A Guide to Polymeric Geomembranes
... the 200 • C test temperature (e.g., HALS; Thomas and Ancelet 1993;Scheirs 2009). Degradation in physical and mechanical properties was monitored using the HLMI test (21.6 kg/190 • C; ASTM D1238), single-point notched constant tensile load (SP-NCTL) SCR test at 30% of the GMB initial yield stress (ASTM D5397--Appendix), and tensile strength and elongation at break (Type V; ASTM D6693). ...
... For the HLMI, the data imply that cross-linking degradation reactions took place, leading to an increase in the polymer's molecular weight and, consequently, to a decrease in the HLMI values Scheirs 2009;Grause et al. 2020). HLMI started to decrease simultaneously with F B and ε B in all solutions, suggesting that the polymeric changes de- Fig. 4. Variation with incubation time at 85 • C of (a) normalized high-load melt index (HLMI) (HLMI t /HLMI o ) and (b) normalized stress crack resistance (SCR) (SCR t /SCR o ) in L1 (pH 0.5), L2 pH (1.25), and L3 pH (2.0). ...
... This may be attributed to the fourfold higher concentration of H 2 SO 4 in L1 relative to L2 and L3, despite the small differences in their pHs. The high acid concentration in L1 may lead to greater deactivation of HALS, forming inactive salts that reduce its effectiveness in protecting the polymer from oxidation(Keck-Antoine et al. 1999;Yamashita and Ohkatsu 2003;Pospíšil et al. 2007;Scheirs 2009). HALS-derived salts may in turn exhibit different solubility properties compared to the original HALS molecules, which could have led to the lower HP-OIT residual value and the much slower depletion rate in L1 compared to the other two solutions. ...
The long-term performance of a high-density polyethylene geomembrane (GMB) immersed in acidic solutions is assessed over a 10-year accelerated ageing period. The immersion solutions had pH values of 0.5, 1.25, and 2.0, with chemistry likely encompassing that found after the leaching of copper, nickel, and uranium in heap leaching processes. With seven more years of data beyond previous studies on the same GMB, this work provides improved estimates of antioxidant depletion times at typical liner temperatures, as well as new data on the changes in physical and mechanical properties due to degradation over time. Despite the significant increase in acid concentration, degradation was shown to be independent of pH. Based on the most conservative estimates, the time to nominal failure of the GMB examined exceeds 210 years at 20 °C, and 35 years at 50 °C when immersed in the low pH solutions. In a composite liner configuration, the time to nominal failure was estimated to be over 120 years at 50 °C, over 390 years at 30 °C, and over 1400 years at 10 °C.
... High-density polyethylene (HDPE) geomembranes are widely deployed at sewage water treatment plants with high corrosion resistance, durability, and impact strength [1,2]. As shown in Figure 1, multiple anaerobic lagoons are located in sewage treatment plants operated by Melbourne Water Corporation (MWC), Australia, to treat sewage from the city. ...
... The local solar intensity is also plotted, to verify that geomembrane temperature changes with the ambient environment condition. The acquired thermal image sequences were collected from the thermal camera, and the temperatures of the monitored region were calculated using (2). Given that the sampling rate of the thermal camera was set as 10 s/frame, cooling constants were calculated every 10 s. ...
... Although the geomembrane is still cooling during the night (see Figure 8), the tiny difference in cooling constants between the soil and non-soil regions is not helpful. It is noted that ambient temperature will change according to the solar intensity as the environment receives the heat from the sunlight, and the ambient air temperature will be used to calculate the cooling constant in (2). stants of regions on the geomembrane were large during the daytime (13:01:13-14:11:15 in day 1, 07:07:55-17:11:15 in day 2, and 07:41:15-14:01:15 in day 3), where the solar intensity was not equal to 0 while, after sunset, where the solar intensity was equal to 0, the cooling constants of points in all regions were approximately equal to 0. This is because of the lack of heat stimulus during the night. ...
This study presents a novel approach for monitoring waste substrate digestion under high-density polyethylene (HDPE) geomembranes in sewage treatment plants. The method integrates infrared thermal imaging with a clustering algorithm to predict the distribution of various substrates beneath Traditional outdoor large-scale opaque geomembranes, using solar radiation as an excitation source. The technique leverages ambient weather conditions to assess the thermal responses of HDPE covers. Cooling constants are used to reconstruct thermal images, and clustering algorithms are explored to segment and identify different material states beneath the covers. Laboratory experiments have validated the algorithm’s effectiveness in accurately classifying varied regions by analyzing transient temperature variations caused by natural excitations. This method provides critical insights into scum characteristics and biogas collection processes, thereby enhancing decision-making in sewage treatment management. The methodology under development is anticipated to undergo rigorous evaluation across various floating covers at a large-scale sewage treatment facility in Melbourne. Subsequent to field validation, the implementation of an on-site, continuous thermography monitoring system is envisioned to be further advanced.
... High-density polyethylene (HDPE) geomembranes (GMBs) play an essential role in various geoenvironmental barrier systems, as they serve to contain liquids and gases with a design life that spans from decades to millennia (Giroud and Bonaparte 1989;Rowe et al. 1998Rowe et al. , 2004Rowe et al. , 2020Rowe and Sangam 2002;Sangam and Rowe 2002;Rowe 2005;Abdelaal et al. 2014bAbdelaal et al. , 2023aAbdelaal et al. , 2023bRowe 2017, 2020a;Clinton and Rowe 2023;Rowe and Somuah 2023;Zafari et al. 2023aZafari et al. , 2023bZafari et al. , 2024. HDPE GMBs are prone to various degradation mechanisms when exposed to long-term field exposure conditions Hsuan et al. 2008;Scheirs 2009), resulting in a reduction in both their mechanical and physical properties (Rowe 2005(Rowe , 2020Abdelaal et al. 2014a). The oxidative degradation of a GMB consists of three conceptual stages (Hsuan and Koerner 1998): Stage I, the depletion of antioxidants assessed by oxidative inductive time; Stage II, the induction period to the onset of polymer degradation; and Stage III starts when polymer degradation occurs resulting in a measurable reduction in GMB properties such as tensile properties (ASTM 2020b), melt flow index (MFI; ASTM 2013), and stress crack resistance (SCR; ASTM 2020a). ...
... Texturing the surface of GMBs is used to increase the interface friction between the GMB and soil or geosynthetic liners with which they are in contact (Koerner 2005;Müller 2007;Scheirs 2009). This texturing enhances the interaction between the GMB and the material it contacts, thereby improving the veneer stability of the lining system on side slopes. ...
... At temperatures of 55 and 75 • C, the oxidation rate may differ significantly between the three GMBs due to variations in their surface area, core thickness, and presence of additives or texturing, affecting how antioxidants are consumed. However, at the higher temperature of 85 • C, the oxidation rate increases to the point where the physical loss by extraction becomes the dominant factor (Scheirs 2009). At such elevated temperatures, antioxidants may rapidly diffuse to the surface and volatilize or get extracted. ...
The effect of blown-film co-extrusion texturing (using entrained nitrogen gas) on the long-term performance of high-density polyethylene geomembranes (GMBs) immersed in synthetic municipal solid waste leachate is examined over an approximately 8-year period. Antioxidant depletion of the textured part is shown to be much faster than that of the smooth edge. Likewise, the degradation in the tensile break properties at 85 °C is faster for the textured part than for the smooth-edge portion and smooth equivalent. The updated estimates for antioxidant depletion time based on data at four different temperatures (40, 55, 75, and 85 °C) over 98 months of data collection are compared with predictions based on 34 months of data, and the implications are discussed. Nominal failure was reached at 75 °C, and this combined with data at 85 °C allows prediction of the time between depletion of standard oxidative induction time and nominal failure at lower temperatures. The effect of salt concentration in incubation fluid on the time to degradation is examined. Finally, the paper comments on the uses of textured versus smooth GMB.
... High-density polyethylene geomembranes (HDPE) are used as part of barrier systems in different geoenvironmental applications to provide containment to fluids such as landfill leachate, tailing fluids, and others (Hsuan and Koerner 1998;Scheirs 2009;Abdelaal et al. 2019; Di Battista and Rowe 2020; Morsy and Rowe 2020;Francey and Rowe 2022b;Francey and Rowe 2023). The service life of the geomembrane is a function of sheet resistance to ageing, stress due to indentions or wrinkles, geomembrane thickness, chemical composition of the in-contact leachate, adjacent materials, and temperature (Hsuan and Koerner 1998;Tognon et al. 2000;Sangam and Rowe 2005;Take rt al. 2007;Scheirs 2009, Rowe andIslam 2009;Rowe et al 2010a,b;Rowe and Yu 2019). ...
