Stone materials, even against the background of the emergence of durable fiberglass products and lightweight foam concrete blocks, retain high demand in the construction market. At the same time, technologies for the use of traditional materials also do not stand still, forcing engineers and designers to pay more attention to technical documentation. For stone and reinforced stone structures, there is its own regulatory documentation that regulates both the standards for the production of target materials and the methods of their use directly during construction processes.
Code of practice for stone and reinforced stone building structures
The current edition of SP 15.13330.2012 applies to the development of new projects for stone and reinforced structures, as well as to the reconstruction of existing buildings. An important emphasis in the document is on the features of the operation of structures in the Russian climate. The rules establish requirements for structures that are built not only from natural stone, but are also derivatives of clay materials. At the same time, SP 15.13330.2012 “Stone and stone-and-stone structures” does not apply to the design of construction projects that are planned to be operated under conditions of increased dynamic loads and in earthquake-prone territories. The same applies to tunnels, bridges, pipes, thermal and hydraulic units. The requirements confirm the safety and operational suitability of structures, which is expressed in the technical characteristics of the materials and their parameters. In particular, the standards relate to the properties of stone products used in the construction of mortars, individual technological solutions and methods of reinforcement.
In addition to the structural parameters, the joint venture approves the requirements for elements associated with stone structures. For example, adjacent parts of coatings or binders should not contribute to the spread of fire throughout the building or its individual parts. Warming of stone and reinforced stone structures, in particular, should be carried out taking into account the fire resistance limits, which are determined by the calculation and analytical method in the process of fire tests.
The main provisions of GOST for stone structures
In relation to stone structures and structures, GOST regulates the methods of masonry testing and the parameters of bricks as one of the main materials for construction projects of this type. As for testing, the standard applies to walls and block structures, taking into account operating conditions and technical and construction requirements of a particular project. In turn, the brick according to GOST is defined as a piece product designed to perform masonry on a building mixture. The purpose of the structure can be defined as load-bearing structures, self-supporting walls, cladding, etc.
The standard distinguishes single, hollow, silicate and ceramic bricks. Dimensions may also vary. To begin with, it is worth noting the difference between working and non-working parameters. In the first case, we are talking about the dimensions between the faces of the vertical protrusions, which form the thickness of the structure with a single masonry. The non-working size of a brick according to GOST is defined as the length between the vertical edges, which determines the length of the wall. Actual product length varies from 250 to 288 mm, width - from 60 to 138 mm, and thickness - from 55 to 88 mm. It should also be borne in mind that the technical rules for the construction of walls, in particular, impose restrictions on the use of certain brick formats.
SNiP for stone and reinforced stone structures
Norms SNiP regulate design processes related to structural solutions for walls, panel parts of structures, block elements and all kinds of brickwork. At the same time, the possibility of deviating from the established rules is retained, but only in the presence of appropriate justification. In addition, the standards approve the standards for the preparation of solutions taking into account the humidity regime, compliance with the requirements for strength and stability of the planned facility.
The updated version of SNiP for stone and reinforced-stone structures II-22-81 also pays attention to measures that provide construction opportunities in the winter - including the use of heat engineering means. The requirements for preservation of thermal and humidity conditions due to industrial heaters directly on the construction site, frost-resistant additives and plasticizers for solutions are considered. The brands of concrete that can be used in the same system with stone structures are also considered separately. For example, this applies to heavy, porous, porous, cellular and silicate grades of concrete. It is allowed to use insulation materials for concrete, but only on condition that such additions do not lower the tensile strength of the mortar to 0.7 MPa.
What are stone and reinforced stone building structures?
Almost always, stone structures are made in the form of masonry, which, in turn, forms the basis of engineering structures and buildings. Specifically, such structures can be represented by external walls, arches, ceilings, pipe parts, manifolds, towers and foundations. And in each case, the stone, its derivatives or imitation materials are an integral element. The masonry itself can be characterized by different indicators of durability, strength, fire resistance, biological security and thermal insulation ability. Among the negative operational properties of masonry, massiveness, high weight and high labor input during construction are distinguished. However, the optimization of the parameters of raw materials allowed us to minimize these weaknesses. As confirmation, you can bring brick walls, characterized by sustained correct geometry, low weight and good insulating properties.
Armstone constructions can be called a modification of ordinary masonry or brickwork. The difference lies in providing the design with metal rods that increase the strength characteristics of the object. Reinforcement itself can be represented by different materials - both traditional rods and a mesh that is more flexible in terms of styling. Also, modern reinforcement of stone and reinforced stone structures can be performed with thin (6-8 mm) fiberglass rods, steel bandages and plates. In classical schemes, reinforcing and reinforcing is carried out internally by a longitudinal, transverse or circular method, but depending on the type of construction, the principle of an external lining can be applied.
