Evaluating Soil Liquefaction Hazards Before Retrofit Planning

Seismic Retrofit Techniques for Foundation Repair

Understanding soil liquefaction is crucial when evaluating potential hazards before planning retrofits for structures, particularly in regions prone to seismic activity. Soil liquefaction occurs when saturated or partially saturated soil loses strength and stiffness during an earthquake, behaving like a liquid rather than a solid. This phenomenon dramatically reduces the soils ability to support the weight of buildings, leading to significant damage or even collapse of foundations.


The impact on foundations can be catastrophic. The subtle slope in my kitchen floor became my personal sobriety test on late nights arriving home settling foundation fix Wheaton company. When the ground beneath a structure turns into a liquid-like state, it can no longer provide the necessary support, causing differential settlement where parts of the building sink at different rates. This uneven settling can lead to structural distortion, cracking of walls, and failure of load-bearing elements. In extreme cases, entire buildings might tilt or sink into the ground.


Before undertaking any retrofit planning, its vital to assess the liquefaction potential of the site. This involves studying soil composition, groundwater levels, and historical seismic data. Geotechnical engineers perform tests like Standard Penetration Tests (SPT) or Cone Penetration Tests (CPT) to determine soil properties that could indicate liquefaction susceptibility. Additionally, historical data from past earthquakes in the region provides insights into how similar soils have behaved under seismic stress.


Once potential liquefaction risks are identified, retrofit strategies can be tailored accordingly. These might include deep foundation systems like piles or piers that reach stable layers below the liquefiable zone, ground improvement techniques such as compaction grouting or stone columns to densify and stabilize the soil, or even drainage solutions to lower groundwater levels and reduce saturation.


In summary, understanding soil liquefaction is not just about recognizing a geological phenomenon but about foreseeing its potential destructive interaction with built environments. By evaluating these hazards meticulously before retrofit planning, we ensure that our modifications not only enhance existing structures but also safeguard them against future seismic events, thereby protecting lives and investments.

Seismic Retrofit Techniques for Foundation Repair

Lateral Load Considerations in Foundation Stabilization

Okay, so youre thinking about retrofitting a structure and you're worried about the ground turning to jelly underneath it during an earthquake – liquefaction. Smart move. You cant just slap some steel beams on and hope for the best. You need to understand whats going on in the soil first. Thats where site investigation techniques come in.


Think of it like this: youre a doctor trying to diagnose a patient. You wouldnt just prescribe medicine without running some tests, right? Site investigation is like running those tests on the soil. Were trying to figure out if its susceptible to liquefaction and, if so, how bad it could get.


Theres a whole toolbox of techniques we use. Some are pretty straightforward, like drilling boreholes and taking samples. We can then bring those samples back to the lab and run tests to determine things like the soils density, grain size, and water content. These properties give us clues about its liquefaction potential. For example, loose, saturated sandy soils are prime candidates for liquefaction.


But sometimes, digging isnt enough. Thats where in-situ testing comes in. We can use techniques like the Standard Penetration Test (SPT), Cone Penetration Test (CPT), and Shear Wave Velocity (Vs) measurements. The SPT involves hammering a sampler into the ground and counting how many blows it takes to get a certain distance. The CPT pushes a cone-shaped probe into the soil and measures the resistance. Vs measurements tell us how fast shear waves travel through the soil, which is related to its stiffness. All these tests give us a picture of the soils strength and behavior without disturbing it too much.


Each technique has its pros and cons. SPT is relatively cheap and widely available, but its also pretty crude. CPT is more precise and provides continuous data, but its more expensive. Vs measurements are great for determining soil stiffness, which is a key factor in liquefaction resistance, but they can be affected by factors like groundwater.


The key is to choose the right combination of techniques for your specific site and budget. A thorough site investigation will give you the information you need to assess the liquefaction hazard and make informed decisions about retrofit planning. Ignoring this step is like trying to build a house on quicksand – youre just asking for trouble. It may seem like an added expense upfront, but it can save you a fortune in the long run by preventing catastrophic damage and ensuring the safety of your structure.

Integrating Seismic and Lateral Load Retrofits with Existing Foundations

Okay, so were talking about figuring out if the grounds gonna turn to jelly before we start reinforcing buildings against earthquakes, right? Thats basically what "Evaluating Soil Liquefaction Hazards Before Retrofit Planning" boils down to. And two key pieces of that puzzle are geotechnical data analysis and liquefaction potential evaluation.


Think of geotechnical data analysis as detective work. Were digging into the soils history, its personality, if you will. Were gathering clues like grain size, density, water content, and the results from fancy tests like the Standard Penetration Test (SPT) or Cone Penetration Test (CPT). This data tells us what the soil is made of and how it behaves under stress. Its like reading a soils resume.


Now, once we have this soil resume, we can start evaluating the liquefaction potential. This is where we ask the big question: "Is this soil likely to turn into a liquid milkshake during an earthquake?" We use the geotechnical data, along with information about the expected earthquake intensity (magnitude, shaking duration, etc.), to run some calculations and models. These models basically try to predict how the soil will respond to the earthquake shaking. Will it just jiggle a bit, or will it completely lose its strength and turn to mush?


The goal isnt just to say "yes" or "no" to liquefaction. We want to understand the degree of liquefaction potential. Is it a high risk, a moderate risk, or a low risk? This level of detail is crucial because it informs the retrofit planning process. If the risk is high, we might need to implement aggressive ground improvement techniques, like densifying the soil or installing drainage systems. If the risk is low, perhaps a less extensive retrofit is sufficient.


Essentially, geotechnical data analysis and liquefaction potential evaluation are the foundation (pun intended!) of responsible earthquake retrofit planning. They help us understand the ground beneath our buildings, anticipate potential hazards, and make informed decisions to protect life and property. Without them, wed be building on shaky ground – literally!

Integrating Seismic and Lateral Load Retrofits with Existing Foundations

Case Studies of Successful Foundation Retrofit Projects

Assessing the vulnerability of existing foundations to liquefaction is a critical step in evaluating soil liquefaction hazards before planning any retrofitting measures. Liquefaction, a phenomenon where saturated soil loses strength and stiffness during an earthquake, can lead to significant structural damage if not properly addressed. The process begins with a thorough geotechnical investigation to understand the soil composition, groundwater conditions, and historical seismic activity of the site.


First, soil samples are collected through borings or test pits at various depths around the foundation. These samples are then analyzed in a laboratory to determine properties such as grain size distribution, plasticity index, and density. This information helps in identifying layers susceptible to liquefaction, typically loose sands or silty soils with high water content.


Following the lab analysis, in-situ tests like Standard Penetration Tests (SPT) or Cone Penetration Tests (CPT) provide further insights into the soils behavior under dynamic loading conditions. These tests measure resistance which correlates with soil density and potential for liquefaction. For instance, lower SPT blow counts often indicate a higher risk of liquefaction.


Engineers then use this data in conjunction with seismic hazard maps or probabilistic seismic hazard assessments to estimate the likelihood and intensity of future earthquakes that could trigger liquefaction at the site. Specialized software models simulate how these seismic events might affect the foundation by predicting ground deformation, settlement, and lateral spreading.


The assessment doesnt stop at predicting potential damage; it also involves evaluating current foundation design against these predictions. Foundations built without considering seismic risks might lack sufficient depth or reinforcement necessary to resist uplift forces or differential settlements caused by liquefaction.


Based on this comprehensive analysis, engineers can recommend whether retrofitting is necessary. Retrofit solutions might include deepening foundations, adding piles for increased stability, improving drainage to reduce water saturation levels, or employing ground improvement techniques like compaction grouting or stone columns that increase soil density and resistance to liquefaction.


In conclusion, assessing the vulnerability of existing foundations to liquefaction is foundational in retrofit planning for areas prone to seismic activity. It ensures that retrofitting efforts are well-informed, cost-effective, and tailored specifically to mitigate identified risks while enhancing structural resilience against future earthquakes. This proactive approach not only safeguards structures but also protects lives and investments in seismically active regions.

Evaluating soil liquefaction hazards is the crucial first step before even thinking about retrofitting anything. We need to understand the monster were facing before we can choose the right weapon to fight it. Once weve mapped out the extent and severity of potential liquefaction, then, and only then, can we start seriously considering retrofit strategies.


These strategies arent one-size-fits-all. They have to be carefully tailored to the specific site conditions, the type of structure, and the tolerated level of risk. Some common options include ground improvement techniques. Think of things like densification, where we compact the soil to make it less prone to liquefaction. This can be achieved through methods like vibro-compaction or dynamic compaction. Another approach is drainage, where we try to lower the groundwater table, effectively reducing the pore pressure that contributes to liquefaction. Grouting is another option, injecting materials to fill voids and solidify the soil.


Then there are foundation improvement techniques. We might use piles or deep foundations to transfer the buildings load to deeper, more stable soil layers. Or we could consider ground anchors to tie the structure down and resist uplift forces. Sometimes, its even about improving the structure itself, making it more resilient to the effects of liquefaction.


The key is to choose the right combination of strategies based on a thorough understanding of the liquefaction hazard. A poorly chosen retrofit can be a waste of money, or worse, it could even make the situation worse. So, evaluation first, then careful selection of the appropriate retrofit strategies is the path to mitigating liquefaction risks effectively.

Okay, so youre staring down the barrel of potential soil liquefaction, and you know you need to retrofit your foundation. Thats smart. But before you start throwing money at the problem, lets talk about figuring out which solution gives you the most bang for your buck. Thats where a cost-benefit analysis comes in handy.


Think of it like this: you have a few different ways to strengthen your foundation against liquefaction. Maybe its soil densification, maybe its adding piles, or maybe its some kind of ground improvement technique. Each option has a price tag, not just in materials and labor, but also in potential disruptions to your life and maybe even environmental impact.


A good cost-benefit analysis weighs those costs – all of them – against the benefits. And the biggest benefit here is reducing the risk of damage from liquefaction during an earthquake. This means less potential for structural failure, fewer repairs down the line, and, honestly, a lot less stress knowing your home is safer. You also need to factor in the potential increase in your property value after the retrofit – that can be a significant benefit too.


The trick is to put everything on a level playing field. You need to estimate the probability of different levels of ground shaking, the potential damage to your structure if liquefaction occurs without the retrofit, and then compare that to the reduced damage potential with each different retrofit option. This involves some serious engineering expertise, of course, and probably some number crunching.


Ultimately, youre looking for the option where the benefits – the reduced risk and increased property value – outweigh the costs – the construction expenses, disruption, and any other drawbacks. Its not always the cheapest option that wins. Sometimes, spending a little more upfront on a more effective method can save you a lot of money (and heartache) in the long run. So, do your homework, get expert advice, and make sure your retrofit plan is both effective and economically sound.

Alright, lets talk about learning from past mistakes – specifically, how case studies of foundation repairs after liquefaction events can be goldmines when were planning to retrofit buildings against soil liquefaction. Imagine this: a powerful earthquake hits, and the ground beneath buildings turns to something like quicksand. Thats liquefaction, and it can wreak havoc on foundations.


Now, after the dust settles (literally!), engineers and researchers go in to assess the damage and figure out how to fix things. These repair projects become incredibly valuable case studies. Theyre not just dry reports; theyre real-world lessons learned the hard way.