... There are two common methods for welding HDPE geomembranes: fusion welding and extrusion welding. Fusion welding is used for welding panel overlaps and serves as the primary technique for creating the majority of the weld length in the geomembrane barrier system (Scheirs 2009 repair defects in HDPE geomembrane sheets (Seeger and Muller 2003;Touze-Foltz et al. 2008;Scheirs 2009). Extrusion welds require a skilled operator and pre-weld preparation, such as removing dirt, controlling welding pressure, and adequately grinding the sheet surface. ...
... There are two common methods for welding HDPE geomembranes: fusion welding and extrusion welding. Fusion welding is used for welding panel overlaps and serves as the primary technique for creating the majority of the weld length in the geomembrane barrier system (Scheirs 2009 repair defects in HDPE geomembrane sheets (Seeger and Muller 2003;Touze-Foltz et al. 2008;Scheirs 2009). Extrusion welds require a skilled operator and pre-weld preparation, such as removing dirt, controlling welding pressure, and adequately grinding the sheet surface. ...
The effect of ageing at 85°C of extrusion welds of 1.5 mm-thick high-density polyethylene (HDPE) geomembrane, immersed in synthetic municipal solid waste leachate, is investigated with respect to its standard oxidative induction time (Std-OIT) and stress crack resistance (SCR). Results show that the heat-affected zones (HAZ) adjacent to the squeeze-out bead (flashing) may exhibit faster STD-OIT depletion than the sheet. Generally, individual weld SCR failure times were observed to be between that of the notched and unnotched sheet. Welds with high welding-induced geometric irregularities (WIGI), and overheated fusion and extrusion welds are shown to result in SCR failure times close to that of a notched sheet during immersion time. The average time to nominal failure (taken to be when tNF =250 hours) of Cool and Good welding parameter combinations ranges between 3% and 15% shorter than the unnotched sheet. Differences in tNF were attributed to accelerated craze formation in welds with high WIGI from stress concentration. No significant difference was observed between the SCR values of fusion and extrusion welds during 40 months of immersion in MSW-L3. This paper shows that overgrind negatively impacts the SCR of welds and accelerates the degradation of SCR.
... There are two common methods of welding HDPE geomembranes: fusion welding and extrusion welding. Most welds involve fusion welding of the edges of two geomembrane sheets (Scheirs 2009;Rowe and Shoaib 2017;Francey and Rowe 2022). Extrusion welding is normally used where fusion welding is not practical (e.g., for repairs, curves, and other welds not accessible to fusion welding machines (Seeger and Muller, 2003;Touze-Foltz et al., 2008;Scheirs 2009). ...
... Most welds involve fusion welding of the edges of two geomembrane sheets (Scheirs 2009;Rowe and Shoaib 2017;Francey and Rowe 2022). Extrusion welding is normally used where fusion welding is not practical (e.g., for repairs, curves, and other welds not accessible to fusion welding machines (Seeger and Muller, 2003;Touze-Foltz et al., 2008;Scheirs 2009). Extrusion welding requires on-site preparation of the material (e.g., grinding) to be welded and requires a skilled operator capable of managing grinding depth/width, welding machine angle, welding speed, preheat and weld temperature, and the pressure on the welding bead (Toepfer 2015). ...
... The geomembrane surfaces were prepared by cleaning and grinding to remove the oxidized surface and waxy layers (Hsuan, 2000;Scheirs, 2009;Toepfer, 2015;Gilson-Beck and Giroud, 2022). The extrusion welding was performed by a licensed geosynthetic installer using a Demtech extruder at a landfill site on a summer day when the geomembrane sheet temperature at the time of the welding was 37 • C. In each case, the geomembrane sheets were preheated (to temperature T p ) with hot air to reduce the amount of heat required and increase the size of the molten bead (extrudate) and avoid thermal shock that can lead to weakening of the polymeric structure along the edge of the welding bead (Mollard et al., 1996). ...
The stress crack resistance (SCR) of high-density polyethylene (HDPE) geomembrane extrusion welds is examined for a 1.5 mm HDPE geomembrane and three different welding parameter combinations (denoted as “Cool”, “Good”, and “Overheated”). Results are reported for unnotched welds, unnotched sheet, and notched sheet. The average SCR for a Good extrusion weld is 23% of that of the unnotched sheet SCR. Little variation is found between the three welding parameter combinations for low geometry irregularity SCR weld specimens. There is no statistically significant difference between a good-quality fusion and extrusion weld. However, operator-dependent weld induced geometric irregularity (WIGI) greatly affects the SCR of extrusion welds. Extrusion welds with high WIGI have an average unnotched SCR of only 9% of the unnotched sheet. Extrusion welds with an overground surface can have an unnotched SCR as little as 1% of the best extrusion weld. Deleterious weld bead geometries are identified to provide a framework with which engineers can identify “high-risk” extrusion welds with respect to stress cracking.
... High-density polyethylene geomembranes (HDPE GMBs) are an essential component of the landfill barrier system (Abdelaal et al. 2019;Hsuan et al. 2008;Morsy et al. 2021;). The primary function of the GMBs is to prevent the leakage of fluids and gasses over the lifespan of the landfills, which may reach from decades to centuries (Rowe et al. 2004;Scheirs 2009). HDPE is usually selected due to its high resistance to chemical degradation compared to other polymeric geomembranes (Koerner et al. 2017;Scheirs 2009). ...
... The primary function of the GMBs is to prevent the leakage of fluids and gasses over the lifespan of the landfills, which may reach from decades to centuries (Rowe et al. 2004;Scheirs 2009). HDPE is usually selected due to its high resistance to chemical degradation compared to other polymeric geomembranes (Koerner et al. 2017;Scheirs 2009). HDPE GMBs consist of 96 to 97.5% of polyethlene resin, 2 to 3% carbon black, and 0.5 to 1% of other additives (i.e., stabilizers and antioxidants) (Hsuan & Koerner 1998). ...
... HDPE GMBs consist of 96 to 97.5% of polyethlene resin, 2 to 3% carbon black, and 0.5 to 1% of other additives (i.e., stabilizers and antioxidants) (Hsuan & Koerner 1998). The additives delayed the polymer thermo-oxidative degradation which may occur during the manufacture process, installation, and ageing (Hsuan & Koerner 1998;Scheirs 2009). During installation, HDPE GMBs rolls are welded in-situ to create continuous impermeable seal using high welding temperatures. ...
... g/cm 3 (ASTM D883). Therefore, HDPE resins are assumed to have higher chemical resistance than LLDPE due to their higher crystallinity (Scheirs 2009). BPO resins are made of a blended resin that may be composed of different polyolefins such as PE and polypropylene (Martuscelli et al., 1980;Teh et al., 1994;Rachtanapun et al., 2004) or PE of different densities such as HDPE and LLDPE (Lee and Jho 1998;Schellenberg and Fienhold 1998;Munaro and Akcelrud 2008). ...
... Another notable difference between MxA15 and MxC15 was their initial HP-OIT. The relatively high initial HP-OIT value of MxC15 (>400 min) implies that hindered amine light stabilizers (HALS) were part of the antioxidant/stabilizer package of MxC15 only (Scheirs 2009). ...
... In this case, the retention time beyond the full depletion of effective antioxidants (either those detected by Std-or HP-OIT) was the longest for BzSW15 then MxC15 then LxD15 and the shortest Stage II was still for MxA15. With the high resistance of HALS to depletion in pH 13.5 (Scheirs 2009), it seems that the presence of these high molecular weight antioxidants within the GMB could be one of the reasons responsible for the longer NR= Not reached-NI= Not investigated-UD= Undefined based on the current incubation duration. *Std-OIT r = 3 min for MxA15 and MxC15; = 5 min for LxD15 and LxE15; = 6 min for BzSw15. ...
The durability of five 1.5-mm thick geomembranes (GMBs) is investigated in pH 0.5 and 13.5 synthetic mining solutions using immersion tests. Two high density polyethylene (HDPE), two linear low density polyethylene (LLDPE), and one blended polyethylene (BPO) GMBs are investigated at 85 • C for incubation durations of 4.5-6.5 years. It is shown that the degradation of all five GMBs in the high pH solution is faster than in the low pH solution. In the pH 0.5 solution, one of the HDPEs and the BPO GMBs exhibited polymer degradation before or at the time of the depletion of their antioxidants. In pH 13.5, four out of the five GMBs exhibited degradation and followed the conceptual three-stage degradation model until nominal failure. However, there is no correlation between the long-term performance of these GMBs and their resin type or their initial properties since one of the examined LLDPEs outperformed all the higher density/crystallinity GMBs with higher initial properties while the other LLDPE did not perform well. Thus, when selecting a GMB for a desired application, the relative performance of different candidate GMBs can be only assessed using immersion tests using the solutions expected in the field.