Varieties of stone and reinforced structures
The masonry configurations are distinguished by several characteristics, the main of which is continuity. The design can be lightweight monolithic or multilayer, including also layers of cladding and thermal insulation. Moreover, the technological layers can be both inside and outside, which will determine the complexity of the masonry itself. A solid monolithic structure is more often used in the northern regions, since it is distinguished by frost resistance and high thermal conductivity. Lightweight types of stone and reinforced stone structures are hole, porous and porous-hole masonry. Hollow blocks and bricks are often used to save on material and reduce load requirements in terms of floors. This masonry is beneficial to use in the construction of low-rise buildings and on the upper floors of high-rise buildings.
Materials for stone structures
The masonry is formed by individual elements, among which the already mentioned bricks, blocks, silicate products, etc. The entire range of stone materials can be divided into natural and artificial. The first group includes heavy and lightweight products of regular and irregular shape. These can be natural rocks of granite, marble, sandstone, limestone, etc. Actually, the production process will consist in mechanical external processing of minerals with the achievement of certain shapes and sizes. The production of agglomerates containing stone chips is also practiced. In this case, the structure will be of artificial origin, but the raw materials will still remain natural.
As for artificial materials directly, autoclave, calcining and non-calcining products are included in this category. Standard walls made of autoclaved bricks are characterized by high strength and durability. Clay and hollow bricks are also common, which can be used not only in self-supporting structures, but also as cladding. Artificial stone materials include concrete monolithic elements. Masonry foundations and ceilings are formed from block products of this type. Such designs are most often performed with reinforcement, since cement in combination with bulk fillers is not able to provide sufficient tensile strength.
Facing building materials for stone structures
Stone is usually associated with the construction of reliable parts of buildings that are under heavy load. But decorative trim is no less widely represented in this niche. First of all, the segment of stone cladding materials is tiled products. Natural and durable coating can be made of dense limestone, syenite, granite and marble. Aesthetic qualities will depend on the methods of factory processing of elements and textures. By the way, it is in this niche that agglomerate production technologies are actively used, since due to inclusions from stone chips, various patterns and patterns can be formed.
Not without its decorative value and brick. For external decoration, ceramic, clinker and front facing bricks with a thickness of 60-80 mm are used. Due to special firing in furnaces, this facing material is endowed with frost resistance and fire resistance. For interior design in order to reduce the load on the walls and floors, it is recommended to use gypsum brick. It is easy to handle and stack, and after installation, you can cover it with paintwork. The only drawback of gypsum is its high moisture absorption, so it is undesirable to use it for the bathroom and kitchen.
Design of stone and reinforced stone structures
Development of a design solution is carried out taking into account the requirements for the characteristics of the structure, methods of manufacturing the material and direct erection. In the calculations using indicators such as structural stability, its strength and spatial immutability. In modern design, they are also guided by the principles of divided calculation. This means that the preparation of documentation is separately performed for the building as a whole and its parts. In addition, the design of stone and reinforced stone structures for buildings with a height of 36 m (12 floors) is allowed only on the condition of materials of increased strength corresponding to cement grades 150-300. The documentation also provides protection against external influences such as moisture, wind, mechanical stress, etc. In the case of reinforced structures, special attention is paid to metal elements, steel ligaments, connecting and embedded parts.
Masonry mortars
The reliability and durability of structures and structures made of stone is largely determined by the used building mixtures. The binder component is not just a connecting link for individual masonry elements. Responsible technological tasks, caused by damping functions, fall on it. They allow buildings to cope with dynamic loads. At a basic level, stone and reinforced stone structures are constructed from cement mortar without special additives. Such mixtures are prepared for standard single-type brickwork. As the masonry or cladding becomes more complex, additional requirements are made to the project for the strength of the mortar, its adhesive ability and resistance to various external influences. To improve operational properties, technologists include plasticizers, modifiers and other additives in their compositions, aimed at maintaining or improving certain qualities of the building mixture. In relation to stone structures, such qualities as vibration resistance, viscosity and moisture resistance are especially important, since the porous structure of masonry materials is initially characterized by high penetration.
Conclusion
Stone and its derivatives constitute the basic resource for the construction of engineering structures and buildings. Mostly this applies to facilities that are subject to high technical and operational requirements. At the same time, normative manuals on stone and stone-stone structures segment both consumables and masonry structures according to a variety of characteristics. They relate to strength factors, structural configuration, dimensions and protective properties. Extensive classification, coupled with a variety of methods for the construction of stone structures allows more fully and accurately implement design decisions.