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43-518: The building measures approximately 50 feet by 40 feet, and has a two-story concrete block addition built in 1955. It features arched windows and a projecting arched entryway topped by a pagoda style roof. It was constructed with a $ 31,000 grant from the Carnegie Foundation . It was listed on the National Register of Historic Places in 1978. The Monroe County Public Library vacated

86-763: A stub . You can help Misplaced Pages by expanding it . Concrete block A concrete block , also known as 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

129-595: 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

172-546: A major museum with similar roof construction, was ordered permanently closed 21 June 2024 because of severely deteriorated roof panels dating from its opening in 1969. While repair options were proposed, the centre's ultimate owner, the provincial government of Ontario , had previously announced plans to relocate the centre and therefore requested the facility be closed immediately rather than paying for repairs. Approximately 400 other public buildings in Ontario are understood to contain

215-646: A polymer-modified stucco or plaster compound, or a covering of siding materials such as natural or manufactured stone, veneer brick , metal or vinyl siding . AAC materials can be routed, sanded, or cut to size on-site using a hand saw and standard power tools with carbon steel cutters. Autoclaved aerated concrete is also known by various other names, including autoclaved cellular concrete (ACC), autoclaved concrete , cellular concrete , porous concrete , Aircrete , Thermalite , Hebel , Aercon , Starken , Gasbeton , Airbeton , Durox , Siporex (silicon pore expansion), Suporex , H+H and Ytong . AAC

258-424: 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

301-585: A roofing collapse, other buildings were found to have issues with their RAAC construction, with some of these only being discovered to have been made from RAAC during the crisis. During the 2023 crisis, it was observed that it was likely for RAAC in other countries to exhibit problems similar to those found in the United Kingdom. The original site of the Ontario Science Centre in Toronto, Canada,

344-713: 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,

387-484: 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

430-527: Is a concrete-based material used for both exterior and interior construction. One of its advantages is quick and easy installation because the material can be routed , sanded, or cut to size on-site using a hand saw and standard power tools with carbon steel cutters. AAC is well suited for high-rise buildings and those with high temperature variations. Due to its lower density, high-rise buildings constructed using AAC require less steel and concrete for structural members. The mortar needed for laying AAC blocks

473-414: Is five times less than the production of other building materials. There is no loss of raw materials in the production process, and all production waste is returned to the production cycle. Production of aerated concrete requires less energy than for all other masonry products, thereby reducing the use of fossil fuels and associated carbon dioxide (CO 2 ) emissions. The curing process also saves energy, as

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516-407: Is mixed and cast in forms, aluminium powder reacts with calcium hydroxide and water to form hydrogen . The hydrogen gas foams and doubles the volume of the raw mix creating gas bubbles up to 3 millimetres ( 1 ⁄ 8  in) in diameter—it has been described as having bubbles inside like "a chocolate Aero bar ". At the end of the foaming process, the hydrogen escapes into the atmosphere and

559-424: Is often caused by RAAC's high susceptibility to water infiltration due to its porous nature, which causes corrosion of internal reinforcements in ways that are hard to detect. This places increased tensile stress on the bond between the reinforcement and concrete, lowering the material's service life. Detailed risk analyses are required on a structure-by-structure basis to identify areas in need of maintenance and lower

602-429: Is produced using no aggregate larger than sand. Quartz sand (SiO 2 ), calcined gypsum, lime (mineral) and/or cement and water are used as a binding agent. Aluminum powder is used at a rate of 0.05%–0.08% by volume (depending on the pre-specified density). In some countries, like India and China, fly ash generated from coal-fired power plants , and having 50–65% silica content, is used as an aggregate. When AAC

645-417: Is reduced due to the lower number of joints. Similarly, less material is required for rendering, because AAC can be shaped precisely before installation. Even though regular cement mortar can be used, most buildings that use AAC materials use thin bed mortar in thicknesses around 3.2 millimetres ( 1 ⁄ 8  in), depending on the national building codes. Unlike most other concrete applications, AAC

688-612: Is replaced by air, leaving a product as light as 20% of the weight of conventional concrete. When the forms are removed from the material, it is solid but still soft. It is then cut into either blocks or panels and placed in an autoclave chamber for 12 hours. During this steam pressure hardening process, when the temperature reaches 190 °C (374 °F) and the pressure reaches 800 to 1,200 kPa (8.0 to 12.0 bar; 120 to 170 psi), quartz sand reacts with calcium hydroxide to form calcium silicate hydrate , which gives AAC its high strength and other unique properties. Because of

731-580: 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

774-770: The AAC was used. This problem was addressed in 1972 by the Swedish Radiation Safety Authority, and by 1975, Ytong abandoned alum shale in favor of a formulation made from quartz sand, calcined gypsum, lime (mineral), cement, water and aluminium powder currently in use by most major brands. In 1978, Siporex Sweden opened the Siporex Factory in Saudi Arabia , establishing the Lightweight Construction Company - Siporex - LCC SIPOREX, targeting markets in

817-721: The Middle East, Africa, and Japan. This factory was still in use in 2018. Today, the production of AAC is widespread, concentrated in Europe and Asia with some facilities located in the Americas. Egypt has the sole manufacturing plant in Africa. Although the European AAC market has seen a reduction in growth, Asia is experiencing a rapid expansion in the industry, driven by an escalating need for residential and commercial spaces. Currently, China has

