |
| Polystyrene concrete lintels | 1190–2998 | 180–300 | 115–180 |
| Window blocks | 595–1200 | 295–400 | 250–400 |
The product line includes half-wall semi-blocks.
When designing and at the stage of pouring the foundation, it is important to know exactly what size of products the plant produces at the construction site.
Manufacturing methods
Expanded polystyrene blocks are purchased at the factory or made independently.
The first method is preferable, since the manufacturer has the ability to accurately follow the recipe of the mixture. After purchasing the building material, you can immediately start construction.
If you make it yourself, you will have to withstand 28 days before the start of laying for a full set of strength blocks.
In the factory and at home, polystyrene foam blocks are made in two ways: injection molding and vibration pressing.
Injection method
The casting method produces products of low and medium strength, suitable only for the construction of non-load-bearing insulating walls.
GOST allows the use of recycled polystyrene raw materials as a filler. To obtain it, polystyrene is ground in special machines.
The composition of the mixture for structural and thermal insulation blocks can include only polystyrene granules. Secondary raw materials are prohibited in these cases.
Further, the manufacturing algorithm is as follows:
- The mixer is fed with polystyrene granules, water, plasticizer (latex), mixed for two minutes.
- Cement is introduced into the mixture, without turning off the mixer, it is continuously mixed for 3 minutes.
- If necessary, add sand in the correct proportion.
- Prepare the molds by lubricating their inside with machine oil.
- After thorough mixing, the solution is poured into molds.
- After 2-3 days in summer or after 5-7 days in winter, the forms are freed from the frozen blocks - they are stripped.
- In some industries, drying is carried out in autoclaves.
- Leave the finished products for curing.
The proportions of ingredients for concrete of different density are collected in the table.
| Density, kg / m3 | Cement, kg | Water, l | Expanded polystyrene, m3 | Latex, kg |
| 200 | 200 | 100 | 0,84 | 2 |
| 250 | 250 | 120 | 0,84 | 3 |
| 300 | 300 | 150 | 0,84 | 3,5 |
When making polystyrene concrete with your own hands, you need to stock up on the necessary number of forms for blocks and lintels. For curing, it is necessary to have a sufficient amount of free space, protected from precipitation.
Vibrocompression
Stages of work:
- Preparation of raw materials, measuring the number of components.
- Mixing of components in a concrete mixer.
- Vibratory pressing.
- Drying in a drying chamber in production or under shelter from rain and sunlight at home.
The method differs in the proportion of components. For strength, quartz or washed river sand is added to the composition of block polystyrene.
The table contains recipes for concrete based on 1 cube of finished products.
| Strength grade | Portland cement, kg | Sand, kg | Polystyrene, kg / m3 | Latex, l | Water, l |
| D300 | 160 | 75 | 9 | 3,5 | 95 |
| D400 | 190 | 110 | 10 | 4 | 115 |
| D500 | 215 | 180 | 11 | 5 | 130 |
The recipes are characterized by a reduced water content, the mixture is thick. Casting of such a composition is impossible. To eliminate air voids, pressing is used.
Calculating the number of blocks
It is not difficult to calculate the required number of blocks for building a house, knowing the size of the building.
Calculation sequence:
- Calculate the perimeter of the building.
- Multiply the length of the perimeter by the height to get the total wall area.
- By multiplying the length and height of the block, you get its area.
- By dividing the area of the walls by the area of one structural element, they find out the number of products required for the construction.
- The supplier's prices always indicate the number of blocks in 1 m3. The figure can be obtained independently by dividing 1 m3 by the volume of the element. For example, one standard block with dimensions 598x298x200 mm occupies a volume of 0.0356 m3. Therefore, in 1m3 of such blocks there will be 1 / 0.0356 = 28 pieces.
Some publications recommend subtracting the dimensions of door and window openings from the area of the walls. This should not be done, as the resulting "savings" will be used for dressing in the corners of the building.
Features of masonry and decoration
Special glue is used for masonry. It has high thermal insulation properties and increased adhesion. In addition, the adhesive is very flexible and allows a joint thickness of 3-5 mm to be achieved.
The seams are sealed with the same compound that was used for the masonry.
Adhesives set quickly, so they mix as much solution as needed for 15-20 minutes of work at once. It is allowed to correct the position of the block in the masonry within 10-15 minutes, after this time you will have to remove the mortar and re-lay the masonry.
Every 3-4 rows, a steel reinforcing mesh is laid, which will help to avoid cracks in the walls during shrinkage.
The final finishing is carried out 3-4 months after the end of the laying, until this moment shrinkage occurs.
Walls outside and inside are subject to mandatory protection - plaster, siding, and other means. The blocks are hygroscopic, mechanical stress leaves dents on the surface. Under the influence of precipitation and sunlight, polystyrene concrete is gradually destroyed.
During further operation, one should take into account the difficulties with hanging household appliances and furniture on the wall. One attachment point cannot be loaded above 20 kg. Choose a dowel with a length of at least 60 mm and a diameter of 6 mm. Holes for fasteners are drilled 1–2 mm less than the dowel diameter, since polystyrene concrete is subject to mechanical compression.
For plaster, you should choose specialized mixtures, do not use sand-cement compositions. It is important to pay attention to the compatibility of building and finishing materials, to use special primers and adhesives.
The correct choice of polystyrene blocks and finishing materials allows you to build a reliable, warm house. It is easy to work with the blocks, the precise geometric shape makes it easy to get smooth walls.
