PRS – Summary Published TechnicalPapers & International Research I Neoweb Reinforcement Research and Full Scale Trafficking Testing (Han J., et al, University of Kansas, USA) About Dr Jie Han (head researcher) Dr Han is a world leading geotechnical researcher at the University of Kansas His research focused on geosynthetics, earth-retaining structures, ground improvement, pile foundations, and pavement design, including research in Japan and China Dr Han has published over 150 technicalpapers and is a member of several technical committees and leading editorial boards Han, J., Pokharel, S.K., Parsons, R L., Leshchinsky, D., and Halahmi, I (2010) Effect of Infill Material on the Performance of Geocell-reinforced Bases, 9th International Conference on Geosynthetics, ICG 2010, Brazil, May 2327 Plate load tests proved how Neoloy-based Neoweb significantly improved the performance of inferior quality infill materials, including poorly-graded Kansas River sand, quarry waste and well graded AB-3 aggregate, particularly when compared to unreinforced bases Han, J., Yang, X.M., Leshchinsky, D., and Parsons, R.L (2008) “Behavior of Geocell-Reinforced Sand under a Vertical Load,” Journal of Transportation Research Board, 2045, 95-101 Despite the effectiveness of Neoweb geocells, their acceptance for base reinforcement of roads was not widespread due to the lack of design methods, and inadequate understanding of its load transfer mechanisms This study was designed to evaluate the impact of three-dimensional cellular structure in order to model the load transfer mechanisms between 3D geocells and soil Pokharel, S.K , Han J., Leshchinsky, D., Parsons, R.L., Halahmi, I (2009) “Experimental Evaluation of Influence Factors for Single Geocell-Reinforced Sand, Transportation Research Board (TRB) Annual Meeting, Washington, D.C., January 11-15 These tests investigated the effect of Neoweb shape and type on the bearing capacity and reinforcement mechanisms The results showed that the Neoloy-based Neoweb geocells increased the bearing capacity and stiffness and reduced settlement of the compacted sand base course significantly more than geocells fabricated from HDPE (high-density polyethylene) Han, J., S.K Pokharel, Yang, X., Parsons, R L., Leshchinsky, D (2010) Accelerated Pavement Testing Of GeocellReinforced Bases, Preliminary Research Report Submitted to PRS, June 10 The research program was aimed to significantly advance applications of geocells as base reinforcement, provide methods for geotechnical and highway engineers to properly design geocell-reinforced bases The report summarizes the conclusions of the experiments on geocell-reinforced bases over soft subgrade using Accelerated pavement testing (APT) facility at Kansas State University Pokharel, S.K (2010) Experimental Study on Geocell-Reinforced Bases under Static and Dynamic Loading, PhD dissertation, Civil, Environmental, and Architectural Engineering and Graduate Faculty of the University of Kansas Experimental studies were performed on Neoloy-based Neoweb (NAP) geocells using medium and large scale plate loading tests and full-scale moving wheel tests The results demonstrated clear benefits of Neoweb reinforcement in terms of increased stiffness and bearing capacity, wider stress distribution and reduced Technical References 1/6 3-Mar-11 permanent deformation In addition the studied proposed and verified a design method for Neoloy-based Neoweb reinforced granular bases for unpaved roads Yang, X (2010) Numerical Analyses of Geocell-Reinforced Granular Soils under Static and Repeated Loads, PhD dissertation, Civil, Environmental, and Architectural Engineering and Graduate Faculty of the University of Kansas Three-dimensional numerical models were developed in this study to simulate the behavior of Neoloy-based Neoweb (NAP) reinforced soil under static and repeated loads A mechanistic-empirical model was developed for Neoloy-based Neoweb geocells -reinforced soil under repeated loads This model was developed based on the stress-dependent response model in the current mechanistic-empirical pavement design guide (MEPDG) The mechanistic-empirical design methods for paved and unpaved roads with geocell-reinforced bases were also described Pokharel, S.K., Han, J., Manandhar, C., Yang, X.M., Leshchinsky, D., Halahmi, I., and Parsons, R.L (2011) “Accelerated Pavement Testing of Geocell-Reinforced Unpaved Roads over Weak Subgrade.” Accepted for Journal of Transportation Research Board, the 10th International Conference on Low-Volume Roads, July 24-27, Lake Buena Vista, Florida, USA Full-scale