One of the most popular building wall materials is cellular concrete. It gained its popularity due to the light weight of building blocks, ease of processing and affordability. Before you start masonry work using blocks made of cellular concrete, you need to clarify a few points for yourself.
Fragility.
First of all, do not forget that cellular concrete products are quite fragile. To a greater extent, this applies to blocks with the brands D300, D350, D400, which have high thermal insulation characteristics and lightness, but at the same time low density and strength. Special care must be taken with profiled and shaped products.
In order to protect these products from accidental damage during loading and unloading operations and during transportation, many manufacturers stack them on special pallets and wrap them with plastic wrap. True, these measures are not always sufficient, since delivery to the construction site is often carried out along a bumpy access road, which is also associated with a huge risk of damage to the products.
High moisture absorption.
It is also necessary not to forget that cellular concrete products absorb moisture very strongly. Concrete blocks and other products made of aerated concrete should never be stacked directly on the ground. If the blocks are packed in pallets and plastic film, then it is not recommended to break the packaging until the start of masonry work. If you purchased the blocks in bulk, then it is better to put them on wooden boards and cover them with foil or roofing felt from external precipitation.
Foundation.
Masonry work of cellular concrete blocks must be carried out on a reliable and solid foundation. The basement of the house or the upper part of the foundation slab must be at least 20 cm from the projected ground level. This is due to the fact that it is possible to protect the lower rows of concrete blocks from getting wet. The horizontal surface of the foundation wall must be carefully leveled to prevent possible ruptures of the waterproofing film. On top of the leveled screed, it is necessary to lay horizontal waterproofing, which will isolate from moisture from the ground, and also prevent its capillary spread to the walls.
Kladochnyy rastvor. Proizvodit’ kladku blokov neobkhodimo na spetsial’nyy kladochnyy rastvor. V zavisimosti ot tochnosti izgotovleniya blokov prinimayut resheniye klast’ ikh na traditsionnyy shvy (1 — 1,5 sm) ili na tonkiye (1 — 3 mm). Pri stroitel’stve odnosloynykh naruzhnykh sten bez ispol’zovaniya dopolnitel’nogo uteplitelya rekomenduyut ispol’zovat’ spetsial’nyye teplosberegayushchiye rastvory (pri kladke na tolstyy shov) ili kleyevyye rastvory (pri kladke na tonkiy shov). Po svoim svoystvam teplosberegayushchiye rastvory v bol’shey stepeni skhodny s teploizolyatsionnym kharakteristikam legkikh betonov. Yesli Vy vypolnyayete kladku mnogosloynoy steny to, kak pravilo, yeyo mozhno vypolnyat’ na tsementno-izvestkovyy stroitel’nyy rastvor. On namnogo deshevle teplosberegayushchego rastvora, no imeyet boleye nizkiye teploizolyatsionnyye kharakteristiki. V lyubom sluchaye, pri vypolnenii stroitel’nykh rabot po vozvedeniyu nesushchikh sten neobkhodimo strogo priderzhivat’sya rekomenduyemoy marki dlya betonnykh blokov i rastvora, ukazannykh v proyekte. Yesli Vy vybrali vypolneniye kladochnykh rabot s ispol’zovaniyem kleyevogo rastvora na tonkikh shvakh, to osoboye vnimaniye udelyayte tochnosti proizvodimykh rabot. Kazhdyy ryad blokov neobkhodimo tshchatel’no ukladyvat’ v gorizonte, podravnivat’ i ochishchat’ poverkhnost’ ot pyli. Polucheniye tonkogo shva kleyevogo rastvora dostigayetsya primeneniyem spetsial’nogo dozatora s vozmozhnost’yu regulirovki tolshchiny shva ili spetsial’noy kel’my s zubchatym krayem. Za odin raz rekomenduyut nanosit’ rastvor na rasstoyaniye ne boleye 3 — 4 metrov, dlya togo chtoby on ne uspel vysokhnut’ do momenta montazha bloka.
Masonry mortar.
It is necessary to lay the blocks on a special masonry mortar. Depending on the accuracy of manufacturing blocks, they decide to put them on traditional seams (1 – 1.5 cm) or on thin ones (1 – 3 mm). When building single-layer external walls without the use of additional insulation, it is recommended to use special heat-saving solutions (when laying on a thick seam) or adhesive solutions (when laying on a thin seam). In terms of their properties, heat-saving mortars are more similar to the heat-insulating characteristics of lightweight concrete. If you are laying a multi-layer wall, it can usually be done with a cement-lime mortar. It is much cheaper than a heat-saving solution, but has lower thermal insulation characteristics. In any case, when performing construction work on the construction of load-bearing walls, it is necessary to strictly adhere to the recommended grade for concrete blocks and mortar specified in the project. If you have chosen to perform masonry work using adhesive mortar on thin seams, then pay special attention to the accuracy of the work performed. Each row of blocks must be carefully laid in the horizon, trimmed and cleaned of dust. Obtaining a thin seam of the adhesive solution is achieved by using a special dispenser with the ability to adjust the thickness of the seam or a special trowel with a serrated edge. At one time, it is recommended to apply the solution at a distance of no more than 3 – 4 meters, so that it does not have time to dry before the installation of the block.