860-672: The Second World War. In Europe, it gained popularity in the mid-1950s as a cheaper and more lightweight alternative to conventional reinforced concrete, with documented widespread use in a number of European countries as well as Japan and former territories of the British Empire. RAAC was used in roof, floor and wall construction due to its lighter weight and lower cost compared to traditional concrete, and has good fire resistance properties; it does not require plastering to achieve good fire resistance and fire does not cause spalls . RAAC

903-585: The United States. AAC is increasingly used worldwide by developers. Reinforced autoclaved aerated concrete (RAAC) is a reinforced version of autoclaved aerated concrete, commonly used in roofing and wall construction. The first structural reinforced roof and floor panels were manufactured in Sweden, soon after the first autoclaved aerated concrete block plant started up there in 1929, but Belgian and German technologies became market leaders for RAAC elements after

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946-591: The building in 1970; by 1978 and through the 1980s it was used by various nonprofits. On April 27, 1985 Glenn Danzig 's Deathrock band Samhain (band) performed there during their Unholy Passion EP tour. Since 1994, the former library houses the Monroe County Historical Society. This article about a property in Monroe County, Indiana on the National Register of Historic Places is

989-557: The chance of catastrophic failure. Professional engineering concern about the structural performance of RAAC was first publicly raised in the United Kingdom in 1995 following inspections of cracked units in British school roofs, and was subsequently reinforced in 2022 when the Government Property Agency declared the material to be life-expired, and in 2023 when, following the partial or total closure of 174 schools at risk of

1032-457: 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

1075-648: The compressive strength of regular concrete. In 1978, the first AAC material factory - the LCC Siporex- Lightweight Construction Company - was opened in the Persian Gulf state of Saudi Arabia , supplying Gulf Cooperation Council countries with aerated blocks and panels. Since 1980, there has been a worldwide increase in the use of AAC materials. New production plants are being built in Australia, Bahrain , China, Eastern Europe , India and

1118-413: 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

1161-402: 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

1204-657: The largest Aircrete market globally, with several hundred manufacturing plants. The most significant AAC production and consumption occur in China, Central Asia, India, and the Middle East, reflecting the dynamic growth and demand in these regions. Like other masonry materials, the product Aircrete is sold under many different brand names. Ytong and Hebel are brands of the international operating company Xella, headquartered in Duisburg. Other more internationally renowned brand names in Europe are H+H Celcon (Denmark) and Solbet (Poland). AAC

1247-485: 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

1290-531: The material and are under review, but no other closures were anticipated at the time of the Science Centre closure. The high resource efficiency of autoclaved aerated concrete contributes to a lower environmental impact than conventional concrete, from raw material processing to the disposal of aerated concrete waste. Due to continuous improvements in efficiency, the production of aerated concrete blocks requires relatively little raw materials per m of product and

1333-424: 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

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1376-603: The mid-1920s, AAC provides insulation, fire, and mold -resistance. Forms include blocks, wall panels, floor and roof panels, cladding (façade) panels and lintels. It is also an insulator. AAC products see use in construction, such as industrial buildings, residential houses, apartment buildings, and townhouses. Their applications include exterior and interior walls, firewalls, wet room walls, diffusion-open thermal insulation boards, intermediate floors, upper floors, stairs, opening crossings, beams and pillars. Exterior uses require an applied finish to guard against weathering, such as

1419-586: 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

1462-463: The relatively low temperature used, AAC blocks are not considered to be a fired brick but a lightweight concrete masonry unit . After the autoclaving process, the material is stored and shipped to construction sites for use. Depending on its density , up to 80% of the volume of an AAC block is air. AAC's low density also accounts for its low structural compression strength. It can carry loads of up to 8,000 kPa (1,200 psi), approximately 50% of

1505-463: 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

1548-416: The steam curing takes place at relatively low temperatures and the hot steam generated in the autoclaves is reused for subsequent batches. AAC has been produced for more than 70 years and has several advantages over other cement construction materials, one of the most important being its lower environmental impact. AAC has been produced for more than 70 years. However, some disadvantages were found when it

1591-602: 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

1634-480: The wall, and whether it is a load-bearing partition or not, among other factors. Autoclaved aerated concrete Autoclaved aerated concrete ( AAC ) is a lightweight, precast, cellular concrete building material, eco-friendly, suitable for producing concrete-like blocks . It is composed of quartz sand , calcined gypsum , lime , portland cement , water and aluminium powder . AAC products are cured under heat and pressure in an autoclave . Developed in

1677-461: 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

1720-424: 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

1763-571: Was established in Sweden in 1939, and presently licenses and owns plants in 35 locations around the world. Josef Hebel of Memmingen established another cellular concrete brand, Hebel, which opened their first plant in Germany in 1943. Ytong AAC was originally produced in Sweden using alum shale , which contained combustible carbon beneficial to the production process. However, these deposits were found to contain natural uranium , which decays over time to radon , which then accumulates in structures where

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1806-534: Was first created in the mid-1920s by the Swedish architect and inventor Dr. Johan Axel Eriksson (1888–1961), along with Professor Henrik Kreüger at the Royal Institute of Technology . The process was patented in 1924. In 1929, production started in Sweden in the city of Yxhult . "Yxhults Ånghärdade Gasbetong" later became the first registered building materials brand in the world : Ytong. Another brand, "Siporex",

1849-496: Was used in construction in Europe, in buildings constructed after the mid-1950s. RAAC elements have also been used in Japan as walling units owing to their good behaviour in seismic conditions. RAAC has been shown to have limited structural reinforcement bar ( rebar ) integrity in 40 to 50 year-old RAAC roof panels, which began to be observed in the 1990s. The material is liable to fail without visible deterioration or warning. This

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