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5/18/2018 EmergingTrendsinConcrte-slidepdf.com http://slidepdf.com/reader/full/emerging-trends-in-concrte 1/32 EMERGING TRENDS IN CONCRTE.  Concrete is inevitable component of the construction Industr. !rom the time immemorial till date "e cannot do "ithout Concrete The usage of concrete, world wide, is twice as much as steel, wood, plastics, and aluminum combined. Concrete's use in the modern world is only exceeded by the usage of naturally occurring water!  Concrete is widely used for making architectural structures, foundations, brick/block walls, pavements, bridges/overpasses, highways, runways, parking structures, dams, pools/reservoirs, pipes, footings for gates, fences and poles and even boats.  Concrete gives strength, beauty durability and most of all bassis to reach any heights.asonary work and other architectural and interior design all depend on the Concrete structure that encompasses the building.  Todays famous concrete structures include the "ur# $halifa %world's tallest building&, oover (am, the )anama Canal and the *oman )antheon.  Concrete is also the basis of a large commercial industry, with all the positives and negatives that entails. +n the nited -tates alone, concrete production is a 0 billion per year industry, considering only the value of the readymixed concrete sold each year.123 4iven the si5e of the concrete industry, and the fundamental way concrete is used to shape the infrastructure of the modern world, it is difficult to overstate the role this material plays today.  Concrete production is the process of mixing together the various ingredients6water, aggregate, cement, and any additives6to produce concrete. Concrete production is timesensitive. 7nce the ingredients are mixed, workers must put the concrete in place before it hardens.  There is a wide variety of e8uipment for processing concrete6from hand tools to heavy industrial machinery. 9hichever e8uipment builders use however, the ob#ective is to produce the desired building material6ingredients must be properly mixed, placed, shaped, and retained within time constraints. 7nce the mix is where it should be, the curing process must be controlled to ensure the concrete attains desired attributes. (uring concrete preparation, various technical details may affect the 8uality and nature of the
Transcript

EMERGING TRENDS IN CONCRTE.

Concrete is inevitable component of the construction Industry. From the time immemorial till date we cannot do without ConcreteThe usage of concrete, world wide, is twice as much as steel, wood, plastics, and aluminum combined. Concrete's use in the modern world is only exceeded by the usage of naturally occurring water!Concrete is widely used for making architectural structures, foundations, brick/block walls, pavements, bridges/overpasses, highways, runways, parking structures, dams, pools/reservoirs, pipes, footings for gates, fences and poles and even boats.Concrete gives strength, beauty durability and most of all bassis to reach any heights.Masonary work and other architectural and interior design all depend on the Concrete structure that encompasses the building. To-days famous concrete structures include the Burj Khalifa (world's tallest building), Hoover Dam, the Panama Canal andthe Roman Pantheon.Concrete is also the basis of a large commercial industry, with all the positives and negatives that entails. In the United States alone, concrete production is a $30 billion per year industry, considering only the value of the ready-mixed concrete sold each year.[23] Given the size of the concrete industry, and the fundamental way concrete is used to shape the infrastructure of the modern world, it is difficult to overstate the role this material plays today.Concrete production is the process of mixing together the various ingredientswater, aggregate, cement, and any additivesto produce concrete. Concrete production is time-sensitive. Once the ingredients are mixed, workers must put the concrete in place before it hardens.There is a wide variety of equipment for processing concretefrom hand tools to heavy industrial machinery. Whichever equipment builders use however, the objective is to produce the desired building materialingredients must be properly mixed, placed, shaped, and retained within time constraints. Once the mix is where it should be, the curing process must be controlled to ensure the concrete attains desired attributes. During concrete preparation, various technical details may affect the quality and nature of the productTo-day new innovation of Concrete product are coming in the market and there are numerous improvisation of Concrete application introduced for strength application.From onsite application to Pre-cast concrete blocks and slabs in various shapes and sizes adorn the modern building and it remains the architects and engineers delight to deploy concrete in todays infrastructure industry. Some of the emerging trends in the application of Concrete are discussed below.1)Translucent concreteTranslucent Concrete is also known as Light transmitting Concrete having transmitting properties owing to embedded light optical fibres.Light is conducted through the concrete structure and shadow is casted onto one side which appear as silhouettes through the material.Translucent concrete is used in fine architecture as a faade material and for cladding of interior walls. Light-transmitting concrete has also been applied to various design products.There are several methods of producing translucent concrete exist. All are based on a fine grain concrete (ca. 95%) and only 5% light conducting elements that are added during casting process. After setting, the concrete is cut to plates or stones with standard machinery for cutting stone materials.Natural light is also deployed after ensuring enough light is available.Wall mounting systems with some form of lighting, are also designed to achieve uniform illumination on the full plate surface. Usually mounting systems similar to natural stone panels are used.2)REACTIVE POWDER CONCRETEReactive Powder Concrete is an ultra high-strength and high ductility composite material with advanced mechanical properties.. It consists of a special concrete where its microstructure is optimized by precise gradation of all particles in the mix to yield maximum density. It uses extensively the pozzolanic properties of highly refined silica fume and optimization of the Portland cement chemistry to produce the highest strength hydrates.RPC represents a new class of Portland cement-based material with compressive strengths in excess of 200 MPa range. By introducing fine steel fibers, RPC can achieve remarkable flexural strength up to 50 MPa. The material exhibits high ductility with typical values for energy absorption approaching those reserved for metals.RPC is a better alternative to High Performance Concrete and has the potential to structurally compete with steel.Its superior strength combined with higher shear capacity results in significant dead load reduction and limitless structural member shape. With its ductile tension failure mechanism, RPC can be used to resist all but direct primary tensile stresses. This eliminates the need for supplemental shear and other auxiliary reinforcing steel.RPC provides improve seismic performance by reducing inertia loads with lighter members, allowing larger deflections with reduced cross sections, and providing higher energy absorption. Its low and non-interconnected porosity diminishes mass transfer making penetration of liquid/gas or radioactive elements nearly non-existent. Cesium diffusion is non-existent and Tritium diffusion is 45 times lower than conventional containment materials.3) Self-consolidating concrete or self-compacting concreteSelf-Consolidating concrete (SCC) is a high-performance concrete that can flow easily into tight and constricted spaces without segregating and without requiring vibration. SCC is a mixture that is fluid, but is also stable to prevent segregation and is also referred to as self-compacting, self-leveling, or self-placing concrete,To achieve the desired flow ability a new generation of super plasticizers based on polycarboxylate ethers works best. They produce better water reduction and slower slump loss than traditional super plasticizers. The required level of fluidity is greatly influenced by the particular application under consideration. Obviously the most congested structural members demand the highest fluidity. However, element shape, desired surface finish, and travel distance can also determine the required fluidity.Generally, the higher the required flowability of the SCC mix, the higher the amount of fine material needed to produce a stable mixture. However, in some cases, a viscosity-modifying admixture (VMA) can be used instead of, or in combination with, an increased fine content to stabilize the concrete mixture.Such concrete can be used for casting heavily reinforced sections, places where there can be no access to vibrators for compaction and in complex shapes of formwork which may otherwise be impossible to cast, giving a far superior surface than conventional concrete.

