Concrete mixer

Last updated

Concrete mixer GH-SA.jpg
Concrete mixer

A concrete mixer (also cement mixer) is a device that homogeneously combines cement, aggregate (e.g. sand or gravel), and water to form concrete. A typical concrete mixer uses a revolving drum to mix the components. For smaller volume works, portable concrete mixers are often used so that the concrete can be made at the construction site, giving the workers ample time to use the concrete before it hardens. An alternative to a machine is mixing concrete by hand. This is usually done in a wheelbarrow; however, several companies have recently begun to sell modified tarps for this purpose.

Contents

The concrete mixer was invented by Columbus, Ohio industrialist Gebhardt Jaeger. [1]

History

One of the first concrete mixers ever was developed in 1900 by T.L. Smith in Milwaukee. The mixer already exhibited the still common basic construction with a tiltable conical drum (as double cone at that time) with blades. On February 9, 1904, the first portable concrete mixer was patented by Richard Bodlaender, an inventor from Breslau, Germany. [2] This concrete mixer was horse-drawn and called 'Mortar Mixer'. It worked by replacing the front wheels with a large drum that held large paddles for mixing the cement. [3] 1925, at least two mixers, built 25 years ago, were still in use (serial numbers 37 and 82). The Smith Mascot in essence has the same construction of the small mixers used today. In the 1920s, the T.L. Smith Company in Milwaukee built the world's largest concrete mixers. Mixers of this company were used e. g. for the construction of the Wilson Dam (six 2-yard and two 4-yard mixers, at the time the largest single installation of the largest concrete mixers in the world), the first stadium of the Ohio State University and the Exchequer Dam. [4] Roscoe Lee was granted a patent in 1934 for his transit concrete mixer design. This design made it possible for new trucks to be turned into concrete mixers by using a crane to put a drum on the back of the truck. [3] It was less expensive than a cement truck dedicated to only carrying cement and allowed the trucks used to continue to be adapted for other things. [2] Concrete mixers have continued to advance. Recently, research detailing a forward simulation model of an energy-saving concrete mixer using hydraulic technology was released based on Matlab/Simulink technology. [5]

Industrial mixers

Today's market increasingly requires consistent homogeneity and short mixing times for the industrial production of ready-mix concrete, and more so for precast/prestressed concrete. This has resulted in refinement of mixing technologies for concrete production. Different styles of stationary mixers have been developed, each with its own inherent strengths targeting different parts of the concrete production market. The most common mixers used today fall into three categories:

Twin shaft concrete mixer for a concrete plant Twin shaft concrete mixer.JPG
Twin shaft concrete mixer for a concrete plant

All the mixer styles have their own inherent strengths and weaknesses, and all are used throughout the world to varying degrees of popularity.

Trucks and trailers

Concrete mixing transport trucks

Operation diagram of a truck mixer Operation of a truck mixer.gif
Operation diagram of a truck mixer

Special concrete transport trucks (in-transit mixers) are made to mix concrete and transport it to the construction site. They can be charged with dry materials and water, with the mixing occurring during transport. They can also be loaded from a "central mix" plant; with this process the material has already been mixed prior to loading. The concrete mixing transport truck maintains the material's liquid state through agitation, or turning of the drum, until delivery. These trucks have an interior turbine that pushes the mixed concrete up against gravity inside the drum. The interior of the drum on a concrete mixing truck is fitted with a spiral blade. In one rotational direction, the concrete is pushed deeper into the drum. This is the direction the drum is rotated while the concrete is being transported to the building site. This is known as "charging" the mixer. When the drum rotates in the other direction, the Archimedes' screw-type arrangement "discharges", or forces the concrete out of the drum. From there it may go onto chutes to guide the viscous concrete directly to the job site. If the truck cannot get close enough to the site to use the chutes, the concrete may be discharged into a concrete pump, connected to a flexible hose, or onto a conveyor belt which can be extended some distance (typically ten or more metres). A pump provides the means to move the material to precise locations, multi-floor buildings, and other distance-prohibitive locations. Buckets suspended from cranes are also used to place the concrete. The drum is traditionally made of steel but on some newer trucks, fibreglass has been used as a weight reduction measure. Most cement trucks weigh a substantial amount empty, meaning they have very heavy tare weights. United States weight laws under the Federal Bridge Formula (FBF) require a three-axle ready mixed concrete truck to weigh 48,000 pounds (22,000 kg) or under. This leaves only 18,000 pounds (8,200 kg) for concrete to be carried, as 30,000 pounds (14,000 kg) is the tare weight of the truck. [7]

