Masonry

The rubble masonry is used for strip foundations of small buildings, retaining walls and for buildings in general. Distinguish the strip foundation of rubble and concrete masonry . For the construction of massive foundations, bridge supports and retaining walls , mainly massive masonry is used . In dry and hot weather, structures made of buta and butobeton are treated as monolithic concrete structures ^[3] .

• Masonry - masonry made of irregularly shaped natural stones. The “scapula” masonry is rational when a mortar is spread under the scapula under each stone, on which the stone is laid and settled down with the handle of the trowel . The voids formed between the individual stones are filled with crushed stone in the solution. On the outside, a bedded stone of large sizes and possibly the same height (a mile away) is laid, and first, dry make-up with a rough joke of stones is made ^[4] .
• Shovel masonry “under the scapula” - rubble masonry in horizontal rows on a solution with fitting stones, filling the voids with gravel and dressing the joints in verst rows ^[5] .
• The rubble masonry “under the bay” - rubble masonry with the filling of voids with a liquid solution with a mobility of 130-150 mm ^[6] without selecting a stone and without observing the dressing of joints, performed in the formwork or between the sheer walls of the trenches ^[7] ; allowed only for foundations up to 10 m high and only in non-subsiding soils ^[8] .
• The rubble masonry “under the bracket” - the type of masonry “under the scapula”, is used in the construction of piers and pillars, is made of stones of the same height, selected using the template ^[8] .
• Rubble masonry is a type of ancient masonry.
• Rubble cobblestone masonry is a type of ancient dry masonry .
• Concrete masonry - concrete mix with rubble stones recessed in it; the mixture is inactive with a draft of a cone of 3-5 cm; stones up to 30 cm in size, but not more than 1/3 of the thickness of the structure in an amount of not more than 50% of the volume of the structure ^[6] . The technological process of masonry consists of applying a layer of concrete mix with a height of 20 cm and sinking (squeezing) rubble stone into it; the operation is repeated until the design height of the structure is reached ^[6] . On top of the masonry, a leveling belt is made of concrete or mortar.

The laying of rubble strip foundations of cobblestone is carried out only in a spacer with the walls of the trench . The stones are laid manually on the solution without formwork.

The rubble strip foundations are laid “under the bay” in the formwork or completely with the walls of the trench: the first row of large bedded rubble stones 25–30 cm thick is laid dry on pre-compacted soil with crushed stone, compaction of the stone layer with a rammer or sledgehammer and pouring with grout ^[9] on clay , lime or cement , depending on the degree of responsibility and purpose of the structure ^[10] .

Studying, or a device from buta foundations, is done for small buildings or structures - cottages , sheds , retaining walls, basement walls, etc.

The foundation is bottled directly into the ditch dry with the crushing of each row of buta 20–25 cm thick ^[10] , depending on the size of the stones with a fragment of stone on the front side of the masonry, filled with a solution of voids and dressing the joints ^[3] . The bottom layer is drilled dry, the unevenness is smoothed out after each layer by clay; the upper 2-3 rows are filled with lime mortar ^[10] .

Under the “heavy” buildings, lower level rowing consists of laying large buta stones along the bottom of the foundation ditch with lime mortar and leveling it with a dense crushed stone so that the next bed is as tight as possible, the lower row stone compounds are overlapped with the upper row stone ^[10] .

The foundation is excavated in such a way that stones are placed on the thick lime along both sides along the length of the foundation, forming in the middle a void, which is filled with buty, densely crushed and filled with liquid lime ^[10] . With moist soil, foundation foundation is produced on cement mortar ^[10] .

For structures and buildings subject to groundwater filtration, wave impacts and significant pressure on the foundation, foundation is drilled from a selected slab or cobblestone , one bracket for each row, on a cement mortar, in accordance with the correct dressing of the joints, both face and face and inside the foundation wall ^[10] . Walls are drilled from chipped rubble slab or cobblestone, on lime or cement mortar, placing stones alternately with a poke and a prone or one row with a poke and another with a prone, observing that in the vertical direction all the seams of the lower row are covered with stones of the upper row, that is, it is necessary to comply with the dressing of joints to prevent the formation of subsequently cracks and crevices ^[10] .

With a thickness of 60–70 cm, rubble masonry is carried out in tiers 1.0–1.2 m high; with decreasing thickness, the tier height decreases ^[6] .

The rubble masonry is carried out by a link of masons of 2-3 people; when the masonry thickness is less than 80 cm, the work is carried out by the "two" link, otherwise - the "three" ^[6] .

Row masonry

Rubble masonry in rows - consists of horizontal rows of buta, up to 30 cm thick; the beds are carefully aligned, the face and the burrs can be without scraping; when erecting, for example, the socles of residential and public buildings, beds, the face and burrs of rubble slabs, they are trimmed cleanly along the corner ^[11] . When laying a stone, the horizontalness of the bed is checked so that it does not burst later.