Emerging Trends and Innovations in ConcreteBuildings Home > Emerging Trends New advancements in concrete and cement-based products are completely changing the design and construction worlds.New Technologies

Many new technologies are changing the way we build and what we build with concrete. Adding optical fibers to a concrete mix generates translucent concrete. This see-through development is changing the perception of concretes opaque mass.

Reactive powder concrete is extremely workable, durable and yields ultra-high strengths without using coarse aggregates. Reaching compressive strengths of 30,000psi, this new-age concrete also has tensile strength with the inclusion of steel and synthetic fibers. More. Self Consolidating Concrete (SCC) eliminates the need for mechanical consolidation and yields a smooth surface finish without mix segregation. More.

First Use of Ultra-High Performance Concrete for an Innovative Train Station CanopyBy V. H. Perry and D. Zakariasen, Lafarge Canada Inc.

Figure 1. Shawnessy Light Rail Transit Station, Calgary, Canada.

The Shawnessy Light Rail Transit (LRT) Station, constructed during fall 2003 and winter 2004, forms part of a southern expansion to Calgary's LRT system and is the world's first LRT system to be constructed with ultra-high performance concrete (UHPC). The innovative project, designed by Enzo Vicenzino of CPV Group Architects Ltd., is owned by the City of Calgary, managed by the Transportation Project Office (TPO), and constructed by general contractor, Walter Construction.The DesignThe station's twenty-four thin-shelled canopies, 5.1 m by 6 m (16.7 ft by 19.7 ft), and just 20 mm (0.79 in.) thick, supported on single columns, protect commuters from the elements. UHPC technology has a unique combination of superior technical characteristics including ductility, strength, and durability, while providing highly moldable products with a high quality surface aspect. The contract document specified a minimum requirement of 130 MPa (19,000 psi). In addition to the canopies, the components include struts, columns, beams, and gutters. The volume of material used totaled 80 m3 (105 yd3).

Manufacturing and InstallationThe precast canopy components were individually cast and consist of half-shells, columns, tie beams, struts, and troughs. Table 1 summarizes test data from production of the twenty-four canopies.

Table 1. Test Results LRT Canopies

Mean value after 72 hours thermal treatmentStandard development

PropertyMPa (psi)MPa (psi)

Compressive strengthFlexural strength152 (22,000)18 (2,600)6.2 (900)3.4 (500)

Figure 2. Half-canopy in steel form.

The columns and half-shells were injection cast in closed steel forms (Figure 2). Troughs were cast through displacement molding, while struts and tie beams were produced using conventional gravity two-stage castings.

The columns were installed on the concrete platform first. Then, the right and left half-shells, along with the tie beams, were pre-assembled in the plant and transported to the site where they were lifted (by crane) over the railway tracks, for placement on the columns (Figure 3). Upon arrival at the site, the canopies were set on temporary scaffolding, and struts were attached to the shells and previously installed columns with welded connections.

Figure 3. Canopies ready for transportation.

ConclusionThe material's unique combination of superior properties and design flexibility facilitated the architect's ability to create the attractive, off-white, curved canopies. Overall, this material offers solutions with advantages such as speed of construction, improved aesthetics, superior durability, and impermeability against corrosion, abrasion and impactwhich translates to reduced maintenance and a longer life span for the structure.

This project was the first of its type in the world using this mix for thin, architectural, curved canopies. While this solution demonstrates many of the benefits of the material technology, it is apparent that the true benefits are not fully recognized. Furthermore, the material is still in its infancy, and, in the next few years, much progress is anticipated in the area of optimized solutions.Ultra-High Performance Concrete (UHPC), also known as reactive powder concrete (RPC), is a high-strength, ductile material formulated by combining portland cement, silica fume, quartz flour, fine silica sand, high-range water reducer, water, and steel or organic fibers. The material provides compressive strengths up to 200 MPa (29000 psi) and flexural strengths up to 50 MPa (7000 psi).

The materials are usually supplied in a three-component premix: powders (portland cement, silica fume, quartz flour, and fine silica sand) pre-blended in bulk-bags; superplasticizers; and organic fibers. The ductile behavior of this material is a first for concrete, with the capacity to deform and support flexural and tensile loads, even after initial cracking. The use of this material for construction is simplified by the elimination of reinforcing steel and the ability of the material to be virtually self placing or dry cast.The superior durability characteristics are due to a combination of fine powders selected for their grain size (maximum 600 micrometer) and chemical reactivity. The net effect is a maximum compactness and a small, disconnected pore structure.

The following is an example of the range of material characteristics for UHPC:

STRENGTH

Compressive 120 to 150 MPa (17000 to 22000 psi)

Flexural 15 to 25 MPa (2200 to 3600 psi)

Modulus of Elasticity 45 to 50 GPa (6500 to 7300 ksi)

DURABILITY

Freeze/thaw (after 300 cycles) 100%

Salt-scaling (loss of residue) < 60 g/m2 (< 0.013 lb/ft3)

Abrasion (relative volume loss index) 1.7

Oxygen permeability Chemical Admixtures

Chemical admixtures are the ingredients in concrete other than portland cement, water, and aggregate that are added to the mix immediately before or during mixing. Producers use admixtures primarily to reduce the cost of concrete construction; to modify the properties of hardened concrete; to ensure the quality of concrete during mixing, transporting, placing, and curing; and to overcome certain emergencies during concrete operations.

Successful use of admixtures depends on the use of appropriate methods of batching and concreting. Most admixtures are supplied in ready-to-use liquid form and are added to the concrete at the plant or at the jobsite. Certain admixtures, such as pigments, expansive agents, and pumping aids are used only in extremely small amounts and are usually batched by hand from premeasured containers.

The effectiveness of an admixture depends on several factors including: type and amount of cement, water content, mixing time, slump, and temperatures of the concrete and air. Sometimes, effects similar to those achieved through the addition of admixtures can be achieved by altering the concrete mixture-reducing the water-cement ratio, adding additional cement, using a different type of cement, or changing the aggregate and aggregate gradation.

