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Koerner R.M.,Drexel University | Hsuan Y.G.,Drexel University | Koerner G.R.,Geosynthetic Institute | Gryger D.,Gannett Fleming Inc.
Geotextiles and Geomembranes | Year: 2010

The need for a geotextile to be used for protection against geomembrane puncture by stones and gravel has been recognized for many years. There are presently several methods available for selecting such geotextiles. This paper, however, focuses on the " GRI-Method" , which was originally based on short-term tests and was extended empirically for long-term performance. The reduction factor for creep behavior (RFCR) is of particular interest since its impact on the resulting geotextile design is the greatest.The paper presents results of a 10-year long creep puncture study which is configured exactly the same as was the original short-term testing program. The results indicate that the six ≈38. mm high puncturing cones result in yield of the geomembrane at pressures of 34 and 52. kPa and one even had a small break. The six 12. mm high cones at pressures of 430 and 580 kPa also resulted in geomembrane yield but only by a nominal amount and there were no breaks.As a consequence of these creep test results, the original table for creep reduction factors (RFCR) has been revised into more conservative values. In this regard, the originally published RFCR table should be replaced accordingly. © 2010 Elsevier Ltd.


Wong W.-K.,Geosynthetic Institute | Hsuan Y.,Drexel University
Transportation Research Record | Year: 2012

This paper presents the interaction between carbon black and antioxidants in high-density polyethylene. The 11 formulations prepared for this study were composed of furnace black with particle sizes of 27 and 75 nm at 2% to 5% by weight and different concentrations of antioxidants Irganox 1010 and Irgafos 168. The chemical interactions between the carbon black and the antioxidants were accelerated by elevated temperatures of 85 C in a forced-air oven. The relative amount of antioxidants retained in the samples throughout the incubation was measured using the oxidative induction time (OIT) test. The results showed that the initial OIT value increased with the weight percentage of the carbon black in the sample. A higher initial OIT value was found in the samples that had been blended with the 27-nm carbon black than in those blended with the 75-nm carbon black at the same concentration. Also, faster OIT depletion was detected in the samples that had been blended with the 27-nm carbon black than in those blended with the 75-nm carbon black at greater than 2% by weight. The carbon black-antioxidant interaction was found to be influenced by the carbon black-specific surface area and physical structure. Overall, the OIT decreased substantially faster in the samples with carbon black than in those without it. The reactions between the carbon black and the antioxidants were so strong that only a minor difference in the depletion rate was observed between the two antioxidant formulations.


Koerner R.M.,Drexel University | Koerner G.R.,Geosynthetic Institute
Journal of GeoEngineering | Year: 2011

Mechanically stabilized earth (MSE) walls reinforced by geogrids and geotextiles have seen a tremendous growth over the past thirty years. However, along with this growth has come numerous failures consisting of excessive deformation and, in some cases, actual collapse. Of the 82-cases in the authors data base, improper drainage control was the cause in 68% of them. As a result, this paper is focused on both internal drainage issues within the reinforced soil mass within the reinforced soil mass (46%) and external drainage issues around the soil mass (22%). After a brief introduction of the technology some elements of traditional design will be presented. The issue of proper versus improper methods of drainage control will then form the core of the paper. A summary and recommendations section aimed at preventing drainage problems in the future will conclude the paper.


Koerner R.M.,Drexel University | Koerner G.R.,Geosynthetic Institute
Geotechnical Testing Journal | Year: 2010

There are two performance tests available for the selection of fabrics and additives when contemplating a geotextile bag, container, or tube application. They are the "hanging bag test" and the "pillow test." Both tests are described in this paper along with data generated by their use. While both can be used for selection purposes, the advantages of the pillow test over the hanging bag test are quite compelling. Items favoring the pillow test are much smaller size, need for less dredged or slurried infill material, better field simulated orientation, and the capability of monitoring hydraulic head versus time behavior. This last item is most important since dredging pressures are always involved and the simulated behavior of the pillow test gives good insight into the anticipated behavior of the full-scale application. Copyright © 2010 by ASTM International.


Koerner G.R.,Geosynthetic Institute | Koerner R.M.,Drexel University
Geotextiles and Geomembranes | Year: 2011

It is common practice to use needle-punched nonwoven geotextiles as puncture protection for geomembranes against sharp objects like gravel or stones in either the soil above or the underlying soil/rock below. There are several design and experimental methods available for geotextile selection in this regard. None, however, directly address the type of resin or fiber from which the geotextile is made. This paper does exactly that insofar as a direct comparison of similar mass per unit area polyester (PET) versus polypropylene (PP) geotextiles are concerned. Furthermore, two types of PP geotextiles are evaluated; one made from continuous filaments and the other from staple fibers. Three different size and shaped puncture probes are used in the testing program. All three are ASTM Standards, i.e., D4833, D5495 and D6241. The test results clearly indicate that geotextiles made from PP fibers outperform those made from PET fibers at all masses evaluated. Clearly, the present trend of using PP resin for heavy nonwoven protection geotextiles seems justified on the basis of these test results. In addition, the continuous filament PP and staple fiber PP geotextiles performed equivalently over all mass ranges for the three different types of puncture tests. © 2010 Elsevier Ltd.


Koerner R.M.,Drexel University | Koerner R.M.,Geosynthetic Institute | Koerner G.R.,Geosynthetic Institute
Geotextiles and Geomembranes | Year: 2015

This paper reviews sixty-nine (69) field failures involving geotextile filters which performed unsatisfactorily and are categorized herein as failures. They are grouped into four categories; inadequate design, atypical soils, unusual permeants, and improper installation. In the first category are poor fabric selection, poor fabric design, socked drainage pipe and reversing flow conditions. In the second category are fine grained soils, gap-graded soils, dispersive clays and ochre. In the third category are sludges, turbid water, alkaline water, leachates and agricultural waste liquids. In the fourth category are lack of intimate contact and completely adhesive clogging of surfaces. While not the topic of the paper, it should be noted that, most of these same conditions are known to be troublesome to sand filters as well as to geotextile filters. © 2015 Elsevier Ltd.