trafficking tests were conducted at the Accelerated Pavement Testing facility with different types of infill materials including AB3 aggregate, quarry waste (QW), and Recycled Asphalt Pavement (RAP) base courses over A-7-6 clay subgrade The test results demonstrated that Neoloy-based Neoweb reinforcement improved the performance of unpaved AB3 and RAP sections in terms of rut depth and angle of stress distribution compared to the unreinforced section The QW section also showed better performance Yang X.M., Han, J., Pokharel, S.K., Manandhar, C., Parsons, R.L., Leshchinsky D., and Halahmi, I (2010) “Accelerated Pavement Testing of Unpaved Roads with Geocell-Reinforced Sand Bases.” Submitted for publication This paper presents the findings from an accelerated pavement test (APT) on unpaved road sections involving Neoweb reinforcement of sand bases Test results demonstrated that the Neoloy-based Neoweb had a significant effect in improving the stability of unpaved roads and reducing the permanent deformation The geocellreinforced sand layer behaved equivalently to high-quality A-1 aggregate of the same thickness Thakur, J.K., Han, J., Leshchinsky D., Halahmi, I., and Parsons, R.L (2010), “Creep Deformation of Unreinforced and Geocell-reinforced Recycled Asphalt Pavements.” Submitted for publication Recycled Asphalt Pavement (RAP) is a removed and reprocessed pavement material containing asphalt and aggregates Although RAP can be used as a base course material for pavement applications, permanent deformation or rutting is a concern due to creep deformation Since Neoloy-based Neoweb can provide longterm lateral confinement to granular materials, it is expected that Neoweb can reduce creep deformation of RAP, therefore enabling its wide-spread use Yuu, J., Han, J., Rosen, A., Parsons, R L., Leshchinsky, D (2008) “Technical Review of Geocell-Reinforced Base Courses over Weak Subgrade,” The First Pan American Geosynthetics Conference & Exhibition proceedings (GeoAmericas), Appendix VII, Cancun, Mexico This paper provides a review of 26 technicalpapers on geocell-reinforced base course and identifies the key influencing factors Most studies have demonstrated that significant enhancement of the performance of base layer can be achieved using geocells It is also recognized that geometric variables of geocells, quality of infill soil, subgrade strength, and loading type, and location are the most influential factors on the performance of geocellreinforced course Despite the effectiveness of this system, the acceptance of geocells for base reinforcement of roads is limited due to the lack of design methods Pokharel, S.K., J Han, D Leshchinsky, R.L Parsons, and I Halahmi (2010) Investigation of Factors Influencing Behavior of Single Geocell-reinforced Bases under Static Loading Provisionally accepted for publication in Journal of Geotextile and Geomembrane Pokharel, S.K., J Han, D Leshchinsky, R.L Parsons, and I Halahmi (2009) “Behavior of Geocell-Reinforced Granular Bases under Static and Repeated Loads”, Contemporary Topics in Ground Modification, Problem Soils, and GeoTechnical References 2/6 3-Mar-11 Support, (Eds Iskander, M., Laefer, D.F., and Hussein, M.H.), 2009 International Foundation Congress & Equipment Expo, March 15-19, Orlando, Florida ASCE Geotechnical Special Publication 187, pp 409-416 Research and literature shows a significant gap between the applications and theories of geocell reinforcement outlining the need for more research This study was to investigate the behavior of reinforced bases using a single geocell under static and repeated loads on a loading plate The experimental results show that the single geocell could increase the stiffness by approximately 50% and the maximum load by 100% as compared with those of the unreinforced base The repeated test shows that the geocell-reinforced base had the percentage of elastic deformation increase with the number of cycles of the repeated load up to 95% Pokharel, S.K., J Han, R.L Parsons, Qian, Y., D Leshchinsky, and I Halahmi (2009) “Experimental Study on Bearing Capacity of Geocell-Reinforced Bases,” 8th International Conference on Bearing Capacity of Roads, Railways and Airfields, Champaign, Illinois, June 29 - July AASHTO reports approximately 1/5 of pavement failures are due to insufficient structural strength Inadequate bearing capacity of underlying weak subgrade and inefficient load transfer from the base course are of the main reasons for pavement failures These facts have lead to efforts to improve the state of pavement design practice and to develop sustainable pavement