Five Functions

Admixtures are classed according to function. There are five distinct classes of chemical admixtures: air-entraining, water-reducing, retarding, accelerating, and plasticizers (superplasticizers). All other varieties of admixtures fall into the specialty category whose functions include corrosion inhibition, shrinkage reduction, alkali-silica reactivity reduction, workability enhancement, bonding, damp proofing, and coloring. Air-entraining admixtures, which are used to purposely place microscopic air bubbles into the concrete, are discussed more fully in "Air-Entrained Concrete."

Water-reducing admixtures usually reduce the required water content for a concrete mixture by about 5 to 10 percent. Consequently, concrete containing a water-reducing admixture needs less water to reach a required slump than untreated concrete. The treated concrete can have a lower water-cement ratio. This usually indicates that a higher strength concrete can be produced without increasing the amount of cement. Recent advancements in admixture technology have led to the development of mid-range water reducers. These admixtures reduce water content by at least 8 percent and tend to be more stable over a wider range of temperatures. Mid-range water reducers provide more consistent setting times than standard water reducers. Retarding admixtures, which slow the setting rate of concrete, are used to counteract the accelerating effect of hot weather on concrete setting. High temperatures often cause an increased rate of hardening which makes placing and finishing difficult. Retarders keep concrete workable during placement and delay the initial set of concrete. Most retarders also function as water reducers and may entrain some air in concrete.

Accelerating admixtures increase the rate of early strength development, reduce the time required for proper curing and protection, and speed up the start of finishing operations. Accelerating admixtures are especially useful for modifying the properties of concrete in cold weather.

Superplasticizers, also known as plasticizers or high-range water reducers (HRWR), reduce water content by 12 to 30 percent and can be added to concrete with a low-to-normal slump and water-cement ratio to make high-slump flowing concrete. Flowing concrete is a highly fluid but workable concrete that can be placed with little or no vibration or compaction. The effect of superplasticizers lasts only 30 to 60 minutes, depending on the brand and dosage rate, and is followed by a rapid loss in workability. As a result of the slump loss, superplasticizers are usually added to concrete at the jobsite.

Corrosion-inhibiting admixtures fall into the specialty admixture category and are used to slow corrosion of reinforcing steel in concrete. Corrosion inhibitors can be used as a defensive strategy for concrete structures, such as marine facilities, highway bridges, and parking garages, that will be exposed to high concentrations of chloride. Other specialty admixtures include shrinkage-reducing admixtures and alkali-silica reactivity inhibitors. The shrinkage reducers are used to control drying shrinkage and minimize cracking, while ASR inhibitors control durability problems associated with alkali-silica reactivity.

Autoclaved Cellular ConcreteConcrete Basics Home > Autoclaved Cellular Concrete Developed in Sweden in the late 1920s, autoclaved cellular concrete (ACC) is a lightweight precast concrete building material that is cured under elevated pressure inside special kilns called autoclaves. Though ACC has been used successfully throughout most of the world since the end of World War II, ACC made a mark in the United States only recently. ACC, sometimes known as autoclaved aerated concrete, is made with all fine materials-nothing coarser than finely ground sand. What makes ACC different from lightweight aggregate concrete is that ACC contains millions of microscopic cells that are generated during the manufacturing process. In addition, ACC is unlike many other concrete products because it may be drilled, sawed, chiseled, nailed, or screwed using conventional carpentry tools. Several Formulas

Although several formulas are used for manufacturing ACC, the basic raw materials are portland cement, limestone, aluminum powder, water, and a large proportion of a silica-rich material-usually sand or fly ash. Once raw materials are mixed into a slurry and poured into greased molds, the aluminum powder reacts chemically to create millions of tiny hydrogen gas bubbles. These microscopic, unconnected cells cause the material to expand to nearly twice its original volumesimilar to the rising of bread doughimparting the lightweight cellular quality to ACC. After a setting time ranging from 30 minutes to 4 hours, the foam-like material is hard enough to be wire cut into the desired shapes and moved into an autoclave for curing. The autoclave uses high-pressure steam at temperatures of about 356 F (180C) to accelerate the hydration of the concrete and spur a second chemical reaction that gives ACC its strength, rigidity, and dimensional stability. Autoclaving can produce in 8 to 14 hours concrete strengths equal to strengths obtained in a concrete moist-cured for 28 days at 70 F (21C). The final products are usually shrink wrapped in plastic and transported directly to the construction site. ACC, which is about one-fourth of the weight of conventional concrete, is available in blocks, wall and roof panels, lintels, and floor slabs. Each of these products can be manufactured in a range of sizes depending on specific applications, allowing for maximum efficiency and flexibility in construction. ACC can be used for all types of structures ranging from single-family housing to large industrial complexes. ACC is an inert, nontoxic substance that has an energy-efficient and pollution-free manufacturing process. Perhaps the most significant environmental benefit of using ACC is that fly ash can be used as the silica-rich component. The electric utility industry generates more than 50 million tons of fly ash each yearonly a fraction of which can be recycled. ACC is reasonably frost and sulfate resistant, allowing it to be used around the world in all climatic zones and for a wide range of applications. When it is used on the exterior, ACC is normally protected by stucco or other protective coatings. ACC also is an inorganic material, making it 100 percent termite and vermin proof and resistant to rotting and mold.

Concrete Masonry UnitsMasonry Home > Products and Properties > Concrete Masonry Units

Since 1882, when the first concrete block was molded, concrete masonry has become a standard building material. Concrete blocks create structures that are economical, energy efficient, fire-resistant, and involve minimal maintenance. In addition, concrete masonry allows architectural freedom and versatility. The standard concrete block is a rectangular 8X8X16-inch unit (200X200X400 mm) made mainly of portland cement, gravel, sand, and water. The concrete mixture may also contain ingredients such as air-entraining agents, coloring pigment, and water repellent. During the manufacturing process, a machine molds moist, low-slump concrete into the desired shapes. These blocks then undergo an accelerated curing process at elevated temperatures inside a special chamber. This is generally followed by a storage or drying phase. Concrete masonry is widely used to construct small and large structures. The most common application of concrete masonry is walls for buildings. However, other uses for concrete masonry units include retaining walls, chimneys, fireplaces, and firesafe enclosures of stairwells, elevator shafts, and storage vaults. Concrete masonry units can be manufactured for virtually any architectural or structural function. Split-face block units have been fractured lengthwise or crosswise by machine to produce a rough stone-like texture. The split face exposes the aggregates in the various planes of fracture. A patented slotted concrete block provides high sound absorption, making it ideal for use in gymnasiums, factories, bowling alleys, or other places where noise generation is high. Glazed concrete masonry units are used in swimming pools where sanitation and a durable, attractive finish are needed. For more information, contact the National Concrete Masonry Association Architect Magazine Profiles Block Plant

A modern block plant in operation. Blocks move along conveyor throughout plant.

