prefabricated structural members of buildings and installations, made from large natural or artificial stones assembled on-site. They are used for erecting residential, public, and industrial buildings. Depending on their purpose, the large blocks are manufactured at plants from various types of concrete (lightweight, heavy, cellular, and silicate), as well as from brick and ceramic stone; they are sometimes cut at quarries from natural stone, such as tuff or coquina. The large-block structures may be solid, hollow, or with slits or circular cavities that improve their insulation effectiveness. The weight of the large blocks usually does not exceed 3 tons. Various parts of buildings, such as foundations, exterior and interior walls, and partitions, may be assembled from the large blocks. The large-block structures of continuous foundations and basement walls may be used not only in large-block houses but also in buildings with brick and large-panel structures.
Large-block housing construction in the USSR took shape during the first five-year plans. The first six-story and eight-story apartment houses using walls made from large lightweight con-crete blocks were built in Moscow in in 1927–28 (engineers G. B. Krasin, S. V. Kostyrko, and A. F. Loleit). In 1931 a residential district in Leningrad was built up with large-block high-rise dwellings, and in subsequent years large-block dwellings were erected in Khar’kov, Magnitogorsk, Sverdlovsk, and other Soviet cities.
Large-block structures for the exterior walls of buildings, made from blocks of lightweight and cellular concretes (slag concrete, lightweight aggregate concrete, and gas concrete) with a volumetric weight of 1,100–1,600 kg/m3, are the most common in contemporary construction. A thickness of 30 to 60 cm is chosen for large-block walls, depending on the heat-engineering and strength properties of the material of the block and on the climatic conditions of the construction area. The width and height of the blocks are chosen on the basis of the system used for sectioning the wall (dividing the wall of a large-block building into structural parts). A distinction is made among two-row, three-row, and four-row systems for sectioning walls. The tworow system, in which each floor has two horizontal seams and the wall of each succeeding floor is assembled from three blocks (the pier, sill, and lintel blocks), is most often used. In addition to the basic types, belt, end, quoin, base, cornice, and other blocks are used. Wall blocks with finished exterior and interior surfaces are manufactured at plants.
Large blocks of heavy silicate concrete (volumetric weight, 1,900—2,000 kg/m3), with three or four rows of vertical slits, are also used for erecting exterior walls. The use of large blocks made of brick or ceramic stone (“brick blocks”) as wall materials makes possible mechanization of the process of erecting the walls of buildings.
Large-block structures for interior walls are usually made from heavy concrete. Depending on the sound-insulation and strength requirements, they are usually 30–40 cm thick. The wall blocks are set in mortar joints 2 cm thick, and the joints are sealed. In multistory large-block buildings, the inserts of the lintel and belt blocks are welded to the protruding reinforcement rods from the adjacent floor slabs, thus connecting all the walls and providing general stability of the building. Large-block structures are usually used in building up to 12 stories high.
N. V. MOROZOV