Talk:Cellular confinement

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Vandalism by person's affiliated with or sympathetic to a specific commercial company (April 10, 2012)[edit]

Entire sections were erased and promotions for the PRESTO company were inserted, either by someone affiliated or sympathatic to the company and and intended to erase valid, verifiable, netural, referenced scientific material made by a commmercial competitor of this company. The ClueBot NG robot worked beautifully and restored the previous version. — Preceding unsigned comment added by YSchary (talkcontribs) 11:23, 21 May 2012 (UTC)

Disruptive Editing and Blatant Abuse of Wikipedia policies (Dec 29, 2012)[edit]

In another round of editing by an unidentified editor 67.202.219.216, an entire section of content - verifiable and referenced almost sentence by sentence - has been completely deleted and replaced by biased, non-neutral and entirely un-verified content. No attempt was made by this editor via the discussion pages to document the reasons for the radical "workover". Based on inappropriate over-referencing of a commerical interest(presto) to the complete eradication of a competing category of material (and company), is hard to avoid the suspician that external business "sympathies" or "interests" are behind, what can only be referred to as a "hatchet job". The editing abuses violate multiple Wikipedia guideliness, warranting esclation procedures to deal with this disruptive content, behavior and editor. This new unverifiable version will be deleted and the previous Wikipedia-compliant version is being restored. The previous version described why one material has advantages over the other and was fully documented with verifiable references.

LINE BY LINE REBUTTAL OF DISRUPTIVE EDITING[edit]

History of Cellular Confinement[edit]

This section is biased toward one particular company and needs to be edited to make it a more neutral point of a view.

Recent Developments in Cellular Confinement Technology[edit]

<Entire previous version of section with neutral referenced content deleted in its entirety - no attempt was made to integrate the new content or relate to the verifiable statements.>

1. "Virgin HDPE is the most commonly used material for geocells, because leading researchers have emphasised its suitability for long term applications." REPLY <While HDPE is the most common material, the claim that "leading researchers have emphasized its suitability for long term" is not verified. All research that I am familiar states exactly the opposite.>

2. "Large thermal contraction and expansion of cells due to daily seasonal temperature changes are not a factor due to the fact that cellular confinement is always placed in the ground." REPLY <Maintaining the geocell geometry is critical to its performance. Whereas ALL polymers expand and shrink in response to temperature changes, this thermal cycling of a geocell is a very relevant factor, particularly if the "ground" is in Arctic or equatorial regions. Small deformations in the geometry can lead to a loss of confinement, and damage a pavement system.

3."Presto Products, the originator and longest standing manufacturer of the material have indicated that not one installation has failed out of thousands of installations over the span of more than three decades from the effects of creep or stress cracking." REPLY <The description of Presto products sounds a commercial plug and is innacurate. The statement of no failures is a wildly unverified statement (and I know of at least one glaring failure). Regarding creep - all polymers suffer creep - its just a question of degree and time, and at one point the geocells lose their dimensional stability. A main point of the previous (deleted) version was that in "traditional" erosion protection applications loading is not heavy, and these parameters are less critical, whereas in large earth retention structures and in load support of paved roads, rails and ports these are very relevant factors.>

4. "Unfortunately, competitive desires to circumnavigate time tested standards of use of geocells <besides the unprofessional language used here, there are valid opposing opinions as to the validity of current testing standards, as evidenced by the US standards ASTM technical committee 35 currently developing new standards for geocells> have created a false science" <because its something new and different it does not deserve to being labelled with something as silly as 'false science'?> "whereby thermal expansion coefficient and creep reduction factors, and higher tensile stiffness and strength is marketed as real factors" <these are well-known, non-controversial, standard engineering factors used for testing in a variety of industries, and are referenced in many studies relating to geosynthetics and geocells> "using in most that are relevant when indeed it is only a trojan horse for marketing of less suitable feed stock" <inappropriate and unacceptable language>. "Virgin resin is still the most desireable of materials" <this statement is so incomplete it is hard to argue with>