The March 2008 issue of Hanley-Wood's Architect magazine takes a closer look at how concrete masonry units (CMU) are manufactured. They note how prevalent these units are (nearly 8 billion produced in 2007 in North America), and how they are nearly taken for granted, too. They say how the blocks value lies in its versatilitycertainly not in portability and that the plant they visited ships its nearly 3 million units within a 50-mile radius.

They hit it right on the head: block, or CMU, is versatile. They also hit on a sustainability topic that deserves emphasizing. The fact that most units are manufactured and used locally makes them sustainable in all locations. Whether the cement is shipped in from a distance or manufactured locally as well, it represents a small portion of each unit (8.5% to 12% by weight), or only about 3 lbs per block (each block weighs from 25 to 35 pounds each).

In the U.S., CMU are manufactured to conform to ASTM C140, Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units. C140 and it annexes cover the standard CMU and various other concrete masonry products such as concrete brick, segmental retaining wall units (SRWs), interlocking pavers, grid pavers, and roof pavers. This standard ensures consistent properties like size, density (weight), absorption, and strength.

These units are made from very dry concrete mixes that are placed into steel molds, vibrated and compacted, then demolded and cured. Architect says that molding takes a mere 6.5 seconds at the plant they visited, but the curing goes on for 24 hours. Some other plants may be on cycles of 18 hours or 36 hours. Read the article from Architect.

Additional information about block manufacturing can be found in PCAs Concrete Masonry Handbook for Architects, Engineers, Builders, (EB008) and in the NCMA TEK sheets at www.ncma.org.ASTM C140 Standard on CMU Reorganized

The Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units, ASTM C140, was reorganized late in 2007 and published in January 2008. Designers and specifiers should be familiar with this document, as it is used for evaluating characteristics of concrete masonry units and related concreate units. The big change in this version from previous ones is that annexes were added to address each type of masonry unit, outlining the appropriate test procedures for that type of unit.Not all units are tested the same way, and not all methods are applicable to all unit types. Units serve different purposes and need different properties in service. They should be tested for properties pertinent to each type of unit.For instance, dimensions of CMU and concrete brick should both be verified. While it is necessary to check the width, height, and length of the overall unit, for CMU, it is also necessary to check the thickness of face shells and webs.C140 provides testing procedures that are commonly used. Methods describe sampling, measurement of dimensions, compressive strength, absorption, unit weight (density), moisture content, flexural load, and ballast weight. Specifically, the annexes are: Annex 1, Concrete Masonry Units

Annex 2, Concrete Brick

Annex 3, Segmental Retaining Walls

Annex 4, Concrete Interlocking Paving Units

Annex 5, Concrete Grid Paving Units

Annex 6, Concrete Roof Pavers

Annex 7, Determining Plate Thickness Requirements for Compression TestingSome common units covered under ASTM C140: CMU, concrete brick, grid pavers.

Concrete masonry unit (CMU)Concrete brickGrid paver

Controlled Low-Strength Material Concrete Basics Home > Controlled Low-Strength Material In 1964, the U.S. Bureau of Reclamation documented the first known use of controlled low-strength material (CLSM). Plastic soil-cement, as the Bureau called it, was used as pipe bedding on over 320 miles (515 km) of the Canadian River Aqueduct Project in northwestern Texas. Since 1964, CLSM has become a popular material for projects such as structural fill, foundation support, pavement base, and conduit bedding. CLSM is a self-compacted, cementitious material used primarily as a backfill in lieu of compacted backfill. Several terms are currently used to describe this material, including flowable fill, controlled density fill, flowable mortar, plastic soil-cement, soil-cement slurry, K-Krete, and other names. CLSM is defined as a material that results in a compressive strength of 1200 psi (8 MPa) or less. Most current CLSM applications require unconfined compressive strengths of 200 psi (1.4 MPa) or less. This lower strength requirement is necessary to allow for future excavation of CLSM. The term CLSM can be used to describe a family of mixtures for a variety of applications. For example, the upper limit of 1200 psi (8 MPa) allows use of this material for applications where future excavation is unlikely, such as structural fill under buildings. Low density CLSM describes a material with distinctive properties and mixing procedures. Future CLSM mixtures may be developed as anticorrosion fills, thermal fills, and durable pavement bases. CLSM is composed of water, portland cement, aggregate, and fly ash. It is a fluid material with typical slumps of 10 inches (254 mm) or more. It has the consistency of a milk shake. Fast Discharge

Like most concrete, CLSM may be mixed in central-mix concrete plants, ready-mixed concrete trucks or pugmills. Once CLSM is transported to the jobsite, the mixture may be placed using chutes, conveyors, buckets, or pumps depending upon the application and its accessibility. A truck often can be discharged in less than 5 minutes. A constant supply of CLSM will keep the material flowing and will make it flow horizontal distances of 300 feet (91 m) or more. Although CLSM may be placed continuously in most applications, care must be taken when backfilling around pipes. For pipe bedding and backfilling, CLSM is placed in lifts to prevent the pipes from floating. Internal vibration or compaction is not needed to consolidate CLSM mixtures. Its fluidity is sufficient to consolidate under its own weight. The fluidity/flowability and self-compacting properties of CLSM mixtures make CLSM an economical alternative to compacted granular material due to savings of labor and time during placing. CLSM is also an all-weather construction materialit will displace any standing water left in a trenchmaking it a ideal material for many projects. The primary application of CLSM is as structural fill or backfill in place of compacted soil. The flowable characteristics of CLSM mean that it can readily be placed into a trench and into tight or restricted-access areas where placing and compacting fill is difficult. CLSM also makes an excellent bedding material for pipe, electrical, telephone, and other types of conduits because the mixture easily fills voids beneath the conduit and provides uniform support. CLSM will not settle or rut under loads, making the material an ideal pavement base. Additionally, CLSM can be placed quickly and support traffic load within hours of placement-minimizing repair time and allowing a rapid return to traffic. CLSM may be equal to or less than the cost of using standard compacted backfill. Since 1979, the Iowa Department of Transportation has used CLSM to structurally modify more than 40 substandard bridges by converting them into culverts. CLSM is also used to fill large voids such as old tunnels and sewers. In a Milwaukee project, 830 cubic yards (635 cubic meters) of CLSM were used to fill an abandoned tunnel. A ready-mixed concrete producer can aid in developing a mix design for CLSM. However, when ordering CLSM, consider the following: Strength: Applications that require removal of CLSM at a later date usually limit the maximum compressive strength to less than 200 psi (1.4 MPa). Setting and Early Strength: Hardening time can be as short as one hour, but can take up to 8 hours depending on mix design and trench conditions. Density in Place: Density of normal CLSM in place typically ranges from 90 to 125 pounds per cubic foot (1440 to 2000 kg/cubic meters). Flowability: Flowability can be enhanced through the use of fly ash or air entrainment. Durability: CLSM materials are not designed to resist freezing and thawing, abrasive or erosive actions, or aggressive chemicals.