... High density polyethylene (HDPE) geomembranes (GMBs) are used as part of the barrier system in different geoenvironmental applications to provide containment to liquids and gases with a design life that can exceed 500 years (Priyanto et al. 2019). Under long-term field exposure conditions, HDPE GMBs are susceptible to various degradation mechanisms Hsuan et al. 2008;Scheirs 2009) that ultimately result in a reduction in their mechanical properties and hence their resistance to sustain long-term tensile strains (Abdelaal et al. 2014a;Rowe 2020). The degradation of a GMB involves three different conceptual stages (Hsuan and Koerner 1998): Stage I, the antioxidant depletion assessed in terms of the oxidative induction time; Stage II, the induction time to the onset of polymer degradation; and Stage III, polymer degradation resulting in a measurable change of the GMB properties [e.g., tensile properties (ASTM 2020a); melt flow index (MFI; ASTM 2013); stress crack resistance (SCR; ASTM 2020b)]. ...
... This coextrusion method results in higher shear strength compared to other texturing techniques such as sprayon texturing and patterning texturing (Erickson et al. 2008). However, the expansion of the injected gas may affect the core thickness of the GMB and result in an asperity height that varies along the GMB surface and hence may reduce the GMB mechanical properties (Scheirs 2009). While such variability of the GMB thickness can give a large coefficient of variation in the mechanical properties , it presents significant challenges to assess the SCR of textured GMBs. ...
... For instance, the unaged break properties (both strength and strain) of xTB were 30% lower than those of xTBs while zTA had a 50% reduction in the break properties relative to zTAs for Type IV specimens (Table 1). This reduction is attributed to the variation in thickness of textured GMBs (i.e., at and in between the asperities) that resulted in stress concentration at the grooves between the asperities initiating the rupture of the specimens at these points (Scheirs 2009;Morsy and Rowe 2019). Due to such failures that were dependent on the thickness variation within the specimen, there was a notable variability in the tensile break properties of the textured parts of the roll (for both the unaged and aged samples) that can be also deduced from their standard deviations relative to the smooth edge (e.g., 13 kN=m versus 2.0 kN=m for the break strength of xTB and xTBs, respectively; Table 1). ...
The longevity of two white multilayered textured geomembranes, manufactured with a smooth edge for welding, is examined when immersed in synthetic municipal solid waste leachate at five temperatures (40, 55, 65, 75, and 85°C) for 50 months. The textured and smooth parts of the geomembranes had similar initial chemical and physical properties, but the core of the smooth edge was thinner. It is shown that, depending on the relative effects of the difference in the core thickness and the surface area exposed to a solution, antioxidant depletion of the textured portion may be either faster or slower than the smooth edge. However, due to the lesser core thickness of the smooth edge of both geomembranes, the degradation in the tensile stress at break properties at 85°C is faster for the smooth edge than for the textured portion of the roll even when the antioxidant depletion was faster for the textured part. Thus, any assessment of the likely service life of the textured geomembrane requires consideration of both the smooth and textured portions of a multilayered textured geomembrane.
... A key geosynthetic product is the pad geomembrane (GMB) liner that allows the collection of leach solutions after passage through the ore (often called the pregnant leach solution; PLS) for recovery of valuable metals and prevents migration of contaminants to the surrounding environment. Under the field conditions, the GMB is exposed to extreme pH in addition to high vertical pressures from the large stacking heights of the ore on top of the pad (Lupo 2010) and together these represent one of the most aggressive service environments for GMB liners (Scheirs 2009). In addition, under some circumstances pyrite-rich tailings may have a low pH, while red mud may have a high-pH pore water in contact with a liner or cover. ...
... The 1.5 mm thick black smooth HDPE GMB (manufactured by Solmax International, Varennes, QC, in 2008; Table 1) had an initial HP-OIT 0 (ASTM D5885) of 960 min, which implies the presence of hindered amine light stabilizers (HALS) as part of the antioxidant package of this GMB (Scheirs 2009). The GMB had a medium-density, high-molecular-weight hexene copolymer resin with a density of 0.936 g/cc (ASTM D1505). ...
... The only GMB property that showed the same behaviour of Stage II duration with increasing the pH was the depletion of the HP-OIT in which increasing the pH increased the HP-OIT residual values (Fig. 12). This limited depletion of HP-OIT (specifically in L8 and L7) can be attributed to the basic nature of HALS (as part of the HP-OIT package), which is expected to show good resistance to strong caustic solutions (Scheirs 2009;Abdelaal and Rowe 2017). This implies that the antioxidants detected by HP-OIT at the residual values in L8 may have a role in delaying the initiation of the GMB degradation. ...
The degradation in physical and mechanical properties of a 1.5 mm thick HDPE geomembrane immersed in seven different low pH and three high pH simulated mining solutions is examined at temperatures between 95 and 40 °C for 3 years. The solutions with pH between 0.5 and 13.5 encompass solutions found in copper, nickel, uranium, gold, and silver heap leach pads. The geomembrane did not exhibit any chemical degradation during the three years of incubation in all the low-pH solutions. However, in the solutions with pH 9.5, 11.5, and 13.5, some of the geomembrane’s physical and mechanical properties are shown to reach nominal failure at 95 and 85 °C. While the geomembrane examined shows superior performance in the acidic environments than in the basic solutions examined, its performance in such extremely basic environments is still better than in neutral reduced municipal solid waste leachate. Using Arrhenius’ modelling, the predicted times for the antioxidant depletion stage of the geomembrane examined in composite liner configuration range between 31 years in pH 13.5 to 51 years in pH 0.5 for pad liners at 50 °C, exceeding a typical leaching period of the ore of around 20 years in different heap leaching operations.
... GMs are synthetic materials composed of resin, used as a matrix, and additives to provide protection and specific properties [9,10]. Resin is prone to oxidation, leading to material degradation and photodegradation. ...
... Oxidation causes carbonyl group formation, which indicates the GM degradation stage. Hence, GMs require the inclusion of antioxidants and stabilizers (AO/S) to protect against oxidation and carbon black to protect against exposure to ultraviolet (UV) [10][11][12]. Because AO/S deplete over time, AO/S levels are determined to indicate the GM degradation stages, as conceptualized by Hsuan and Koerner [13]. ...
... Among a variety of GM types, high-density polyethylene (HDPE) GM is the most widely used worldwide [9,10,14,15], and particularly for mine site reclamation covers, including at 11 of 12 sites found in the literature [16,17]. ...
High-density polyethylene (HDPE) geomembranes (GM) are used in mine site reclamation cover systems to limit water and oxygen ingress into sulphide tailings or waste rocks, thereby reducing acid mine drainage generation. The objective of this paper is to assess the actual properties of small-scale GMs after 20 years of service in the cover system of an existing mine site. GM samples were exhumed from this site and laboratory tested to determine the standard (Std) and high pressure (HP) oxidative-induction times (OITs), tensile properties, and hydraulic and oxygen sorption/diffusion properties. Unfortunately, the initial properties of the virgin GM before the installation were not available. Properties gathered from this study were then compared to literature data or to minimal requirements for virgin HDPE GMs as defined by the Geosynthetic Research Institute (GRI). Results showed Std-OIT values exceeding the minimum requirement of 100 min for virgin GMs while the HP-OIT values are lower than the minimum requirement of 400 min. The tensile properties exceed the requirements. The fluid-tightening properties do not appear to be affected to date: the equivalent hydraulic conductivity is around 10–14 m/s, and the oxygen diffusion coefficient is around 10–13 m2/s. The GMs thus show acceptable performance to date. Further studies will be needed in the future to determine more long-term GM behaviour where the data from this study will constitute reference values (in the absence of initial properties).
... High-density polyethylene (HDPE) geomembranes (GMBs) are used extensively as hydraulic barriers to minimize the migration of fluids such as landfill leachate, tailings fluid, chlorinated water, and many others (Bouazza and Van Impe 1998;Hsuan 2000;Gulec et al. 2004;Rowe et al. 2004;Thiel and Smith 2004;Rowe 2005Rowe , 2012Rowe , 2018Rowe , 2020Rowe et al. 2009;Ewais et al 2014aEwais et al , 2014bJafari et al. 2014;Chou et al. 2020;McWatters et al. 2020;Li et al. 2021;Morsy et al. 2021;Tuomela et al. 2021). HDPE is often chosen over other polymeric GMB due to its relatively high resistance to chemical degradation and greater service life (Scheirs 2009;Koerner et al. 2017;Rowe 2020). Additives, such as of antioxidants and (or) carbon black, are often incorporated into HDPE GMBs to provide protection during manufacturing and installation, and to extend the service life of GMB (Hsuan and Koerner 1998;Rowe and Sangam 2002;Müller 2007;Scheirs 2009;Abdelaal et al. 2019;Rowe and Jefferis 2022). ...