Silvi Materials front discharge concrete mixer truck with three lift axles including one tag axle. This concrete truck was manufactured by Oshkosh Inc. Silvi concrete mixer truck.jpg
Silvi Materials front discharge concrete mixer truck with three lift axles including one tag axle. This concrete truck was manufactured by Oshkosh Inc.
This Kayaba Rocket concrete mixer delivers concrete in Japan CementMixerM2439.jpg
This Kayaba Rocket concrete mixer delivers concrete in Japan

"Rear discharge" trucks require both a driver and a "chuteman" to guide the truck and chute back and forth to place concrete in the manner suitable to the contractor. Newer "front discharge" trucks have controls inside the cab of the truck to allow the driver to move the chute in all directions. The first front discharge mixer, patented in 1974, was designed and built by Royal W. Sims of Holladay, Utah, United States.

Concrete mixers are equipped with two or more axles. Four-, five- and six-axle trucks are the most common, with the number being determined by the load and local legislation governing allowable loads on the road.

The axles are necessary to distribute the load evenly, allow operation on weight restricted roads, and reduce wear and tear on normal roads. A two- or three-axle truck during the winter when road weight limits are reduced has no usable payload in many jurisdictions. Other areas may require expensive permits to operate.

Additional axles other than those used for steering ("steers") or drivetrain ("drives") may be installed between the steers and drives, or behind the drives. Mixers commonly have multiple steering axles as well, which generally result in very large turning radii. To facilitate maneuvering, the additional axles may be "lift axles", which allows them to be raised off the ground so that they do not scrub (get dragged sideways across the ground) on tight turns, or increase the vehicle's turning radius. Axles installed behind the drives are known as "tag axles" or "booster axles", and are often equipped to turn opposite to the steering axle to reduce scrubbing and automatically lift when the truck is put into a reverse gear.

Tractor trailer combination mixers where the mixer is installed on a trailer instead of a truck chassis are used in some jurisdictions, such as the province of Quebec where even six-axle trucks would have trouble carrying a useful load.[ clarification needed ]

Concrete mixers generally do not travel far from their plant, as the concrete begins to set as soon as it is in the truck. Many contractors require that the concrete be in place within 90 minutes after loading. Some trucks in dry climates are equipped with the capability of adding water in spray form during the trip, especially on long trips. If the truck breaks down or for some other reason the concrete hardens in the truck, workers may need to enter the barrel with jackhammers [8] or the company has to scrap the entire drum.[ citation needed ] [9]

Stephen Stepanian filed a patent application for the first truck mixer in 1916. [10]

Trucks weigh 9,100 to 14,000 kilograms (20,000 to 30,000 lb), and can carry roughly 20,000 kilograms (40,000 lb) of concrete although many varying sizes of mixer truck are currently in use. The most common truck capacity is 10 cubic yards (7.6 m3).

Most concrete mixers in the UK are limited to a speed of 90 kilometres per hour (56 mph).

Concrete mixer trailers

0.75 m3 (1 cubic yard) cart-away mixing trailer CartAwayMixingTrailer.JPG
0.75 m³ (1 cubic yard) cart-away mixing trailer

A variant of standard concrete transportation is the concrete (or, cement) mixing trailer. These small versions of transit-mix trucks are used to supply short loads of concrete. They have a concrete mixing drum with a capacity of between 0.76 and 1.34 cubic metres (1 and 1.75 cu yd). Cart-aways are usually pulled behind a pick-up truck and batched from smaller batching systems. The mixing trailer system is popular with rental yards and building material locations, which use them to supply ready-mix to their regular customer base.

Metered concrete trucks

Metered concrete truck Metered concrete truck.jpg
Metered concrete truck

Metered concrete trucks or volumetric mobile mixers contain concrete ingredient materials and water to be mixed on the truck at the job site to make and deliver concrete according to the amount needed.

