How is the reinforcement of aerated concrete

During the construction of industrial and civil structures for masonry, reinforcement of aerated concrete is made in accordance with GOST 5781-82 and GOST 10884-94, where the number of reinforcing rods of at least two is provided. Such blocks are used for low-rise construction, where often there is doubt about the absolute strength of the foundation, which can give a small drawdown, which will exponentially affect the walls (cracks). Below we will look at the rules for the installation of metal reinforcement, as well as show you the video in this article on this topic as a supplement.

Block laying and reinforcement

What does it give

• Considering the deformative properties (fragility of the blocks), the tendency to cracking is very high, and therefore, according to the above-mentioned GOST, reinforced walls are made of aerated concrete, which is an extremely necessary measure. Such fasteners designs are carried out in its different places, depending on the type of project and the stability of the region.
• The reinforcement frame in the form of a belt is laid on the level of overlap for uniform distribution of vertical loads, triggering on tension.
• In the process of laying the wall on the row of blocks, two special longitudinal grooves are made according to the diameter of the metal rod, where the reinforcement is placed in two rows (such a measure of strengthening, as a rule, is undertaken for each row).
• These methods allow you to avoid block cracking, as in the photo next to the subtitle, and give the integrity of the masonry itself..

Note. According to GOST 31359-2007, load-bearing walls of aerated concrete can be erected at a height of not more than 20 m (5 floors). For self-supporting walls, a height of 30m (9 floors) is allowed.

Reinforcement

Attention! According to their chemical properties, autoclave cellular blocks are very close to heavy concrete, but at the same time, aerated concrete has a weak alkaline reaction - pH = 9-10.5 plus a high porosity of the structure. These two factors greatly weaken the protection of metal fittings from moisture and air, which, unlike dense concrete, penetrate inside the masonry here.

Therefore, when laying the rods into the center of the structure, they should be protected with insulation in the form of glue or cement-sand mortar (in the dry parts of the building - partitions - such insulation is not required).

Any laying is subject to three types of loads that you see above in the schematic diagram (these are the main types of loads). In this regard, the instruction given in GOST 5781-82 and GOST 10884-94, requires mandatory transverse reinforcement, which provides structural strength in tension, tearing and fracture.

In those cases, if the distance from one overlap to another is more than 3 m, then at least two level reinforcements in height must be made.

If you have a conventional construction, where the distance between the floors is not more than 3m, then reinforcement of aerated concrete masonry is made only in the subwindow zone, but if all the walls are blank, simply divide the height in half and install the rods at this level (also find out how the concrete is heated by the welding machine ).

Blocks can be chute or conventional, and if there is already a seat in the chute, then in normal you will have to do it yourself, pour cement sand (fine-grained-concrete) or glue mortar there and only after that place the reinforcement.

Cutting out the groove is easy enough, due to the porous structure of the stone, but chipping is possible during cutting, therefore, in order not to split the thin (remaining) wall, leave a distance of at least 60 mm from the edge of the block.

For carrying reinforced jumpers, it is best to use tray blocks (in the shape of the letter P, and in the West they are usually called U-shaped), and if they are laid out in one row, they will form a long tray in which it is very convenient to put the reinforcement on the prefabricated solution.

In cases where the wall (partition) thickness is not more than 200 mm, it usually costs only one horizontal rod with a thickness of 8-12 mm, but if the building height exceeds 1.5 floors, then in this case, two-row reinforcement is again used.

Look at the photo above - there you see how the reinforced aerated concrete lintels are rounded together with the grooves, repeating their outlines, and you see solid bars there, without breaks. Therefore, if it turns out that the transition needs to be done in this place, then the reinforcement must either be displaced and inserted into the middle of the span, or tied at the corner with knitting wire (special steel soft wire).

Of course, you can use electric or gas welding to dock the reinforcement, but this is very inconvenient and takes a lot of time compared to knitting the joints.

Should remember

Запомните, что в любом случае следует армировать стены большой длины, так как у них большая парусность, и они подвергаются боковому давлению ветра, сто может вызвать растрескивание кладки от изгиба. Также, помимо подоконной зоны следует укреплять прутьями первый ряд газобетонных блоков - они несут на себе практически всю вертикальную и боковую нагрузку от стены и перекрытия. Для осуществления поставленной задачи используют прут А-III, толщиной не менее 8 мм и лишь в особых случаях допускается сечение 6 мм. (Ш читайте также статью «Штроборез для газобетона: конструкционные особенности и применение»).

For maximum protection of masonry from cracking under loads of different nature, reinforcement is carried out both on the first and on every fourth row of aerated concrete blocks and this does not take into account the vertical reinforcement, which is done in areas prone to earthquakes for seismic resistance. Vertical reinforcement depends on the degree of risk and a special order is issued for the construction of buildings by the relevant authorities.

Note. Diamond drilling of holes in concrete and in blocks of autoclave production can be carried out in those cases if there are no metal bridges in the way of the drill, which the drill simply breaks about. It should also be borne in mind that cutting reinforced concrete with diamond circles is possible in cases where no reinforcement is found on the cutting path.

In those cases when it is necessary to cut the concrete along with the rods, you need to purchase a special abrasive disc for cutting reinforced concrete.

Conclusion

Безусловно, армирование газобетонной и любой другой кладки занимает определённое время, которым вы, возможно, не располагаете, но это стоит ваших усилий. Дело в том, что цена ремонта растрескавшейся стены окажется несоизмеримо выше времени, затраченного на укладку металлических прутьев (см.также статью «Защита бетона от влаги: способы и применяемые материалы»).