stabilization techniques This study investigated the improvement provided by river sand and quarry waste as infill materials for Neoloy-based Neoweb pavement structures Results showed an increase in bearing capacity, stiffness, and percent of elastic deformation for each cycle and reduce permanent deformation II Contribution to Pavement Reinforcement (Rajagopal, et al, Indian Institute of Technology, Madras, India and Kief, PRS-Israel) About Dr K Rajagopal Dr Rajagopal is an internationally recognized leader in the field of geotechnical engineering He has received numerous honors and distinctions, published hundreds of articles in leading Indian and international professional journals and conference proceedings, and authored textbooks Dr Rajagopal is active in a large number of professional organizations, and has organized and chaired over a dozen international conferences Dr Rajagopal has also been involved in research and industry consulting in geosynthetics and geotechnical engineering for leading international institutes and organizations About Dr Ofer Kief Dr Kief is an international expert in geotechnical engineering, pavement design and geosynthetics with unique expertise in restraining expansive clay subgrades Dr Kief has professional experience in the design, planning, consulting, management, and supervision for the public and private sector road, rail, airport and marine port projects involving geosynthetics in dozens of countries worldwide Kief, O., and Rajagopal, K (2008) “Three Dimensional Cellular Confinement System Contribution to Structural Pavement Reinforcement.” Geosynthetics India ’08, Hyderabad, India This paper describes the advantages of 3D geocells in road pavements an expanding economy like India Reviewing testing performed in Germany (Meyer, et al), the authors calculate the reinforcement factor (5x) and describe in detail how the NPA (Novel Polymeric Alloy), Neoloy Neoweb reinforcement mechanism works The paper concludes that Neoweb geocell technology can significantly reduce road repair, rehabilitation, maintenance, and most importantly the precious raw materials, thereby making the rapid infrastructure development more sustainable Unni, A., Rajagopal, K., Veeragavan, A (2010) Some Observations from Laboratory Plate Load Tests on Pavement Structures with and without Neoweb Geocell Layers”, Preliminary Report Submitted to PRS, Indian Institute of Technology, Chennai, India Dr K Rajagopal presented an in-depth examination of geocell technology and testing to quantify the strength and stiffness of reinforced soil The results of lab tests and models were described as well as the design principles for using geocells projects with expansive clays (black cotton soil) common in India It is noted that India faces very problematic soils in its multi-billion dollar program to modernize the Indian transportation infrastructure Technical References 3/6 3-Mar-11 III Geogrid Trial Road Base (Van Gurp, Westeral, KOAC-NPC institute, Holland) About Dr Christ van Gurp Dr van Gurp is a Senior Manager of the Research Division of KOAC•NPC is a well-known expert in road engineering and structural pavements Dr Gurp has professional experience in consulting, teaching and research and has published and lectured around the world KOAC•NPC is the leading independent specialized institute for research and consultancy in entire area of civil engineering, with emphasis on road construction elements Van Gurp, C.A.P.M., Westera, G.E (2008) “Geogrid Trial Road Base NL 2008”, KOAC-NPC, Netherlands, Final Report The leading road research and standards institute in Holland conducted controlled field trials for geosynthetics reinforcement of road bases Test data was based on deformation and stiffness trials of full-scale structures in controlled sites (enclosed hangars) Neoweb was the only geocell manufacturer among leading geogrid manufacturers In addition, Neoweb was also the only geosynthetic reinforcement tested that could accommodate inferior aggregate material as the road base infill The results showed that Neoweb had the highest Road Base Thickness Reduction Factor of any tested product (up to 72% average unlimited), and substantially exceeded the known values for geogrids IV Earth Retention – Seismic Research (Leshchinsky, D., et al, U of Delaware, USA) About Dr Dov Leshchinsky Dr Leshchinsky is world renowned for his work as a geotechnical engineer and particularly his development of computer aided design Dr Leshchinsky has been involved with cutting edge geotechnical technology consulting for the past 20 years with US governmental