Stones are placed: one row with a poke, the other with a spoon or alternately; in the latter case, 1/4 of the stones should be poking, without which there cannot be sufficient strength - solidity in the masonry. The width of each poke is 1.5-2.0 of its thickness, the length is 3-5 row thickness. At any size of the stone, the seams are always located in the dressing; voids formed between the stones inside the wall are filled with pieces of stone fitted to their size and crushed by a small crushed stone. In the manufacture of such masonry, the exact execution of the above is strictly observed, the stones lie in place with their natural bed without lining, stone laying with a rib is not allowed ^[11] . The resistance of the masonry is 4/5 of the resistance of the stone.

Such masonry often, for example in bridges , has corners made of calf stone, its rows correspond to the rows of the cladding and are displayed simultaneously. The masonry is good in the mechanical sense for buildings where greater resistance is required in the outer part of the wall than the inner one, for example, in supporting walls, sloping wings of bridges, etc. ^[11] This masonry is also used in the construction of bridge foundations , if the pressure on the masonry is not exceeds its strength resistance by 3.5 pounds per 1 inch ^{2 [11]} . In this case, the entire abutment or only the corners are faced with a hewn stone to give the structure an aesthetic appearance and protect it from atmospheric influences , impacts of ice floes.

When erecting foundations for irresponsible buildings (sheds) and fences, rubble laying in irregular rows is allowed, in which each row of stone has a different thickness, but the beds are aligned in all the stones. For fences and agricultural structures, ordinary rubble masonry is used, erected not in rows but in mosaics (see below “Lesbos masonry”). During the construction of the foundation from such a masonry, cement mortar is used for stone buildings, and lime for wooden ones ^[11] . Since such masonry results in incorrect seams and nests filled only with mortar, in order to give a decent appearance, for example, a fence, all such wide seams in the masonry are filled with small stones ^[11] . The resistance of such a masonry is not greater than the resistance of the solution on which it is folded.

The rubble “lesbos masonry” is named after the island of Lesbos in Delphi , an ancient Greek city in southwestern Phocis ( Greece ). According to legend, craftsmen came who knew how to lay out walls with cut geometry in the form of a saw. The ruins of the city of Eretria with such bizarre masonry date back to the 2nd millennium BC. e.

Concrete foundations are a type of monolithic foundations, but unlike them, when concreting into the mass of concrete laid in the formwork , they rub down rubble stones , which save concrete without compromising strength ^{[12] [3]} .

First, the concrete mixture is poured into the formwork in layers up to 20 cm and stones are embedded in it, the size of which does not exceed 1/3 of the thickness of the masonry with a distance between the stones and the formwork of 5 cm, then the masonry is compacted by layer-by-layer vibration. Interruptions in operation are allowed after the stones are embedded in the concrete mix layer with compaction.

The characteristics of soils, the level of groundwater in the area, and the severity of the structure affect the choice of foundation construction. If it is necessary to deepen the foundation below the groundwater level, it is protected by horizontal waterproofing , at the level of the base of the foundation, and vertical, along the inner and outer faces of the foundation above the ground ^[12] .

Foundations are erected as soon as possible after digging trenches. Immediately upon completion of all construction work after the installation of foundations, in order to prevent changes in the chemical and physico-mechanical properties of soils, the sinuses between the walls of foundations and trenches / ditches are filled with soil ^[12] .

After arranging rubble foundations and backfilling of the sinuses between the foundations and the walls of the trench, a blind area is arranged around the entire perimeter of the structure to prevent the melt and rainwater from soaking the soil under the foundations, causing them to sag ^[12] .

To prevent moisture from seeping from the ground into the walls and damping them, foundations are raised above ground level, this part of the foundation is called a base . Between the base and the wall, a waterproofing is necessarily arranged.

Concrete masonry is carried out by a team of masons-concrete workers of 8 people: two carry out the installation and dismantling of the formwork, two prepare the stone and transport it to the place of laying, two lay the concrete mixture, two fill it with stones ^[6] .

In construction, rubble stones weighing up to 30 kg are used; if more, skirting is performed - stones are pricked into smaller ones, a joke is parallel to it — sharp corners are chipped to fit the shape of the stones to the parallelepiped ^[8] .

The rubble masonry is carried out with the same tool as the brickwork , but with the addition of a specific tool - a rectangular sledge hammer weighing 4.8 kg, designed for breaking and splintering large stones ^[6] . To process the stones, a hammer- cam with a mass of 2.3 kg is used, which sharp edges are chipped off, and the rubble stone is laid and crushed during laying ^[8] .

