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37-424: Sandcrete is usually used as hollow rectangular blocks similar to concrete masonry units , often 45 centimetres (18 in) wide, 15 centimetres (5.9 in) thick, and 30 centimetres (12 in) with hollows that run from top to bottom and occupy around one third of the volume of the block. The blocks are joined together with mortar . The final compressive strength of sandcrete can be as high as 4.6 N/mm, which

74-668: A cinder block in North American English , breeze block in British English , concrete masonry unit ( CMU ), or by various other terms , is a standard-size rectangular block used in building construction . The use of blockwork allows structures to be built in the traditional masonry style with layers (or courses) of staggered blocks. Concrete blocks may be produced with hollow centers (cores) to reduce weight , improve insulation and provide an interconnected void into which concrete can be poured to solidify

111-454: A 1 inch (25 mm) layer of sandy concrete. Before this layer sets, terrazzo workers partially embed metal divider strips in the concrete wherever there is to be a joint or change of color in the terrazzo. For the final layer, terrazzo workers blend and place into each of the panels a fine marble chip mixture that may be color-pigmented. While the mixture is still wet, workers toss additional marble chips of various colors into each panel and roll

148-445: A combination of both. Metal strips often divide sections, or changes in color or material in a pattern. Additional chips may be sprinkled atop the mix before it sets. After it is cured it is ground and polished smooth or otherwise finished to produce a uniformly textured surface. "Terrazzo" is also often used to describe any pattern similar to the original terrazzo floors. Modern forms of terrazzo include polished concrete . Although

185-405: A flexible membrane can be installed so that cracks do not appear on the surface. Unbonded includes the sand cushion method which uses wire reinforcing, an isolation sheet, and sand dusting that absorbs any movement from the concrete slab. Although terrazzo derives from the mosaic artform, it does not necessarily place individual pieces in a decorative pattern. Instead, small pieces are thrown into

222-595: A greater surface on which to spread a mortar bed and for easier handling. Most concrete blocks have two cores, but three- and four-core units are also produced. A core also allows for the insertion of steel reinforcement to span courses in order to increase tensile strength . This is accomplished by grouting the voids of blocks containing rebar with concrete. Thus reinforced, concrete block walls are better able to resist lateral forces such as wind load and seismic forces. Cores may also be filled with expanded-polystyrene (EPS) block foam insulation, substantially increasing

259-560: A high input of energy. Gourdin and Kingery (1975) estimate that the production of any given amount of lime requires about five times that amount of wood. Recent experiments by Affonso and Pernicka have shown that only twice the amount is needed, but that would still amount to 4.5 metric tonnes of dry wood for the floors in Çayönü. Other sites with terrazzo floors include Nevalı Çori, Göbekli Tepe , Jericho , and Kastros ( Cyprus ). Terrazzo artisans create walls, floors, patios , and panels by exposing marble chips and other fine aggregates on

296-424: A ribbed or solid two-block unit; such factory-produced units are called "split-rib" or "split-face" blocks. Blocks may be scored by grooves the width of a mortar joint to simulate different block modules. For example, an 8-by-16-inch (200 mm × 410 mm) block may be scored in the middle to simulate 8-by-8-inch (200 mm × 200 mm) masonry, with the grooves filled with mortar and struck to match

333-718: A sand base and without mortar or reinforcing (gravity wall), or using blocks (typically an architectural style of block or clad with a veneer such as brick) with a concrete base, steel reinforcing and mortar (piling wall). Other very common, non-structural uses for concrete block walls (especially in American schools) are as interior fire-rated and extremely durable partition walls, and as exterior backup curtain walls for attachment of building envelope systems (rigid foam insulation and an air/vapor barrier) and veneers (stucco, steel, brick, or split-face concrete block). Concrete masonry walls may be ungrouted, partially grouted, or fully grouted,

370-497: A structural system is the Masonry Standards Joint Committee's Building Code Requirements & Specification for Masonry Structures (TMS 402/602-16). The compressive strength of concrete blocks and masonry walls varies from approximately 3.4 to 34.5 MPa (500–5,000 psi) based on the type of concrete used to manufacture the unit, stacking orientation, the type of mortar used to build

407-485: A thousand years. In the early Neolithic settlement of Çayönü in eastern Turkey about 90 m (970 sq ft) of terrazzo floors have been uncovered. The floors of the PPN B settlement of Nevalı Çori measure about 80 m (860 sq ft). They are 15 cm (5.9 in) thick, and contain about 10–15% lime. These floors are almost impenetrable to moisture and very durable, but their construction involved