agencies, geotechnical outfits and leading geosynthetic manufacturers He is widely published (approximately 250 technicalpapers and reports) and lectures to professional transportation and geotechnical engineers as well as at national and international conference and symposia The following three papers authored by Dr Leshchinsky (et al) reviewed testing of Neoweb earth retention walls at the shake table National Seismic Research Institute in Japan The tests on a variety of wall types replicated seismic activity similar to a severe earthquake The study concluded that geocells can be used successfully to form gravity walls as well as reinforcement layers even when subjected to a very high seismic load beyond that of the Kobe earthquake The study resulted in recommended seismic reduction factors (0.3-0.4) that are used in the design of gravity and reinforced walls Dr Leshchinsky noted, however, that geocells made from HDPE are unsuitable for long-term applications, and guidelines were given to PRS to further the development of its Neoloy based Neoweb geocell for demanding applications requiring long-term performance The editors of Geosynthetics magazine expressed the following opinion: “Professor Leshchinsky and I note that this article…departs from this policy in an effort to offer a guideline, an example, of how product development for the geosynthetics industry can be done effectively We hope these lessons can further advance the geosynthetics industry into the 21st century with much success.” Leshchinsky, D (2009) “Research and Innovation: Seismic Performance of Various Geocell Earth-retention Systems,” Geosysnthetics, No 27, No 4, 46-52 Leshchinsky, D., Ling, H.I., Wang, J-P., Rosen, A., Mohri, Y (2009) “Equivalent Seismic Coefficient in Geocell Retention Systems,” Geotextiles and Geomembranes Journal, No 27, 9-18 Ling, H.I., Leshchinsky, D., Wang, J.P., Mohri, Y and Rosen, A (2009) “Seismic Response of Geocell Retaining Walls: Experimental Studies”, Journal of Geotechnical and Geoenvironmental Engineering, 135, No 4, 516-524 Technical References 4/6 3-Mar-11 V Railway Embankments (Leshchinsky, B., Ling, H., et al, U of Columbia, USA) About Dr Ling Dr Ling is an internationally recognized geotechnical engineering professor and consultant He is a member of the several geosynthetics committees and is on the editorial board for several professional journals and NSF Panels He is active in organizing national and international conferences and meetings, collaborates actively with international institutions/agencies, and has published books and research works in field of soil mechanics and soft ground engineering, including a focus on earthquake engineering About Ben Leshchinsky Ben Leshchinsky is a Ph.D Candidate in Geotechnical Engineering, in the Department of Civil Engineering at Columbia University, NY, USA These papers describe research on loading tests of model rail embankments The tests measured the strength and deformation behavior of Neoloy based Neoweb in different embankment configurations The results showed that Neoweb greatly restricted vertical deformation by 40-72% and lateral displacement by 50-67% under loading The Neoweb was stable under controlled cyclic loading within the stress amplitude of many transportation applications (roadways, train, ballast, etc.) The researchers concluded that “The confinement mechanism of reinforcement was very effective making the railway ballast/Neoweb composite very stiff, strong and durable.” Leshchinksy, B., Ling H., Leshchinksy, D., Liming L (2010) “Summary of Reinforced Embankment Tests for PRS Mediterranean Ltd.”, Research Paper, Columbia University, January Leshchinksy, B., (2011) “Enhancing Ballast Performance using Geocell Confinement,” Accepted for Advances in Geotechnical Engineering, publication of Geo-Frontiers 2011 conference, Dallas, Texas, USA, March 13-16 Railway Articles (Russian Railway Research Institute’s -VNII ZhT) Poretsky N, (2009) “Railbed Score – out of 5, 14; New Material will Protect the Road Bed from Vibrations”, Gudok (transportation newspaper) September, 2009 Neoweb is currently undergoing testing at the Russian Railway Research Institute’s (VNII ZhT) Experimental Test Loop at Shcherbinka Station (near Moscow) The Head Supervisor of the Geotechnical Evaluation Center of RZhD, Vitaly Leonyuk, stated that the Neoweb reinforcement subbase layer prevents deformation in the embankment and structural layers as a result of the dynamic loading, and enables trains to pass over these problematic sections at higher speeds and at heavier axle loads Technical References 