1. Stones are not dumped into the trenches ( pit ), they are fed through the trenches in the absence of workers in the trenches ^[8] .
2. For the descent of workers in the trenches ( pit ) and lifting on the scaffold, ladders with railings or step ladders are installed. In winter, they are regularly cleaned of snow and ice.

Masonry density and strength

The strength of the masonry made of irregularly shaped stones is much lower than the strength of the stone itself and even for masonry using M100 brand mortar from ragged buta only 5-8% of the stone's strength ^[13] . With the same strength of stone and mortar, the strength of the masonry from the bedding buta is 1.5 times, and from the stone of the correct form, 3.5 times higher than the masonry from the ragged buta ^[13] .

The standard bulk density of limestone rubble masonry with a bulk density of 2200-2500 kg / m ³ is 2100 kg / m ^{3 [14]} . When calculating, the own weight of plaster equal to 15 kg / m ^{2 is} also taken into account ^[14] . In the case of wet plaster, its thickness is usually 1.5 cm; standard volumetric mass of plaster from cement or mixed mortar is 1800 kg / m ³ , from lime mortar - 1600 kg / m ^{3 [14]} .

Design masonry resistances

Design resistance to compression of rubble masonry

The calculated resistance R to the compression of rubble masonry from torn buty according to SP 15.13330.2012 ^[15] .

Design compressive strength of concrete masonry

The calculated compressive strengths R of the concrete masonry according to SP 15.13330.2012 ^[15] .

Design resistance of solid stone masonry

The calculated resistance of the masonry made of solid stones on cement-lime, cement-clay and lime mortar axial tensile R _t , tensile bending R _tb and the main tensile stresses in bending R _tw , shear R _sq when calculating the cross-sections of the masonry passing along the horizontal and vertical joints are given in the table below ^[15] .

Design resistance to axial tension of concrete masonry

The calculated axial tensile strength R _{t of the} concrete masonry according to SP 15.13330.2012 ^[15] .

Masonry Modules

Moduli of elasticity and deformation of masonry

Moduli of elasticity E ₀ and deformation moduli E of masonry according to SP 15.13330.2012 ^[15] .

Masonry Shift Module

The shear modulus of masonry is ^[15] : G = 0.4E ₀ .

Masonry Coefficients

Coefficient of working conditions

The calculated masonry compressive resistances given in the tables above are multiplied by the coefficient of working conditions γ _c according to SP 15.13330.2012 ^[15] .

Masonry creep coefficient

Creep coefficient of masonry according to SP 15.13330.2012 ^[15] .

Masonry linear expansion coefficient

The coefficient of linear expansion of masonry according to SP 15.13330.2012 ^[15] .

Bending coefficient

Coefficient of longitudinal bending of masonry φ according to SP 15.13330.2012 ^[15] .

Coefficient of friction

The masonry friction coefficient μ (mu) according to SP 15.13330.2012 ^[15] .

Normative literature

• Strength Department of large-panel and stone buildings TSNIISK them. Kucherenko Gosstroy of the USSR with the participation of the Research Institute of Building Physics and the Institute Bashkir Grazhdanproekt. The allowance for SNiP II-22-81 "On the design of stone and reinforced stone structures" / Approved by order of the Central Research Institute of Scientific and Technical Research named after Kucherenko Gosstroy of the USSR from 08/15/1985 No. 243 / l .. - M .: VDPP Gosstroy of the USSR, 1989.
• TSNIISK them. Кучеренко — институт ОАО "НИЦ "Строительство". СП 15.13330.2012 «Каменные и армокаменные конструкции» (Актуализированная редакция СНиП II-22-81*) / Внесён Техническим комитетом по стандартизации ТК 465 «Строительство». Утверждён приказом Министерства регионального развития Российской Федерации (Минрегион России) от 29.12.2011 № 635/5.. — М. , 2013. — Электронный фонд ПНТД .

Техническая литература

• Журавлёв И. П. , Лапшин П. А. «Каменщик: Учебное пособие для учащихся лицеев и училищ». - 2nd, add. и перераб.. — Ростов н/Д : «Феникс», 2003. — 416 с. — (Начальное профессиональное образование). - 5,000 copies. — ISBN 5-222-03437-2 .
• Скалеух Н. В. «Строительство и оборудование гаража». — М. : «Цитадель», 2001. — 256 с. - 11,000 copies. — ISBN 5-7657-0156-6 .
• Борисов А. Г. «Справочник строителя: полный комплекс строительных и отделочных работ для сдачи дома в эксплуатацию». — М. : « АСТ », «Астрель», 2008. — С. 93—94. — 327 с. — (Строительство и дизайн). — Доп, тираж: 4 000 экз. — ISBN 978-5-17-037842-5 (ООО «Издательство АСТ»), 978-5-271-14158-4 (ООО «Издательство Астрель»).

• Broaching, device from the foundation buta // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
• Booth // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.