High-Strength ConcreteConcrete Basics Home > High-Strength Concrete In the early 1970s, experts predicted that the practical limit of ready-mixed concrete would be unlikely to exceed a compressive strength greater than 11,000 psi (76 MPa). Over the past two decades, the development of high-strength concrete has enabled builders to easily meet and surpass this estimate. Two buildings in Seattle, Washington, contain concrete with a compressive strength of 19,000 psi (131 MPa). The primary difference between high-strength concrete and normal-strength concrete relates to the compressive strength that refers to the maximum resistance of a concrete sample to applied pressure. Although there is no precise point of separation between high-strength concrete and normal-strength concrete, the American Concrete Institute defines high-strength concrete as concrete with a compressive strength greater than 6000 psi (41 MPa). Manufacture of high-strength concrete involves making optimal use of the basic ingredients that constitute normal-strength concrete. Producers of high-strength concrete know what factors affect compressive strength and know how to manipulate those factors to achieve the required strength. In addition to selecting a high-quality portland cement, producers optimize aggregates, then optimize the combination of materials by varying the proportions of cement, water, aggregates, and admixtures. When selecting aggregates for high-strength concrete, producers consider the strength of the aggregate, the optimum size of the aggregate, the bond between the cement paste and the aggregate, and the surface characteristics of the aggregate. Any of these properties could limit the ultimate strength of high-strength concrete. Admixtures

Pozzolans, such as fly ash and silica fume, are the most commonly used mineral admixtures in high-strength concrete. These materials impart additional strength to the concrete by reacting with portland cement hydration products to create additional C-S-H gel, the part of the paste responsible for concrete strength. It would be difficult to produce high-strength concrete mixtures without using chemical admixtures. A common practice is to use a superplasticizer in combination with a water-reducing retarder. The superplasticizer gives the concrete adequate workability at low water-cement ratios, leading to concrete with greater strength. The water-reducing retarder slows the hydration of the cement and allows workers more time to place the concrete. High-strength concrete is specified where reduced weight is important or where architectural considerations call for small support elements. By carrying loads more efficiently than normal-strength concrete, high-strength concrete also reduces the total amount of material placed and lowers the overall cost of the structure. The most common use of high-strength concrete is for construction of high-rise buildings. At 969 ft (295 m), Chicago's 311 South Wacker Drive uses concrete with compressive strengths up to 12,000 psi (83 MPa) and is the tallest concrete building in the United States.

Insulating Concrete Forms Concrete Basics Home > Insulating Concrete Forms Insulating concrete form systems (ICFs) have been successfully used by European and Canadian builders for decades, yet the systems did not make a mark in the United States until the 1990s. This builder-friendly wall system, which is a variation of poured-in-place concrete construction, has found its way into many new homes across every region and in every price range. In conventional poured-in-place construction, a crew erects forms of plywood, steel, or aluminum that make a mold in the shape of the desired walls. After placing rebar to reinforce the wall, the crew pours concrete inside the cavity. Once the concrete hardens, the crew strips the forms to leave the reinforced concrete walls. Unlike these removable forms, ICFs are designed to stay in place as a permanent part of the wall assembly. The formwork functions as the insulation and the concrete functions as the structure. A handful of these systems are manufactured from hybrid combinations of insulating materials, including wood fiber and cement, or plastic foam beads and cement. Far more commonly available are ICFs made with expanded or extruded polystyrene, containing up to 20 percent recycled materials. Expanded polystyrene is formed by expanding plastic beads in a mold and is similar to vending machine coffee cups. Extruded polystyrene is made by expanding plastic resin and extruding through a die and is similar to grocery store meat trays.

Foam form units typically provide at least 2 inches (5 cm) of insulation on both faces of a concrete wall, which can commonly be 4 to 12 inches thick. The result is a solid assembly with strong thermal properties that holds down energy costs. The integral, permanent insulation allows builders to create super-efficient insulated wallsfrom an effective R-20 to R-40-in a fraction of the time required with wood or steel frame.

The Basics

There are two ways ICFs can arrive on the job: as blocks or planks. The block systems arrive at the site with plastic or metal ties and foam, pre-formed and ready to stack and interlock almost like children's building blocks. Plank systems come as separate panels or planks of foam that are assembled on site with individual ties. The block systems offer labor savings through faster assembly on the site while the plank systems offer savings through more compact shipping.

Within these two basic ICF types, individual systems can vary in the profile of the wall they create. "Flat" systems yield a continuous thickness of concrete, like a conventionally poured wall. The wall produced by "grid" systems has a waffle pattern where the concrete is thicker at some points than others. "Post and beam" systems have just thatdiscrete horizontal and vertical columns of concrete that are completely encapsulated in foam insulation. Whatever their differences, all major ICF systems are engineer-designed, code-accepted and field-proven.

While the formwork is stacked or assembled vertical and horizontal reinforcement is installed. Then contractors pump concrete into the cavity to create a solid structural wall with insulation on both sides. Once crews complete the wall, electricians cut channels for cables and wires into the forms. Plumbers can work in a similar way, placing cold and hot water lines in the insulation after the concrete is poured.

The insulation provided by the forms gives builders the ability to successfully place concrete even during extremes of weather. Few weather conditions affect a pour because the form insulates the concrete, allowing it to cure while isolated from outside temperature or humidity. Because of ideal curing conditions created within the forms , the risk of serious cracks developing is diminished. The left-in-place forms provide a continuous insulation and sound barrier.

ICFs can be cut to any shape to allow for unique home designs or site conditions. Because ICFs provide a flat, continuous surface to work on, troweled finishes generally go onto ICFs with little advance preparation. In addition, the ends of the ties themselves are typically designed to accept fasteners to permit interior drywall to be installed directly over the forms. Similarly, this built-in furring permits mechanical attachment of exterior finishes like lath for stucco, furred and direct attached siding, or masonry veneer. There are even brick ledge forms to help further simplify brick installation.

Currently, ICFs are used to build walls for all types of buildings, and several manufacturers have additional forming components that will allow the construction of attached concrete floors and/or roofs. There are several brands of foam forming systems readily available in almost every region of the country.