On-site and portable concrete mixers

This portable concrete/mortar mixer has wheels and a towing tongue so that it can be towed by a motor vehicle and moved around the worksite by hand, and its rotation is powered by mains electricity. The lever allows the concrete/mortar to be tipped into a wheelbarrow. Cement mixer2.jpg
This portable concrete/mortar mixer has wheels and a towing tongue so that it can be towed by a motor vehicle and moved around the worksite by hand, and its rotation is powered by mains electricity. The lever allows the concrete/mortar to be tipped into a wheelbarrow.
An outdated model of a small-scale concrete mixer. These older mixers are heavy and can not be moved as easily. They are still self-powered with electric motors. ConcreteMixer4.JPG
An outdated model of a small-scale concrete mixer. These older mixers are heavy and can not be moved as easily. They are still self-powered with electric motors.

For smaller jobs, such as residential repairs, renovations, or hobbyist-scale projects, many cubic yards of concrete are usually not required. Bagged cement is readily available in small-batch sizes, and aggregate and water are easily obtained in small quantities for the small work site. To service this small-batch concrete market, many types of small portable concrete mixers are available.

A typical portable concrete mixer uses a small revolving drum to mix the components. For smaller jobs the concrete made at the construction site has no time lost in transport, giving the workers ample time to use the concrete before it hardens.

Portable concrete mixers may be powered by gasoline engines, although it is more common that they are powered by electric motors using standard mains current.

These concrete mixers are further divided based on their loading mechanism. Cement, sand and other aggregates are loaded in a hydraulically operated hopper and then poured into the mixing drum for final mixing. They can be unloaded by tilting the drum. In hand-feed concrete mixers, cement, sand and other aggregates are directly added to the mixing drum manually. Both of these types of concrete mixers are popular in construction activities in Africa, some Middle Eastern countries and in the Indian subcontinent.

Self-loading concrete mixers

Two concrete mixers (Arutua) Arutua - Laurent Seignobos 3.jpg
Two concrete mixers (Arutua)

Self-loading concrete mixers are unique machines designed to batch, mix and transport concrete. They consist of a rotating drum mounted on an operator-driven cab-mounted chassis frame fitted with a loading bucket.

The operator of the self-loading concrete mixers batches and introduces the ingredients required for mixing concrete (cement, stone aggregates etc.) into the drum using the loading bucket. The drum is usually reversible type, tilt type or a combination of both. A predetermined volume of water is discharged to the drum via a water dispensing unit. The mixture is rotated at mixing speeds within the drum until the concrete discharges via a fitted chute.

Self-loading concrete mixers are suited for construction sites where concrete batching plants are unavailable, underfoot conditions are not suited for concrete transit mixer trucks or labor availability is scarce or constrained. Applications include urban and rural construction, concrete pavement maintenance, bridge and tunnel construction, township-level highways construction, foundation construction, national defense facilities, construction of high-speed railways, etc.

Operating code

Operating concrete mixers correctly is one of the biggest safety issues in construction zones. Workers whose tasks are related to concrete processing currently[ when? ] number more than 250,000. Over 10 percent of those workers, 28,000, experienced a job-related injury or illness, and 42 died in just one year.[ when? ][ where? ] [11] [12] [13]

See also

Related Research Articles

<span class="mw-page-title-main">Concrete</span> Composite construction material

Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined.

<span class="mw-page-title-main">Truck</span> Commercial or utilitarian motor vehicle

A truck or lorry is a motor vehicle designed to transport freight, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction, with a cabin that is independent of the payload portion of the vehicle. Smaller varieties may be mechanically similar to some automobiles. Commercial trucks can be very large and powerful and may be configured to be mounted with specialized equipment, such as in the case of refuse trucks, fire trucks, concrete mixers, and suction excavators. In American English, a commercial vehicle without a trailer or other articulation is formally a "straight truck" while one designed specifically to pull a trailer is not a truck but a "tractor".

<span class="mw-page-title-main">Road surface</span> Road covered with durable surface material

A road surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, macadam, hoggin, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled (hard-surfaced) and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently used roads. Unmetalled roads, also known as gravel roads or dirt roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic.

<span class="mw-page-title-main">Asphalt concrete</span> Composite material used for paving

Asphalt concrete is a composite material commonly used to surface roads, parking lots, airports, and the core of embankment dams. Asphalt mixtures have been used in pavement construction since the beginning of the twentieth century. It consists of mineral aggregate bound together with bitumen, laid in layers, and compacted.