5. "Laboratory studies, full-scale moving wheel tests, and field demonstrations have long since proven cellular confinement with virgin HDPE to have superior perfomance." <This is actually palgerizes an actual statement from the previous version that was twisted to fit their agenda, ignoring the reference from a scholarly article summarizing years of research on a different material (novel polymeric alloy). The statement is also somewhat problematic, since these tests refer to actual tests of a manufactured geocell product (and comparison between the HDPE traditional based geocells and the new novel polymeric alloy based geocells and not virgin chemicals used to produce them. The original statement was backed up by over 20 published research articles based on years of research by one of the world's renown experts in the field.>

Application vs. Long-term Performance[edit]

"HDPE-based geocells have been successfully installed in thousands of projects worldwide." <this is the first non-biased statement> "Walls stand outside Presto Products' original manufacturing site, south facing and are tested every year for decades with no signifcant degredation found despite being exposed to the harsh Wisconsin year round elements." <Not sure why 1 project from thousands is mentioned and why it is actually a wall at the Presto, a specific commercial interest. There is no documentation of the claim. Nor is the height and loading of the wall mentioned which might be quite low and therefore less relevant.> UV, frost, heat, moisture, and other natural insitu effects have little effect on virgin HDPE weld strength or strip strength. <dont' know if this refers to the one specific wall or in general nor is it verifiable>

In short an entire discussion of the evolution of geocell applications in the previous version, in terms of slope protection vs. long term load support possibilities has been deleted unjustifiably.

The Development of Standards for Testing Geocells[edit]

An entire section describing why the current standards for geocells were based on old concepts from the world of 2D and how these standards ignore modern developments used to test plastic polymer in other industries was jettisoned. No explanation, reason, rebuttal, etc.

The Impact of Temperature on Performance[edit]

Another section that was simply deleted with no attempt made to relate to the contents.


YSchary (talk) 15:44, 29 December 2011 (UTC)


Proposed Changes Posted on Talk Page for Discussion (June, 2011)[edit]

General Statement[edit]

Editing changes made by editor 76.199.161.180 to the section on HDPE To New Polymer Materials are biased, non-verifiable and in direct violation of the Wikipedia NPOV policy. The section on HDPE To New Polymer Materials was deleted in its entirety by editor 76.199.161.180. This editor also deleted neutral content and citations, as well as casting unprofessional and unsubstantiated aspirations on properly referenced material (as well as deleting the specific material and references) in direct violation of the Wikipedia guidelines. These NPOV content changes and deletions seem to be a response by one company to new developments in the field by a competitor.

The following content documents the existing text of the section on HDPE To New Polymer Materials as of June 22, 2011 detailing why the content is biased and not neutral. The proposed ammended section is posted at the bottom.

From HDPE to new polymeric alloys[edit]

Non-neutral content from 76.199.161.180 edited version

Competition in the business has led to questionable assertions to differentiate cellular confinement materials. While traditional HDPE based geocells may deform in small measure plastically over time, questions about their effectiveness for long-term reinforcement are for the most part overstated,because although geocells from advanced polymeric alloys can provide stiffness and confinement,they do not enable new, critical applications...

ANALYSIS OF LACK OF NEUTRALITY IN STATEMENT:

  • Statement casts aspirations on fair competition in market.
  • Statement uses faulty logic: it acknowledges “HDPE geocell deform …over time”, but addresses doubts about the “long-term reinforcement” issue, by acknowledging that “advanced polymeric alloys are stiffer and stronger”, but then stating unsubstantiated opinion that “they do not enable new applications”.
  • So-called “Assertions” were propoerly documented in the previous version that the editor deleted. 76.199.161.180 stated his/her opinion rather than relate to published research by leading researchers in the field.
  • Why are “questions” about the effectiveness of HDPE for the most part “overstated”? – the long-term effectiveness is in question and the question should be addressed. Instead of discussing the properly referenced research, the editor erased referenced research work and gave dismissive and misleading opinion (that new alternatives don’t have new applications).
  • Negates the possibility that new polymeric alloys that have been developed by a competitor may have a different lifespan than existing HDPE based geocells.
  • Not factual by categorically denying that such polymeric alloys may enable new, critical applications.
  • While development claims were attributed to a specific company, this author has deleted the one link to that of a competitor.

