- №1.Features of the production of foam blocks
- №2.Advantages and disadvantages of foam blocks
- №3.The size of foam blocks
- №4.Density and frost resistance of
- No. 5 foam concrete blocks. The structure of the
- №6.What else to consider in the external examination of the foam block?
Foam blocks allow you to build a warm strong house as soon as possible. This material conquered domestic builders with its operational qualities, therefore its range and number of manufacturers is constantly growing. Unfortunately, the percentage of foam blocks produced by the artisanal method without taking into account any standards is also increasing, so it is becoming more and more difficult to choose high-quality material. Which foam blocks will suit in each case and what to look for when buying in order to get really high-quality, durable and durable material?
№1.Features of the production of foam blocks
The basis of the foam block is cement, sand and water
.To the thoroughly mixed mixture add a special foam, which is usually obtained on the basis of surfactant or foam concentrate. A homogeneous mass is cut or laid out in forms, leaving it to freeze in the open air or in an autoclave.
Not the most difficult production process allows you to manufacture foam blocks to questionable companies, which led to the flooding of the market with products that do not comply with GOST.Factory packaging in plastic wrap, the presence of pallets and markings indicating the density, purpose and permissible errors in size indirectly indicates the integrity of the manufacturer.
In the general production scheme of foam blocks there are some differences, which for the most part relate to the formation of individual blocks, which determines the quality and geometry of the product. According to the manufacturing technology, foam blocks are divided into the following types:
- molded block .The wet mass is poured into the prepared form-cells of given sizes. Hardening occurs within approximately 10 hours. This is the most economical way, but the accuracy is not the highest. Now more and more often use a more modernized version, when the blocks pass automatic demolding .In this case, a special machine with partitions is used, into which the mass is poured, and after its solidification, the finished blocks are squeezed out, which allows to get products with the best geometry;
- threaded unit .Such products are obtained by cutting the raw mass with a steel string or by cutting one large frozen foam block into elements with the desired parameters. Thus it is possible to achieve more accurate dimensions of the product;
- reinforced block .For its production, polypropylene fiber is added to the mixture, which increases the strength of the finished product.
Often foam blocks are confused with gas concrete .What are the differences? The main one is hiding in the composition. For the manufacture of foam block and aerated concrete, a mixture of cement, sand and water is used, and the blowing agents are different. Instead of a special foam, lime and aluminum dust are added to the aerated concrete, as a result of the interaction of which hydrogen is released, foaming the mass. The internal structure differs: in aerated concrete, the pores are solid. In addition, it necessarily undergoes heat treatment, and therefore costs more.
№2.Advantages and disadvantages of foam blocks
If the foam block is made with high quality and in compliance with all requirements, then it gets a lot of excellent performance, for which he gained such significant popularity.
The main advantages of foam blocks:
- high compressive strength .This indicator reaches 3-5 MPa and grows with time. A comparison of the newly manufactured foam block and foam block, which has been in operation for 50 years, showed that the density of the latter is 3 times higher;
- low density .For blocks of different brands, this indicator is 400-1200 kg / m3;
- light weight , which allows you to simplify the transportation of material, construction work and reduce the load on the foundation;
- usability .Large and lightweight blocks allow you to build a house quickly and easily. It is easy to process the material, so it can be given any shape;
- thermal insulation properties .Due to the porous structure and a large amount of air inside the material( up to 40-80%), the insulating properties of the material increase. Compared to brick, the thermal conductivity of the D700 foam block is 3.5 times lower. In practice, this means that it is possible to make masonry of a smaller thickness, reducing the load on the foundation, and in areas with a warm climate, provided that the masonry is of good quality, it can do without additional thermal insulation;
- soundproof qualities of .The porous structure of the foam block makes it possible to largely dampen external noise, especially low frequencies. A wall 30 cm thick absorbs noise 60 dB;
- environmental friendliness .Foam blocks are absolutely harmless to human health, are made from environmentally friendly materials, and the blowing agent used in the production does not produce harmful gases. Foam blocks do not rot and do not decompose;
- high fire resistance, moisture resistance and frost resistance .The material almost does not absorb moisture, and because of this, the closed structure of the pores of the foam blocks easily withstand dozens of cycles of freezing and thawing, without losing strength and integrity;
- acceptable cost .1 m3 of foam block is many times cheaper than solid wood, timber and much cheaper than brick, therefore, building a house from a foam block will be more economical.