Concrete PavementConcrete Basics Home > Concrete Pavement Since the first strip of concrete pavement was completed in 1893, concrete has been used extensively for paving highways and airports as well as business and residential streets. There are four types of concrete pavement: Plain pavements with dowels that use dowels to provide load transfer and prevent faulting, Plain pavements without dowels, in which aggregate interlock transfers loads across joints and prevents faulting, Conventionally reinforced pavements that contain steel reinforcement and use dowels in contraction joints, and Continuously reinforced pavements that have no contraction joints and are reinforced with continuous longitudinal steel. To prepare for paving, the subgradethe native soil on which the pavement is builtmust be graded and compacted. Preparation of the subgrade is often followed by the placing of a subbasea layer of material that lies immediately below the concrete. The essential function of the subbase is to prevent the displacement of soil from underneath the pavement. Subbases may be constructed of granular materials, cement-treated materials, lean concrete, or open-graded, highly-permeable materials, stabilized or unstabilized. Once the subbase has hardened sufficiently to resist marring or distortion by construction traffic, dowels, tiebars, or reinforcing steel are placed and properly aligned in preparation for paving. There are two methods for paving with concreteslipform and fixed form. In slipform paving, a machine rides on treads over the area to be pavedsimilar to a train moving on a set of tracks. Fresh concrete is deposited in front of the paving machine which then spreads, shapes, consolidates, screeds, and float finishes the concrete in one continuous operation. This operation requires close coordination between the concrete placement and the forward speed of the paver. In fixed-form paving, stationary metal forms are set and aligned on a solid foundation and staked rigidly. Final preparation and shaping of the subgrade or subbase is completed after the forms are set. Forms are cleaned and oiled first to ensure that they release from the concrete after the concrete hardens. Once concrete is deposited near its final position on the subgrade, spreading is completed by a mechanical spreader riding on top of the preset forms and the concrete. The spreading machine is followed by one or more machines that shape, consolidate, and float finish the concrete. After the concrete has reached a required strength, the forms are removed and curing of the edges begins immediately. Joints Control Cracking

After placing and finishing concrete pavement, joints are created to control cracking and to provide relief for concrete expansion caused by temperature and moisture changes. Joints are normally created by sawing. Once joints have been inserted, the surface must be textured. To obtain the desired amount of skid resistance, texturing should be done just after the water sheen has disappeared and just before the concrete becomes non-plastic. Texturing is done using burlap drag, artificial-turf drag, wire brooming, grooving the plastic concrete with a roller or comb equipped with steel tines, or a combination of these methods. The chosen method of texturing depends on the environment, and the speed and density of expected traffic. Curing begins immediately after finishing operations and as soon as the surface will not be marred by the curing medium. Common curing methods include using white pigmented liquid membrane curing compounds. Occasionally, curing is accomplished by waterproof paper or plastic covers such as polyethylene sheets, or wet cotton mats or burlap. As the concrete pavement hardens, it contracts and cracks. If the contraction joints have been correctly designed and constructed, the cracks will occur below the joints. As the concrete continues to contract, the joints will open-providing room for the concrete to expand in hot weather and in moist conditions. Once the pavement hardens, the joints are cleaned and sealed to exclude foreign material that would be damaging to the concrete when it expands. The pavement is opened to traffic after the specified curing period and when tests indicate that the concrete has reached the required strength. Immediately before the pavement is opened to public traffic, the shoulders are finished and the pavement is cleaned.

ShotcreteConcrete Basics Home > Shotcrete Shotcrete refers to a process in which compressed air forces mortar or concrete through a hose and nozzle onto a surface at a high velocity and forms structural or non-structural components of buildings. The relatively dry mixture is consolidated by the force of impact and develops a compressive strength similar to normal- and high-strength concrete. Materials used in the shotcrete process are generally the same as those used for conventional concrete-portland cement, lightweight aggregate, water, and admixtures. Shotcrete projects also call for the same types of reinforcement specified for conventional concrete, including deformed bars, welded wire fabric, and prestressing steel. Wet or Dry

Shotcrete may be applied to surfaces using a dry- or wet-mix method. The wet-mix concrete method consists of portland cement and aggregate premixed with water before the pump pushes the mixture though the hose. Additional compressed air is added at the nozzle to increase the velocity of the mixture. In the dry-mix process, compressed air propels a premixed blend of portland cement and damp aggregate through the hose to the nozzle. In the nozzle, water is added from a separate hose and completely mixed with the dry mixture just as both streams are being projected onto the prepared surface. Generally, the shotcrete gun nozzle is held at a right angle 2 to 6 feet (0.6 to 1.8 meter) from the surface. In most cases, shotcrete can be deposited in the required thickness in a single application. For some vertical and overhead applications and for some smooth finishes, shotcrete must be applied in 1 to 2-inch (2.5 to 5 cm) thick layers. Once shotcrete is placed, it can be finished in a variety of methods, including natural finish, broom finish, various rough trowel finishes, and smooth steel trowel finish. After finishing, the concrete must be cured for a period of at least seven days. Since its invention in 1911, the shotcrete process has been used successfully for a wide variety of building projects, including all types of residential and non-residential buildings. Shotcrete, which can be applied to horizontal or vertical surfaces, is especially suited for curved or thin concrete structures and shallow repairs. Other applications include swimming pools, grain silos, fire-proofing structural steel, and many civil engineering structures such as bridges, tunnels, dams, tanks, and earth retention systems. Although using shotcrete to form walls is new in the United States, the process has been used in other countries for years. A recent innovation that has made shotcrete more suitable for construction is the incorporation of insulation into the wall unit. The new system consists of 4-foot-by-8-foot panels (1.1x2.5 m) of a polystyrene core sandwiched between layers of wire mesh. Workers erect a frame of wire mesh or rebar in the shape of exterior walls, install conduit, pipe, and other utilities between the polystyrene and the wire mesh, and then spray the entire structure. The concrete covers the foam and hardens to form a reinforced wall with built-in insulation.