SUGGESTED NEUTRAL STATEMENT: See rewritten section below on Recent Developments in Cellular Confinement Technology


Non-neutral content from 76.199.161.180 edited version

Tens of thousands of installations without failure are in service - many for over thirty years.

ANALYSIS OF LACK OF NEUTRALITY IN STATEMENT:

  • Generalization - ignores the enormous difference between different types of geocell applications
  • Misleading – longevity depends on project conditions, certain types of projects are exposed to extreme conditions where others are not.
  • Differentiation - requirements of slope and channel applications differ considerably from long-term project of retaining walls and asphalt pavements.
  • Non-verifiable opinion - Tens of thousands of installations without failure is a statistic that is dubious and cannot be verified

SUGGESTED NEUTRAL STATEMENT: See new section below on Application vs. Lifespan


Non-neutral content from 76.199.161.180 edited version

However, newcomers to the industry are attempting to create concerns about long standing standards of performance.

ANALYSIS OF LACK OF NEUTRALITY IN STATEMENT:

  • Name calling – painting established veteran players in the geocell field as newcomers is unacceptable.
  • “Long-standing standards of performance” are inadequate in the first place. These are based on basic virgin material properties/composition, which do not give a direct indicator of performance in the field, when subject to loading, environmental factors and time
  • It is professionally and scientifically feasible to propose new testing standards specifically developed for geocells (for example of actual geocell sections, and not small strips)
  • PRS decided that HDPE is insufficient material for its own product and decided to invest in development of a new generation of material.


Non-neutral content from 76.199.161.180 edited version

The untested systems have focused on the development of advanced polymeric alloys that claim exponentially higher fatigue limits and resistance to environmental factors, particularly high temperatures well over 120°F (49°C )degrees F. Such properties mean very little as cellular confinement never reach such high temperatures as they are buried into the earth in their applications. Of course, it is understood by knowledgeable Engineers that even in the heat of the summer day, the earth remains relatively cool.

ANALYSIS OF LACK OF NEUTRALITY IN STATEMENT:

  • Language is inappropriate, unprofessional, incorrect, and condescending.
  • “Untested” systems – clearly false accusation. * Thermal performance and resistance to environmental factors was tested by certified laboratories utilizing sophisticated and industry-wide methods. NPA material was tested by DMA (Dynamic Mechanical Analysis), which analyzes storage modulus (elasticity), loss modulus (plasticity) and loss tangent (an index for major change in mechanical properties, calculated as ratio between loss modulus and storage modulus) as function of temperature in the range -150°C to +150°C.
  • Effective range of NPA by internationally certified laboratories was shown to be ≤-50°C (_122°F) to ≥+50°C (+122°F).
  • HDPE exhibits unstable and unpredictable creep behavior above this range.
  • Testing by certified laboratories of resistance to environmental factors such as oxidation showed that stabilizers in NPA could be up to 100x higher than stabilizers used in HDPE
  • High temperatures on geocells can be achieved if geocells are dark, exposed and subject to strong solar radiation.
  • Cellular confinement although mostly underground may be exposed to high temperatures in: earth retention fascia, slope/channel/geomembrane protection where soil infill is incomplete or may have eroded in isolated cells, under the asphalt pavement during hot and even warm mix asphalt paving process (100-150°C); base layer of unpaved desert roads, where soil cover may have blown off
  • Although earth remains relatively cool, in certain instances soil surface temperatures in deserts can exceed 70°C and have even been reported reach 80°C (Hadley 1970; Körner & Cochrane 1983)
  • Current standards test materials only at ambient temperatures and ignore the impact of temperature on performance, particularly long-term performance.
  • Well known principle in polymer chemistry that temperature is used to simulate (or predict?) accelerated creep rate of polymers for lifespan of over 100 years (ASTM D6992)
  • Well known principle in polymer chemistry that storage modulus (plasticity) for geocells is dependent upon temperature.
  • Sophisticated analysis of performance by DMA enables determination of effective temperature service range.

