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Papers by Helmut Zanzinger

Research paper thumbnail of Technical Notes from the Berlin 2 HDPE Geomembrane Workshop: Assessing Remaining Service Life

Nearly all engineered systems have a finite service life. This includes geomembrane (GMB) barrier... more Nearly all engineered systems have a finite service life. This includes geomembrane (GMB) barriers (liners) as part of the system for the containment of valuable product (potable water, gold solutions, etc.) and contaminated/obnoxious liquids/solids (coal ash, meat processing waste, etc.). All exposed high-density polyethylene (HDPE) GMBs will degrade by oxidation in service and fail by quasi-brittle stress cracking. Clearly, facility owners need to know when a liner will no longer perform its containment function.

Research paper thumbnail of Evaluation of the Durability of PE-HD Geosynthetic Barriers Using High-Pressure Autoclave Tests

International Journal of Geosynthetics and Ground Engineering

Research paper thumbnail of Oxidative lifetime prediction of a polypropylene woven geotextile by applying high temperature and moderately increased oxygen pressure

Geotextiles and Geomembranes

Research paper thumbnail of Contributor contact details

Geosynthetics in Civil Engineering, 2007

Research paper thumbnail of Self-Healing Properties of Geosynthetic Clay Liners

Geosynthetics International, 2001

The sealing effect and containment of moisture in landfill covers and liners containing geosynthe... more The sealing effect and containment of moisture in landfill covers and liners containing geosynthetic clay liners (GCLs) are largely influenced by moisture retention, swelling, and the self-healing behaviour of bentonite used in GCLs. The method of binding of GCLs also significantly affects the behaviour. To examine these aspects, percent swell and swell pressure tests under different effective pressures were conducted on two sodium-based GCLs. Permittivity tests were performed on GCL specimens with different hole diameters and also on specimens dried at 20 and 60 o C. The test results are presented and discussed. The study shows that the GCLs considered have a good self-healing capacity for the case of desiccation cracks or punctures. In addition, the method of binding the GCL components, i.e., stitch-bonded or needlepunched, has a significant influence.

Research paper thumbnail of Evaluation of Clay Geosynthetic Barriers in Landfill Cover Systems

Geosynthetics in Civil and Environmental Engineering, 2009

Research paper thumbnail of Contribution to the Long-Term Shear Strength of a Needle Punched GCL

International Journal of Geosynthetics and Ground Engineering, Mar 1, 2016

For the evaluation of the long-term internal shear strength of a needle punched geosynthetic clay... more For the evaluation of the long-term internal shear strength of a needle punched geosynthetic clay liner, long-term shear creep rupture tests have been carried out. The tests were carried out at elevated temperature of 80°C in de-ionized water with the purpose to accelerate the creep of the fibres so that faster failure times are forced. A normal stress of 50 kPa was applied while the shear stress was varied for each test. The test results showed that the time to shear failure directly depend on the applied shear stress and the shear stresses showed a clear correlation with failure times. The long-term internal shear stress has been determined through an extrapolation of the regression line at the test temperature of 80°C. In addition to lifetime prediction, the applicable shear stress was calculated for a minimum of 100 years under a normal stress of 50 kPa at a given field temperature of 30°C.

Research paper thumbnail of Clay geosynthetic barriers performance in landfill covers

Clay geosynthetic barriers (GBR-Cs) used in landfill covers must ensure lining on the long term. ... more Clay geosynthetic barriers (GBR-Cs) used in landfill covers must ensure lining on the long term. The primary mode of ageing of bentonite GBR-Cs in covers is the coupling of cation exchange and hydrationdesiccation cycles. The objective of this paper is to synthesize the optimal conditions to prevent a loss of performance of GBR-Cs in covers with time, based on a literature review. Various parameters will be discussed. The literature review will put in light the lack of consistent information from study to study. This enforces the need for a list of information to collect in future excavations. Such a list is proposed in the third section of this paper followed by the presentation of results from recent excavations performed by the first author. Formatted Formatted Formatted

Research paper thumbnail of Long-term internal shear strength of a reinforced GCL based on shear creep rupture tests