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444-636: A weighted roller (100–125 pounds (45–57 kg)) over the entire surface. In the 1970s, polymer -based terrazzo was introduced and is called thin-set terrazzo. Initially polyester and vinyl ester resins were used as the binder resin. Today, most of the terrazzo installed is epoxy terrazzo. The advantages of this material over cementitious terrazzo include a wider selection of colors, 1 ⁄ 4 to 3 ⁄ 8 inch (6.4 to 9.5 mm) installation thickness, lighter weight, faster installation, impermeable finish, higher strength, and less susceptibility to cracking. The disadvantage of epoxy resin–based terrazzo

481-454: Is better than simply using less Portland cement. Addition of coarse aggregates has been tried, since this is a cheap way to increase compressive strength, but since the cement content of sandcrete is small, so is the amount of water that is added to the sand/cement mix to cure it. Adding more solid materials makes the mix much less fluid, making it difficult to cast into blocks. Concrete masonry unit A concrete block , also known as

518-521: Is much less than concrete 's 40 N/mm. Sandcrete is unsuitable for load-bearing columns, and is mainly used for walls, or for foundations if no suitable alternative is available. As material for walls, its strength is less than that of fired clay bricks, but sandcrete is considerably cheaper. Sandcrete is the main building material for walls of single-storey buildings (such as houses and schools) in countries such as Ghana and Nigeria . Research has shown using organic ash to replace Portland cement, which

555-494: Is that it can only be used for interior, not exterior, applications. Epoxy-based terrazzo will lose its color and slightly peel when used outdoors, whereas cement-based terrazzo will not. In addition to marble aggregate blends, other aggregates have been used, such as mother of pearl and abalone shell. Recycled aggregates include: glass, porcelain, concrete, and metal. Shapes and medallions can be fabricated on site by bending divider strips, or off site by water-jet cutting . When

592-588: The R-value of the resulting wall to be in compliance with the US national energy code. A variety of specialized shapes exist to allow special construction features. U-shaped blocks, or knockout blocks, have notches to allow the construction of bond beams or lintel assemblies, using horizontal reinforcing grouted into place in the cavity. Blocks with a channel on the end, known as "jamb blocks", allow doors to be secured to wall assemblies. Blocks with grooved ends permit

629-471: The cement that was then ground and polished. Together, these methods create the generic form of terrazzo that involves pieces of stone that are bonded to a cement bed. Terrazzo was first introduced in the United States in the late 1890s, but did not achieve popularity until the 1920s. Until then it was hand polished with a long handled tool called a galera . Due to its likelihood of cracking, terrazzo

666-462: The composition of the blocks. Use of recycled materials within blocks can create different appearances in the block, such as a terrazzo finish, and may help the finished structure earn LEED certification . Lightweight blocks can also be produced using autoclaved aerated concrete ; these are widely used for construction in Finland and other Scandinavian countries, as well as in central Europe, for

703-413: The construction of control joints , allowing a filler material to be anchored between the un-mortared block ends. Other features, such as radiused corners known as " bullnoses ", may be incorporated. A wide variety of decorative profiles also exist. Concrete blocks may be formulated with special aggregates to produce specific colors or textures for finish use. Special textures may be produced by splitting

740-504: The decorative potential. The popularity of terrazzo led to an increase in installers in the 1920s. The National Terrazzo and Mosaic Organization was formed in 1931 to further professionalize the practice of terrazzo installation. One of the best-known examples of terrazzo is the Hollywood Walk of Fame . Created in 1958, the walk honors celebrities in the form of a terrazzo star that displays their name. Archaeologists have adopted

777-402: The entire wall after it is built. Concrete blocks are some of the most versatile building products available because of the wide variety of appearances that can be achieved using them. Those that use cinders ( fly ash or bottom ash ) as an aggregate material are called "cinder blocks" in the United States. They are also known as "breeze blocks", a term derived from "breeze", referring to

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814-426: The floor. Installers use the dividing strips as guides when they work with different colored terrazzo. Additionally, the electric grinding machine and mechanization of the production process cut down on costs and installation time, making terrazzo an affordable flooring option. Art Deco and Moderne styles from the 1920s to 1940s favored terrazzo with the dividers allowing for straight or curved lines that increased

851-471: The history of terrazzo can be traced back to the ancient mosaics of Egypt, its more recent predecessors come from Italy. The form of terrazzo used today derives partly from the 18th century pavimento alla Veneziana ( Venetian pavement) and the cheaper seminato. Pavimento alla Veneziana had workers place marble fragments next to each other in a mortar base. Terrazzo is also related to the technique seminato for which workers tossed larger marble chips into

888-485: The latter two enhancing their structural strength. Additionally, steel reinforcement bars (rebar) can be used both vertically and horizontally inside a concrete block wall to maximize its structural performance. The cells in which the rebar is placed must be grouted for the bars to bond to the wall. For this reason, high-seismic zones typically allow only fully grouted walls in their building codes. The American design code that guides design engineers in using concrete blocks as