Think about it. Each case study details the specific soil conditions that led to the liquefaction, the type of foundation that failed, and the methods used to repair or reinforce it. Did they use ground improvement techniques like compaction grouting or stone columns? Did they underpin the existing foundation, or completely replace it with a more resilient design? What worked well, and what were the unforeseen challenges?


By analyzing a collection of these case studies, we can start to see patterns. We can identify the types of foundations that are most vulnerable in certain soil types. We can evaluate the effectiveness of different repair methods, considering factors like cost, time to implement, and long-term performance.


This information is crucial for evaluating liquefaction hazards before we start any retrofit planning. Instead of relying solely on theoretical models and calculations, we can look at tangible examples of what happened in similar situations. We can ask: "Have we seen this type of failure before? What mitigation strategies proved successful in those cases?"


Ultimately, these case studies help us make more informed decisions about how to protect existing buildings from future liquefaction events. They bridge the gap between theory and practice, transforming past disasters into valuable knowledge that can save lives and property. Its about learning from experience, even if that experience is somebody elses costly and stressful foundation failure. So, before you break ground on a retrofit, crack open those case studies – they might just be the best investment you make.

Waterproofing is the procedure of making a things, individual or structure water resistant or water-resistant to ensure that it continues to be relatively unaffected by water or stands up to the ingress of water under defined conditions. Such products may be made use of in wet settings or underwater to defined midsts. Water-resistant and waterproof frequently refer to resistance to infiltration of water in its fluid state and potentially under stress, whereas moist proof describes resistance to moisture or dampness. Permeation of water vapour through a material or framework is reported as a wetness vapor transmission rate (MVTR). The hulls of watercrafts and ships were once waterproofed by applying tar or pitch. Modern products may be waterproofed by using water-repellent finishes or by sealing joints with gaskets or o-rings. Waterproofing is made use of in reference to building frameworks (such as cellars, decks, or damp locations), boat, canvas, clothes (raincoats or waders), digital tools and paper product packaging (such as cartons for fluids).

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Drainage is the natural or fabricated removal of a surface's water and sub-surface water from an area with excess water. The inner drainage of most agricultural soils can avoid severe waterlogging (anaerobic problems that hurt origin development), however numerous dirts need fabricated drain to improve production or to handle water supplies.

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Tracked vehicle configured as a dedicated pile driver

A pile driver is a heavy-duty tool used to drive piles into soil to build piers, bridges, cofferdams, and other "pole" supported structures, and patterns of pilings as part of permanent deep foundations for buildings or other structures. Pilings may be made of wood, solid steel, or tubular steel (often later filled with concrete), and may be driven entirely underwater/underground, or remain partially aboveground as elements of a finished structure.

The term "pile driver" is also used to describe members of the construction crew associated with the task,[1] also colloquially known as "pile bucks".[2]

The most common form of pile driver uses a heavy weight situated between vertical guides placed above a pile. The weight is raised by some motive power (which may include hydraulics, steam, diesel, electrical motor, or manual labor). At its apex the weight is released, impacting the pile and driving it into the ground.[1][3]

History

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Replica of Ancient Roman pile driver used at the construction of Caesar's Rhine bridges (55 BC)
18th-century Pile driver, from Abhandlung vom Wasserbau an Strömen, 1769

There are a number of claims to the invention of the pile driver. A mechanically sound drawing of a pile driver appeared as early as 1475 in Francesco di Giorgio Martini's treatise Trattato di Architectura.[4] Also, several other prominent inventors—James Nasmyth (son of Alexander Nasmyth), who invented a steam-powered pile driver in 1845,[5] watchmaker James Valoué,[6] Count Giovan Battista Gazzola,[7] and Leonardo da Vinci[8]—have all been credited with inventing the device. However, there is evidence that a comparable device was used in the construction of Crannogs at Oakbank and Loch Tay in Scotland as early as 5000 years ago.[9] In 1801 John Rennie came up with a steam pile driver in Britain.[10] Otis Tufts is credited with inventing the steam pile driver in the United States.[11]

Types

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Pile driver, 1917

Ancient pile driving equipment used human or animal labor to lift weights, usually by means of pulleys, then dropping the weight onto the upper end of the pile. Modern piledriving equipment variously uses hydraulics, steam, diesel, or electric power to raise the weight and guide the pile.

Diesel hammer

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Concrete spun pile driving using diesel hammer in Patimban Deep Sea Port, Indonesia

A modern diesel pile hammer is a large two-stroke diesel engine. The weight is the piston, and the apparatus which connects to the top of the pile is the cylinder. Piledriving is started by raising the weight; usually a cable from the crane holding the pile driver — This draws air into the cylinder. Diesel fuel is injected into the cylinder. The weight is dropped, using a quick-release. The weight of the piston compresses the air/fuel mixture, heating it to the ignition point of diesel fuel. The mixture ignites, transferring the energy of the falling weight to the pile head, and driving the weight up. The rising weight draws in fresh air, and the cycle continues until the fuel is depleted or is halted by the crew.[12]

From an army manual on pile driving hammers: The initial start-up of the hammer requires that the piston (ram) be raised to a point where the trip automatically releases the piston, allowing it to fall. As the piston falls, it activates the fuel pump, which discharges a metered amount of fuel into the ball pan of the impact block. The falling piston blocks the exhaust ports, and compression of fuel trapped in the cylinder begins. The compressed air exerts a pre-load force to hold the impact block firmly against the drive cap and pile. At the bottom of the compression stroke, the piston strikes the impact block, atomizing the fuel and starting the pile on its downward movement. In the instant after the piston strikes, the atomized fuel ignites, and the resulting explosion exerts a greater force on the already moving pile, driving it further into the ground. The reaction of the explosion rebounding from the resistance of the pile drives the piston upward. As the piston rises, the exhaust ports open, releasing the exhaust gases to the atmosphere. After the piston stops its upward movement, it again falls by gravity to start another cycle.

Vertical travel lead systems

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Berminghammer vertical travel leads in use
Military building mobile unit on "Army-2021" exhibition

Vertical travel leads come in two main forms: spud and box lead types. Box leads are very common in the Southern United States and spud leads are common in the Northern United States, Canada and Europe.

Hydraulic hammer

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A hydraulic hammer is a modern type of piling hammer used instead of diesel and air hammers for driving steel pipe, precast concrete, and timber piles. Hydraulic hammers are more environmentally acceptable than older, less efficient hammers as they generate less noise and pollutants. In many cases the dominant noise is caused by the impact of the hammer on the pile, or the impacts between components of the hammer, so that the resulting noise level can be similar to diesel hammers.[12]

Hydraulic press-in

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A steel sheet pile being hydraulically pressed

Hydraulic press-in equipment installs piles using hydraulic rams to press piles into the ground. This system is preferred where vibration is a concern. There are press attachments that can adapt to conventional pile driving rigs to press 2 pairs of sheet piles simultaneously. Other types of press equipment sit atop existing sheet piles and grip previously driven piles. This system allows for greater press-in and extraction force to be used since more reaction force is developed.[12] The reaction-based machines operate at only 69 dB at 23 ft allowing for installation and extraction of piles in close proximity to sensitive areas where traditional methods may threaten the stability of existing structures.

Such equipment and methods are specified in portions of the internal drainage system in the New Orleans area after Hurricane Katrina, as well as projects where noise, vibration and access are a concern.

Vibratory pile driver/extractor

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A diesel-powered vibratory pile driver on a steel I-beam

Vibratory pile hammers contain a system of counter-rotating eccentric weights, powered by hydraulic motors, and designed so that horizontal vibrations cancel out, while vertical vibrations are transmitted into the pile. The pile driving machine positioned over the pile with an excavator or crane, and is fastened to the pile by a clamp and/or bolts. Vibratory hammers can drive or extract a pile. Extraction is commonly used to recover steel I-beams used in temporary foundation shoring. Hydraulic fluid is supplied to the driver by a diesel engine-powered pump mounted in a trailer or van, and connected to the driver head via hoses. When the pile driver is connected to a dragline excavator, it is powered by the excavator's diesel engine. Vibratory pile drivers are often chosen to mitigate noise, as when the construction is near residences or office buildings, or when there is insufficient vertical clearance to permit use of a conventional pile hammer (for example when retrofitting additional piles to a bridge column or abutment footing). Hammers are available with several different vibration rates, ranging from 1200 vibrations per minute to 2400 VPM. The vibration rate chosen is influenced by soil conditions and other factors, such as power requirements and equipment cost.

Piling rig

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A Junttan purpose-built piledriving rig in Jyväskylä, Finland

A piling rig is a large track-mounted drill used in foundation projects which require drilling into sandy soil, clay, silty clay, and similar environments. Such rigs are similar in function to oil drilling rigs, and can be equipped with a short screw (for dry soil), rotary bucket (for wet soil) or core drill (for rock), along with other options. Expressways, bridges, industrial and civil buildings, diaphragm walls, water conservancy projects, slope protection, and seismic retrofitting are all projects which may require piling rigs.

Environmental effects

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The underwater sound pressure caused by pile-driving may be deleterious to nearby fish.[13][14] State and local regulatory agencies manage environment issues associated with pile-driving.[15] Mitigation methods include bubble curtains, balloons, internal combustion water hammers.[16]

See also

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  • Auger (drill)
  • Deep foundation
  • Post pounder
  • Drilling rig

References

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  1. ^ a b Piles and Pile Foundations. C.Viggiani, A.Mandolini, G.Russo. 296 pag, ISBN 978-0367865443, ISBN 0367865440
  2. ^ Glossary of Pile-driving Terms, americanpiledriving.com
  3. ^ Pile Foundations. R.D. Chellis (1961) 704 pag, ISBN 0070107513 ISBN 978-0070107519
  4. ^ Ladislao Reti, "Francesco di Giorgio Martini's Treatise on Engineering and Its Plagiarists", Technology and Culture, Vol. 4, No. 3. (Summer, 1963), pp. 287–298 (297f.)
  5. ^ Hart-Davis, Adam (3 April 2017). Engineers. Dorling Kindersley Limited. ISBN 9781409322245 – via Google Books.
  6. ^ Science & Society Picture Library Image of Valoué's design
  7. ^ Pile-driver Information on Gazzola's design
  8. ^ Leonardo da Vinci — Pile Driver Information at Italy's National Museum of Science and Technology
  9. ^ History Trails: Ancient Crannogs from BBC's Mysterious Ancestors series
  10. ^ Fleming, Ken; Weltman, Austin; Randolph, Mark; Elson, Keith (25 September 2008). Piling Engineering, Third Edition. CRC Press. ISBN 9780203937648 – via Google Books.
  11. ^ Hevesi, Dennis (July 3, 2008). "R. C. Seamans Jr., NASA Figure, Dies at 89". New York Times. Retrieved 2008-07-03.
  12. ^ a b c Pile Foundation: Design and Construction. Satyender Mittal (2017) 296 pag. ISBN 9386478374, ISBN 978-9386478375
  13. ^ Halvorsen, M. B., Casper, B. M., Woodley, C. M., Carlson, T. J., & Popper, A. N. (2012). Threshold for onset of injury in Chinook salmon from exposure to impulsive pile driving sounds. PLoS ONE, 7(6), e38968.
  14. ^ Halvorsen, M. B., Casper, B. M., Matthews, F., Carlson, T. J., & Popper, A. N. (2012). Effects of exposure to pile-driving sounds on the lake sturgeon, Nile tilapia and hogchoker. Proceedings of the Royal Society of London B: Biological Sciences, 279(1748), 4705-4714.
  15. ^ "Fisheries – Bioacoustics". Caltrans. Retrieved 2011-02-03.
  16. ^ "Noise mitigation for the construction of increasingly large offshore wind turbines" (PDF). Federal Agency for Nature Conservation. November 2018.
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  • Website about Vulcan Iron Works, which produced pile drivers from the 1870s through the 1990s
Drilling of deep piles of diameter 150 cm in bridge 423 near Ness Ziona, Israel

 

A deep foundation installation for a bridge in Napa, California, United States.
Pile driving operations in the Port of Tampa, Florida.