Geotextiles and Geomembranes, 2012

ABSTRACT Clay geosynthetic barriers (GBR-C) – a synonym for geosynthetic clay liners (GCL) – used... more ABSTRACT Clay geosynthetic barriers (GBR-C) – a synonym for geosynthetic clay liners (GCL) – used on steep slopes, e.g. landfill capping systems, have to withstand permanent shear forces over the long-term. Thermoplastic materials deform under static load. Creep and chemical ageing processes (e.g. oxidation) also influence the strength of the synthetic fibres over the long-term. The lifetime of these geosynthetics (GSY) is a very important issue as GBR-Cs have to demonstrate their long-term durability for more than 100 years in cases such as e.g. landfill capping systems in Germany.The long-term shear strength will be modelled by applying shear stress for long durations at elevated temperature (i.e. to accelerate ageing). In laboratory tests running up to 2 years on a stitch-bonded GBR-C in deionised (DI) water, specimens experienced internal rupture (i.e. rupture of fibres) at higher shear stress. Results showed the times to shear failure directly depend on the applied shear stress. Using the extrapolation of the regression line of times to shear creep rupture together with a lifetime prediction the applicable shear stress was found to 28 kPa for a minimum of 100 years under a normal stress of 50 kPa at a field temperature of 30 °C. Short-term tests cannot give the answer for any long-term behaviour of GBR-Cs. There is always the need for shear creep rupture tests. This new method determines the long-term shear strength of GBR-Cs for any lifetime.

Research paper thumbnail of Special issue on GCLs

Geotextiles and Geomembranes, 2012

Research paper thumbnail of Fatigue behaviour of a PET-Geogrid under cyclic loading

Geotextiles and Geomembranes, 2010

The lines of 'damage-begin' and 'specimen-break' for dynamic loading of a geogrid were determined... more The lines of 'damage-begin' and 'specimen-break' for dynamic loading of a geogrid were determined in a series of laboratory testing. The cyclic load ratio was set to R ¼ 0.5, loading frequency f ¼ 10 Hz and f ¼ 3 Hz. The test results show clearly that the chosen procedure for the determination and analysis of the beginning of damage and break is reproducible and allow for safe extrapolation for lower load levels. Furthermore the method chosen enables explicit decrease of the required testing time. The assumption of linear damage accumulation was examined in two-step-trials. The number of load cycles to 'break' evaluated in 'one-step-tests' compared with those of 'two-step-loading' are practically the same. The existence of 'damage-lines' for the examined geogrid under a dynamic pulsating load of 10 Hz and 3 Hz and a R-value of 0.5 could be verified. Damage of the specimens occurs only for load-cycles lying between the 'damage-line' and the 'stress-cycle-diagram' ('Woehler-curve'). When it comes to dimensioning against 'damage-beginning' or 'break', higher loading frequencies present the critical case.

Research paper thumbnail of Technical Notes from the Berlin 2 HDPE Geomembrane Workshop: Assessing Remaining Service Life

Nearly all engineered systems have a finite service life. This includes geomembrane (GMB) barrier... more Nearly all engineered systems have a finite service life. This includes geomembrane (GMB) barriers (liners) as part of the system for the containment of valuable product (potable water, gold solutions, etc.) and contaminated/obnoxious liquids/solids (coal ash, meat processing waste, etc.). All exposed high-density polyethylene (HDPE) GMBs will degrade by oxidation in service and fail by quasi-brittle stress cracking. Clearly, facility owners need to know when a liner will no longer perform its containment function.

Research paper thumbnail of Evaluation of the Durability of PE-HD Geosynthetic Barriers Using High-Pressure Autoclave Tests

International Journal of Geosynthetics and Ground Engineering

Research paper thumbnail of Oxidative lifetime prediction of a polypropylene woven geotextile by applying high temperature and moderately increased oxygen pressure

Geotextiles and Geomembranes

Research paper thumbnail of Contributor contact details

Geosynthetics in Civil Engineering, 2007

Research paper thumbnail of Self-Healing Properties of Geosynthetic Clay Liners

Geosynthetics International, 2001

The sealing effect and containment of moisture in landfill covers and liners containing geosynthe... more The sealing effect and containment of moisture in landfill covers and liners containing geosynthetic clay liners (GCLs) are largely influenced by moisture retention, swelling, and the self-healing behaviour of bentonite used in GCLs. The method of binding of GCLs also significantly affects the behaviour. To examine these aspects, percent swell and swell pressure tests under different effective pressures were conducted on two sodium-based GCLs. Permittivity tests were performed on GCL specimens with different hole diameters and also on specimens dried at 20 and 60 o C. The test results are presented and discussed. The study shows that the GCLs considered have a good self-healing capacity for the case of desiccation cracks or punctures. In addition, the method of binding the GCL components, i.e., stitch-bonded or needlepunched, has a significant influence.

