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Alpharetta, GA, United States

The introduction of the Construction Products Regulation (CPR) across all EU countries is intended to remove local barriers to trade for competing products. The CPR encourages specifiers, particularly public bodies and national entities, to specify products needed to perform a particular function using the performance characteristics defined in the relevant harmonised standards. While encouraging competition, this may have the effect of discouraging innovation, particularly iterative development of products. To overcome the possible stifling of innovation the European Commission has built a 'route for innovation' into the CPR. This route, The European Technical Approvals (ETA) process, has been utilised by at least one European geosynthetics manufacturer. This paper examines the reasons behind the decision by Tensar International to apply for an ETA for their hexagonal structure geogrids and looks in detail at the process of applying for an ETA, encouraging other geosynthetic manufacturers to take this route. Source

Doulala-Rigby C.,Tensar International
Design and Practice of Geosynthetic-Reinforced Soil Structures | Year: 2013

Engineers are continually faced with maintaining and developing airfield infrastructure with limited financial resources. Traditional airfield pavement design and construction practices require high-quality and often expensive and non-sustainable materials to fulfil the high construction standards. In many areas of the world, quality materials are unavailable or in short supply. Coupled with the recent emphasis on sustainability and the scarce financial resources due to the recent global recession, engineers are seeking alternative designs and construction methods that can utilise marginal or recycled materials and innovative design practices. Designing with geosynthetics allows a variety of innovative approaches for airfield pavement construction and maintenance. Geosynthetics include a wide variety of products composed of polymers which have been developed to enhance geotechnical and transportation projects offering sustainable solutions at considerable lower cost than traditional methods. Airfield pavement construction in the UK began around 1937 in the UK without a proven design method. It was only in early 1945 that the first design method was published by the UK Defence Estates. This method was essentially empirical, based largely on experience gained constructing some 450 airfields between 1937 and 1945. Since then, airfield design has progressed enormously and extensive research programmes have been conducted by the UK Defence Estates, U.S. Army Engineer Research and Development Centre (ERDC) and other nonmilitary agencies worldwide to develop design and construction guidance for the construction of airfield pavement systems, incorporating the use of geosy nthetics This paper outlines the design requirements and guidance for the construction of flexible airfields in the UK, introducing the benefits of including geosynthetics as a key part of the solution. A variety of case studies are also presented, covering a wide range of geosynthetic applications from the mechanical stabilisation of sub-grade and sub-base layers including projects involving construction of airfield runway extensions over saturated, clayey/peaty soils and also reflective cracking remediation to asphaltic concrete layers. Source

A geogrid reinforced compactable asphaltic concrete composite includes a bottom layer, a first compacted layer of asphaltic concrete, a triaxial geogrid, and a second compacted layer of asphaltic concrete. The first layer and the second layer each include an aggregate having sharp, compound edges, which when mixed in asphaltic cement, create an aggregate interlock within the triaxial geogrid that provides strength to a paved surface. As a result of the triangular aperture geometry of the triaxial geogrid, the geogrid provides an asphalt lateral confinement zone within the composite. The zone allows for the formation of transverse hairline cracks as stresses on the composite necessitate. At elevated temperatures, the asphaltic cement softens and flows into the small transverse cracks, thus enabling the asphalt mats to substantially reseal themselves.

Jas H.,7asConsult BV | Stahl M.,Schussler Plan Ingenieurgesellschaft mbH | Te Kamp L.,ITASCA Consultants GmbH | Konietzky H.,TU Bergakademie Freiberg | Oliver T.,Tensar International
Geotechnical Engineering for Infrastructure and Development - Proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2015 | Year: 2015

The paper describes how numerical and tests have been conducted to reproduce the behaviour of geogrids embedded in granular material under special consideration of the grain-size, relative density, normal stress and installation. Granular soils and geogrids are simulated depending on a specific particle and parallel bond model and calibrated to the results of laboratory tests. An analysis is given of the actual deformations and stresses within the granular material during and after the loading The above knowledge and experience has been used to simulate a wheel passing over a stabilised sub-base on a weak sub-grade. The ultimate aim of this research is to learn how geogrids behave and what parameters are imperative for their fitness for use. © The authors and ICE Publishing: All rights reserved, 2015. Source

Sun X.,University of Kansas | Han J.,University of Kansas | Wayne M.H.,Tensar International | Parsons R.L.,University of Kansas | Kwon J.,Tensar International
Geotechnical Special Publication | Year: 2014

Since it was introduced in the market, triaxial geogrid has been used successfully for subgrade improvement and base course stabilization. Because triaxial geogrid can provide uniform tensile resistance in all directions, it is more efficient to interact with granular material and provide lateral restraint under cyclic loading. The benefit of geosynthetic in stabilizing granular bases has been mostly evaluated by researchers in terms of surface permanent deformation and stress distribution under cyclic loading at a constant intensity. In real applications, applied cyclic loads from vehicles may have different intensities. How the loading intensity affects the benefits of geosynthetics in stabilizing granular bases has not been well understood. In this study, cyclic plate loading tests at different loading intensities were performed on 0.23 m thick unstabilized and triaxial geogrid mechanically stabilized granular bases over soft subgrade with a CBR of 2.0% constructed in a geotechnical testing box (2 m × 2.2 m × 2 m) at the University of Kansas. Two types of triaxial geogrid were used in this study. The intensities of loading applied on a steel plate of 0.30 m in diameter increased from 5 to 45 kN. In these tests, surface deformation, subgrade deformation, and vertical/horizontal stresses at the interface between base and subgrade were monitored by transducers placed at varying distances from the center of the loading plate. Test results indicated that the surface and subgrade permanent deformations and the vertical stresses at the interface between base and subgrade were reduced by the inclusion of a triaxial geogrid. A majority of the surface permanent in each section was contributed by the subgrade permanent deformation. In the mechanically stabilized section, the horizontal stress in the base increased in contrast to the decreased stresses that were measured in the subgrade. The benefits of geosynthetic mechanical stabilization were even more obvious when a heavier-duty geogrid was tested in the geotechnical testing box. © 2014 American Society of Civil Engineers. Source

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