A pile or piling is a vertical structural element of a deep foundation, driven or drilled deep into the ground at the building site. A deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths.

Deep foundations of The Marina Torch, a skyscraper in Dubai

There are many reasons that a geotechnical engineer would recommend a deep foundation over a shallow foundation, such as for a skyscraper. Some of the common reasons are very large design loads, a poor soil at shallow depth, or site constraints like property lines. There are different terms used to describe different types of deep foundations including the pile (which is analogous to a pole), the pier (which is analogous to a column), drilled shafts, and caissons. Piles are generally driven into the ground in situ; other deep foundations are typically put in place using excavation and drilling. The naming conventions may vary between engineering disciplines and firms. Deep foundations can be made out of timber, steel, reinforced concrete or prestressed concrete.

Driven foundations

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Pipe piles being driven into the ground
Illustration of a hand-operated pile driver in Germany after 1480

Prefabricated piles are driven into the ground using a pile driver. Driven piles are constructed of wood, reinforced concrete, or steel. Wooden piles are made from the trunks of tall trees. Concrete piles are available in square, octagonal, and round cross-sections (like Franki piles). They are reinforced with rebar and are often prestressed. Steel piles are either pipe piles or some sort of beam section (like an H-pile). Historically, wood piles used splices to join multiple segments end-to-end when the driven depth required was too long for a single pile; today, splicing is common with steel piles, though concrete piles can be spliced with mechanical and other means. Driving piles, as opposed to drilling shafts, is advantageous because the soil displaced by driving the piles compresses the surrounding soil, causing greater friction against the sides of the piles, thus increasing their load-bearing capacity. Driven piles are also considered to be "tested" for weight-bearing ability because of their method of installation.[citation needed]

Pile foundation systems

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Foundations relying on driven piles often have groups of piles connected by a pile cap (a large concrete block into which the heads of the piles are embedded) to distribute loads that are greater than one pile can bear. Pile caps and isolated piles are typically connected with grade beams to tie the foundation elements together; lighter structural elements bear on the grade beams, while heavier elements bear directly on the pile cap.[citation needed]

Monopile foundation

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A monopile foundation utilizes a single, generally large-diameter, foundation structural element to support all the loads (weight, wind, etc.) of a large above-surface structure.

A large number of monopile foundations[1] have been utilized in recent years for economically constructing fixed-bottom offshore wind farms in shallow-water subsea locations.[2] For example, the Horns Rev wind farm in the North Sea west of Denmark utilizes 80 large monopiles of 4 metres diameter sunk 25 meters deep into the seabed,[3] while the Lynn and Inner Dowsing Wind Farm off the coast of England went online in 2008 with over 100 turbines, each mounted on a 4.7-metre-diameter monopile foundation in ocean depths up to 18 metres.[4]

The typical construction process for a wind turbine subsea monopile foundation in sand includes driving a large hollow steel pile, of some 4 m in diameter with approximately 50mm thick walls, some 25 m deep into the seabed, through a 0.5 m layer of larger stone and gravel to minimize erosion around the pile. A transition piece (complete with pre-installed features such as boat-landing arrangement, cathodic protection, cable ducts for sub-marine cables, turbine tower flange, etc.) is attached to the driven pile, and the sand and water are removed from the centre of the pile and replaced with concrete. An additional layer of even larger stone, up to 0.5 m diameter, is applied to the surface of the seabed for longer-term erosion protection.[2]

Drilled piles

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A pile machine in Amsterdam.

Also called caissons, drilled shafts, drilled piers, cast-in-drilled-hole piles (CIDH piles) or cast-in-situ piles, a borehole is drilled into the ground, then concrete (and often some sort of reinforcing) is placed into the borehole to form the pile. Rotary boring techniques allow larger diameter piles than any other piling method and permit pile construction through particularly dense or hard strata. Construction methods depend on the geology of the site; in particular, whether boring is to be undertaken in 'dry' ground conditions or through water-saturated strata. Casing is often used when the sides of the borehole are likely to slough off before concrete is poured.

For end-bearing piles, drilling continues until the borehole has extended a sufficient depth (socketing) into a sufficiently strong layer. Depending on site geology, this can be a rock layer, or hardpan, or other dense, strong layers. Both the diameter of the pile and the depth of the pile are highly specific to the ground conditions, loading conditions, and nature of the project. Pile depths may vary substantially across a project if the bearing layer is not level. Drilled piles can be tested using a variety of methods to verify the pile integrity during installation.

Under-reamed piles

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Under-reamed piles have mechanically formed enlarged bases that are as much as 6 m in diameter.[citation needed] The form is that of an inverted cone and can only be formed in stable soils or rocks. The larger base diameter allows greater bearing capacity than a straight-shaft pile.

These piles are suited for expansive soils which are often subjected to seasonal moisture variations, or for loose or soft strata. They are used in normal ground condition also where economics are favorable. [5][full citation needed]

Under reamed piles foundation is used for the following soils:-

1. Under reamed piles are used in black cotton soil: This type of soil expands when it comes in contact with water and contraction occurs when water is removed. So that cracks appear in the construction done on such clay. An under reamed pile is used in the base to remove this defect.

2. Under reamed piles are used in low bearing capacity Outdated soil (filled soil)

3.Under reamed piles are used in sandy soil when water table is high.

4. Under reamed piles are used, Where lifting forces appear at the base of foundation.

Augercast pile

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An augercast pile, often known as a continuous flight augering (CFA) pile, is formed by drilling into the ground with a hollow stemmed continuous flight auger to the required depth or degree of resistance. No casing is required. A cement grout mix is then pumped down the stem of the auger. While the cement grout is pumped, the auger is slowly withdrawn, conveying the soil upward along the flights. A shaft of fluid cement grout is formed to ground level. Reinforcement can be installed. Recent innovations in addition to stringent quality control allows reinforcing cages to be placed up to the full length of a pile when required.[citation needed]

Augercast piles cause minimal disturbance and are often used for noise-sensitive and environmentally-sensitive sites. Augercast piles are not generally suited for use in contaminated soils, because of expensive waste disposal costs. In cases such as these, a displacement pile (like Olivier piles) may provide the cost efficiency of an augercast pile and minimal environmental impact. In ground containing obstructions or cobbles and boulders, augercast piles are less suitable as refusal above the design pile tip elevation may be encountered.[citation needed]

Small Sectional Flight Auger piling rigs can also be used for piled raft foundations. These produce the same type of pile as a Continuous Flight Auger rig but using smaller, more lightweight equipment. This piling method is fast, cost-effective and suitable for the majority of ground types.[5][6]

Pier and grade beam foundation

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In drilled pier foundations, the piers can be connected with grade beams on which the structure sits, sometimes with heavy column loads bearing directly on the piers. In some residential construction, the piers are extended above the ground level, and wood beams bearing on the piers are used to support the structure. This type of foundation results in a crawl space underneath the building in which wiring and duct work can be laid during construction or re-modelling.[7]

Speciality piles

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Jet-piles

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In jet piling high pressure water is used to set piles.[8] High pressure water cuts through soil with a high-pressure jet flow and allows the pile to be fitted.[9] One advantage of Jet Piling: the water jet lubricates the pile and softens the ground.[10] The method is in use in Norway.[11]

Micropiles

[edit]

Micropiles are small diameter, generally less than 300mm diameter, elements that are drilled and grouted in place.  They typically get their capacity from skin friction along the sides of the element, but can be end bearing in hard rock as well. Micropiles are usually heavily reinforced with steel comprising more than 40% of their cross section. They can be used as direct structural support or as ground reinforcement elements.  Due to their relatively high cost and the type of equipment used to install these elements, they are often used where access restrictions and or very difficult ground conditions (cobbles and boulders, construction debris, karst, environmental sensitivity) exists or to retrofit existing structures.  Occasionally, in difficult ground, they are used for new construction foundation elements. Typical applications include underpinning, bridge, transmission tower and slope stabilization projects.[6][12][13][14]

Tripod piles

[edit]

The use of a tripod rig to install piles is one of the more traditional ways of forming piles. Although unit costs are generally higher than with most other forms of piling,[citation needed] it has several advantages which have ensured its continued use through to the present day. The tripod system is easy and inexpensive to bring to site, making it ideal for jobs with a small number of piles.[clarification needed]

Sheet piles

[edit]
Sheet piles are used to restrain soft soil above the bedrock in this excavation

Sheet piling is a form of driven piling using thin interlocking sheets of steel to obtain a continuous barrier in the ground. The main application of sheet piles is in retaining walls and cofferdams erected to enable permanent works to proceed. Normally, vibrating hammer, t-crane and crawle drilling are used to establish sheet piles.[citation needed]

Soldier piles

[edit]
A soldier pile wall using reclaimed railway sleepers as lagging.

Soldier piles, also known as king piles or Berlin walls, are constructed of steel H sections spaced about 2 to 3 m apart and are driven or drilled prior to excavation. As the excavation proceeds, horizontal timber sheeting (lagging) is inserted behind the H pile flanges.

The horizontal earth pressures are concentrated on the soldier piles because of their relative rigidity compared to the lagging. Soil movement and subsidence is minimized by installing the lagging immediately after excavation to avoid soil loss.[citation needed] Lagging can be constructed by timber, precast concrete, shotcrete and steel plates depending on spacing of the soldier piles and the type of soils.

Soldier piles are most suitable in conditions where well constructed walls will not result in subsidence such as over-consolidated clays, soils above the water table if they have some cohesion, and free draining soils which can be effectively dewatered, like sands.[citation needed]

Unsuitable soils include soft clays and weak running soils that allow large movements such as loose sands. It is also not possible to extend the wall beyond the bottom of the excavation, and dewatering is often required.[citation needed]

Screw piles

[edit]

Screw piles, also called helical piers and screw foundations, have been used as foundations since the mid 19th century in screw-pile lighthouses.[citation needed] Screw piles are galvanized iron pipe with helical fins that are turned into the ground by machines to the required depth. The screw distributes the load to the soil and is sized accordingly.

Suction piles

[edit]

Suction piles are used underwater to secure floating platforms. Tubular piles are driven into the seabed (or more commonly dropped a few metres into a soft seabed) and then a pump sucks water out at the top of the tubular, pulling the pile further down.

