01.01.2022
We live in an era of an ever-growing ecological crisis. The prolonged disruption of the balance in nature has forced humanity to recognize something that, despite its obviousness, had long escaped its attention: all living organisms inhabiting our planet do not exist in isolation, but depend on the environment and are affected by it. It must be acknowledged that in the field of environmental protection, we have advanced somewhat further than 50 years ago. In anticipating new construction, we have come to realize that any building must not only meet functional and aesthetic requirements, but must also have no negative environmental impact on its surroundings. What we build today must, even many years from now, harmoniously coexist with the surrounding nature and must not pollute it.
Typically, the economic lifespan of housing is calculated at 80 years, while the functional lifespan is 40–50 years. After the service life of a building expires, it is demolished, and the question arises of how to dispose of the spent material, with the possibility of recycling and reuse. Building materials, products, and structures account for 50–60% of construction costs. The selection of efficient, resource- and energy-saving, environmentally clean building materials, products, and structures will significantly reduce construction costs, labor intensity, and energy consumption, while simultaneously increasing the durability, quality, and comfort of buildings, as well as substantially reducing the negative environmental impact. Raw materials for the production of building materials must be widely available and environmentally clean. Among natural materials, these include water, sand, and carbonate rocks (limestone, chalk, marl) and their derivatives — lime and cement. For example, the average specific activity of natural radionuclides in limestone is 22.4 Bq/kg, in sand — 40.3 Bq/kg, in clay — 102.2 Bq/kg, and in granite — 126.8 Bq/kg. A comprehensive analysis of the radiation safety of raw materials and building products demonstrates the advantages of using autoclaved aerated concrete products in residential construction. Their radiation background is several times lower than that of ceramic brick and heavy concrete made with granite aggregate (a material with a significant content of natural radionuclides). The consumption of raw materials per unit of product must be relatively low in order to ensure minimal material intensity of production. The energy intensity of building material production itself must be minimized in order to reduce the extraction of raw materials for the generation of thermal and electrical energy, and to reduce carbon monoxide emissions into the atmosphere. According to data from the Federal Association of Silica Brick Manufacturers (Germany), the total energy consumption in the production of 1 m³ of aerated concrete averages 324.11 kWh/m³, compared to 616 kWh/m³ for hollow ceramic brick.
Extensive analytical work on the technical and economic evaluation of various building materials has shown that aerated concrete structures compare favorably to traditional wall materials in terms of material consumption, energy intensity, capital intensity, and overall labor intensity. For example, the specific capital investment — accounting for associated costs of raw and auxiliary material production and fuel and energy resources — for autoclaved aerated concrete walls is 1.5 times lower than for expanded clay concrete. The energy intensity of production (including the production of binders and aggregates) of aerated concrete panels is approximately 2 times lower than that of expanded clay concrete panels, and aerated concrete wall blocks require 1.8–2.7 times less energy than the production of ceramic stones and clay brick, while thermal energy consumption during the operation of such buildings (per 1 m² of wall) is 10–40% lower. The use of autoclaved aerated concrete blocks in building walls instead of brick reduces construction labor intensity by 1.4–2.0 times.
With the introduction of new regulatory thermal protection standards for buildings, their construction using traditional wall materials (brick and expanded clay concrete panels) became economically unviable, as it would require increasing wall thickness to 1.5–2.0 m. Autoclaved aerated concrete products have a thermal conductivity coefficient 2–3 times lower than that of brick and expanded clay concrete panels. Accordingly, autoclaved aerated concrete walls are 2–3 times warmer than brick walls while maintaining wall structure thicknesses within 375–600 mm. This is advantageous primarily for economic reasons, as the volume of wall structures is also reduced by 2–3 times while simultaneously providing thermal resistance that meets modern standards. In this context, the accelerated development of autoclaved aerated concrete production — as the most effective, practically unrivaled, and industrially established structural and thermal insulation material — is an urgent task. Taking into account that the volume of aerated concrete in a wall structure can constitute 70–100%, scaling up its production will significantly reduce overall labor costs, construction costs, and consequently the market value of housing, while simultaneously meeting the new regulatory thermal protection standards for buildings.
In addition to evaluating the technical and economic performance indicators of various wall materials and products, it is worth addressing another important factor — the microclimate of the indoor living environment, or what is commonly referred to as residential comfort. A well-known comfort rating for living in homes with walls made of different materials was proposed by foreign researchers at an international symposium on autoclaved building materials in Hanover over 30 years ago. According to this rating, homes with wooden walls rank first in comfort, followed by homes with aerated concrete walls, then walls of silicate and ceramic brick, while expanded clay concrete and conventional reinforced concrete walls occupy the last positions. Intermediate positions in this ranking are held by walls made of mixed wall materials and products. As the data shows, in terms of environmental performance, aerated concrete is most similar to timber structures. The use of autoclaved aerated concrete in buildings helps reduce radiation background levels in rooms. Autoclaved aerated concrete “breathes,” regulating indoor humidity. Buildings made of aerated concrete are virtually permanent, with their strength indicators improving over time. Unlike wood, they do not rot, while simultaneously possessing properties similar to both wood and stone. Inspections of buildings with aerated concrete structures that have been in service for up to 60 years have shown complete preservation of the material and suitability for continued use. Moreover, of all wall types used in residential buildings, aerated concrete walls are the warmest — that is, the most energy-efficient. Their equilibrium moisture content is 4 times lower than that of wooden walls, their radioactivity is 5 times lower than that of brick walls, and their vapor permeability (ability to “breathe”) is 3 times higher than that of wood, 5 times higher than brick, and 10 times higher than three-layer reinforced concrete panels. Aerated concrete is classified as a fire-safe material. It does not burn and effectively prevents the spread of fire, and can therefore be used for constructing walls of all fire safety classes.