5/6 3-Mar-11 VI Bearing Capacity Improvement in Road Constructions (Meyer, N., et al, Clausthal University, Germany) About Dr Norbert Meyer Dr Meyer is a leading international geotechnical expert at Clausthal University, Germany Dr Meyer’s research focuses on the function and the structural behavior of geosynthetics in connection with earth materials, with extensive experience with geocell technology and research Head of the Clausthal Institute of Geotechnical Engineering and Mine Surveying, Dr Meyer has extensive project experience, published over 100 technicalpapers and authored and co-authored books and is a member of professional standards committees and review boards About Dr Ansgar Emersleben Dr Emersleben is an assistant professor at Clausthal University, Germany Dr Emersleben research included extensive investigations on geocell technology and reinforcement mechanisms and has been involved for many years with studies and testing of the Neoweb geocell at the Clausthal Institute of Geotechnical Engineering and Mine Surveying Dr Emersleben has published and co-published with Prof Meyer dozens oftechnicalpapers in the field of geocells and geosynthetics These studies published in a number ofpapers have thoroughly evaluated the use of Neoweb geocells for reinforcement of flexible structural pavements Extensive testing was carried out in the laboratory with plate loading of geocells in large scale test boxes, in addition to a number of large field installations in actual roadway constructions were carried with pressure cell instrumentation and monitoring The studies evaluated how the geocell reinforcement mechanisms work, and describe the improved geotechnical engineering forces provided by the soil-cell composite structure Results from comparative field tests – including full- scale field testing based cyclical dynamic loadings – validated the results achieved in laboratory plate box test testing Neoweb increased the load bearing capacity of the soil by a factor of 5, reduced differential settlement by up to 80% and decreased vertical stresses in the soft subgrade by more than 40% Additional plate loading test box studies demonstrated that geocells increase the bearing capacity of the soil and reduce the vertical stress on subgrades by >30-45% Measurements showed that the performance of a 40 cm Neoweb reinforced base layer equaled a 70 cm unreinforced high quality aggregate layer Emersleben A., Meyer M (2009) Interaction Between Hoop Stresses and Passive Earth Resistance in Single and Multiple Geocell Structures, GIGSA GeoAfrica 2009 Conference, Cape Town, South Africa, September 2-5 Emersleben A., Meyer M (2010) Verification of Load Transfer Mechanism of Geocell Reinforced Soil in Large Scale Model Tests and In-Situ Test Fields GeoFlorida 2010: Advances in Analysis, Modeling and Design, Geotechnical Special Publications No 199, Vol 2/4 Emersleben, A and Meyer, N (2008) “Bearing Capacity Improvement of Gravel Base Layers in Road Constructions using Geocells,” International Association for Computer Methods and Advances in Geomechanics (IACMAG), Goa, India Emersleben, A and Meyer, N (2008) “The Use of Geocells in Road constructions over Soft Soil: Vertical Stress and Falling Weight Deflectometer Measurements,” EuroGeo4 - 4th European Geosynthetics Conference, Edinburgh, Scotland, Sept 7-10 Emersleben, A and Meyer, N (2008) “Bearing Capacity Improvement of Asphalt Paved Road Construction Due to the Use of Geocells – Falling Weight Deflectometer and Vertical Stress Measurements,” Proceedings of the 4th Asian Regional Conference on Geosynthetics, Shanghai, China, June 17-20 Meyer, N and Emersleben, A (2005) “Mechanical Behavior of Geocell Reinforced Soils,” Synthetic Materials in Geotechnics, Technical University, Munich, Germany, Sept Meyer, N (2005) "Plate Load Tests and Stress Distribution Measurements During the Reconstruction of the Road K 27", Technical University Clausthal Test Report Technical References 6/6 3-Mar-11 ... (2 011 ) “Enhancing Ballast Performance using Geocell Confinement,” Accepted for Advances in Geotechnical Engineering, publication of Geo-Frontiers 2 011 conference, Dallas, Texas, USA, March 13 -16 ... Engineering, 13 5, No 4, 516 -524 Technical References 4/6 3-Mar -11 V Railway Embankments (Leshchinsky, B., Ling, H., et al, U of Columbia, USA) About Dr Ling Dr Ling is an internationally recognized geotechnical... testing of the Neoweb geocell at the Clausthal Institute of Geotechnical Engineering and Mine Surveying Dr Emersleben has published and co-published with Prof Meyer dozens of technical papers