... HDPE is often chosen over other polymeric GMB due to its relatively high resistance to chemical degradation and greater service life (Scheirs 2009;Koerner et al. 2017;Rowe 2020). Additives, such as of antioxidants and (or) carbon black, are often incorporated into HDPE GMBs to provide protection during manufacturing and installation, and to extend the service life of GMB (Hsuan and Koerner 1998;Rowe and Sangam 2002;Müller 2007;Scheirs 2009;Abdelaal et al. 2019;Rowe and Jefferis 2022). Antioxidants work by serving as an oxidation buffer to the polymer, as the antioxidants themselves are oxidized or slowly diffuse out of the GMB during operation, resulting in an extended GMB service life (Hsuan and Koerner 1998;Rowe and Sangam 2002). ...
... In general, there are two common methods for welding HDPE GMBs, extrusion welding and fusion welding. Extrusion welding is primarily used to weld patches, panel intersections, or repairing defects in the sheet, while fusion welding is used to weld panel overlaps and is used for most of the total seam length within the GMB barrier system (Scheirs 2009). The performance of HDPE GMB fusion seams has not been as extensively studied as the sheet material. ...
The stress crack resistance (SCR) and standard oxidative induction time (Std-OIT) reduction of high- density polyethylene (HDPE) geomembrane (GMB) fusion seams is examined for a 12-year old 1.5 mm HDPE GMB when welded using nine welding parameter combinations. The GMB experienced a decrease in Std-OIT from 135 to 87 min between manufacturing and welding. Welding did not significantly decrease the Std-OIT in the heat-affected zone (HAZs). In general, individual seam SCR failure times fell between the notched and unnotched sheet, with adhered squeeze-out bead seams exhibiting individual failure times closer to the notched sheet and an average time until nominal failure (tNF) ∼21%–35% shorter than the unnotched sheet. Differences in tNF are attributed to residual stresses and (or) accelerated craze formation in seams with adhered squeeze-out beads. Non-adhered squeeze-out seams exhibited a slower tNF similar to that of the unnotched sheet, indicating a seam tNF less than that of the sheet may not be intrinsic to all HDPE fusion seams. High sheet temperatures at the time of welding and higher heat-applied welding parameters are thought to increase the likelihood of squeeze-out bead adherence. This paper shows that squeeze-out adherence can have a deleterious effect on seam SCR.
... This inconsistency in the effect of pH on HP-OIT and later-time Std-OIT depletion rates may be attributed to the different effects of pH on the different antioxidants detected by the two tests. Specifically, increasing the pH from 9.5 to 13.5 is expected to reduce the depletion of the HALS (as inferred from the HP-OIT residual values) detected solely by the HP-OIT and increase the hindered phenol depletion detected by both tests (Scheirs 2009;Abdelaal and Rowe 2017). Consequently, the HP-OIT depletion rate is likely influenced by the pH effects on both antioxidants. ...
... The present study extends the findings from and to cover periods of up to 4.2 years at 95 • C (Fig. 3a), 7.5 years at 85 • C (Fig. 3b) and 9.3 years at 75 • C (Fig. 3c). Results collected at 95 • C and 85 • C suggest consistent cross-linking reactions in all three solutions, leading to an increase in the polymer's molecular weight and consequently to a decrease in the melt index value (Hsuan and Koerner 1998;Scheirs 2009;Grause et al., 2020). At 95 • C, HLMI values reached a minimum of 10% HLMI o after 28, 36 and 51 months of incubation in pH 13.5, 11.5 and 9.5, respectively. ...
The degradation of a HDPE geomembrane in heap leaching environments is evaluated using immersion tests at five temperatures. The incubation solutions had a pH of 9.5, 11.5, and 13.5, relevant to gold and silver pregnant liquor solutions. After 9.3 years, the geomembrane's mechanical properties had reached nominal failure at 95, 85, and 75 • C in all three solutions. It is shown that the pH 13.5 solution had the greatest effect on the anti-oxidant depletion (Stage I) and polymer degradation (Stage III), but was the least aggressive to initiate the degradation (Stage II) compared to the pH 11.5 and 9.5 solutions. Overall, the time to nominal failure (time to 50% of the initial or specified property value) in pH 13.5 was slightly shorter than the pH 9.5 and 11.5 solutions. Based purely on immsersion tests, the time to nominal failure of this specific geeomembrane at 30 o C is predicted to be 150 years in the pH 9.5 and 11.5 solutions, and 140 years in the pH 13.5 solution. Assuming a good liner design that limits the tensile strains in the GMB, nominal failure in a composite liner configuration is predicted to exceed 260 years at 30 • C and the expected value could exceed 1000 years at 10 • C.
... Heap leaching is a process of extracting valuable minerals such as gold, silver, copper, uranium, and nickel from mined rocks using various chemical solutions [1]. Due to the combination of high vertical stress, extreme pH of the solution and high temperatures (sometimes more than 75 o C), heap leaching is considered one of the most aggressive service environments for the geomembrane (GMB) liner [2,3,4,5]. Previous research has extensively examined the durability of polymeric geomembrane liners in heap leach pad applications under different field exposure conditions [5][6][7][8][9]. For example, Abdelaal and Rowe [8] investigated the degradation in physical and mechanical properties of a 1.5 mm thick highdensity polyethylene (HDPE) GMB immersed in seven different mining solutions (pH 0.5, 1.25, 2.0, 9.5, 11.5, and 13.5) at temperatures between 95 and 40 °C for 3 years. ...
... Bituminous geomembranes (BGMs) have relatively high puncture resistance and higher density than polymeric GMBs which make them suitable for geosynthetic barrier systems in mining applications [3,15,16]. BGMs consist of a nonwoven polyester geotextile (NW-GTX) and a glass fleece fibre fully impregnated and coated with Styrene-Butadiene-Styrene (SBS) modified bitumen. ...
A custom-designed apparatus is used to age a 4.8-mm thick bituminous geomembrane (BGM) under single-sided exposure to a synthetic mining solution (pH13.5) at 70oC over a 6-months period. These experiments involve exposing the BGM from the bitumen coat surface only to simulate the BGM’s chemical exposure conditions in the field. The degradation in the tensile and chemical properties of the BGM is compared to double-sided immersed coupons in which the BGM is exposed to the solution from both surfaces. The preliminary results show that the degradation rate of the mechanical properties of the BGM is higher in the double-sided immersion test than single-sided immersion test. However, the difference in the degradation rates of the chemical properties of the bitumen coat between the double-sided and single-sided immersed BGM samples was insignificant.
... This settlement of tailings can result in deformation of the cover system at the reclamation stage; this presents a significant concern when using a GMB [10], as it can introduce strain [15]. The strain in the GMB can lead to stress cracking, ultimately jeopardizing the integrity of the barrier, especially in the case of high-density polyethylene (HDPE) GMBs [15][16][17]. Therefore, a need exists to develop a monitoring system for tracking the displacement and corresponding strain of GMBs in mining cover systems placed on a TSF. ...
... By comparing Fig. 2a and 2b, the modification of the shape of the containment cell can be seen clearly, especially a depression at the top of the cell caused by settlement of the tailings. This settlement affects the tensile stresses in the GMB, which could potentially affect its durability, for example by generating stress cracking of the GMB [15][16][17]. As the integrity of the GMB is crucial for effectively controlling AMD generation and ensuring the overall stability of the containment cell, understanding strain and stresses in the GMB is critical. ...
The abandoned Aldermac mine site, located in the Abitibi- Témiscamingue region of Québec, Canada, is a former polymetallic mine that operated in the 1930s. Over the decades, the sulfidic mine wastes produced by the mine have been exposed to atmospheric conditions, leading to the generation of acid mine drainage (AMD) and contamination of the surrounding environment. In 2008–2009, reclamation works were initiated by the Québec government with the implementation of different techniques based on the characteristics of the different sectors of the mine site. In the southern sector, the production of AMD from the mine wastes pile is controlled by a multilayered cover system, including a 1.5 mm-thick textured high-density polyethylene geomembrane, aimed at limiting ingress of water and oxygen. In 2021, work was carried out to instrument the cover system with an innovative displacement measurement system that was developed and applied to the geomembrane along a sloping transect. The system allows continuous measurements of geomembrane displacement at three locations. This article discusses the installation of these instruments and presents preliminary results. Displacements over a 1-year monitoring period ranged from approximately 4 mm downslope to 32 mm upslope. This corresponded to strains ranged from approximately 0.01% contraction to 0.05% tension.
