Building sites in St. Petersburg and the Leningrad Region are learning to work with autoclaved aerated ceramic stones (4.5 NF), which are manufactured by the brick combine, Pobyeda LSR. The project to build the first multi-story residential building using 4.5 NF stones is now being carried out by the building company, Tsentr dolyevogo stroitelstva (Shared Capital Building Centre) at a site in the Devyatkino District.

We all want to see our homes reliably built, warm and pleasant to look at, and many centuries of experience in house building shows that a house built of brick answers these requirements. And although in recent years the building market has seen the appearance of several novelties — materials put forward as an alternative to traditional brick that cost less, that have fairly good heat-insulation characteristics, and that are even aesthetically pleasant to look at, the very modest experience gained from their practical application shows that so far these new materials are unable to guarantee the ecological benefits or the safety of constructions and building over a period of many long years that are ensured by the use of bricks. The Pobyeda LSR combine has long been manufacturing autoclaved aerated ceramics, including large-format ceramic stones. The 4.5 NF stone (which is the size of 4.5 standard bricks) is one of the most promising sizes in ZAO Pobyeda LSR’s ‘collection’ of autoclaved aerated ceramics. This product fully corresponds to the requirements of GOST (State Standard) 530-95. The 4.5 NF stone successfully underwent tests at the Kucherenko TsNISK to check durability and deformability and at the Institute of Building Physics to check thermo-technical properties.

The secret of autoclaved aerated ceramics lies in the special structure of the material. Internal pores are formed in the bricks and the stones at temperatures of around 1000 degrees Celsius, when thin burning wood-shavings are added. The porous structure of the stone lets the heat build up from inside and holds on to it for a long time. For this reason aerated ceramics are referred to in Russian as ‘warm’. The heat-shielding characteristics of these ceramics are so high that if the outer walls are built from them, there is no need for additional heat-insulating materials. Also, their porous structure and high level of hollowness provide excellent sound insulation, which is very useful in the conditions of a noisy metropolis. And, of course, in terms of comfort, a house made of bricks can only be rivalled by one made of wood.

Size is important

The above-mentioned qualities are equally present in all autoclaved aerated ceramics, but the main advantage of 4.5 NF stone is its attractive and useful size — 250Ч250 Ч 138mm — and its durability characteristics, which make it possible to erect multi-storey residential buildings, while economizing on material costs. When building brick and brick-faced monolithic buildings, where the outer walls have a thickness of 640mm, 4.5NF can be successfully used to replace the smaller bricks, the standard autoclaved aerated bricks and the 2 NF stone. But at building sites, where additional wall-heating systems are used (ventilated faзades and plastered heating elements), the standard building brick is the full or hollow-bodied brick. The combination of walls made from 4.5 NF stone and ventilated faзades is recognized as highly successful technology, since the size of the stones makes it possible to use simple single-row laying, while problems with installing the ventilated faзade on such a wall — provided the recommendations of the ZAO Pobyeda LSR and the building engineers are followed — should not arise. At the same time, the productivity of the bricklayers and the speed of laying can be more than doubled due to the large size of the stones.

An example of economy

Specific information on the economies made by using 4.5 NF stone for walls was provided by Yuri Ivanovitch Balkai, chief technologist at the Tsentr dolyevogo stroitelstva (Shared Capital Building Centre), who made the following claim:

“Before our company took the decision to begin the project for two multi-storey residential blocks made of 4.5 NF stones, we learned that our colleagues — another building company — had lost part of their outer wall facing in a fall. For this reason, the Building Committee decided against using a similar method for erecting outer walls until after the publication of legal documentation on multi-layer walls of the brick + cellular concrete type. So we spent a long time looking under erected frameworks for a new outer wall structure and made a careful study of the possibilities for using alternative materials, such as are now fairly widely available on the market. But comparative analysis showed that it was a wall made of 4.5 NF stone which met all the technical requirements and which proved, despite its apparently high cost, to be the most economic. The laying of 4.5 NF stones can be done by bricklayers with only average qualifications, and the laying process is almost twice as fast as when using ordinary building bricks. The high heat-insulating characteristics of these stones make it possible to reduce the wall thickness and save on additional insulation. Add to this the fact that the mortar used amounted to 0.21 m3 per cubic metre of laying, or 35% less than the amount of mortar used for laying an ordinary brick wall. Thus we calculated that thanks to the considerable reduction in production and technological costs obtained by using 4.5 NF stone, the profitability of the project rose considerably. And then what could be better, more reliable and of greater quality than a house made of brick’ So basically, we don’t think we made any mistakes in our choice.”

The Stroimontazh Corporation also plans to use 4.5 NF stone in its projects. In the building of the new elite Montblanc House, this material will be used together with ventilated faзades.

At present, the Petersburg building companies are developing several other residential building projects, in which 4.5 NF stone is used. This not only points to the popularity of autoclaved aerated ceramics, but bears witness to the triumphal return of traditional building materials. Which means we are going back down the path of development followed by the European building materials market, where once again everything that is natural is in fashion.