The proportions of the pile (diameter to height) are dependent upon the soil type. Sand is difficult to penetrate but provides good holding capacity, so the height may be as short as half the diameter. Clays and muds are easy to penetrate but provide poor holding capacity, so the height may be as much as eight times the diameter. The open nature of gravel means that water would flow through the ground during installation, causing 'piping' flow (where water boils up through weaker paths through the soil). Therefore, suction piles cannot be used in gravel seabeds.[citation needed]

Adfreeze piles

[edit]
Adfreeze piles supporting a building in Utqiaġvik, Alaska

In high latitudes where the ground is continuously frozen, adfreeze piles are used as the primary structural foundation method.

Adfreeze piles derive their strength from the bond of the frozen ground around them to the surface of the pile.[citation needed]

Adfreeze pile foundations are particularly sensitive in conditions which cause the permafrost to melt. If a building is constructed improperly then it can melt the ground below, resulting in a failure of the foundation system.[citation needed]

Vibrated stone columns

[edit]

Vibrated stone columns are a ground improvement technique where columns of coarse aggregate are placed in soils with poor drainage or bearing capacity to improve the soils.[citation needed]

Hospital piles

[edit]

Specific to marine structures, hospital piles (also known as gallow piles) are built to provide temporary support to marine structure components during refurbishment works. For example, when removing a river pontoon, the brow will be attached to hospital pile to support it. They are normal piles, usually with a chain or hook attachment.[citation needed]

Piled walls

[edit]
Sheet piling, by a bridge, was used to block a canal in New Orleans after Hurricane Katrina damaged it.

Piled walls can be drivene or bored. They provide special advantages where available working space dictates and open cut excavation not feasible. Both methods offer technically effective and offer a cost efficient temporary or permanent means of retaining the sides of bulk excavations even in water bearing strata. When used in permanent works, these walls can be designed to resist vertical loads in addition lateral load from retaining soil. Construction of both methods is the same as for foundation bearing piles. Contiguous walls are constructed with small gaps between adjacent piles. The spacing of the piles can be varied to provide suitable bending stiffness.

Secant piled walls

[edit]

Secant pile walls are constructed such that space is left between alternate 'female' piles for the subsequent construction of 'male' piles.[clarification needed] Construction of 'male' piles involves boring through the concrete in the 'female' piles hole in order to key 'male' piles between. The male pile is the one where steel reinforcement cages are installed, though in some cases the female piles are also reinforced.[citation needed]

Secant piled walls can either be true hard/hard, hard/intermediate (firm), or hard/soft, depending on design requirements. Hard refers to structural concrete and firm or soft is usually a weaker grout mix containing bentonite.[citation needed] All types of wall can be constructed as free standing cantilevers, or may be propped if space and sub-structure design permit. Where party wall agreements allow, ground anchors can be used as tie backs.

Slurry walls

[edit]

A slurry wall is a barrier built under ground using a mix of bentonite and water to prevent the flow of groundwater. A trench that would collapse due to the hydraulic pressure in the surrounding soil does not collapse as the slurry balances the hydraulic pressure.

Deep mixing/mass stabilization techniques

[edit]

These are essentially variations of in situ reinforcements in the form of piles (as mentioned above), blocks or larger volumes.

Cement, lime/quick lime, flyash, sludge and/or other binders (sometimes called stabilizer) are mixed into the soil to increase bearing capacity. The result is not as solid as concrete, but should be seen as an improvement of the bearing capacity of the original soil.

The technique is most often applied on clays or organic soils like peat. The mixing can be carried out by pumping the binder into the soil whilst mixing it with a device normally mounted on an excavator or by excavating the masses, mixing them separately with the binders and refilling them in the desired area. The technique can also be used on lightly contaminated masses as a means of binding contaminants, as opposed to excavating them and transporting to landfill or processing.

Materials

[edit]

Timber

[edit]

As the name implies, timber piles are made of wood.

Historically, timber has been a plentiful, locally available resource in many areas. Today, timber piles are still more affordable than concrete or steel. Compared to other types of piles (steel or concrete), and depending on the source/type of timber, timber piles may not be suitable for heavier loads.

A main consideration regarding timber piles is that they should be protected from rotting above groundwater level. Timber will last for a long time below the groundwater level. For timber to rot, two elements are needed: water and oxygen. Below the groundwater level, dissolved oxygen is lacking even though there is ample water. Hence, timber tends to last for a long time below the groundwater level. An example is Venice, which has had timber pilings since its beginning; even most of the oldest piles are still in use. In 1648, the Royal Palace of Amsterdam was constructed on 13,659 timber piles that still survive today since they were below groundwater level. Timber that is to be used above the water table can be protected from decay and insects by numerous forms of wood preservation using pressure treatment (alkaline copper quaternary (ACQ), chromated copper arsenate (CCA), creosote, etc.).

Splicing timber piles is still quite common and is the easiest of all the piling materials to splice. The normal method for splicing is by driving the leader pile first, driving a steel tube (normally 60–100 cm long, with an internal diameter no smaller than the minimum toe diameter) half its length onto the end of the leader pile. The follower pile is then simply slotted into the other end of the tube and driving continues. The steel tube is simply there to ensure that the two pieces follow each other during driving. If uplift capacity is required, the splice can incorporate bolts, coach screws, spikes or the like to give it the necessary capacity.

Iron

[edit]

Cast iron may be used for piling. These may be ductile.[citation needed]

Steel

[edit]
Cutaway illustration. Deep inclined (battered) pipe piles support a precast segmented skyway where upper soil layers are weak muds.

Pipe piles are a type of steel driven pile foundation and are a good candidate for inclined (battered) piles.

Pipe piles can be driven either open end or closed end. When driven open end, soil is allowed to enter the bottom of the pipe or tube. If an empty pipe is required, a jet of water or an auger can be used to remove the soil inside following driving. Closed end pipe piles are constructed by covering the bottom of the pile with a steel plate or cast steel shoe.

In some cases, pipe piles are filled with concrete to provide additional moment capacity or corrosion resistance. In the United Kingdom, this is generally not done in order to reduce the cost.[citation needed] In these cases corrosion protection is provided by allowing for a sacrificial thickness of steel or by adopting a higher grade of steel. If a concrete filled pipe pile is corroded, most of the load carrying capacity of the pile will remain intact due to the concrete, while it will be lost in an empty pipe pile. The structural capacity of pipe piles is primarily calculated based on steel strength and concrete strength (if filled). An allowance is made for corrosion depending on the site conditions and local building codes. Steel pipe piles can either be new steel manufactured specifically for the piling industry or reclaimed steel tubular casing previously used for other purposes such as oil and gas exploration.

H-Piles are structural beams that are driven in the ground for deep foundation application. They can be easily cut off or joined by welding or mechanical drive-fit splicers. If the pile is driven into a soil with low pH value, then there is a risk of corrosion, coal-tar epoxy or cathodic protection can be applied to slow or eliminate the corrosion process. It is common to allow for an amount of corrosion in design by simply over dimensioning the cross-sectional area of the steel pile. In this way, the corrosion process can be prolonged up to 50 years.[citation needed]

Prestressed concrete piles

[edit]

Concrete piles are typically made with steel reinforcing and prestressing tendons to obtain the tensile strength required, to survive handling and driving, and to provide sufficient bending resistance.

Long piles can be difficult to handle and transport. Pile joints can be used to join two or more short piles to form one long pile. Pile joints can be used with both precast and prestressed concrete piles.

Composite piles

[edit]

A "composite pile" is a pile made of steel and concrete members that are fastened together, end to end, to form a single pile. It is a combination of different materials or different shaped materials such as pipe and H-beams or steel and concrete.

'Pile jackets' encasing old concrete piles in a saltwater environment to prevent corrosion and consequential weakening of the piles when cracks allow saltwater to contact the internal steel reinforcement rods

Construction machinery for driving piles into the ground

[edit]

Construction machinery used to drive piles into the ground:[15]

  • Pile driver is a device for placing piles in their designed position.
  • Diesel pile hammer is a device for hammering piles into the ground.
  • Hydraulic hammer is removable working equipment of hydraulic excavators, hydroficated machines (stationary rock breakers, loaders, manipulators, pile driving hammers) used for processing strong materials (rock, soil, metal) or pile driving elements by impact of falling parts dispersed by high-pressure fluid.
  • Vibratory pile driver is a machine for driving piles into sandy and clay soils.
  • Press-in pile driver is a machine for sinking piles into the ground by means of static force transmission.[16]
  • Universal drilling machine.

Construction machinery for replacement piles

[edit]

Construction machinery used to construct replacement piles:[15]

  • Sectional Flight Auger or Continuous Flight Auger
  • Reverse circulation drilling
  • Ring bit concentric drilling

See also

[edit]
  • Eurocode EN 1997
  • International Society for Micropiles
  • Post in ground construction also called earthfast or posthole construction; a historic method of building wooden structures.
  • Stilt house, also known as a lake house; an ancient, historic house type built on pilings.
  • Shallow foundations
  • Pile bridge
  • Larssen sheet piling

Notes

[edit]
  1. ^ Offshore Wind Turbine Foundations, 2009-09-09, accessed 2010-04-12.
  2. ^ a b Constructing a turbine foundation Archived 21 May 2011 at the Wayback Machine Horns Rev project, Elsam monopile foundation construction process, accessed 2010-04-12]
  3. ^ Horns Revolution Archived 14 July 2011 at the Wayback Machine, Modern Power Systems, 2002-10-05, accessed 2010-04-14.
  4. ^ "Lynn and Inner Dowsing description". Archived from the original on 26 July 2011. Retrieved 23 July 2010.
  5. ^ a b Handbook on Under-reamed and bored compaction pile foundation, Central building research institute Roorkee, Prepared by Devendra Sharma, M. P. Jain, Chandra Prakash
  6. ^ a b Siel, Barry D.; Anderson, Scott A. "Implementation of Micropiles by the Federal Highway Administration" (PDF). Federal Highway Administration (US). cite journal: Cite journal requires |journal= (help)
  7. ^ Marshall, Brain (April 2000). "How House Construction Works". How Stuff Works. HowStuffWorks, Inc. Retrieved 4 April 2013.
  8. ^ "jet-pile". Merriam-Webster. Retrieved 2 August 2020.
  9. ^ Guan, Chengli; Yang, Yuyou (21 February 2019). "Field Study on the Waterstop of the Rodin Jet Pile". Applied Sciences. doi:10.3390/app9081709. Retrieved 2 August 2020.
  10. ^ "Press-in with Water Jetting". Giken.com. Giken Ltd. Retrieved 2 August 2020.
  11. ^ "City Lade, Trondheim". Jetgrunn.no. Jetgrunn AS. Retrieved 2 August 2020.
  12. ^ Omer, Joshua R. (2010). "A Numerical Model for Load Transfer and Settlement of Bored Cast In-Situ Piles". Proceedings of the 35th Annual Conference on Deep Foundations. Archived from the original on 14 April 2021. Retrieved 20 July 2011.
  13. ^ "International Society for Micropiles". Retrieved 2 February 2007.
  14. ^ "GeoTechTools". Geo-Institute. Retrieved 15 April 2022.
  15. ^ a b McNeil, Ian (1990). An Encyclopaedia of the history of technolology. Routledge. ISBN 9780415147927. Retrieved 20 July 2022 – via Internet Archive.
  16. ^ "General description of the press-in pile driving unit". Concrete Pumping Melbourne. 13 October 2021. Archived from the original on 25 December 2022. Retrieved 20 July 2022.