... However, accurately assessing the real-life mechanical performance of HDPE poses challenges [4]. The entry of untreated wastewater into the anaerobic lagoons leads to the formation and accumulation of solidified matter, or scum, underneath the covers, forming large volumes known as scumbergs. ...
... These scumbergs exert pressure against the covers, causing deformation with a vertical-length scale of around one meter (uplift) and several meters laterally. Hydraulic loading from the inflow of sewage can cause lateral displacement of the scumbergs, resulting in excessive displacement and mechanical stress on the covers, particularly in regions near the welded joints (refer also to [4]). This issue could disrupt biogas collection channels integrated within the cover, potentially reducing the efficiency of renewable energy collection. ...
This paper presents an overview of integrating new research outcomes into the development of a structural health monitoring strategy for the floating cover at the Western Treatment Plant (WTP) in Melbourne, Australia. The size of this floating cover, which covers an area of approximately 470 m × 200 m, combined with the hazardous environment and its exposure to extreme weather conditions, only allows for monitoring techniques based on remote sensing. The floating cover is deformed by the accumulation of sewage matter beneath it. Our research has shown that the only reliable data for constructing a predictive model to support the structural health monitoring of this critical asset is obtained directly from the actual floating cover at the sewage treatment plant. Our recent research outcomes lead us towards conceptualising an advanced engineering analysis tool designed to support the future creation of a digital twin for the floating cover at the WTP. Foundational work demonstrates the effectiveness of an unmanned aerial vehicle (UAV)-based photogrammetry methodology in generating a digital elevation model of the large floating cover. A substantial set of data has been acquired through regular UAV flights, presenting opportunities to leverage this information for a deeper understanding of the interactions between operational conditions and the structural response of the floating cover. This paper discusses the current findings and their implications, clarifying how these outcomes contribute to the ongoing development of an advanced digital twin for the floating cover.
... Heap leaching is a process of extracting valuable minerals such as gold, silver, copper, uranium, and nickel from mined rocks using various chemical solutions [1]. Due to the combination of high vertical stress, extreme pH of the solution and high temperatures (sometimes more than 75 o C), heap leaching is considered one of the most aggressive service environments for the geomembrane (GMB) liner [2,3,4,5]. Previous research has extensively examined the durability of polymeric geomembrane liners in heap leach pad applications under different field exposure conditions [5][6][7][8][9]. For example, Abdelaal and Rowe [8] investigated the degradation in physical and mechanical properties of a 1.5 mm thick highdensity polyethylene (HDPE) GMB immersed in seven different mining solutions (pH 0.5, 1.25, 2.0, 9.5, 11.5, and 13.5) at temperatures between 95 and 40 °C for 3 years. ...
... Bituminous geomembranes (BGMs) have relatively high puncture resistance and higher density than polymeric GMBs which make them suitable for geosynthetic barrier systems in mining applications [3,15,16]. BGMs consist of a nonwoven polyester geotextile (NW-GTX) and a glass fleece fibre fully impregnated and coated with Styrene-Butadiene-Styrene (SBS) modified bitumen. ...
A custom-designed apparatus is used to age a 4.8-mm thick
bituminous geomembrane (BGM) under single-sided exposure to a synthetic
mining solution (pH13.5) at 70oC over a 6-months period. These
experiments involve exposing the BGM from the bitumen coat surface only
to simulate the BGM’s chemical exposure conditions in the field. The
degradation in the tensile and chemical properties of the BGM is compared
to double-sided immersed coupons in which the BGM is exposed to the
solution from both surfaces. The preliminary results show that the
degradation rate of the mechanical properties of the BGM is higher in the
double-sided immersion test than single-sided immersion test. However, the
difference in the degradation rates of the chemical properties of the bitumen
coat between the double-sided and single-sided immersed BGM samples
was insignificant.
... During exposure to chemical and thermal service conditions, GMBs can exhibit chemical degradation resulting in the loss of their mechanical properties over time (Rowe and Sangam 2002;Hsuan et al. 2008;Scheirs 2009). The degradation of a GMB is conceptually divided into three stages (Hsuan and Koerner 1998), Stage I: the depletion of antioxidants, which is assessed based on the standard and high-pressure oxidative induction time (ASTM D3895-19 and ASTM D5885-20); Stage II: the induction of auto-oxidation of the polymer material, and Stage III: the loss in physical and mechanical properties of the GMB that eventually results in nominal failure (e.g., a drop to 50% of the initial or specified value). ...
... For instance, Morsy and Rowe (2020) showed that the SCR 0 for a 1.5 mm single-layered textured GMB ranged between 150 and 5700 h. This variability can be partially attributed to discontinuities of the textured surface beneath the ligament that can result in the formation of local zones of stress concentration (Müller 2007;Scheirs 2009). Additionally, the textured surfaces can lead to different notch depths for the same GMB resulting in the variation in the eccentricity for the different specimens (and hence max ). ...
The stress crack resistance (SCR) of different multilayered textured geomembranes (GMBs) immersed in synthetic municipal solid waste leachate at 55 and 85 o C for 50 months is assessed using their smooth edge or smooth equivalent GMBs made from the same formulation of the textured GMBs. The difference between the actual thickness of the smooth edge and the nominal thickness of the GMB is shown to result in SCR values that do not reflect the true SCR of the GMB resin when assessed based on the current ASTM standard test procedure. As such, adjustments to the current test method are presented to limit its effect on the SCR values especially when comparing the performance of different GMBs based on SCR. Additionally, due to variations in formulation and thickness between the textured and smooth portions of these GMB rolls, a new double-notching technique is introduced to assess the SCR of the textured portion. Using this technique on samples taken from the textured and smooth portions at different incubation times show similar initial and stabilized SCR values but different SCR degradation rates for the two different parts of the same GMB roll. Thus, relying solely on SCR values obtained from the smooth edge/equivalent GMB may underestimate or overestimate the degradation of multilayered textured GMBs.
... While the increased resin density of HDPE GMBs implies better chemical resistance and hardness, it increases the potential for stress cracking. For LLDPEs, the high side chain branching of the polymer molecule gives them more flexibility and a relatively higher off-roll SCR compared to HDPE Lustiger & Markham 1983;Scheirs 2009). There are several methods for assessing the SCR for a broad range of polymeric materials (Robeson 2013), among which the notched constant tensile load test (NCTL; ASTM D5397) is well accepted and commonly used both in industry and research. ...
... The least affected region appears to be Zone C. This implies that, even in a highly aged HDPE specimen there was a portion of the material experiencing ductile failure (Scheirs 2009). The lengths of Zones A, B and C after ageing were approximately 35 m m, 590 mm and 235 mm, respectively. ...
High-density (HDPE) and linear low-density polyethylene (LLDPE) geomembranes are used in barrier systems in various containment applications. The former is known for its better chemical resistance, while the latter is known for its higher stress-crack resistance (SCR). The SCR of high-density polyethylene is well defined in the literature, but the SCR of LLDPE as well as its failure mechanism are rarely addressed. This paper thus investi-gates the SCR of LLDPE versus HDPE geomembranes based on the fractured plane of unaged and aged specimens examined using the single-point notched constant load tensile test method. The GMBs were aged using a synthetic heap leaching solution with pH 13.5 at 85°C. Failed specimens are analyzed using scanning electron microscopy, after which the differences in fracture surface for both LLDPE and HDPE resins are discussed. The relationship between SCR, tensile break elongation, and melt flow index is also presented for the geomembranes examined.
... BGMs comprise a polyester nonwoven geotextile (NW-GTX) and a glass fleece mat impregnated and coated with bitumen to give a relatively impervious sheet with high mechanical properties. The bitumen used in manufacturing BGMs is typically modified with polymer additives (e.g., styrene-butadiene-styrene (SBS) copolymer) to increase its workable range of temperature and improve its temperature sensitivity (Scheirs 2009;Zhu et al. 2014;Touze-Foltz and Farcas 2017). To improve the interface friction resistance of the BGM with the soil/geosynthetic material above it, the top surface of the BGM is often treated with fine sand. ...
... For example, BGMs have been used in lining and capping municipal solid waste (MSW) and low-level radioactive waste (LLRW) landfills (Breul et al. 2006;Peggs 2008;Daly and Breul 2017;Keys 2021;Richardson and Wingrove 2021). They have also been introduced to mining applications to line mine process solution spillover lagoons, mine tailings storage facilities, and heap leach pads (Scheirs 2009;Lazaro and Breul 2014;Daly and Breul 2017). The growing use of BGMs is attributed to their favourable material characteristics, such as high resistance to punctures, flexibility at lower temperatures, low coefficient of thermal expansion, and higher density relative to polymeric GMBs (Breul et al. 2008;Peggs 2008;Lazaro and Breul 2014). ...