<span class="mw-page-title-main">Heavy equipment</span> Vehicles designed for executing construction tasks

Heavy equipment, heavy machinery, earthmovers, construction vehicles, or construction equipment, refers to heavy-duty vehicles specially designed to execute construction tasks, most frequently involving earthwork operations or other large construction tasks. Heavy equipment usually comprises five equipment systems: the implement, traction, structure, power train, and control/information.

<span class="mw-page-title-main">Dump truck</span> Truck which can tip its bed, dumping its contents

A dump truck, known also as a dumping truck, dump trailer, dumper trailer, dump lorry or dumper lorry or a dumper for short, is used for transporting materials for construction as well as coal. A typical dump truck is equipped with an open-box bed, which is hinged at the rear and equipped with hydraulic rams to lift the front, allowing the material in the bed to be deposited ("dumped") on the ground behind the truck at the site of delivery. In the UK, Australia, South Africa and India the term applies to off-road construction plants only and the road vehicle is known as a tip lorry, tipper lorry, tipper truck, tip truck, tip trailer or tipper trailer or simply a tipper.

<span class="mw-page-title-main">Dumper</span> Truck designed for carrying bulk material

A dumper or dumper truck or dump truck is a truck designed for carrying bulk material, often on building sites. A dumper has a body which tilts or opens at the back for unloading and is usually an open 4-wheeled vehicle with the load skip in front of the driver. The skip can tip to dump the load; this is where the name "dumper" comes from. They are normally diesel powered. A towing eye is fitted for secondary use as a site tractor. Dumpers with rubber tracks are used in special circumstances and provide a more even distribution of weight compared to tires. Continuous tracks allow the operator to carry heavier payload on slick, snowy, or muddy surfaces, and are popular in some countries. Rubber track dumpers offer even weight distribution for transporting heavy payloads over challenging terrains like mud or snow, popular in certain regions. Roll Off Dumpsters, contrastingly, are large, stationary containers designed for substantial waste management, easily loaded and transported by specialized trucks.

<span class="mw-page-title-main">Ready-mix concrete</span> Concrete that is manufactured in a batch plant, according to a set engineered mix design

Ready-mix concrete (RMC) is concrete that is manufactured in a batch plant, according to each specific job requirement, then delivered to the job site "ready to use".

<span class="mw-page-title-main">Silo</span> Structure for storing crops

A silo is a structure for storing bulk materials.

<span class="mw-page-title-main">Concrete recycling</span> Re-use of rubble from demolished concrete structures

Concrete recycling is the use of rubble from demolished concrete structures. Recycling is cheaper and more ecological than trucking rubble to a landfill. Crushed rubble can be used for road gravel, revetments, retaining walls, landscaping gravel, or raw material for new concrete. Large pieces can be used as bricks or slabs, or incorporated with new concrete into structures, a material called urbanite.

<span class="mw-page-title-main">Palletized Load System</span> 10×10 heavy tactical truck

The Palletized Load System (PLS) is a truck-based logistics system that entered service in the United States Army in 1993. It performs long and short distance freight transport, unit resupply, and other missions in the tactical environment to support modernized and highly mobile combat units. It provides rapid movement of combat configured loads of ammunition and all classes of supply, shelters and intermodal containers. It is similar to systems such as the British Demountable Rack Offload and Pickup System (DROPS).

<span class="mw-page-title-main">Concrete pump</span> Machine used for transferring liquid concrete by pumping

A concrete pump is a machine used for transferring liquid concrete by pumping. There are different types of concrete pumps.

<span class="mw-page-title-main">Volumetric concrete mixer</span> Type of concrete mixer

A volumetric concrete mixer is a concrete mixer mounted on a truck or trailer that contains separate compartments for sand, stone, cement and water.

<span class="mw-page-title-main">Articulated hauler</span>

An articulated hauler, articulated dump truck (ADT), or sometimes a dump hauler, is a very large heavy-duty type of dump truck used to transport loads over rough terrain, and occasionally on public roads. The vehicle usually has all-wheel drive and consists of two basic units: the front section, generally called the tractor, and the rear section that contains the dump body, called the hauler or trailer section. Steering is made by pivoting the front in relation to the back by hydraulic rams. This way, all wheels follow the same path, making it an excellent off-road vehicle.

