Geocomp introduces bi-directional shear testing machine

August 24, 2018

Geocomp announced in August it has released an addition to the company’s series of fully-automated laboratory soil testing systems: a Bi-Directional Cyclic Direct Simple Shear (BDCDSS) machine. This table-top unit allows simple shear testing to be performed in two orthogonal horizontal directions rather than the standard single horizontal direction. This system can mimic the stresses …

GEOKON certified to ISO 9001:2015

June 14, 2018

GEOKON Inc., a manufacturer of geotechnical and structural instrumentation, announced in a prepared statement on June 13, 2018, that they have been certified under ISO 9001:2015 from both the American National Standards Institute (ANSI)/ANSI-ASQ National Accreditation Board (ANAB) in the U.S. and the United Kingdom Accreditation Service (UKAS) in the U.K. as of June 1, …

Report from the North American Geosynthetics Society (NAGS)

April 1, 2015

By Bob Mackey ASTM Committee D35 on Geosynthetics The ASTM Committee D35 on Geosynthetics met in New Orleans, La., Jan. 28–30, 2015. There was significant progress within several of the D35 subcommittees as noted here: Subcommittee D35.03 on Permeability and Filtration The issue that generated a great deal of discussion at the January meeting of …

Allowable stress on geonets based on laboratory creep tests

October 1, 2014

By Dhani Narejo and Sam Allen Introduction The first article in this three-part series presented compressive stress-strain behavior of several different geonet structures. The collapse, or rollover, does not occur for many types of geonets. In the absence of a rollover, the compression of geonets is non-linear in most cases with the compression rate being …

Allowable stress on geonets based on laboratory creep tests

August 1, 2014

By Dhani Narejo and Sam Allen Introduction This article focuses on biplanar geonets to the extent of the possible tendency for the two sets of integrally joined ribs to roll over on one another while load is applied. The significance of such a rollover is a reduced transmissivity value as compared to that obtained from …

Geosynthetics committee examines drainage issues

July 17, 2014

Proposed ASTM standard for stormwater catch basin filters. ASTM International in a July 17 press release announced a proposed new standard that will offer a means to reduce the impact of contaminated stormwater entering local drains. WK45326, Specification for Stormwater Catch Basin Filter, will aid community developments, sports facilities, fairgrounds, stadiums, and factories in complying …

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Geonet structure, short-term stress/strain behavior, and creep test methods

June 1, 2014

Part 1: Allowable stress on geonets By Dhani Narejo and Sam Allen Introduction Several types of geonets are used in numerous applications worldwide. Examples of the types of geonets include biplanar, triplanar, spiked or profiled, cuspated, tubular, and three-dimensional (3-D) filament meshes (see Figure 1 and Table 1). Common and emerging applications for these materials …

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The influence of soil type on interface behavior under pullout conditions

Part 3: European experience in pullout tests By Nicola Moraci, Daniele Cazzuffi, Lidia Sarah Calvarano, Giuseppe Cardile, Domenico Gioffrè, and Piergiorgio Recalcati 1. Introduction The rapid increasing application of geosynthetics as reinforcement elements for earth structures requires a careful examination of soil-reinforcement interaction mechanisms. The soil-geosynthetic interaction can be complex because it is affected by …

Long-term pavement testing by FHWA

April 1, 2014

Contamination by subgrade soil causes deterioration in pavements from progressive loss of effective aggregate base thickness. Introduction A major deterioration factor in pavements is the progressive loss of effective aggregate base thickness because of contamination by subgrade soil. In the service life of a pavement, subgrade soil fines migrate upward into the unbound base aggregate …

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Air-channel testing of thermally bonded flexible polypropylene geomembrane seams

April 1, 2013

By Timothy D. Stark, Richard W. Thomas, and Thomas J. Dehlinl Introduction For more than a decade, thermal welding has proven to be an efficient and cost-effective procedure for field-seaming geomembranes. Thermal welding of polyvinyl chloride (PVC) geomembranes has allowed use of air-channel tests in lieu of destructive peel tests to verify field seams meet …