A custom-designed apparatus (referred to as the Ageing Column) is used to age a 4.8-mm thick elastomeric bituminous geomembrane (BGM) under single-sided exposure to a synthetic municipal solid waste (MSW) leachate and a synthetic high pH mining solution (pH 11.5) at 55 °C, 70 °C, and 85 °C. This apparatus involves a closer simulation of the BGM's chemical exposure conditions in the field than the double-sided immersion tests in which the BGM is exposed to the solution from both surfaces. The mechanical, rheological, and chemical properties of the BGM are examined to assess the degradation in the BGM components relative to double-sided immersion experiments. While the single-sided ageing of the BGM reduces the degradation rates in the BGM mechanical properties, it does not affect the degradation rate of the bitumen coat relative to the double-sided exposure. Additionally, the exposure of the BGM to the MSW leachate resulted in faster degradation in its mechanical properties but slower degradation in the bitumen coat than that obtained in the exposure to the mining solution. However, predictions of the time to nominal failure of the BGM established using Arrhenius modelling at different temperatures show that the temperature effect is more significant on the BGM durability than the chemistry of the considered solutions.
... The transport process slowly tries to equalize the concentration difference or the chemical potential of the penetrant in the phases separated by the membrane [9]. From the figures (4 ), (5), (6), (7), (10 ), (11), (12) and (13) which show the relation between the weight gain with the square root of time for immersion of unfilled HDPE and filled with Al 2 O 3, TiO 2 and Hybrid (Al 2 O 3 and TiO 2 ) fillers. Water absorption of HDPE is little because it's non polar. ...
... Water absorption of HDPE is little because it's non polar. In case of composites, the higher absorption was due to the addition of (Al 2 O 3 ) and (TiO 2 ) particles due to hydrophilic nature of these fillers which accelerates the penetration of water [10,11]. ...
... Geomembrane (GMB) liners overlying a geosynthetic clay liner (GCL) or compacted clay liner (CCL) are used as part of the barrier system in different geoenvironmental applications to minimize the migration of contaminants to the surrounding environment (Rowe et al., 2004;Rowe 2005Koerner 2012;Touze-Foltz et al., 2016;Priyanto et al., 2019). Under the long-term field exposure conditions, high density polyethylene (HDPE) GMBs are susceptible to oxidative degradation that results in the reduction of their mechanical properties Hsuan et al., 2008;Scheirs 2009). This may eventually lead to the stress cracking of the GMB liner under sustained field stresses and hence the loss of their hydraulic barrier function (Abdelaal et al., 2014a;. ...
... To enhance the level of conductivity for the conductive skin relative to the other GMB layers, conductive-backed GMBs are typically produced using separate extruders for the core and conductive layer. The conductive skin is then extruded using a different masterbatch stabilized with the desired type and amount of carbon black to ensure higher electrical conductivity of the conductive bottom skin relative to the core and top surface layers (Messmer and Cadwallader 1994;Scheirs 2009). These GMBs can be coextruded with white pigments in the upper skin to reduce the temperature of the exposed GMB. ...
... Geosynthetic barrier systems are typically used in the pad under the ore to protect the surrounding environment from the corrosive leaching solutions and to preserve the precious minerals being extracted. Due to the combination of high overburden pressures (in the case of static heap leaching), extreme pH of the PLS in contact with the liner, and elevated temperatures (sometimes >75°C), heap leaching is considered one of the most aggressive service environments for the GMB liner (Breitenbach and Thiel 2005;Scheirs 2009;Abdelaal et al. 2011;Rowe and Abdelaal 2016). Previous research examined the durability of polymeric geomembrane liners (e.g. ...
... Gulec et al. 2004;Abdelaal et al. 2011;Rowe and Abdelaal 2016;Rowe 2017, 2023;Morsy and Rowe 2017) under the aggressive conditions of the heap leach applications. Recently, bituminous geomembranes (BGMs) have been introduced to mining applications due to their lower coefficient of thermal expansion, higher puncture resistance, and higher density relative to polymeric GMBs but there is a paucity of research into their long-term performance under the service conditions of heap leach pads (Scheirs 2009;Lazaro and Breul 2014;Daly and Breul 2017). ...
The degradation behaviour of a 4.8 mm thick elastomeric bituminous geomembrane (BGM) immersed in pH 0.5, 9.5, and 11.5 synthetic mining solutions is examined over 26 months at 22, 40, 55 and 70°C. The low pH solution simulates the leach solutions found in copper, nickel, and uranium heap leach pads while the two high pH solutions simulate the chemistry and pH found in gold and silver heap leaching facilities. The mechanical, rheological, and chemical properties are examined at different incubation times to assess the degradation in the BGM at different temperatures. It is shown that the degradation rates of all properties are faster in pH 11.5 and 9.5 than in pH 0.5. Additionally, the BGM started to exhibit degradation in its mechanical properties even with a slightly degraded bitumen coat in all the mining solutions at elevated temperatures. The time to nominal failure of the BGM is predicted at different field temperatures using Arrhenius modelling. Due to the relatively fast degradation in the mechanical properties of the BGM, especially at temperatures above 50 o C, the tensile strains in the BGM in the field should be limited so it can meet the required liner design life of heap leaching applications.
... Most of these facilities are lined with polymeric geomembranes such as linear low-density polyethylene, high-density polyethylene, polyvinyl chloride, and polypropylene. This has led to extensive research targeting their short-term and long-term performances (especially for high-density polyethylene) over the last two decades (e.g., Abdelaal et al., 2014b;Abdelaal and Solanki 2022;Cazzuffi and Gioffrè 2020;Eldesouky and Brachman 2020;Marcotte and Fleming 2020;Müller, 2007;Rowe et al., 2020;Rowe and Sangam 2002;Fan 2021, 2022;Scheirs 2009;Stark et al., 2020;Tian et al., 2018;Touze--Foltz et al., 2021;Vahidi et al., 2020). Bituminous geomembranes (BGMs) are also considered a strong candidate for the liner material in these applications due to their high puncture resistance, high mechanical properties, relatively high density, and low coefficient of thermal expansion (Peggs 2008). ...
... Due to the high sensitivity of the bitumen to temperature variations (Petersen 1998), oxidized (treated by blowing hot air) bitumen was historically used for the production of BGMs. Currently, most of the BGMs available in the market involve stabilized bitumen with elastomers such as Styrene-Butadiene-Styrene (SBS) copolymer (Scheirs 2009). These modifications increase the workable range of temperature of the bitumen by reducing the low-temperature brittleness and increasing its flow temperature ranges (Hunter et al., 2015;Touze-Foltz and Farcas 2017). ...
The effect of elevated temperatures on the degradation of an elastomeric bituminous geomembrane (BGM) when exposed to air and deionized (DI) water at temperatures between 22 and 85 °C is investigated using immersion tests. The changes in the mechanical, chemical and rheological properties of the BGM are examined over approximately two years under different ageing conditions. It is shown that the BGM exhibited different degradation rates in its different components when exposed to elevated temperatures that are dependent on the incubation media. In air, the BGM exhibited thermo-oxidative degradation in the elastomeric bituminous coat that changed the bitumen glass transition temperature and increased its rigidity. Further degradation led to the brittleness of the bitumen coat before any degradation in the tensile and puncture strengths of the BGM. In contrast, exposure to DI water resulted in faster degradation of the mechanical properties of the BGM, while the bitumen coat exhibited substantially less degradation than in air. Arrhenius modelling is used to estimate the degradation times of the BGM at a range of field temperatures for both media.
... Similarly, the antioxidant depletion time (td) of BzS20 was 4 months (Std-OITo= 170 minutes; Std-OITr=2.0 minutes), while td for LxD20 was 11 months (Std-OITo= 90 minutes; Std-OITr=2.0 minutes) (Figure 1). The observed Std-OITr values corresponded to 2% of Std-OITo for BzSW15 and BzS20, and 1% of Std-OITo for LxD20 that implies that almost all the antioxidants detected by Std-OIT were consumed after diffusion to the GMB surface either by consumption by free radicals or by accelerated hydrolysis of hindered phenols, that contain ester bridges in their structure, in the basic media (Scheirs 2009). In addition, LxD20 had the lowest Std-OITo and longest td that indicated that its antioxidant package had better resistance to PLS L8 compared to its BPO counterparts. ...