References

[edit]
  • Italiantrivelle Foundation Industry Archived 25 June 2014 at the Wayback Machine The Deep Foundation web portal Italiantrivelle is the number one source of information regarding the Foundation Industry. (Link needs to be removed or updated, links to inappropriate content)
  • Fleming, W. G. K. et al., 1985, Piling Engineering, Surrey University Press; Hunt, R. E., Geotechnical Engineering Analysis and Evaluation, 1986, McGraw-Hill.
  • Coduto, Donald P. Foundation Design: Principles and Practices 2nd ed., Prentice-Hall Inc., 2001.
  • NAVFAC DM 7.02 Foundations and Earth Structures U.S. Naval Facilities Engineering Command, 1986.
  • Rajapakse, Ruwan., Pile Design and Construction Guide, 2003
  • Tomlinson, P.J., Pile Design and Construction Practice, 1984
  • Stabilization of Organic Soils Archived 22 February 2012 at the Wayback Machine
  • Sheet piling handbook, 2010
[edit]
  • Deep Foundations Institute

 

 

Tail of a radio-controlled helicopter, made of CFRP

Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon composite, or just carbon, are extremely strong and light fiber-reinforced plastics that contain carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications.[1][2][3][4]

The binding polymer is often a thermoset resin such as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester, or nylon, are sometimes used.[4] The properties of the final CFRP product can be affected by the type of additives introduced to the binding matrix (resin). The most common additive is silica, but other additives such as rubber and carbon nanotubes can be used.

Carbon fiber is sometimes referred to as graphite-reinforced polymer or graphite fiber-reinforced polymer (GFRP is less common, as it clashes with glass-(fiber)-reinforced polymer).

Properties

[edit]

CFRP are composite materials. In this case the composite consists of two parts: a matrix and a reinforcement. In CFRP the reinforcement is carbon fiber, which provides its strength. The matrix is usually a thermosetting plastic, such as polyester resin, to bind the reinforcements together.[5] Because CFRPs consist of two distinct elements, the material properties depend on these two elements.

Reinforcement gives CFRPs their strength and rigidity, measured by stress and elastic modulus respectively. Unlike isotropic materials like steel and aluminum, CFRPs have directional strength properties. The properties of a CFRP depend on the layouts of the carbon fiber and the proportion of the carbon fibers relative to the polymer.[6] The two different equations governing the net elastic modulus of composite materials using the properties of the carbon fibers and the polymer matrix can also be applied to carbon fiber reinforced plastics.[7] The rule of mixtures for the equal strain case gives:

which is valid for composite materials with the fibers oriented parallel to the applied load. is the total composite modulus, and are the volume fractions of the matrix and fiber respectively in the composite, and and are the elastic moduli of the matrix and fibers respectively.[7] The other extreme case of the elastic modulus of the composite with the fibers oriented transverse to the applied load can be found using the inverse rule of mixtures for the equal stress case:[7]

The above equations give an upper and lower bound on the Young's modulus for CFRP and there are many other factors that influence the true value.

The fracture toughness of carbon fiber reinforced plastics is governed by multiple mechanisms:

  • Debonding between the carbon fiber and polymer matrix.
  • Fiber pull-out.
  • Delamination between the CFRP sheets.[8]

Typical epoxy-based CFRPs exhibit virtually no plasticity, with less than 0.5% strain to failure. Although CFRPs with epoxy have high strength and elastic modulus, the brittle fracture mechanics presents unique challenges to engineers in failure detection since failure occurs catastrophically.[8] As such, recent efforts to toughen CFRPs include modifying the existing epoxy material and finding alternative polymer matrix. One such material with high promise is PEEK, which exhibits an order of magnitude greater toughness with similar elastic modulus and tensile strength.[8] However, PEEK is much more difficult to process and more expensive.[8]

Despite their high initial strength-to-weight ratios, a design limitation of CFRPs are their lack of a definable fatigue limit. This means, theoretically, that stress cycle failure cannot be ruled out. While steel and many other structural metals and alloys do have estimable fatigue or endurance limits, the complex failure modes of composites mean that the fatigue failure properties of CFRPs are difficult to predict and design against; however emerging research has shed light on the effects of low velocity impacts on composites.[9] Low velocity impacts can make carbon fiber polymers susceptible to damage.[9][10][11] As a result, when using CFRPs for critical cyclic-loading applications, engineers may need to design in considerable strength safety margins to provide suitable component reliability over its service life.

Environmental effects such as temperature and humidity can have profound effects on the polymer-based composites, including most CFRPs. While CFRPs demonstrate excellent corrosion resistance, the effect of moisture at wide ranges of temperatures can lead to degradation of the mechanical properties of CFRPs, particularly at the matrix-fiber interface.[12] While the carbon fibers themselves are not affected by the moisture diffusing into the material, the moisture plasticizes the polymer matrix.[8] This leads to significant changes in properties that are dominantly influenced by the matrix in CFRPs such as compressive, interlaminar shear, and impact properties.[13] The epoxy matrix used for engine fan blades is designed to be impervious against jet fuel, lubrication, and rain water, and external paint on the composites parts is applied to minimize damage from ultraviolet light.[8][14]

Carbon fibers can cause galvanic corrosion when CFRP parts are attached to aluminum or mild steel but not to stainless steel or titanium.[15]

CFRPs are very hard to machine, and cause significant tool wear. The tool wear in CFRP machining is dependent on the fiber orientation and machining condition of the cutting process. To reduce tool wear various types of coated tools are used in machining CFRP and CFRP-metal stack.[1]

Manufacturing

[edit]
Carbon fiber reinforced polymer

The primary element of CFRPs is a carbon filament; this is produced from a precursor polymer such as polyacrylonitrile (PAN), rayon, or petroleum pitch. For synthetic polymers such as PAN or rayon, the precursor is first spun into filament yarns, using chemical and mechanical processes to initially align the polymer chains in a way to enhance the final physical properties of the completed carbon fiber. Precursor compositions and mechanical processes used during spinning filament yarns may vary among manufacturers. After drawing or spinning, the polymer filament yarns are then heated to drive off non-carbon atoms (carbonization), producing the final carbon fiber. The carbon fibers filament yarns may be further treated to improve handling qualities, then wound onto bobbins.[16] From these fibers, a unidirectional sheet is created. These sheets are layered onto each other in a quasi-isotropic layup, e.g. 0°, +60°, or −60° relative to each other.

From the elementary fiber, a bidirectional woven sheet can be created, i.e. a twill with a 2/2 weave. The process by which most CFRPs are made varies, depending on the piece being created, the finish (outside gloss) required, and how many of the piece will be produced. In addition, the choice of matrix can have a profound effect on the properties of the finished composite.[17]

Many CFRP parts are created with a single layer of carbon fabric that is backed with fiberglass.[18] A tool called a chopper gun is used to quickly create these composite parts. Once a thin shell is created out of carbon fiber, the chopper gun cuts rolls of fiberglass into short lengths and sprays resin at the same time, so that the fiberglass and resin are mixed on the spot.[19] The resin is either external mix, wherein the hardener and resin are sprayed separately, or internal mixed, which requires cleaning after every use. Manufacturing methods may include the following:

Molding

[edit]

One method of producing CFRP parts is by layering sheets of carbon fiber cloth into a mold in the shape of the final product. The alignment and weave of the cloth fibers is chosen to optimize the strength and stiffness properties of the resulting material. The mold is then filled with epoxy and is heated or air-cured. The resulting part is very corrosion-resistant, stiff, and strong for its weight. Parts used in less critical areas are manufactured by draping cloth over a mold, with epoxy either pre-impregnated into the fibers (also known as pre-preg) or "painted" over it. High-performance parts using single molds are often vacuum-bagged and/or autoclave-cured, because even small air bubbles in the material will reduce strength. An alternative to the autoclave method is to use internal pressure via inflatable air bladders or EPS foam inside the non-cured laid-up carbon fiber.

Vacuum bagging

[edit]

For simple pieces of which relatively few copies are needed (one or two per day), a vacuum bag can be used. A fiberglass, carbon fiber, or aluminum mold is polished and waxed, and has a release agent applied before the fabric and resin are applied, and the vacuum is pulled and set aside to allow the piece to cure (harden). There are three ways to apply the resin to the fabric in a vacuum mold.

The first method is manual and called a wet layup, where the two-part resin is mixed and applied before being laid in the mold and placed in the bag. The other one is done by infusion, where the dry fabric and mold are placed inside the bag while the vacuum pulls the resin through a small tube into the bag, then through a tube with holes or something similar to evenly spread the resin throughout the fabric. Wire loom works perfectly for a tube that requires holes inside the bag. Both of these methods of applying resin require hand work to spread the resin evenly for a glossy finish with very small pin-holes.

A third method of constructing composite materials is known as a dry layup. Here, the carbon fiber material is already impregnated with resin (pre-preg) and is applied to the mold in a similar fashion to adhesive film. The assembly is then placed in a vacuum to cure. The dry layup method has the least amount of resin waste and can achieve lighter constructions than wet layup. Also, because larger amounts of resin are more difficult to bleed out with wet layup methods, pre-preg parts generally have fewer pinholes. Pinhole elimination with minimal resin amounts generally require the use of autoclave pressures to purge the residual gases out.

Compression molding

[edit]

A quicker method uses a compression mold, also commonly known as carbon fiber forging. This is a two (male and female), or multi-piece mold, usually made out of aluminum or steel and more recently 3D printed plastic. The mold components are pressed together with the fabric and resin loaded into the inner cavity that ultimately becomes the desired component. The benefit is the speed of the entire process. Some car manufacturers, such as BMW, claimed to be able to cycle a new part every 80 seconds. However, this technique has a very high initial cost since the molds require CNC machining of very high precision.

Filament winding

[edit]

For difficult or convoluted shapes, a filament winder can be used to make CFRP parts by winding filaments around a mandrel or a core.

Cutting

[edit]

Carbon fiber-reinforced pre-pregs and dry carbon fiber textiles require precise cutting methods to maintain material integrity and reduce defects such as fiber pull-out, delamination and fraying of the cutting edge. CNC digital cutting systems equipped with drag and oscillating are often used to cut carbon fiber pre-pregs, and rotating knives are commonly used to process carbon fiber fabrics. Ultrasonic cutting is another method to cut CFRP pre-pregs and is particularly effective in reducing delamination by minimizing mechanical stress during the cutting process. Waterjet cutting can be the preferred method for thicker and multilayered polymer composites.[20]

Applications

[edit]

Applications for CFRPs include the following:

Aerospace engineering

[edit]
An Airbus A350 with carbon fiber themed livery. Composite materials are used extensively throughout the A350.