Soil-CementConcrete Basics Home > Soil-Cement In 1935, engineers constructed the first experimental soil-cement pavement. The 1.5-mile (2.4 km) stretch of road outside of Johnsonville, South Carolina, represented a significant development because it proved to be a long-sought means to stabilize local soils and provide good economic road base. More than 70 years later, soil-cement pavements are still giving good service at low maintenance costs and more than 100,000 miles (160,900 km) of highway have been built using soil-cement. Soil-cement, also referred to as cement-modified soil and cement-treated aggregate base, is a dense, highly compacted mixture of soil or roadway material, portland cement, and water. Soil material can be almost any combination of sand, silt, clay, gravel, or crushed stone. Granular soils are preferred, however, because they pulverize more easily and require less cement to achieve the required strength and durability. Laboratory tests are performed to determine the proper cement content, compaction, and water requirements of the soil material to be used. The soil-cement can be mixed in a central plant or mixed-in-place. Central plant mixed soil-cement requires a non-cohesive, usually granular material. For mixed-in-place operations, clay or granular soils can be mixed. For mixed-in-place construction, contractors follow four basic steps of soil-cement pavingspreading, mixing, compacting, and curing. When the roadway has been shaped to grade and the soil loosened, the proper quantity of cement is spread on the in-place soil. Mixing machines then thoroughly mix the cement and the required amount of water with the soil. The mixture is next tightly compacted with rollers, shaped to the proper contour and rolled again to achieve a smooth finish. Finally, the soil-cement is cured by spraying water and sealing with a bituminous mixture to supply and maintain the moisture needed for hydration. Soil-cement's advantages of high strength and durability combine with low first cost to make it an economical material. About 90 percent of all the material needed for soil-cement is already in place, keeping handling and hauling costs to a minimum. Like concrete, soil-cement continues to gain strength with age. Because soil-cement is compacted into a tight matrix during construction, the pavement does not deform under traffic or develop potholes as unbound aggregate bases. Soil-cement is capable of bridging over weak subgrade areas and is highly resistant to deterioration caused by seasonal moisture changes and freeze/thaw cycles. The use of soil-cement has expanded since its initial development in 1935. Soil-cement has been used primarily as a base course for roads, streets, highways, airports, and parking areas. More on soil-cement for paving. Soil-cement is also used as slope protection, ditch lining, and foundation stabilization. Soil-cement is used in every state in the United States as well as in all the Canadian

Tilt-up ConcreteConcrete Basics Home > Tilt-up Concrete Simplicity is the key to tilt-up concrete construction. Panels are cast as near to their final position as possiblethe most convenient casting base is most often the concrete floor slab of the building. Wood or steel edge forms are prepared and positioned on the casting base. Reinforcing steel, vapor seal, insulation, door and window frames, electric conduit, and outlet boxes are then positioned. Wall panels are cast on the horizontal base, cured, tilted into a vertical position and moved into place with a mobile crane. Tilt-up concrete is believed to have been developed in the early 1900s. Records indicate that Robert Aiken, an Illinois contractor, used tilt-up methods to build retaining walls and buildings in the Midwest before 1910. However, tilt-up construction did not increase significantly until after World War II when contractors recognized that tilt-up concrete provided a quick, efficient method of meeting the demand for buildings despite a shortage of labor and materials. Tilt-up concrete is an economically viable method for building individually designed reinforced concrete structures. The process requires few forms and makes efficient use of modern mechanical equipment. Ready mixed concrete for tilt-up is locally available and special labor skills are not required. Panels are formed and cast on the jobsite, and can be quickly tilted, lifted, set in place, and braced with the aid of high capacity mobile cranes. This process readily lends itself to mass production-panel lengths and heights are easily changed and adapted to meet any individually designed building. Tilt-up concrete also can be colored, textured, and shaped to meet almost any architectural demand using techniques such as paint, brick facing, curved surfaces, and exposed aggregate. Tilt-up construction is most frequently used for one-story commercial buildings such as warehouses or office buildings, though two-, three-, and four-story office buildings are becoming commonplace. Condominiums and hotels as tall as ten stories have been constructed with tilt-up concrete. However, tilt-up concrete is no longer limited to use in industrial and commercial buildings. In 1993, tilt-up concrete panels were used to construct trickling filter tanks at a wastewater treatment plant.

Gypsum Application through MachineThe old method to apply Gypsum manually took hours of labor and also had poor durability due to manual errors. Now with automation in this field, application through machine is gaining wide spread popularity as its not only faster but also cheaper in long run as very less labor is required.More over the results are much more stronger and durable as compared to old methods. This is the machine which is used to apply Gypsum and we at engineeringcivil.com are thankful to Mr. Chandrahas Amin for submitting this picture to us.

Filed under Construction Equipments | 2 CommentsDump Truck Construction EquipmentDump trucks or production trucks are those that are used for transporting loose material such as sand, dirt, and gravel for construction. The typical dump truck is equipped with a hydraulically operated open box bed hinged at the rear, with the front being able to be lifted up to allow the contents to fall out on the ground at the site of delivery.Dump trucks come in many different configurations with each one specified to accomplish a specific task in the construction chain.

Standard dump truckThe standard dump truck is a full truck chassis with the dump body mounted onto the frame. The dump body is raised by a hydraulic ram lift that is mounted forward of the front bulkhead, normally between the truck cab and the dump body. The standard dump truck also has one front axle, and one or more rear axles which normally has dual wheels on each side. The common configurations for standard dump trucks include the six wheeler and ten wheeler.Transfer dump truckFor the amount of noise made when transferring, the transfer dump truck is easy to recognize. Its a standard dump truck that pulls a separate trailer which can be loaded with sand, asphalt, gravel, dirt, etc. The B box or aggregate container on the trailer ispowered by an electric motor and rides on wheels and rolls off of the trailer and into the main dump box. The biggest advantage with this configuration is to maximize payload capacity without having to sacrifice the maneuverability of the short and nimble dump truck standards.Semi trailer end dump truckThe semi end dump truck is a tractor trailer combination where the trailer itself contains the hydraulic hoist. The average semi end dump truck has a 3 axle tractor that pulls a 2 axle semi trailer. The advantage to having a semi end dump truck is rapid unloading.Semi trailer bottom dump truckA bottom dump truck is a 3 axle tractor that pulls a 2 axle trailer with a clam shell type dump gate in the belly of the trailer. The biggest advantage of a semi bottom dump truck is the ability to lay material in a wind row. This type of truck is also maneuverable in reverse as well, unlike the double and triple trailer configurations.Double and triple trailerThe double and triple bottom dump trucks consist of a 2 axle tractor pulling a semi axle semi trailer and an additional trailer. These types of dump trucks allow the driver to lay material in wind rows without having to leave the cab or stop the truck. The biggest disadvantage is the difficulty in going in reverse.Side dump trucksSide dump trucks consist of a 3 axle trailer pulling a 2 axle semi trailer. It offers hydraulic rams that tilt the dump body onto the side, which spills the material to the left or right side of the trailer. The biggest advantages with these types of dump trucks are that they allow rapid unloading and carry more weight than other dump trucks.In addition to this, side dump trucks are almost impossible to tip over while dumping, unlike the semi end dump trucks which are very prone to being upset or tipped over. The length of these trucks impede maneuverability and limit versatility.Off road dump trucksOff road trucks resemble heavy construction equipment more than they do highway dump trucks. They are used strictly for off road mining and heavy dirt hauling jobs, such as excavation work. They are very big in size, and perfect for those time when you need to dig out roads and need something to haul the massive amounts of dirt to another location.This article was submitted by Er. AnkushFiled under Construction Equipments | 1 CommentFront Loader Construction EquipmentAlso known as a front end loader, bucket loader, scoop loader, or shovel, the front loader is a type of tractor that is normally wheeled and uses a wide square tilting bucket on the end of movable arms to lift and move material around.The loader assembly may be a removable attachment or permanently mounted on the vehicle. Often times, the bucket can be replaced with other devices or tools, such as forks or a hydraulically operated bucket.Larger style front loaders, such as the Caterpillar 950G or the Volvo L120E, normally have only a front bucket and are known as front loaders, where the small front loaders are often times equipped with a small backhoe as well and called backhoe loaders or loader backhoes.Loaders are primarily used for loading materials into trucks, laying pipe, clearing rubble, and also digging. Loaders arent the most efficient machines for digging, as they cant dig very deep below the level of their wheels, like the backhoe can.