Koerner R.M.,Geosynthetic Institute
Geosynthetics | Year: 2010

Robert M. Koerner reflects on the prospects for geosynthetic containment systems at Marcellus formation shale-gas drilling projects. The Marcellus shale formation is extremely thick in its central locations, about 900ft in Pennsylvania. The result is a highly fractured stratum penetrated by a long length of perforated well bore held open by the sand. At least 4,000 new oil and gas wells were drilled in Pennsylvania in 2008, more than in any other state except Texas. The U. S. Environmental Protection Agency warns against this practice because sewage plants are not designed. Thus geo-textiles, drainage materials and composites, geo-pipe, and other related products could also be involved. Lastly, the issue of liner longevity for such an application is a vexing issue for all involved, certainly the local regulatory agency. At the heart of the issue is the eventual disposal of the contaminated brine.


Koerner R.M.,Geosynthetic Institute | Koerner G.R.,Geosynthetic Institute
Geotextiles and Geomembranes | Year: 2013

Following the introduction of mechanically stabilized earth walls with metallic reinforcement in 1966, polymeric reinforced structures (both geotextile and geogrid) followed shortly thereafter. A major item that accompanied this change in reinforcement type was the nature of the backfill soil. Corrosion of metallic reinforcement was no longer an issue with polymer-related geosynthetics and thus locally available fine-grained soils were generally used in place of quarried coarse-grained gravel soil. The cost savings are obvious as are the implications for concerns over inadequate performance. While failures have occurred in both types of reinforced walls, this paper focuses only on geosynthetic reinforced walls.This data base of 171 failed mechanically stabilized earth (MSE) walls with geosynthetic reinforcement includes 44 cases of excessive deformation and 127 cases of collapse of at least part of the wall. The large majority are located in North America and in the USA in particular. The main statistical findings are as follows:. 1.96% were private (as opposed to public) financed walls2.78% were located in North America3.71% were masonry block faced4.65% were 4-12m high5.91% were geogrid reinforced; the other 9% were geotextile reinforced6.86% failed in less than four years after their construction7.61% used silt and/or clay backfill in the reinforced soil zone8.72% had poor-to-moderate compaction9.98% were caused by improper design or construction (incidentally, none (0%) were caused by geosynthetic manufacturing failures)10.60% were caused by internal or external water (the remaining 40% were caused by internal or external soil related issues)In addition to presenting this statistical data, the paper also presents opinions and recommendations in several of the above areas particularly those which are felt to be at the core of why so many these structures are exhibiting performance problems. In general, the critical issues appear to be the following;. •fine grained silt and clay soils used for the reinforced zone backfill,•poor placement and compaction of these same fine grained backfill soils,•drainage systems and utilities being located within the reinforced soil zone,•non-existing water control either behind, beneath or above the reinforced soil zone, and•improperly determined and/or assessed design details.Concern over the situation has prompted the creation of an inspector's certification program, i.e., the Geosynthetic Certification Institute's-Inspector Certification Program (GCI-ICP) expressly for MSE walls, berms and slopes using geosynthetic reinforcement. © 2013 Elsevier Ltd.


Koerner G.R.,Geosynthetic Institute
Geotechnical Special Publication | Year: 2016

This paper describes ongoing research into the monitoring of two adjacent landfill cells with different liquids management strategies at an active municipal solid waste (MSW) landfill. One is a conventional dry cell and the other is a wet, or bioreactor, cell. To understand the waste materials behavior and associated geomembrane long-term behavior, the in-situ conditions are needed and how the various parameters change over time. In this regard, measurements have been taken at both cells for approximately 20-years and are continuing. Both dry and wet cells are monitored for changes in gases, leachate, waste and geomembrane temperatures. Knowing this information will allow for making longevity predictions in regard to both solid waste degradation and geosynthetics behavior. In addition, the data gives insight so as to fine-tuning the design-by-function approach for various situations and materials. © ASCE.


Koerner R.M.,Geosynthetic Institute
Geosynthetics | Year: 2012

All municipal solid waste (MSW) landfills require a final cover system placed over the waste mass within a relatively short period of time. In the U.S. this is within about one year. This final cover is maintained by the landfill owner or operator for 30 years, called the "post-closure care period." An alternative to this traditional final cover is to use an exposed geomembrane cover for the 30-year post-closure care period and then construct the final cover. There are many advantages to this alternative strategy, which are elaborated on in this article. This article also presents both a cost comparison and a sustainability comparison between the two alternatives. These comparisons reveal that the exposed geomembrane cost alternative is 30% of a traditional cover and the carbon footprint (based upon the amount of CO2 generated) for the exposed geomembrane alternative is only 18% of the traditional cover. A closing section is also included as to landfill strategies going beyond 30 years. A recent GSI survey shows that state regulatory agencies are uncertain in this regard. Two alternatives appear as follows: (a) If the traditional final cover is compromised because of the waste's large total and differential settlement, it must be removed; additional waste can be added, and then must be reconstructed. (b) When the exposed geomembrane cover has degraded it must be removed; additional waste can be added, and then a traditional final cover installed. These are, of course, site-specific situations and other possibilities exist as well. It appears as though a dialogue among the parties involved about various possible strategies beyond the 30-year post-closure care period would be worthwhile.

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