The Airbus A350 XWB is 53% CFRP[21] including wing spars and fuselage components, overtaking the Boeing 787 Dreamliner, for the aircraft with the highest weight ratio for CFRP at 50%.[22] It was one of the first commercial aircraft to have wing spars made from composites. The Airbus A380 was one of the first commercial airliners to have a central wing-box made of CFRP and the first with a smoothly contoured wing cross-section instead of partitioning it span-wise into sections. This flowing, continuous cross section optimises aerodynamic efficiency.[citation needed] Moreover, the trailing edge, along with the rear bulkhead, empennage, and un-pressurised fuselage are made of CFRP.[23]

However, delays have pushed order delivery dates back because of manufacturing problems. Many aircraft that use CFRPs have experienced delays with delivery dates due to the relatively new processes used to make CFRP components, whereas metallic structures are better understood. A recurrent problem is the monitoring of structural ageing, for which new methods are required, due to the unusual multi-material and anisotropic[24][25][26] nature of CFRPs.[27]

In 1968 a Hyfil carbon-fiber fan assembly was in service on the Rolls-Royce Conways of the Vickers VC10s operated by BOAC.[28]

Specialist aircraft designers and manufacturers Scaled Composites have made extensive use of CFRPs throughout their design range, including the first private crewed spacecraft Spaceship One. CFRPs are widely used in micro air vehicles (MAVs) because of their high strength-to-weight ratio.

Airbus then moved to adopt CFRTP, because it can be reshaped and reprocessed after forming, can be manufactured faster, has higher impact resistance, is recyclable and remoldable, and has lower processing costs.[29]

Automotive engineering

[edit]
Citroën SM that won 1971 Rally of Morocco with carbon fiber wheels
1996 McLaren F1 – first carbon fiber body shell
McLaren MP4 (MP4/1), first carbon fiber F1 car

CFRPs are extensively used in high-end automobile racing.[30] The high cost of carbon fiber is mitigated by the material's unsurpassed strength-to-weight ratio, and low weight is essential for high-performance automobile racing. Race-car manufacturers have also developed methods to give carbon fiber pieces strength in a certain direction, making it strong in a load-bearing direction, but weak in directions where little or no load would be placed on the member. Conversely, manufacturers developed omnidirectional carbon fiber weaves that apply strength in all directions. This type of carbon fiber assembly is most widely used in the "safety cell" monocoque chassis assembly of high-performance race-cars. The first carbon fiber monocoque chassis was introduced in Formula One by McLaren in the 1981 season. It was designed by John Barnard and was widely copied in the following seasons by other F1 teams due to the extra rigidity provided to the chassis of the cars.[31]

Many supercars over the past few decades have incorporated CFRPs extensively in their manufacture, using it for their monocoque chassis as well as other components.[32] As far back as 1971, the Citroën SM offered optional lightweight carbon fiber wheels.[33][34]

Use of the material has been more readily adopted by low-volume manufacturers who used it primarily for creating body-panels for some of their high-end cars due to its increased strength and decreased weight compared with the glass-reinforced polymer they used for the majority of their products.

Civil engineering

[edit]

CFRPs have become a notable material in structural engineering applications. Studied in an academic context as to their potential benefits in construction, CFRPs have also proved themselves cost-effective in a number of field applications strengthening concrete, masonry, steel, cast iron, and timber structures. Their use in industry can be either for retrofitting to strengthen an existing structure or as an alternative reinforcing (or prestressing) material instead of steel from the outset of a project.

Retrofitting has become the increasingly dominant use of the material in civil engineering, and applications include increasing the load capacity of old structures (such as bridges, beams, ceilings, columns and walls) that were designed to tolerate far lower service loads than they are experiencing today, seismic retrofitting, and repair of damaged structures. Retrofitting is popular in many instances as the cost of replacing the deficient structure can greatly exceed the cost of strengthening using CFRP.[35]

Applied to reinforced concrete structures for flexure, the use of CFRPs typically has a large impact on strength (doubling or more the strength of the section is not uncommon), but only moderately increases stiffness (as little as 10%). This is because the material used in such applications is typically very strong (e.g., 3 GPa ultimate tensile strength, more than 10 times mild steel) but not particularly stiff (150 to 250 GPa elastic modulus, a little less than steel, is typical). As a consequence, only small cross-sectional areas of the material are used. Small areas of very high strength but moderate stiffness material will significantly increase strength, but not stiffness.

CFRPs can also be used to enhance shear strength of reinforced concrete by wrapping fabrics or fibers around the section to be strengthened. Wrapping around sections (such as bridge or building columns) can also enhance the ductility of the section, greatly increasing the resistance to collapse under dynamic loading. Such 'seismic retrofit' is the major application in earthquake-prone areas, since it is much more economic than alternative methods.

If a column is circular (or nearly so) an increase in axial capacity is also achieved by wrapping. In this application, the confinement of the CFRP wrap enhances the compressive strength of the concrete. However, although large increases are achieved in the ultimate collapse load, the concrete will crack at only slightly enhanced load, meaning that this application is only occasionally used. Specialist ultra-high modulus CFRP (with tensile modulus of 420 GPa or more) is one of the few practical methods of strengthening cast iron beams. In typical use, it is bonded to the tensile flange of the section, both increasing the stiffness of the section and lowering the neutral axis, thus greatly reducing the maximum tensile stress in the cast iron.

In the United States, prestressed concrete cylinder pipes (PCCP) account for a vast majority of water transmission mains. Due to their large diameters, failures of PCCP are usually catastrophic and affect large populations. Approximately 19,000 miles (31,000 km) of PCCP were installed between 1940 and 2006. Corrosion in the form of hydrogen embrittlement has been blamed for the gradual deterioration of the prestressing wires in many PCCP lines. Over the past decade, CFRPs have been used to internally line PCCP, resulting in a fully structural strengthening system. Inside a PCCP line, the CFRP liner acts as a barrier that controls the level of strain experienced by the steel cylinder in the host pipe. The composite liner enables the steel cylinder to perform within its elastic range, to ensure the pipeline's long-term performance is maintained. CFRP liner designs are based on strain compatibility between the liner and host pipe.[36]

CFRPs are more costly materials than commonly used their counterparts in the construction industry, glass fiber-reinforced polymers (GFRPs) and aramid fiber-reinforced polymers (AFRPs), though CFRPs are, in general, regarded as having superior properties. Much research continues to be done on using CFRPs both for retrofitting and as an alternative to steel as reinforcing or prestressing materials. Cost remains an issue and long-term durability questions still remain. Some are concerned about the brittle nature of CFRPs, in contrast to the ductility of steel. Though design codes have been drawn up by institutions such as the American Concrete Institute, there remains some hesitation among the engineering community about implementing these alternative materials. In part, this is due to a lack of standardization and the proprietary nature of the fiber and resin combinations on the market.

Carbon-fiber microelectrodes

[edit]

Carbon fibers are used for fabrication of carbon-fiber microelectrodes. In this application typically a single carbon fiber with diameter of 5–7 μm is sealed in a glass capillary.[37] At the tip the capillary is either sealed with epoxy and polished to make carbon-fiber disk microelectrode or the fiber is cut to a length of 75–150 μm to make carbon-fiber cylinder electrode. Carbon-fiber microelectrodes are used either in amperometry or fast-scan cyclic voltammetry for detection of biochemical signalling.

Sports goods

[edit]
A carbon-fiber and Kevlar canoe (Placid Boatworks Rapidfire at the Adirondack Canoe Classic)

CFRPs are now widely used in sports equipment such as in squash, tennis, and badminton racquets, sport kite spars, high-quality arrow shafts, hockey sticks, fishing rods, surfboards, high end swim fins, and rowing shells. Amputee athletes such as Jonnie Peacock use carbon fiber blades for running. It is used as a shank plate in some basketball sneakers to keep the foot stable, usually running the length of the shoe just above the sole and left exposed in some areas, usually in the arch.

Controversially, in 2006, cricket bats with a thin carbon-fiber layer on the back were introduced and used in competitive matches by high-profile players including Ricky Ponting and Michael Hussey. The carbon fiber was claimed to merely increase the durability of the bats, but it was banned from all first-class matches by the ICC in 2007.[38]

A CFRP bicycle frame weighs less than one of steel, aluminum, or titanium having the same strength. The type and orientation of the carbon-fiber weave can be designed to maximize stiffness in required directions. Frames can be tuned to address different riding styles: sprint events require stiffer frames while endurance events may require more flexible frames for rider comfort over longer periods.[39] The variety of shapes it can be built into has further increased stiffness and also allowed aerodynamic tube sections. CFRP forks including suspension fork crowns and steerers, handlebars, seatposts, and crank arms are becoming more common on medium as well as higher-priced bicycles. CFRP rims remain expensive but their stability compared to aluminium reduces the need to re-true a wheel and the reduced mass reduces the moment of inertia of the wheel. CFRP spokes are rare and most carbon wheelsets retain traditional stainless steel spokes. CFRPs also appear increasingly in other components such as derailleur parts, brake and shifter levers and bodies, cassette sprocket carriers, suspension linkages, disc brake rotors, pedals, shoe soles, and saddle rails. Although strong and light, impact, over-torquing, or improper installation of CFRP components has resulted in cracking and failures, which may be difficult or impossible to repair.[40][41]

Other applications

[edit]
Dunlop "Max-Grip" carbon fiber guitar picks. Sizes 1mm and Jazz III.
Dunlop "Max-Grip" carbon fiber guitar picks. Sizes 1mm and Jazz III.

The fire resistance of polymers and thermo-set composites is significantly improved if a thin layer of carbon fibers is moulded near the surface because a dense, compact layer of carbon fibers efficiently reflects heat.[42]

Strandberg Boden Plini neck-thru & bolt on versions that both utilize carbon fiber reinforcement strips to maintain rigidity.

CFRPs are being used in an increasing number of high-end products that require stiffness and low weight, these include:

  • Musical instruments, including violin bows; guitar picks, guitar necks (fitted with carbon fiber rods), pickguards/scratchplates; drum shells; bagpipe chanters; piano actions; and entire musical instruments such as carbon fiber cellos, violas, and violins, acoustic guitars and ukuleles; also, audio components such as turntables and loudspeakers.
  • Firearms use it to replace certain metal, wood, and fiberglass components but many of the internal parts are still limited to metal alloys as current reinforced plastics are unsuitable.
  • High-performance drone bodies and other radio-controlled vehicle and aircraft components such as helicopter rotor blades.
  • Lightweight poles such as: tripod legs, tent poles, fishing rods, billiards cues, walking sticks, and high-reach poles such as for window cleaning.
  • Dentistry, carbon fiber posts are used in restoring root canal treated teeth.
  • Railed train bogies for passenger service. This reduces the weight by up to 50% compared to metal bogies, which contributes to energy savings.[43]
  • Laptop shells and other high performance cases.
  • Carbon woven fabrics.[44][45]
  • Archery: carbon fiber arrows and bolts, stock (for crossbows) and riser (for vertical bows), and rail.
  • As a filament for the 3D fused deposition modeling printing process,[46] carbon fiber-reinforced plastic (polyamide-carbon filament) is used for the production of sturdy but lightweight tools and parts due to its high strength and tear length.[47]
  • District heating pipe rehabilitation, using a CIPP method.

Disposal and recycling

[edit]

The key aspect of recycling fiber-reinforced polymers is preserving their mechanical properties while successfully recovering both the thermoplastic matrix and the reinforcing fibers. CFRPs have a long service lifetime when protected from the sun. When it is time to decommission CFRPs, they cannot be melted down in air like many metals. When free of vinyl (PVC or polyvinyl chloride) and other halogenated polymers, CFRPs recycling processes can be categorized into four main approaches: mechanical, thermal, chemical, and biological. Each method offers distinct advantages in terms of material or energy recovery, contributing to sustainability efforts in composite waste management.

