Masonry Building Materials

an extensive group of building materials and articles of stonelike composition. A distinction is made between natural masonry materials, which are obtained by mechanical processing of rock (they may sometimes be produced without special processing), and artificial materials, which are produced by technological processing of a mineral raw material. Because of their good construction qualities (durability, strength, and frost resistance) and the wide distribution and unlimited reserves of natural raw materials, masonry materials are widely used in modern construction. They are the basic building materials for housing, public, and industrial construction, as well as various engineering structures.

In terms of shape, masonry materials are divided into materials consisting of irregularly shaped pieces (quarrystone or crushed rock) and dimension articles with a regular shape (blocks, slabs, and shaped articles). They are divided according to density into three groups: heavy (more than 1, 800 kg/m³), light (1, 800–1, 200 kg/m3), and very light (less than 1, 200 kg/ m3). Artificial masonry materials used as thermal insulation materials may have a density of about 500 kg/cu m.

The main index of masonry materials is the compressive strength, which is characterized by a grade. According to this feature, masonry materials are divided into high-strength (10–300 meganewtons per sq m [MN/m²], or about 100–3, 000 kilograms-force per sq cm [kgf/cm2]), average (2.5–10.0 MN/m²), and low-strength (0.4–5.0 MN/m²). The tensile strength of masonry building materials is less than their compressive strength by a factor of 7–15; therefore, masonry materials are often reinforced with fibrous materials (asbestos, fiberglass, or organic fiber) or metal (steel reinforcement). The masonry materials used in exterior structures should have some degree of frost and water resistance. Depending on the area of use, masonry materials are also rated according to water absorption, acid resistance, and wearability.

The natural masonry materials are divided into the following basic varieties, according to the method of mechanical processing used: sand and gravel, which are produced by sifting and washing appropriate friable rock; quarrystone, which is produced mainly by mining of limestones, sandstones, and other sedimentary rock in blasting operations; crushed rock; cut stone and blocks, which are sawn from light rock (tuff and coquina) directly in the quarries using stone-cutting machines; and racing stones, slabs, and shaped articles, which are made at specialized stone-working enterprises from decorative rock (marble, granite, and limestone).

Various requirements established by the appropriate Construction Standards and Rules and GOST (All-Union State Standard) apply to natural masonry building materials (hydraulic-engineering structures, road construction, or the external or internal finishing of buildings), depending on their purpose. The most widespread natural masonry materials—sand, gravel and crushed rock—are widely used as fillers in manufacturing concretes and mortars. Quarrystone is used mainly in laying the foundations of buildings and retaining walls. Sawn stone and blocks are used mainly as local wall materials. Facing stone, slabs, and shaped pieces with various surfaces (finishes)—for example, split, hewn, ground, and polished—are used largely for exterior and interior finishing of buildings, for flooring, and for manufacturing steps, parapets, and partitions because of their good decorative qualities and durability as well as a reduction in their cost as a result of introducing modern processing methods (diamond tools, thermal treatment, and mechanized methods of splitting).

Rock is widely used as a raw material for manufacturing various artificial masonry materials (for example, ceramics, glass, and thermal insulation materials), as well as inorganic binders (gypsum, lime, and cement). The production of these materials and articles involves processes that alter the composition, structure, and properties of the natural materials. Artificial masonry materials may be produced from clay and other ceramics, with subsequent firing (clay brick and ceramic stone); from silicate melts (stone casting, slag casting, and glass products); and from mixtures containing a binder, such as products made of concrete and mortar (for example, concrete, reinforced-concrete, and silica-concrete panels and blocks; silica brick).

The most important and most industrial artificial masonry materials are concrete and reinforced-concrete structural members and products based on mineral binders (cement and lime).