... Em particular, as geomembranas texturizadas de PEAD são escolhidas para projetos ambientalmente sensíveis, como aterros sanitários e atividades de mineração, devido à sua capacidade de aumentar o atrito e, por consequência, melhorar o fator de segurança, reduzindo assim o risco de falhas por deslizamento entre camadas. Existem dois principais métodos de fabricação para geomembranas texturizadas de PEAD: o processo de matriz plana, no qual a textura é impressa por meio de calandras, e o processo de matriz circular ou balão, que envolve a injeção de nitrogênio para criar a textura (Junior et al., 2022;Scheirs, 2009). ...
... However, to utilize HDPE, which has excellent performance, in complexly shaped and large-scale hulls and marine structures, appropriate welding and joining technologies are needed to ensure structural integrity. Since fusion welding is practically difficult to use, it is necessary to explore joining methods using extrusion-based equipment [23][24][25]. ...
High-density polyethylene (HDPE) has emerged as a promising alternative to fiber-reinforced plastic (FRP) for small vessel manufacturing due to its durability, chemical resistance, lightweight properties, and recyclability. However, while thermoplastic polymers like HDPE have been extensively used in gas and water pipelines, their application in large, complex marine structures remains underexplored, particularly in terms of joining methods. Existing techniques, such as ultrasonic welding, laser welding, and friction stir welding, are unsuitable for large-scale HDPE components, where extrusion welding is more viable. This study focuses on evaluating the impact of key process parameters, such as the preheating temperature, hot air movement speed, and nozzle distance, on the welding performance of HDPE. By analyzing the influence of these variables on heat distribution during the extrusion welding process, we aim to conduct basic research to derive optimal conditions for achieving strong and reliable joints. The results highlight the critical importance of a uniform temperature distribution in preventing defects such as excessive melting or thermal degradation, which could compromise weld integrity. This research provides valuable insights into improving HDPE joining techniques, contributing to its broader adoption in the marine and manufacturing industries.
... The industry uses the term HDPE widely when, in fact, it is MDPE that has been used. MDPE offers various advantages, including being resistant to ultraviolet light and chemicals [17], preventing shrinkage of saltwater, which is the source material for salt, and speeding up the crystallization process, and making the resulting salt whiter and cleaner because it does not interact directly with the soil [6,18]. Susanto et al. [19] modified the conventional salt manufacturing method using a liner, increasing the quantity and quality of salt production in the Jepara Regency to 67% with the NaCl content from 90 to 98.4%. ...
The application of the latest technological innovations has been promoted worldwide to increase farm productivity, including in salt farming. This research aims to determine the determinants of adoption decisions for salt production technology called geomembrane and estimate the adoption impact on technical efficiency. The data in this study is cross-sectional from 215 small-scale salt farmers on Madura Island, East Java, Indonesia. The data was analyzed using logistic regression to identify which factors influenced farmers’ decisions to use geomembrane. The influence of adoption on farmers' technical efficiency was then assessed using propensity score matching (PSM) and data envelopment analysis (DEA). The findings indicate that age and the dummy variables of gender, land ownership, profit-sharing involvement, and membership in the People's Salt Business Group (KUGAR) all had a significant impact on adoption rates. The findings of controlling matched samples using the PSM process reveal that geomembrane application improves and greatly increases farmers' technical efficiency. Those who used geomembranes displayed greater technical efficiency than those who did not. These findings imply that salt production technology should be promoted more to increase productivity, especially geomembrane adoption, through outreach and dissemination of information, including for landowners involved in the profit-sharing system.
... The industry uses the term HDPE widely when, in fact, it is MDPE that has been used. MDPE offers various advantages, including being resistant to ultraviolet light and chemicals [17], preventing shrinkage of saltwater-which is the source material for salt-speeding up the crystallization process, and making the resulting salt whiter and cleaner because it does not interact directly with the soil [6,18]. produced more, and dependence on imports can be reduced. ...
Salt farming has been a hereditary occupation in the coastal communities of Madura Island; however, salt productivity in this area is still relatively low. The government has introduced a new production technology, called a geomembrane, as part of their efforts. The application of the latest technological innovations has been promoted worldwide to increase farm productivity, including in salt farming. This research aims to determine the determinants of adoption decisions for salt production technology and estimate the adoption impact on technical efficiency. The data in this study are cross-sectional from 215 small-scale salt farmers on Madura Island, East Java, Indonesia. The data were analyzed using logistic regression to identify which factors influenced farmers’ decisions to use geomembranes. The influence of adoption on farmers’ technical efficiency was then assessed using propensity score matching (PSM) and data envelopment analysis (DEA). The findings indicate that age and the dummy variables of gender, land ownership, profit-sharing involvement, and membership in the People’s Salt Business Group (KUGAR) all had a significant impact on adoption rates. The findings of controlling matched samples using the PSM process reveal that geomembrane application improves and greatly increases farmers’ technical efficiency. Those who used geomembranes displayed greater technical efficiency than those who did not. These findings imply that salt production technology should be promoted more to increase productivity, especially geomembrane adoption, through outreach and dissemination of information, including for landowners involved in the profit-sharing system. The government should keep supporting salt farmers and motivate them to adopt geomembrane technology to ensure the sustainability of salt production in the coastal communities on Madura Island.
... High-density polyethylene (HDPE) geomembranes show high chemical and mechanical resistance, associated with a low manufacturing cost and a very low permeability coefficient, i.e., typically 10 -11 to 10 -13 cm s -1 . [1][2][3][4][5][6] Geomembranes are exposed to climate conditions during the construction time for landfill applications. However, regarding pond applications, exposure to climate conditions on slopes above the water table continues for a lifetime and an exposed geomembrane can initiate UV, thermal, and oxidative degradations. ...
High-density polyethylene (HDPE) geomembranes are commonly used as an environmental protection liner due to their good chemical and mechanical resistances and low cost. Ultraviolet (UV) radiation is an essential issue in durability studies for pond applications. This study evaluated a 1.5-mm thick HDPE geomembrane exposed to ultraviolet fluorescent radiation for 8760 h in a laboratory and thermoanalytical and physical analyses were conducted towards the understanding of its performance after exposure. According to the results, although the geomembrane maintained the ductile behavior, it showed a 52.48% final decrease in stress crack resistance (SCR) compared to virgin SCR. Moreover, a considerable antioxidant depletion occurred after 8760 h exposure shown by the Std. OIT (standard oxidative-induction time) results, demonstrating a Std. OIT value decrease of 89.19% compared to the virgin Std. OIT. Such a behavior contributed to the susceptibility of thermal effects in the DSC (differential scanning calorimetry) curves and the losses observed in the SCR values, attesting the geomembrane's oxidative degradation mechanism occurred and changed the polymer's structure.
... Lamellar structure antioxidants, such as 1010 and 3114, have a flat, flexible structure that allows them to move between polymer chains. 15 In contrast, antioxidants 168, 330, and BHT have a three-dimensional structure. Among these, BHT has the lowest molecular weight of 220, accounting for approximately one-third of the molecular weights of 3114, 168, and 330 and one-fifth of 1010. ...
High voltage power capacitors employ the oil-impregnated polypropylene film as the insulation. The swelling phenomenon might drive the antioxidants and small molecules within the film to migrate into the oil. It is necessary to comprehensively investigate the physical migration mechanism of antioxidants and their impact on the electrical performance of the oil-film combination insulation system and, consequently, formulate the proper selective prescription of antioxidants. Theoretical elucidation of the competitive interaction mechanism between the film and the oil in attracting antioxidant molecules was achieved through the calculation of inter-molecular binding energy, and the migration coefficient ηm was introduced to quantify the migration characteristics of antioxidants. Experimentally, the effects of antioxidants on the space charge distribution of the film, the dielectric properties of the oil, and the breakdown characteristics of both the film and oil were investigated. The experimental conclusions are consistent with theoretical analysis. The lamellar structure antioxidant molecules with ηm > 1 tend to migrate from the film to the oil, which results in increased dielectric loss and decreased breakdown strength of the insulating oil. In addition, the presence of phosphorus atoms in phosphite antioxidants contributes to a reduction in the breakdown strength of the film. For capacitor grade polypropylene film, in addition to the synergistic effect between different types of antioxidants on the thermo-oxidative stability, the structure of the antioxidant molecules and its influence on the electrical performance of the oil–film systems should also be taken into account.
... HDPE geomembrane is often used as an anti-seepage material for the lining of landfills, surface water 2 storage sites and waste dumps. During the installation and use of the geomembrane, there is a series of tensile actions on the geomembrane [8], so the mechanical performance is an important indicator of the practical application of the geomembrane, and the tensile test is also the main means to test its mechanical performance. ...