Process Matrix recovery Fiber recovery Degradation of Mechanical Properties Advantages/Drawbacks
Mechanical X X X +No use of hazardous chemical substances  +No gas emissions  +Low-cost energy needed  +Big volumes can be recycled

-Poor bonding between fiber/matrix -Fibers can damage the equipment

Chemical   X   +Long clean fibers +Retention of mechanical properties +Sometimes there is high recovery of the matrix

-Expensive equipment -Possible use of hazardous solvent

Thermal   X X +Fiber length retention +No use of hazardous chemical substances +better mechanical properties than mechanical approach +Matrix used to produce energy

-Recovered fiber properties highly influenced by process parameters -some processes have no recovery of matrix material

Mechanical Recycling

[edit]

The mechanical process primarily involves grinding, which breaks down composite materials into pulverulent charges and fibrous reinforcements. This method is focused on both the thermoplastic and filler material recovery; however, this process shortens the fibers dramatically. Just as with downcycled paper, the shortened fibers cause the recycled material to be weaker than the original material. There are still many industrial applications that do not need the strength of full-length carbon fiber reinforcement. For example, chopped reclaimed carbon fiber can be used in consumer electronics, such as laptops. It provides excellent reinforcement of the polymers used even if it lacks the strength-to-weight ratio of an aerospace component.[48]

Electro fragmentation

[edit]

This method consists in shredding CFRP by pulsed electrical discharges. Initially developed to extract crystals and precious stones from mining rocks, it is now expected to be developed for composites. The material is placed in a vessel containing water and two electrodes. The high voltage electrical pulse generated between the electrodes (50-200 kV) fragments the material into smaller pieces.[49] The inconvenient of this technique is that the energy consumed is 2.6 times the one of a mechanical route making it not economically competitive in terms of energy saving and needs further investigation.

Thermal Recycling

[edit]

Thermal processes include several techniques such as incineration, thermolysis, pyrolysis, gasification, fluidized bed processing, and cement plant utilization. This processes imply the recovery of the fibers by the removal of the resin by volatilizing it, leading to by-products such as gases, liquids or inorganic matter.[50]

Oxidation in fluidized bed

[edit]

This technique consists in exposing the composite to a hot and oxygen-rich flow, in which it is combusted (450–550 °C, 840–1,020 °F) . The working temperature is selected in function of the matrix to be decomposed, to limit damages of the fibers. After a shredding step to 6-20 mm size, the composite is introduced into a bed of silica sand, on a metallic mesh, in which the resin will be decomposed into oxidized molecules and fiber filaments. These components will be carried up with the air stream while heavier particles will sink in the bed. This last point is a great advantage for contaminated end-of-life products, with painted surfaces, foam cores or metal insert. A cyclone enables the recovery of fibers of length ranging between 5 and 10 mm and with very little contamination . The matrix is fully oxidized in a second burner operating at approximatively 1,000 °C (1,850 °F) leading to energy recovery and a clean flue gas.[51]

Chemical Recycling

[edit]

The chemical recycling of CFRPs involves using a reactive solvent at relatively low temperatures (below 350°C) to break down the resin while leaving the fibers intact for reuse. The solvent degrades the composite matrix into smaller molecular fragments (oligomer), and depending on the chosen solvent system, various processing parameters such as temperature, pressure, and catalysts can be adjusted to optimize the process. The solvent, often combined with co-solvents or catalysts, penetrates the composite and breaks specific chemical bonds, resulting in recovered monomers from the resin and clean, long fibers with preserved mechanical properties. The required temperature and pressure depend on the type of resin, with epoxy resins generally needing higher temperatures than polyester resins. Among the different reactive mediums studied, water is the most commonly used due to its environmental benefits. When combined with alkaline catalysts, it effectively degrades many resins, while acidic catalysts are used for more resistant polymers. Other solvents, such as ethanol, acetone, and their mixtures, have also been explored for this process.

Despite its advantages, this method has some limitations. It requires specialized equipment capable of handling corrosive solvents, hazardous chemicals, and high temperatures or pressures, especially when operating under supercritical conditions. While extensively researched at the laboratory scale, industrial adoption remains limited, with the technology currently reaching a Technology Readiness Level (TRL) of 4 for carbon fiber recycling.[52]

Dissolution Process

[edit]

The dissolution process is a method used to recover both the polymer matrix and fibers from thermoplastic composites without breaking chemical bonds. Unlike solvolysis, which involves the chemical degradation of the polymer, dissolution simply dissolves the polymer chains into a solvent, allowing for material recovery in its original form. An energy analysis of the process indicated that dissolution followed by evaporation was more energy-efficient than precipitation. Additionally, avoiding precipitation helped minimize polymer loss, improving overall material recovery efficiency. This method offers a promising approach for sustainable recycling of thermoplastic composites.[53]

Biological Recycling

[edit]

The biological process, though still under development, focuses on biodegradation and composting. This method holds promise for bio-based and agro-composites, aiming to create an environmentally friendly end-of-life solution for these materials. As research advances, biological recycling may offer an effective means of reducing plastic composite waste in a sustainable manner.[54]

Carbon nanotube reinforced polymer (CNRP)

[edit]

In 2009, Zyvex Technologies introduced carbon nanotube-reinforced epoxy and carbon pre-pregs.[55] Carbon nanotube reinforced polymer (CNRP) is several times stronger and tougher than typical CFRPs and is used in the Lockheed Martin F-35 Lightning II as a structural material for aircraft.[56] CNRP still uses carbon fiber as the primary reinforcement,[57] but the binding matrix is a carbon nanotube-filled epoxy.[58]

See also

[edit]