925-424: The material's inherent thermal insulation characteristics, as are expanded clay aggregate blocks. Blocks come in modular sizes, with the most popular typically referred to (by their thickness) as "4-inch", "6-inch", "8-inch", and "12-inch". In the US, concrete blocks are nominally 16 in (410 mm) long and 8 in (200 mm) wide. Their actual dimensions are 3 ⁄ 8 inch (9.5 mm) less than

962-414: The mortar base creating a more uniform surface appearance. Decorative patterns are often created by using dividers which creates lines between different colored terrazzo mixtures. Cracking is a common form of failure and is often caused by the structural system that supports the terrazzo rather than the material itself. Contact with alkalis or acids can deteriorate the bonding agents used in terrazzo. As

999-406: The most recent, thin set method ( epoxy resin). Bonded terrazzo is applied over a sand-cement mortar underbed which sits on top of a concrete slab. The sand-cement layer allows for variations in the finished concrete slab that it sits on. Monolithic terrazzo is applied directly over an extremely flat and high quality concrete sub-floor. Thin-set terrazzo does not require a concrete sub-floor. Instead,

1036-589: The nominal dimensions (to allow for 3 ⁄ 8 -inch mortar joints between blocks in any orientation). In Ireland and the UK, blocks are usually 440 mm × 215 mm × 100 mm (17.3 in × 8.5 in × 3.9 in) excluding mortar joints. In Australia, New Zealand and Canada, blocks are usually 390 mm × 190 mm × 190 mm (15.4 in × 7.5 in × 7.5 in) excluding mortar joints. Block cores are typically tapered so that their top surface (as laid) has

1073-470: The small cinders and cinder-dust that are created by partially burned coal. However, in the United States breeze blocks also refer specifically to decorative blocks used on exterior walls to allow the breeze through, which were an important feature of Mid-Century Modern design, popularised by Edward Durrell Stone . In Australia, they are often known as besser blocks (because the Besser Company

1110-402: The surface of finished concrete or epoxy -resin. Much of the preliminary work of terrazzo workers is similar to that of cement masons . Marble-chip, cementitious terrazzo requires three layers of materials. First, cement masons or terrazzo workers build a solid, level concrete foundation that is 3 to 4 inches (76 to 102 mm) deep. After the forms are removed from the foundation, workers add

1147-478: The term terrazzo to describe the floors of early Neolithic buildings ( PPNA and PPNB , ca. 9,000–8,000 BC) in Western Asia constructed of burnt lime and clay, colored red with ochre and polished. The embedded crushed limestone gives it a slightly mottled appearance. The use of fire to produce burnt lime, which was also used for the hafting of implements, predates production of fired pottery by almost

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1184-461: The terrazzo is thoroughly cured, helpers grind it with a terrazzo grinder , which is somewhat like a floor polisher , only much heavier. Slight depressions left by the grinding are filled with a matching grout material and hand- troweled for a smooth, uniform surface; it is then cleaned, polished, and sealed. Terrazzo installation includes both bonded and unbonded methods. Bonded systems include: bonded underbed, monolithic, chemically bonded, and

1221-602: The true joints. Concrete block, when built with integral steel reinforcement , is a very common building material for the load-bearing walls of buildings, in what is termed concrete block structure ( CBS ) construction. One of the common foundation types for American suburban houses is the "crawl space foundation" which consists of a concrete block wall on the perimeter on which dimensional lumber floor joists are supported. Retaining walls , which can also be constructed of concrete blocks, can be constructed, either using blocks designed to be set back each course and used with

1258-403: The wall, and whether it is a load-bearing partition or not, among other factors. Terrazzo Terrazzo is a composite material, poured in place or precast, which is used for floor and wall treatments. It consists of chips of marble , quartz , granite , glass , or other suitable material, poured with a cementitious binder (for chemical binding), polymeric (for physical binding), or

1295-461: The western United States, where they are easily obtainable, porous lava rock gravels are used for weight reduction. They also have an added decorative effect to certain types of block, such as split-face, due to their distinct red and black colors. Lower-density blocks may use industrial wastes , such as fly ash or bottom ash , as an aggregate. Recycled materials, such as post-consumer glass, slag cement, or recycled aggregate, are often used in

1332-424: Was a major supplier of machines that made concrete blocks), and also as grey blocks or concrete masonry units (CMUs). Clinker blocks use clinker (ash created as a waste product from impurities in minerals such as coal, limestone and iron-ore), also called slag. Concrete blocks are made from cast concrete (e.g. portland cement and aggregate , usually sand and fine gravel , for high-density blocks). In

1369-473: Was used at a small scale in comparison to the large expanses we see today. Two inventions resulted in its rise in popularity: divider strips and the electric grinding machine. The invention of divider strips by L. Del Turco and Bros. in 1924 contained the cracking of terrazzo by allowing the material greater space to expand and shrink after installation. This invention made terrazzo a durable and reliable material in addition to allowing for further design work within

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