The main disadvantages of the foam block:
- low bending strength. According to this indicator, the material is significantly inferior to concrete and reinforced concrete, however, as the density increases, the strength of the products also grows, but at the same time the thermal insulation properties decrease. Remember that foam concrete increases strength over time and reaches the indicators required for the construction of buildings by as early as 28 days. The newly manufactured foam block is not recommended, and it is this material that is often on the market at the height of construction work, and therefore does not interfere with it before construction to allow it to stand for 3-4 weeks after purchase;
- often the geometry of the blocks is far from ideal, which complicates the installation. It is better to buy foam blocks from reliable manufacturers who offer quality products with the most accurate dimensions;
- natural shrinkage .Within two months after the completion of construction, the foam block shrinks, which is associated with curing. Shrinkage reaches 2-4 mm per linear meter. Since it is uniform, the structure is not in danger, but the work on finishing will linger for several months;
- is not the best appearance, therefore houses built of foam concrete blocks are additionally finished with, for example, decorative or ordinary brick, they build ventilated facades, etc.
Foam blocks have more advantages than disadvantages, and if you choose the right material, the construction will be durable and reliable. houses up to three floors high can be built from foam blocks. Reinforcement of walls is recommended to increase strength.
foam blocks The first thing that is taken into account when buying a foam block is its size. Today, almost all manufacturers make foam blocks of this size :
- 20 * 40 * 60 cm( height / depth / length) for load-bearing external walls;
- 30 * 20 * 60 cm for load-bearing internal walls;
- 10 * 30 * 60 cm for curtain walls and partitions.
All foam blocks in a batch should be exactly the same size as the - a guarantee that they will fit exactly together. Check before buying can be done by measuring the parameters of the blocks and comparing them, or by installing the blocks on a flat surface, so you can compare the dimensions of the products and see how closely they fit together. The presence of gaps and steps on the surface of the blocks is not allowed - this will not only increase construction costs, but may also lead to the formation of cold bridges.
№4.Density and frost resistance of
foam blocks Density is a key characteristic of foam blocks. For this parameter, the material is assigned one brand or another. Density is denoted by the letter D , foam blocks from D 400 to D 1200 are on the market. Foam blocks with different densities are used for different purposes:
- heat insulating foam blocks of the brands D 400 and D 500 have a thermal conductivity of about 0.12 W / mºС, weigh 11-19 kg, are highly porous, are used for wall insulation;
- structural insulation blocks of the brands D 600- D 900 have a coefficient of thermal conductivity in the range of 0.14-0.29 W / mºС and weight 23-35 kg. Can be used for the construction of load-bearing walls in houses of small number of floors;
- construction blocks of the brands D 1000- D 1200 with a thermal conductivity coefficient of 0.36 W / mºC and a weight of 39-47 kg are used for the construction of load-bearing walls and floors.
With increasing density, the insulating characteristics of the blocks fall as the amount of air trapped in its structure decreases.
Another characteristic of foam blocks is frost resistance , i.e.the number of freeze and defrost cycles that a material can withstand without changing its properties. This indicator is designated by the letter F , followed by a number indicating the number of permissible freezing and defrost cycles. This figure ranges from 15 to 75 .The highest level of frost resistance is suitable for areas with extremely harsh climates.
No. 5.Structure of the
foam block foam blocks must be strong .If you managed to grind a piece of material between your fingers, then the manufacturer saves on cement or violates technology. In any case, such material for the construction of load-bearing walls can not be used. Between fingers, only heat-insulating foam blocks with a density of up to 15 kg / cm2 can be rubbed.
The block should not contain cracks - their presence indicates an existing internal stress as a result of an incorrect drying process. The block structure should be uniform throughout the mass, and the bubbles should be small( no more than 1 mm) and spherical in shape - oval-shaped bubbles indicate the fragility of the product. Both the uneven color of the block and the presence of divorces should be alerted.
№6.What else to consider in the external examination of the foam block?
Since the production of foam blocks does not require special equipment, today the number of unscrupulous businessmen offering products that do not conform to state-of-the-art standards is growing, therefore it becomes more and more difficult to choose truly durable and high-quality material. When external inspection of the foam block should be guided by such signs of quality material:
- color should be from light gray to dark gray .The whitish color indicates that lime was used in production, which adversely affects the strength characteristics and environmental friendliness;
- lack of traces of black grease , since their presence will not allow normal plaster wall surface. The fact is that the responsible manufacturers use high-quality self-decomposing lubricant for molds, which leaves no residue on the block. For savings, used engine oil can be used, which creates a film on the product, and in this place the plaster will simply peel off;
- good foam block does not sink in water ;
- quality products must be packed in film, otherwise excessive drying of the block will result in the formation of a mesh of microcracks;
- foam blocks must have quality certificates , and a normal manufacturer is ready to provide full information about their products, so hiding some data should be alerted;
- too low price is also an indirect sign that the manufacturer has saved and violated the production technology.
And, finally, it is better to to trust proven large-scale manufacturers of , which have been on the market for a long time - so the guarantee is higher that the construction will be durable and the foam block will meet your expectations.