References

[edit]
  1. ^ a b Nguyen, Dinh; Abdullah, Mohammad Sayem Bin; Khawarizmi, Ryan; Kim, Dave; Kwon, Patrick (2020). "The effect of fiber orientation on tool wear in edge-trimming of carbon fiber reinforced plastics (CFRP) laminates". Wear. 450–451. Elsevier B.V: 203213. doi:10.1016/j.wear.2020.203213. ISSN 0043-1648. S2CID 214420968.
  2. ^ Geier, Norbert; Davim, J. Paulo; Szalay, Tibor (1 October 2019). "Advanced cutting tools and technologies for drilling carbon fibre reinforced polymer (CFRP) composites: A review". Composites Part A: Applied Science and Manufacturing. 125: 105552. doi:10.1016/j.compositesa.2019.105552. hdl:10773/36722.
  3. ^ Dransfield, Kimberley; Baillie, Caroline; Mai, Yiu-Wing (1 January 1994). "Improving the delamination resistance of CFRP by stitching—a review". Composites Science and Technology. 50 (3): 305–317. doi:10.1016/0266-3538(94)90019-1.
  4. ^ a b Kudo, Natsuko; Fujita, Ryohei; Oya, Yutaka; Sakai, Takenobu; Nagano, Hosei; Koyanagi, Jun (30 June 2023). "Identification of invisible fatigue damage of thermosetting epoxy resin by non-destructive thermal measurement using entropy generation". Advanced Composite Materials. 33 (2): 233–249. doi:10.1080/09243046.2023.2230687. ISSN 0924-3046.
  5. ^ Kopeliovich, Dmitri. "Carbon Fiber Reinforced Polymer Composites". Archived from the original on 14 May 2012.. substech.com
  6. ^ Corum, J. M.; Battiste, R. L.; Liu, K. C; Ruggles, M. B. (February 2000). "Basic Properties of Reference Crossply Carbon-Fiber Composite, ORNL/TM-2000/29, Pub57518" (PDF). Oak Ridge National Laboratory. Archived (PDF) from the original on 27 December 2016.
  7. ^ a b c Courtney, Thomas (2000). Mechanical Behavior of Materials. United States of America: Waveland Press, Inc. pp. 247–249. ISBN 1-57766-425-6.
  8. ^ a b c d e f Chawla, Krishan (2013). Composite Materials. United States of America: Springer. ISBN 978-0-387-74364-6.
  9. ^ a b Liao, Binbin; Wang, Panding; Zheng, Jinyang; Cao, Xiaofei; Li, Ying; Ma, Quanjin; Tao, Ran; Fang, Daining (1 September 2020). "Effect of double impact positions on the low velocity impact behaviors and damage interference mechanism for composite laminates". Composites Part A: Applied Science and Manufacturing. 136: 105964. doi:10.1016/j.compositesa.2020.105964. ISSN 1359-835X.
  10. ^ Ma, Binlin; Cao, Xiaofei; Feng, Yu; Song, Yujian; Yang, Fei; Li, Ying; Zhang, Deyue; Wang, Yipeng; He, Yuting (15 February 2024). "A comparative study on the low velocity impact behavior of UD, woven, and hybrid UD/woven FRP composite laminates". Composites Part B: Engineering. 271: 111133. doi:10.1016/j.compositesb.2023.111133. ISSN 1359-8368.
  11. ^ Aminakbari, Nariman; Kabir, Mohammad Zaman; Rahai, Alireza; Hosseinnia, Amirali (1 January 2024). "Experimental and Numerical Evaluation of GFRP-Reinforced Concrete Beams Under Consecutive Low-Velocity Impact Loading". International Journal of Civil Engineering. 22 (1): 145–156. Bibcode:2024IJCE...22..145A. doi:10.1007/s40999-023-00883-9. ISSN 2383-3874.
  12. ^ Ray, B. C. (1 June 2006). "Temperature effect during humid ageing on interfaces of glass and carbon fibers reinforced epoxy composites". Journal of Colloid and Interface Science. 298 (1): 111–117. Bibcode:2006JCIS..298..111R. doi:10.1016/j.jcis.2005.12.023. PMID 16386268.
  13. ^ Almudaihesh, Faisel; Holford, Karen; Pullin, Rhys; Eaton, Mark (1 February 2020). "The influence of water absorption on unidirectional and 2D woven CFRP composites and their mechanical performance". Composites Part B: Engineering. 182: 107626. doi:10.1016/j.compositesb.2019.107626. ISSN 1359-8368. S2CID 212969984. Archived from the original on 1 October 2021. Retrieved 1 October 2021.
  14. ^ Guzman, Enrique; Cugnoni, Joël; Gmür, Thomas (May 2014). "Multi-factorial models of a carbon fibre/epoxy composite subjected to accelerated environmental ageing". Composite Structures. 111: 179–192. doi:10.1016/j.compstruct.2013.12.028.
  15. ^ Yari, Mehdi (24 March 2021). "Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced Polymers". corrosionpedia.com. Archived from the original on 24 June 2021. Retrieved 21 June 2021.
  16. ^ "How is it Made". Zoltek. Archived from the original on 19 March 2015. Retrieved 26 March 2015.
  17. ^ Syed Mobin, Syed Mobin; Azgerpasha, Shaik (2019). "Tensile Testing on Composite Materials (CFRP) with Adhesive" (PDF). International Journal of Emerging Science and Engineering. 5 (12): 6. Archived (PDF) from the original on 21 August 2022. Retrieved 21 August 2022 – via IJESE.
  18. ^ Glass Companies, Molded Fiber (2018), Technical Design Guide for FRP Composite Products and Parts (PDF), vol. 1, p. 25, archived from the original (PDF) on 21 August 2022, retrieved 21 August 2022
  19. ^ Unknown, Chris (22 January 2020). "Composite Manufacturing Methods". Explore Composites!. Archived from the original on 21 August 2022. Retrieved 21 August 2022.
  20. ^ "Cutting of Fiber-Reinforced Composites: Overview". Sollex. 6 March 2025. Retrieved 31 March 2025.
  21. ^ "Taking the lead: A350XWB presentation" (PDF). EADS. December 2006. Archived from the original on 27 March 2009.
  22. ^ "AERO – Boeing 787 from the Ground Up". Boeing. 2006. Archived from the original on 21 February 2015. Retrieved 7 February 2015.
  23. ^ Pora, Jérôme (2001). "Composite Materials in the Airbus A380 – From History to Future" (PDF). Airbus. Archived (PDF) from the original on 6 February 2015. Retrieved 7 February 2015.
  24. ^ Machado, Miguel A.; Antin, Kim-Niklas; Rosado, Luís S.; Vilaça, Pedro; Santos, Telmo G. (November 2021). "High-speed inspection of delamination defects in unidirectional CFRP by non-contact eddy current testing". Composites Part B: Engineering. 224: 109167. doi:10.1016/j.compositesb.2021.109167.
  25. ^ Machado, Miguel A.; Antin, Kim-Niklas; Rosado, Luís S.; Vilaça, Pedro; Santos, Telmo G. (July 2019). "Contactless high-speed eddy current inspection of unidirectional carbon fiber reinforced polymer". Composites Part B: Engineering. 168: 226–235. doi:10.1016/j.compositesb.2018.12.021.
  26. ^ Antin, Kim-Niklas; Machado, Miguel A.; Santos, Telmo G.; Vilaça, Pedro (March 2019). "Evaluation of Different Non-destructive Testing Methods to Detect Imperfections in Unidirectional Carbon Fiber Composite Ropes". Journal of Nondestructive Evaluation. 38 (1). doi:10.1007/s10921-019-0564-y. ISSN 0195-9298.
  27. ^ Guzman, Enrique; Gmür, Thomas (dir.) (2014). A Novel Structural Health Monitoring Method for Full-Scale CFRP Structures (PDF) (Thesis). EPFL PhD thesis. doi:10.5075/epfl-thesis-6422. Archived (PDF) from the original on 25 June 2016.
  28. ^ "Engines". Flight International. 26 September 1968. Archived from the original on 14 August 2014.
  29. ^ Szondy, David (28 March 2025). "Airbus previews next-gen airliner with bird-inspired wings". New Atlas. Retrieved 7 April 2025.
  30. ^ "Red Bull's How To Make An F1 Car Series Explains Carbon Fiber Use: Video". motorauthority. 25 September 2013. Archived from the original on 29 September 2013. Retrieved 11 October 2013.
  31. ^ Henry, Alan (1999). McLaren: Formula 1 Racing Team. Haynes. ISBN 1-85960-425-0.
  32. ^ Howard, Bill (30 July 2013). "BMW i3: Cheap, mass-produced carbon fiber cars finally come of age". Extreme Tech. Archived from the original on 31 July 2015. Retrieved 31 July 2015.
  33. ^ Petrány, Máté (17 March 2014). "Michelin Made Carbon Fiber Wheels For Citroën Back In 1971". Jalopnik. Archived from the original on 18 May 2015. Retrieved 31 July 2015.
  34. ^ L:aChance, David (April 2007). "Reinventing the Wheel Leave it to Citroën to bring the world's first resin wheels to market". Hemmings. Archived from the original on 6 September 2015. Retrieved 14 October 2015.
  35. ^ Ismail, N. "Strengthening of bridges using CFRP composites." najif.net.
  36. ^ Rahman, S. (November 2008). "Don't Stress Over Prestressed Concrete Cylinder Pipe Failures". Opflow Magazine. 34 (11): 10–15. Bibcode:2008Opflo..34k..10R. doi:10.1002/j.1551-8701.2008.tb02004.x. S2CID 134189821. Archived from the original on 2 April 2015.
  37. ^ Pike, Carolyn M.; Grabner, Chad P.; Harkins, Amy B. (4 May 2009). "Fabrication of Amperometric Electrodes". Journal of Visualized Experiments (27). doi:10.3791/1040. PMC 2762914. PMID 19415069.
  38. ^ "ICC and Kookaburra Agree to Withdrawal of Carbon Bat". NetComposites. 19 February 2006. Archived from the original on 28 September 2018. Retrieved 1 October 2018.
  39. ^ "Carbon Technology". Look Cycle. Archived from the original on 30 November 2016. Retrieved 30 November 2016.
  40. ^ "The Perils of Progress". Bicycling Magazine. 16 January 2012. Archived from the original on 23 January 2013. Retrieved 16 February 2013.
  41. ^ "Busted Carbon". Archived from the original on 30 November 2016. Retrieved 30 November 2016.
  42. ^ Zhao, Z.; Gou, J. (2009). "Improved fire retardancy of thermoset composites modified with carbon nanofibers". Sci. Technol. Adv. Mater. 10 (1): 015005. Bibcode:2009STAdM..10a5005Z. doi:10.1088/1468-6996/10/1/015005. PMC 5109595. PMID 27877268.
  43. ^ "Carbon fibre reinforced plastic bogies on test". Railway Gazette. 7 August 2016. Archived from the original on 8 August 2016. Retrieved 9 August 2016.
  44. ^ Lomov, Stepan V.; Gorbatikh, Larissa; Kotanjac, Željko; Koissin, Vitaly; Houlle, Matthieu; Rochez, Olivier; Karahan, Mehmet; Mezzo, Luca; Verpoest, Ignaas (February 2011). "Compressibility of carbon woven fabrics with carbon nanotubes/nanofibres grown on the fibres" (PDF). Composites Science and Technology. 71 (3): 315–325. doi:10.1016/j.compscitech.2010.11.024.
  45. ^ Hans, Kreis (2 July 2014). "Carbon woven fabrics". compositesplaza.com. Archived from the original on 2 July 2018. Retrieved 2 January 2018.
  46. ^ Ali Nahran, Shakila; Saharudin, Mohd Shahneel; Mohd Jani, Jaronie; Wan Muhammad, Wan Mansor (2022). "The Degradation of Mechanical Properties Caused by Acetone Chemical Treatment on 3D-Printed PLA-Carbon Fibre Composites". In Ismail, Azman; Dahalan, Wardiah Mohd; Öchsner, Andreas (eds.). Design in Maritime Engineering. Advanced Structured Materials. Vol. 167. Cham: Springer International Publishing. pp. 209–216. doi:10.1007/978-3-030-89988-2_16. ISBN 978-3-030-89988-2. S2CID 246894534.
  47. ^ "Polyamid CF Filament – 3D Druck mit EVO-tech 3D Druckern" [Polyamide CF Filament – 3D printing with EVO-tech 3D printers] (in German). Austria: EVO-tech. Archived from the original on 30 April 2019. Retrieved 4 June 2019.
  48. ^ Schinner, G.; Brandt, J.; Richter, H. (1 July 1996). "Recycling Carbon-Fiber-Reinforced Thermoplastic Composites". Journal of Thermoplastic Composite Materials. 9 (3): 239–245. doi:10.1177/089270579600900302. ISSN 0892-7057.
  49. ^ Roux, Maxime; Eguémann, Nicolas; Dransfeld, Clemens; Thiébaud, Frédéric; Perreux, Dominique (1 March 2017). "Thermoplastic carbon fibre-reinforced polymer recycling with electrodynamical fragmentation: From cradle to cradle". Journal of Thermoplastic Composite Materials. 30 (3): 381–403. doi:10.1177/0892705715599431. ISSN 0892-7057.
  50. ^ Bernatas, Rebecca; Dagréou, Sylvie; Despax-Ferreres, Auriane; Barasinski, Anaïs (2021). "Recycling of fiber reinforced composites with a focus on thermoplastic composites". Cleaner Engineering and Technology. 5: 100272. Bibcode:2021CEngT...500272B. doi:10.1016/j.clet.2021.100272.
  51. ^ Naqvi, S. R.; Prabhakara, H. Mysore; Bramer, E. A.; Dierkes, W.; Akkerman, R.; Brem, G. (1 September 2018). "A critical review on recycling of end-of-life carbon fibre/glass fibre reinforced composites waste using pyrolysis towards a circular economy". Resources, Conservation and Recycling. 136: 118–129. Bibcode:2018RCR...136..118N. doi:10.1016/j.resconrec.2018.04.013. ISSN 0921-3449.
  52. ^ Zhang, Jin; Chevali, Venkata S.; Wang, Hao; Wang, Chun-Hui (15 July 2020). "Current status of carbon fibre and carbon fibre composites recycling". Composites Part B: Engineering. 193: 108053. doi:10.1016/j.compositesb.2020.108053. ISSN 1359-8368.
  53. ^ Cousins, Dylan S.; Suzuki, Yasuhito; Murray, Robynne E.; Samaniuk, Joseph R.; Stebner, Aaron P. (1 February 2019). "Recycling glass fiber thermoplastic composites from wind turbine blades". Journal of Cleaner Production. 209: 1252–1263. Bibcode:2019JCPro.209.1252C. doi:10.1016/j.jclepro.2018.10.286. ISSN 0959-6526.
  54. ^ Bernatas, Rebecca; Dagreou, Sylvie; Despax-Ferreres, Auriane; Barasinski, Anaïs (1 December 2021). "Recycling of fiber reinforced composites with a focus on thermoplastic composites". Cleaner Engineering and Technology. 5: 100272. Bibcode:2021CEngT...500272B. doi:10.1016/j.clet.2021.100272. ISSN 2666-7908.
  55. ^ "Zyvex Performance Materials Launch Line of Nano-Enhanced Adhesives that Add Strength, Cut Costs" (PDF) (Press release). Zyvex Performance Materials. 9 October 2009. Archived from the original (PDF) on 16 October 2012. Retrieved 26 March 2015.
  56. ^ Trimble, Stephen (26 May 2011). "Lockheed Martin reveals F-35 to feature nanocomposite structures". Flight International. Archived from the original on 30 May 2011. Retrieved 26 March 2015.
  57. ^ Pozegic, T. R.; Jayawardena, K. D. G. I.; Chen, J-S.; Anguita, J. V.; Ballocchi, P.; Stolojan, V.; Silva, S. R. P.; Hamerton, I. (1 November 2016). "Development of sizing-free multi-functional carbon fibre nanocomposites". Composites Part A: Applied Science and Manufacturing. 90: 306–319. doi:10.1016/j.compositesa.2016.07.012. hdl:1983/9e3d463c-20a8-4826-89f6-759e950f43e6. ISSN 1359-835X. S2CID 137846813. Archived from the original on 1 October 2021. Retrieved 1 October 2021.
  58. ^ "AROVEX™ Nanotube Enhanced Epoxy Resin Carbon Fiber Prepreg – Material Safety Data Sheet" (PDF). Zyvex Performance Materials. 8 April 2009. Archived from the original (PDF) on 16 October 2012. Retrieved 26 March 2015.
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