SUGGESTED NEUTRAL STATEMENT: See the section below on The Development of Standards for Testing Geocells and The Impact of Temperature on Performance


Non-neutral content from 76.199.161.180 edited version

Therefore, The so called alloys have no real additional benefit beyond those made of HDPE. Further, such "alloys" are made from less expensive materials and allow for less flexibility of finished product creating some problems for installations crews in cool climates.

ANALYSIS OF LACK OF NEUTRALITY IN STATEMENT:

  • To state “the so called alloys” have no real additional benefit beyond those made of HDPE is biased, unsubstantiated and not factual.
  • So-called alloy is Neoloy®, a polymeric nano-composite alloy based on dimensionally stable polymer nano-fibers (polyester or nylon) in a polyolefin matrix, developed by PRS after many years of research, development and testing. The engineering properties and comparison with HDPE-based geocells can be measured by accepted testing procedures and verifiable scientific testing methods.
  • Alloys involve more expensive materials (polyster) and time-consuming processes, top-of-line equipment
  • Lack of flexibility – NPA is characterized by flexibility at low temperatures similar to HDPE with elastic behavior similar to engineering thermoplastics.

NEW CONTENT TO BE POSTED[edit]

Recent Developments in Cellular Confinement Technology[edit]

Despite the effectiveness of the geocell technology, particularly in slope and channel applications, its use in base reinforcement of paved roads and railways was limited due to the lack of design methods, lack of advanced research in the last two decades and limited understanding of the reinforcement mechanisms (Yuu, et al. 2008).)[1] Recent research in the last few years on geocell reinforcement for roadway applications has been conducted at the University of Kansas as well as at other leading research institutes, to understand the mechanisms and influencing factors of geocell reinforcement, evaluate its effectiveness in improving roadway performance, and develop design methods for roadway applications (Han, et al. 2011).[2] This research was conducted on geocells manufactured from a novel polymeric alloy (NPA), called Neoloy®, developed by PRS[3]. This novel polymeric alloy is a composite polymeric alloy based on nano-fibers (polyester and nylon) in a polyolefin matrix. The NPA combines the desired properties of polyethylene and polyester, thus enabling a more effective use of geocells in new critical applications, such as reinforcement for earth retention, load support in pavements and railroads and more (Leshchinsky, et al, 2009).[4]

While HDPE is the commonly used material for geocells, it may not be suitable for long term applications. Large thermal contraction and expansion of cells due to daily seasonal temperature changes combined with high intrinsic thermal coefficient of the infill material could lead to progressive failure. Stress cracking of exposed facing could occur in low temperatures. Low; stiffness and strength may lead to significant creep having poor long-term stability (Leshchinsky, et al, 2009). )[5] Research demonstrated that NPA geocells have a lower thermal expansion coefficient and creep reduction factor, and higher tensile stiffness and strength than HDPE geocells.(Thakur, et al, 2010)[6]; and NPA increased the bearing capacity and reduced settlement of compacted sand base courses significantly more than geocells fabricated from HDPE (Pokharel, 2011, et al)[7].