The deep bucket on the front loader can normally store around 3 6 cubic meters of dirt, as the bucket capacity of the loader is much bigger than the bucket capacity of a backhoe loader. Loaders arent classified as excavating machinery, as their primary purpose is other than moving dirt.In construction areas, mainly when fixing roads in the middle of the city, front loaders are used to transport building materials such as pipe, bricks, metal bars, and digging tools. Front loaders are also very useful for snow removal as well, as you can use their bucket or as a snow plow. They can clear snow from the streets and highways, even parking lots.They will sometimes load the snow into dump trucks which will then haul it away.Unlike the bulldozer, most loaders are wheeled and not tracked. The wheels will provide better mobility and speed and wont damage paved roads near as much as tracks, although this will come at the cost of reduced traction. Unlike backhoes or tractors fitted with a steel bucket, large loaders dont use automotive steering mechanisms, as they instead steer by a hydraulically actuated pivot point set exactly between the front and rear axles.This is known as articulated steering and will allow the front axle to be solid, therefore allowing it to carry a heavier weight.Articulated steering will also give a reduced turn in radius for a given wheelbase. With thefront wheels and attachment rotating on the same axis, the operator is able to steer his load in an arc after positioning the machine, which can come in quite handy. The problem is that when the machine is twisted to one side and a heavy load is lifted high in the air, it has a bigger risk of turning over.This article was submitted by Er. AnkushFiled under Construction Equipments | 1 CommentForkliftSometimes called a forklift truck, the forklift is a powerful industrial truck that is used to lift and transport material by steel forks that are inserted under the load. Forklifts are commonly used to move loads and equipment that is stored on pallets. The forklift was developed in 1920, and has since become a valuable piece of equipment in many manufacturing and warehousing operations.Types of ForkliftsThe most common type of design with forklifts is the counter balance. Other types of designs include the reach truck and side loader, both of which are used in environments where the space is at a minimum.

Control and capabilityForklifts are available in many types and different load capacities. In the average warehouse setting,most forklifts have load capacities of around five tons. Along with the control to raise and lower the forks, you can also tilt the mast to compensate for the tendency of the load to angle the blades towards the ground and risk slipping it off the forks. The tilt will also provide a limited ability to operate on ground that isnt level.There are some variations that allow you to move the forks and backrest laterally, which allows easier placement of a load. In addition to this, there are some machines that offer hydraulic control to move the forks together or further apart, which removes the need for you to get out of the cab to manually adjust for a different size load.Another forklift variation that is sometimes used in manufacturing facilities, will utilize forklifts with a clamp attachment that you can open and close around a load, instead of having to use forks. Products such as boxes, cartons, etc., can be moved with the clamp attachment.SafetyForklifts are rated for loads at a specified maximum weight and a specified forward type center of gravity. All of this information is located on a nameplate that is provided by the manufacturer and the loads cannot exceed these specifications. One of the most important aspects of operating a forklift is the rear wheel steering. Even though this helps to increase maneuverability in tight cornering situations, it differs from the traditional experience of a driver with other wheeled vehicles as there is no caster action. Another critical aspect of the forklift is the instability. Both the forklift and the load must be considered a unit, with a varying center of gravity with every movement of the load.You must never negotiate a turn with a forklift at full speed with a raised load, as this can easily tip the forklift over.This article was submitted by Er. AnkushFiled under Construction Equipments | 0 CommentsVarious Types Of CranesA crane is a tower or derrick that is equipped with cables and pulleys that are used to lift and lower material. They are commonly used in the construction industry and in the manufacturing of heavy equipment. Cranes for construction are normally temporarystructures, either fixed to the ground or mounted on a purpose built vehicle.They can either be controlled from an operator in a cab that travels along with the crane, by a push button pendant control station, or by radio type controls. The crane operator is ultimately responsible for the safety of the crews and the crane.Mobile CranesThe most basic type of crane consists of a steel truss or telescopic boom mounted on a mobile platform, which could be a rail, wheeled, or even on a cat truck. The boom is hinged at the bottom and can be either raised or lowered by cables or hydraulic cylinders.

Telescopic CraneThis type of crane offers a boom that consists of a number of tubes fitted one inside of the other. A hydraulic mechanism extends or retracts the tubes to increase or decrease the length of the boom.

Tower CraneThe tower crane is a modern form of a balance crane. When fixed to the ground, tower cranes will often give the best combination of height and lifting capacity and are also used when constructing tall buildings.

Truck Mounted CraneCranes mounted on a rubber tire truck will provide great mobility. Outriggers that extend vertically or horizontally are used to level and stabilize the crane during hoisting.

Rough Terrain CraneA crane that is mounted on an undercarriage with four rubber tires, designed for operations off road. The outriggers extend vertically and horizontally to level and stabilize the crane when hoisting. These types of cranes are single engine machines where the same engine is used for powering the undercarriage as it is for powering the crane. In these types of cranes, the engine is normally mounted in the undercarriage rather thanin the upper portion.

Loader CraneA loader crane is a hydraulically powered articulated arm fitted to a trailer, used to load equipment onto a trailer. The numerous sections can be folded into a small space when the crane isnt in use.

Overhead CraneAlso refered to as a suspended crane, this type is normally used in a factory, with some of them being able to lift very heavy loads. The hoist is set on a trolley which will move in one direction along one or two beams, which move at angles to that direction along elevated or ground level tracks, often mounted along the side of an assembly area.

In the excavation world, cranes are used to move equipment or machinery. Cranes can quickly and easily move machinery into trenches or down steep hills, or even pipe. There are many types of cranes available, serving everything from excavation to road work.Cranes are also beneficial to building bridges or construction. For many years, cranes have proven to be an asset to the industry of construction and excavating. Crane operators make really good money, no matter what type of crane they are operating.


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