Ligation of seams.
When erecting walls, one must not forget about the need for dressing the seams with adjacent rows. The dressing must be performed in such a way that it overlaps at least 6 cm of the surface of the lower block. In most cases, when building walls on an adhesive solution, blocks with profiled side faces (tongue-and-groove connection) are used. In this case, the adhesive solution must be applied only on a horizontal surface. When using conventional blocks with smooth planes, both horizontal and vertical joints are filled with mortar.
Multilayer walls.
The construction of multilayer walls can be done in several ways. In the first case, all layers of the wall structure are erected simultaneously, in the other case, the bearing (internal) part of the wall with anchor ties is constructed, and then the heat-insulating material is laid and the front layer is mounted. In most cases, the laying of a multi-layer wall is performed from the construction of the inner layer (bearing wall). To ensure the possibility of connecting the front layer with the bearing part of the wall during masonry work, special connections (anchors) made of galvanized or stainless steel are laid in the bearing wall. They must be placed approximately every 40 – 50 cm in the vertical plane and every 70 – 75 cm in the horizontal. The thickness of the anchors should not exceed 6 mm. The anchors must enter the wall to a depth of at least 5 cm. For the construction of the supporting structure (structural layer), as a rule, blocks of cellular concrete 24 cm thick with the D500 or D600 grade are used. The outer (front) layer can be made either from cellular blocks (most often 12 cm thick), or from any front brick (hyper-pressed concrete, ceramic silicate or clinker). Between the front and bearing layers of the wall, it is necessary to leave a space 10 cm wide for partial or complete filling with heat-insulating material. As a heater, you can use polystyrene, polystyrene or mineral wool. If, during the construction of a multilayer wall, a special mortar with excellent thermal insulation characteristics is used, then the thickness of the insulation, for example, polystyrene, can be reduced by an average of 2 cm.
Wall connection.
All load-bearing (structural) walls of one floor must be made of building blocks with the same characteristics, they must be laid on the same mortar, building evenly around the entire perimeter of the building. The thickness of the load-bearing walls must be at least 24 cm. In order to correctly pair the outer and inner walls, they are recommended to be erected simultaneously, with the appropriate dressing. If the walls have to be built at different times, then in the places of the planned interface it is necessary to lay anchors at least in every third horizontal seam.
Jumpers and crowns.
To strengthen walls and openings, it is imperative to use lintels and crowns. Over the door and window openings, special jumpers should be laid, and crowns should be laid at the level of the ceiling. It is also necessary to strengthen the outer walls above the attic floor by arranging reinforced concrete columns in the attic wall, ending with a crown. Depending on the structural features of the wall, various options for strengthening it are chosen. When arranging a crown that reinforces the wall at the level of the ceiling, it is imperative to insulate it in order to avoid the occurrence of cold bridges. In multilayer walls, in the composition of which there is already a heater, there is no problem with the insulation of the crown. There are some features of cellular concrete that must be considered during construction:
- the structure of cellular concrete is characterized by a highly porous structure, has excellent thermal insulation characteristics and low weight,
- due to the low level of thermal conductivity of the material, the wall can have a smaller thickness
- easy and soft to handle
- economical when working – when cutting, a small amount of technological waste remains,
- are fragile and can be easily damaged during transportation,
- blocks with profiled sides are currently offered, which makes it possible to refuse mortar in vertical joints,
- having a large block format, allows you to increase the pace of masonry work,
- is a universal material, it can be used for arranging external walls (without insulation), internal load-bearing, as well as dividing (interior partitions),
- cellular concrete is used not only for the production of blocks, but also for the manufacture of lintels, heat-insulating crowns, narrow slabs, etc.,
- due to their low density, cellular concrete products have excellent soundproofing characteristics,
- walls built of cellular concrete must be reliably protected from moisture, as the material has high absorbent characteristics,
- cellular concrete products cannot be used as a facade facing material, as they have high water absorption and porosity.
When building houses from cellular concrete, it is always necessary to remember its properties. The correct use of cellular concrete in construction will allow you to get a reliable and warm house with sufficient strength and high durability.