Laboratory plate loading tests on geocells showed that the performance of geocell-reinforced bases depends on the elastic modulus of the geocell. The geocell with a higher elastic modulus had a higher bearing capacity and stiffness of the reinforced base. Geocells made from NPA were found significantly better in ultimate bearing capacity, stiffness, and reinforcement relative to geocells made from HDPE (Pokharel, et al, 2009).[8] NPA geocells showed better creep resistance and better retention of stiffness and creep resistance particularly at elevated temperatures, verified by plate load testing, numerical modeling and full scale trafficking tests (Pokharel, et al 2011).[9]

Laboratory studies, full-scale moving wheel tests, and field demonstrations (cosponsored by US DOT Department_of_Transportation as well as state DOTs) in this comprehensive research program have demonstrated clear benefits of NPA (novel polymeric alloy geocell reinforcement in terms of increased stiffness and bearing capacity, wider stress distribution, reduced permanent deformation, and prolonged roadway life. Field demonstrations have shown that the NPA geocell is a viable option to reinforce silty sand in roadway construction. The design methods developed and calibrated in this research can help engineers design future roadway applications using geocells (Han, et al. 2011).[10]

In fact this close cooperation and iterative research and development process between private industry and academia was cited by the editor of Geosynthetics magazine, as: “an example of how product development for the geosynthetics industry can be done effectively… and can further advance the geosynthetics industry into the 21st century with much success.”[11]

Application vs. Long-term Performance[edit]

HDPE-based geocells have been successfully installed in thousands of projects worlwide. However, it is incumbent to differentiate between low load applications, such as slope and channel applications, and new heavy-duty applications, such as in the base layer of asphalt pavement structures of heavily trafficked motorways and highways. While, the vast majority of polymeric materials used in geocells creep over time and under loading, the question is; what is the rate of degradation, under what conditions, and how this will impact performance and/or fail? For example, the lifespan of geocells in slope protection projects with vegetative surface cover is less critical as established vegetative growth and root interlock stabilizes the slope soil mass. This in effect compensates for any long-term loss of confinement in the geocells. Similarly, load support applications for low volume roads that are not subject to heavy loading, are often of limited design life; therefore any minor loss of performance is tolerable. However, in critical applications such as reinforcement of the structural layer of asphalt highway pavements, long term dimensional stability is critical. The required design life for such roads under heavy traffic loads is typically 20-25 years, which require verifiable long-term durability.

The Development of Standards for Testing Geocells[edit]

Until recently, standards and testing methods for geocells have not kept pace with the many developments in the fields of material sciences and polymer chemistry. Scientific techniques for testing, verification and quality assurance of plastics, such as TMA - Thermomechanical analysis, DMA - Dynamic Mechanical Analysis, Stepped Isothermal Method (SIM) and CTE - Coeffecient of Thermal expansion. These methods are particularly suited for predicting long-term behavior, accumulated plastic strain in a geosynthetic under loading under different mechanical stresses, frequencies and temperatures. These methods are supported by ASTM and ISO and widely accepted testing methods used by the pipe, automobile, electronic, military, security and construction industries. Current testing standards for geocells are based on tests developed for 2D planar geosynthetics. These do not fully reflect the composite behavior of 3D geometry in soil, or test long-term parameters such as: dynamic loading, permanent plastic deformation, effect of temperatures, environmental durability, etc. Therefore, new standards for geocells were proposed and under discussion by leading experts in geosynthetics in ASTM technical committee D-35. The goal is to set new industry standards that more accurately reflect 3D geocell geometry and material performance in the field rather than lab tests of individual strips and virgin materials that are used by most manufacturers today.

The Impact of Temperature on Performance[edit]

Even though geocells are installed underground it is a well known thermoplastic principle that temperature affects performance. Geosynthetics used in critical applications, such as geomembranes, routinely utilize accelerated test methods, which use temperature to stimulate aging over time to evaluate their mechanical durability. Unfortunately, ASTM/ISO procedures commonly utilized in other industries to evaluate performance at elevated temperatures, oxidation/UV resistance parameters (OIT/HPOIT), etc., have not been adopted by the geocell industry. This is due in part to the fact that in the past, HDPE geocells were used in the subbase/subgrade interface and the impact of thermal temperatures were of less concern. However, newly developed stronger and stiffer NPA geocells enable the use of geocells in the upper base layer of structural pavements underneath the asphalt layer. In this critical application, long-term performance factors, such as the impact of temperature on long-term performance are more critical.
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