<span class="mw-page-title-main">Concrete plant</span> Equipment that combines various ingredients to form concrete

A concrete plant, also known as a batch plant or batching plant or a concrete batching plant, is equipment that combines various ingredients to form concrete. Some of these inputs include water, air, admixtures, sand, aggregate, fly ash, silica fume, slag, and cement. A concrete plant can have a variety of parts and accessories, including: mixers, cement batchers, aggregate batchers, conveyors, radial stackers, aggregate bins, cement bins, heaters, chillers, cement silos, batch plant controls, and dust collectors.

<span class="mw-page-title-main">Open wagon</span> Railway wagons for transportation of bulk goods

Open wagons form a large group of railway goods wagons designed primarily for the transportation of bulk goods that are not moisture-retentive and can usually be tipped, dumped or shovelled. The International Union of Railways (UIC) distinguishes between ordinary wagons and special wagons (F/6). Open wagons often form a significant part of a railway company's goods wagon fleet; for example, forming just under 40% of the Deutsche Bahn's total goods wagon stock in Germany.

<span class="mw-page-title-main">Types of concrete</span> Building material consisting of aggregates cemented by a binder

Concrete is produced in a variety of compositions, finishes and performance characteristics to meet a wide range of needs.

<span class="mw-page-title-main">Reversing drum mixer</span>

A reversing drum mixer is a type of concrete mixer that produces concrete in single batches. The entire drum rotates around its axis as materials are loaded through a charge chute at one end of the drum and exit through a discharge chute at the opposite end of the drum.

<span class="mw-page-title-main">Stephen Stepanian</span>

Stephen Stepanian was an Armenian American inventor and owner of numerous patents including the Elevator and Conveyor, Compound Tool, and the Wrench. He is also accredited as the inventor of a self-discharging motorized transit mixer that was the predecessor of the concrete mixer truck. Stepanian is often called the "father of the ready-mix concrete industry."

<span class="mw-page-title-main">Mack Granite</span>

The Mack Granite is a series of heavy duty and severe service trucks built by Mack Trucks. It has a long, low-profile hood and a high-visibility cab. Designed as straight trucks for local construction, waste removal, and other vocational jobs, it is also available as a semi-tractor. Introduced in 2001, it remains in production as of today.

References

  1. Hunker, Henry L. (2000). Columbus, Ohio: A Personal Geography . Ohio State University Press. pp.  196. ISBN   978-0-8142-0857-1.
  2. 1 2 "Who Invented the Portable Mixer Anyway?". Concrete Construction. 1 March 2000. Retrieved 4 December 2023.
  3. 1 2 www.plant-planet.co.uk, 12asd (25 August 2021). "Brief History of Concrete Mixer Trucks" . Retrieved 4 December 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  4. The T. L. Smith Company, ed. (1927). Smith concrete mixers and pavers. Catalogue no. 526. Milwaukee. Retrieved 9 October 2019.{{cite book}}: CS1 maint: location missing publisher (link)
  5. Jinxiang Zhao; Xinhui Liu; Zhenyang Xin; Yanhong Han (2009). "Research on the energy-saving technology of concrete mixer truck". 2009 4th IEEE Conference on Industrial Electronics and Applications. pp. 3551–3554. doi:10.1109/ICIEA.2009.5138867. ISBN   978-1-4244-2799-4. S2CID   16722402 . Retrieved 4 December 2023.
  6. "Photos planetary mixer". Rometa Editor.
  7. Tyrell, Andrew (4 December 2023). "Truck Weights" (PDF). 2019 Cement & Concrete Fly-In. Retrieved 4 December 2023.
  8. "Control Technology for Ready-mix Truck Drum Cleaning" (PDF). U.S. Department of Health and Human Services. 31 May 2001. Retrieved 21 October 2013.
  9. Basham, Kim (1 April 1996). "Cleaning out fresh and hardened concrete". Concrete Construction. Retrieved 12 September 2023.
  10. Portland Cement Association: History of Ready Mixed Concrete industry site
  11. BAYNES, CHRIS (13 February 2017). "Horror as worker in mid 20s killed in 'concrete mixer accident' on building site". Daily Mirror.
  12. Giovanny, Fausto (1 March 2017). "Man killed while cleaning cement mixer, cops say". New Jersey Local News.
  13. Department of labor. "Workers Safety Series:Concrete Manufacturing". osha.org.