Research paper thumbnail of Evaluation of Clay Geosynthetic Barriers in Landfill Cover Systems

Geosynthetics in Civil and Environmental Engineering, 2009

Research paper thumbnail of Contribution to the Long-Term Shear Strength of a Needle Punched GCL

International Journal of Geosynthetics and Ground Engineering, Mar 1, 2016

For the evaluation of the long-term internal shear strength of a needle punched geosynthetic clay... more For the evaluation of the long-term internal shear strength of a needle punched geosynthetic clay liner, long-term shear creep rupture tests have been carried out. The tests were carried out at elevated temperature of 80°C in de-ionized water with the purpose to accelerate the creep of the fibres so that faster failure times are forced. A normal stress of 50 kPa was applied while the shear stress was varied for each test. The test results showed that the time to shear failure directly depend on the applied shear stress and the shear stresses showed a clear correlation with failure times. The long-term internal shear stress has been determined through an extrapolation of the regression line at the test temperature of 80°C. In addition to lifetime prediction, the applicable shear stress was calculated for a minimum of 100 years under a normal stress of 50 kPa at a given field temperature of 30°C.

Research paper thumbnail of Clay geosynthetic barriers performance in landfill covers

Clay geosynthetic barriers (GBR-Cs) used in landfill covers must ensure lining on the long term. ... more Clay geosynthetic barriers (GBR-Cs) used in landfill covers must ensure lining on the long term. The primary mode of ageing of bentonite GBR-Cs in covers is the coupling of cation exchange and hydrationdesiccation cycles. The objective of this paper is to synthesize the optimal conditions to prevent a loss of performance of GBR-Cs in covers with time, based on a literature review. Various parameters will be discussed. The literature review will put in light the lack of consistent information from study to study. This enforces the need for a list of information to collect in future excavations. Such a list is proposed in the third section of this paper followed by the presentation of results from recent excavations performed by the first author. Formatted Formatted Formatted

Research paper thumbnail of Long-term internal shear strength of a reinforced GCL based on shear creep rupture tests

Geotextiles and Geomembranes, 2012

ABSTRACT Clay geosynthetic barriers (GBR-C) – a synonym for geosynthetic clay liners (GCL) – used... more ABSTRACT Clay geosynthetic barriers (GBR-C) – a synonym for geosynthetic clay liners (GCL) – used on steep slopes, e.g. landfill capping systems, have to withstand permanent shear forces over the long-term. Thermoplastic materials deform under static load. Creep and chemical ageing processes (e.g. oxidation) also influence the strength of the synthetic fibres over the long-term. The lifetime of these geosynthetics (GSY) is a very important issue as GBR-Cs have to demonstrate their long-term durability for more than 100 years in cases such as e.g. landfill capping systems in Germany.The long-term shear strength will be modelled by applying shear stress for long durations at elevated temperature (i.e. to accelerate ageing). In laboratory tests running up to 2 years on a stitch-bonded GBR-C in deionised (DI) water, specimens experienced internal rupture (i.e. rupture of fibres) at higher shear stress. Results showed the times to shear failure directly depend on the applied shear stress. Using the extrapolation of the regression line of times to shear creep rupture together with a lifetime prediction the applicable shear stress was found to 28 kPa for a minimum of 100 years under a normal stress of 50 kPa at a field temperature of 30 °C. Short-term tests cannot give the answer for any long-term behaviour of GBR-Cs. There is always the need for shear creep rupture tests. This new method determines the long-term shear strength of GBR-Cs for any lifetime.

Research paper thumbnail of Special issue on GCLs

Geotextiles and Geomembranes, 2012

Research paper thumbnail of Fatigue behaviour of a PET-Geogrid under cyclic loading

Geotextiles and Geomembranes, 2010

The lines of 'damage-begin' and 'specimen-break' for dynamic loading of a geogrid were determined... more The lines of 'damage-begin' and 'specimen-break' for dynamic loading of a geogrid were determined in a series of laboratory testing. The cyclic load ratio was set to R ¼ 0.5, loading frequency f ¼ 10 Hz and f ¼ 3 Hz. The test results show clearly that the chosen procedure for the determination and analysis of the beginning of damage and break is reproducible and allow for safe extrapolation for lower load levels. Furthermore the method chosen enables explicit decrease of the required testing time. The assumption of linear damage accumulation was examined in two-step-trials. The number of load cycles to 'break' evaluated in 'one-step-tests' compared with those of 'two-step-loading' are practically the same. The existence of 'damage-lines' for the examined geogrid under a dynamic pulsating load of 10 Hz and 3 Hz and a R-value of 0.5 could be verified. Damage of the specimens occurs only for load-cycles lying between the 'damage-line' and the 'stress-cycle-diagram' ('Woehler-curve'). When it comes to dimensioning against 'damage-beginning' or 'break', higher loading frequencies present the critical case.