Ashlar(redirected from Mason's drag)
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a term applied to items made of natural stone, especially in the form of rectangular blocks, used in their natural form in construction and measured during quarrying by the piece or in cubic meters.
Most ashlar is produced for use in walling; it is made from porous rocks, such as limestones, volcanic tuffs, and coquina, which have good heat-insulation properties and which are relatively light and suitable for processing by cutting, hewing, and hammering. It is quarried by opencut or, less often, underground mining methods with stonecutting and coal-cutting machines and cable saws.
Three types of ashlar are produced for walling. Machine-cut wall ashlar with a sawed surface finish is produced in the USSR with the following standard dimensions: 19 × 19 × 39 cm and 19 × 24 × 49 cm (for limestone products), and 29 × 19 × 39 cm (for tuff products). The weight of the blocks does not exceed 40 kg, and the density ranges from 1,200 to 2,200 kg/m3; the ultimate compressive strength ranges from 0.4 to 40 megapascals per m2 (4–400 kg-force per cm2). Rough-hewn wall ashlar is quarried from tuffs by coal-cutting machines; it is hewn on the face side on milling machines or by hand to dimensions of 30 × 20 × (30–55) cm. Large-block wall ashlar is produced in various sizes, up to blocks as high as the height of a building floor. The face side of porous ashlar has a sawed, hewn, or, rarely, polished texture. More than 10 million cu m of limestone ashlar and 2 million cu m of tuff ashlar are produced annually in the USSR.
Blocks of dense rock, such as granites, basalts, and marbles, are produced for subsequent finishing into facing sheets (made from decorative stone) and stone for walling (for socles and retaining walls). They are quarried only by opencut methods with explosives. Further working is accomplished manually or with pneumatic or steam-jet tools (for granite) or milling machines (for basalt). The dimensions of granite ashlar blocks are (45 or 60) × 17 × (50 or more) cm, and those of basalt blocks are 30 × 20 × (30–60) cm. The face side of dense ashlar has a steam-jet, point, grooved, riffled, hewn, or polished texture.
In the USSR ashlar is produced in the Ukraine (limestone and granite), Azerbaijan and Moldavia (limestone), Armenia (tuff and basalt), the Kabardinian-Balkar ASSR (tuff), and Georgia (teschenite). Ashlar is also produced in France, Italy, Great Britain, the USA, Czechoslovakia, and Yugoslavia.
REFERENCESProizvodstvo prirodnykh kamennykh stenovykh materialov i legkikh zapolnitelei. Moscow, 1962.
Atsagortsian, Z. A. Prirodnye kamennye materialy Armenii. Moscow, 1967.
Grigorovich, M. B., and M. G. Nemirovskaia. Mineral’noe syr’e dlia promyshlennosti stroitel’nykh materialov i ego otsenka pri geologorazvedochnykh rabotakh. Moscow, 1974.
Z. A. ATSAGORTSIAN