Aquatic solar energy cross-season heat-storage technology can store and transfer abundant solar energy from the non-heating season to the heating season, which is one of the important technical routes for renewable energy to be used for clean building heating. Anti-seepage components are an important part of the thermal storage of the water body. As a common anti-seepage material for the thermal storage of the water body, a geomembrane is laid on the pool body and the top cover. In this paper, the mechanical and permeability changes of two kinds of geomembranes are analyzed based on the tests under different temperature environments. The results show that GM 1 has better thermal stability. The elongation at break of GM 1 increases by 33% and GM 2 by 189% when the temperature rises by 40 °C. The osmotic coefficient of GM 1 is reduced by 45% and GM 2 by 58%.
... For TBS, the variable thickness of these textured GMBs resulted in stress concentration at the grooves between the asperities initiating the rupture of the specimens at these points, and this in turn caused large variations in the results (Scheirs 2009;Morsy and Rowe 2019;Zafari et al. 2023aZafari et al. , 2023b. For the conductive-backed GMBs (i.e., xTD and yTA), the variation in the results increased due to the delamination of the conductive layer in some of the specimens during the tensile tests (Zafari et al. 2023b). ...
The degradation behaviour of five multilayered textured white geomembranes (GMBs) is investigated when immersed in two synthetic low-level waste (LLW) leachates with pH 7 and 9 at a range of temperatures (40–85 °C) for 48–55 months. Results are compared to the performance of the GMBs in synthetic municipal solid waste (MSW) leachate. Increasing pH from 7 to 9 gives slightly faster antioxidant depletion in LLW leachate. The estimated time to nominal failure for the GMBs is at least 20% longer in LLW leachate than in MSW leachate containing surfactant that accelerates both antioxidant depletion and stress cracking. Thus, MSW leachate can be used as a conservative proxy to estimate the service life of a GMB in contact with LLW leachate. Two GMBs are considered very highly likely to meet the required 550 year design life of the near-surface disposal facilities even based on the most conservative prediction of the time to nominal failure for the GMBs.
... Smooth GMBs made of high-density polyethylene (HDPE) with thickness of 1.5 mm and 0.5 mm, respectively, were examined. The HDPE was used due to its relatively high resistance to chemical degradation (Scheirs 2009;Rowe 2020). For the 1.5-mm-thick GMB, central circular holes with diameters of 50 mm (Test 1), 20 mm (Test 3), and 10 mm (Test 4), respectively, were punctured in the 590 mm-diameter GMB specimens before testing. ...
Experiments are conducted to investigate leakage through circular GMB holes overlain and underlain by both tailings with various hole diameters and GMB thicknesses. Finite element analyses are performed to explore the effect of hydraulic conductivities (k) of subgrade (underliner) and tailings above the GMB (overliner) on water head contours dissipation. Analytical solution is developed for predicting leakage through circular GMB hole overlain and underlain by both tailings. Results show that the effect of subgrade on leakage is highly dependent on the ratio of k between the underliner and the overliner. If the ratio > 100, no head loss occurs in the subgrade; if the ratio < 0.01, all the head loss occurs in the subgrade. With the deposition of fines from overliner into subgrade, a low permeable filter cake is formed on the subgrade surface, notably increasing the impact of underliner on leakage. With the increasing ratio of k between underliner and overliner from 0.01, 0.1, 1, 10, and to 100, the ratio of leakage relative to a highly permeable subgrade increases from 0.01, 0.1, 0.56, 0.93, and to 1. An intimate interface contact can be achieved when the GMB is underlain by silty sand tailings as subgrade (foundation) material.
... Two geotextile samples (20 × 30 cm 2 ) were exposed for 500 h and 1000 h, respectively. The reason for using these exposure times for UV radiation is that continuous submissions of 500 h and 1000 h can be equivalent to 1 and 2 years of exposure to these materials in an open environment [28], respectively. After exposure, subsamples were taken from each sample to perform mechanical and thermal analysis of the aged material. ...
A Hydroelectric Power Plant (HPP) presents erosion problems on reservoir slopes and margins. Geomats are a biotechnical composite technology increasingly used to protect soils against erosion. Survivability or durability of geomats is essential for successful application. This work analyses the degradation of geomats exposed in the field for more than six years. These geomats were used as erosion-control treatment in a slope at HPP Simplício in Brazil. The degradation of the geomats in the laboratory was also analysed through exposure in a UV ageing chamber for 500 h and 1000 h. Degradation was quantitatively evaluated by testing the tensile strength of the geomat wires and thermal tests such as thermogravimetry (TG) and differential scanning calorimetry (DSC). The results showed that the geomat wires exposed in the field had a greater decrease in resistance compared to the samples exposed in the laboratory. In the samples collected in the field, it could be observed that the degradation of the virgin sample occurred earlier than in the exposed samples, contrary to what was observed in the TG tests carried out with the samples exposed in the laboratory. The DSC analysis showed that the samples had similar behaviours for the melting peaks. This evaluation of the wires of the geomats was presented as an alternative to analysing the tensile strengths of discontinuous geosynthetic materials such as the geomats.
... BGMs consist of a core nonwoven polyester geotextile (NW-GTX) and a glass fleece sheet as the reinforcement layer that is impregnated and coated with bitumen to create a flexible and impermeable sheet (Peggs, 2008;Bannour et al., 2013). The bitumen used in the production of BGMs is typically stabilized using elastomers such as styrene-butadienestyrene (SBS) (Touze-Foltz and Farcas, 2017) to improve its workable temperature (Scheirs, 2009;Touze-Foltz and Farcas, 2017). The top surface of the BGM is typically sanded to increase the interface friction strength while the bottom surface is bonded to a polyester film to protect the BGM from upward root penetration (Breul et al., 2008;Lazaro and Breul, 2014). ...
The effect of thickness (4.8 and 4.1 mm) on the degradation of two bituminous geomembranes (BGMs), when immersed in a synthetic leachate is investigated over a period of 33 months. Based on the data collected at four different temperatures (20, 40, 55, 70 • C), it is shown that the 4.1 mm has slightly faster degradation than the 4.8 mm thick BGM. Due to the reduced conditions of the examined leachate, the degradation in the chemical and rheological properties of the bitumen coat was relatively lower than in air and water immersion. However, the presence of a surfactant in the leachate increased the degradation of the polymeric back film and the reinforcement layer responsible for the mechanical properties of the BGM. The time to nominal failure of the two BGMs is predicted at a typical range of landfill liner temperatures using Arrhenius modelling. The predictions at temperatures >20 • C suggest that the examined BGMs may not be suitable for the containment of solid wastes containing surfactants due to the fast degradation in their mechanical properties.
... geomembrane facilities [7]. To enhance durability and reduce the likelihood of leaks, thicker sections of HDPE are recommended for applications requiring greater tensile strength and to accommodate welds. ...
High-density polyphenylene geomembranes are utilized as large-scale floating covers in anaerobic water treatment plants for the purpose of collecting renewable biogas energy and preventing the emission of odorous by-products. During degradation, the accumulation of scum, the presence of biogas pockets and sewage can negatively impact the structural integrity of the covers and hinder degradation efficiency. Traditional methods are insufficient in identifying the substances under the covers. In this study, a thermography technique was developed and tested in lab-scale experiments using ambient weather information to inspect the geomembranes. The technique was then applied to a remote monitoring investigation of large-scale floating covers located at a sewage treatment plant. Long-term monitoring of two regions on the covers was conducted using a thermal camera, with ambient weather information recorded to help analyze temperature changes. The acquired thermal image sequences were analyzed, resulting in the creation of a segmented cover map indicating the profiles of substances. The results of the on-site thermal imaging field trials verify the effectiveness of the developed remote sensing thermography technique, which has the potential to assist in future asset maintenance, remove scum efficiently and enhance anaerobic degradation efficiency at sewage water treatment plants.
... Seaming (welding) in the field is one of the key elements affecting the integrity of the barrier. Polymeric GMBs can be welded or seamed by either thermal methods or chemical welding (Scheirs 2009). Thermal methods rely on fusion of surfaces to be joined with applied heat and pressure (e.g., wedge welding, hot air welding, extrusion welding). ...
... It is then mixed to give a homogeneous distribution and dispersion. The molten resin is forced through a flat-die or round-die (blown-film) [15][16][17]. Geomembrane texturing techniques vary from manufacturer to manufacturer. The technique influences the microtexture's and macrotexture's strength and durability of the geomembrane [18]. ...
In mining, due to the high environmental responsibility and the high load supported, the geomembrane-soil interface must guarantee parameters (such as friction angle and adhesion) that contribute to the stability of the barrier system. The use of a textured High-Density Polyethene (HDPE) geomembrane, known as a structured geomembrane, guarantees uniformity in asperity height due to the manufacturing process (flat-die). The present work presents the results of direct shear tests of the geomembrane-soil interface carried out for the liner project of a mining company, where the processing of bauxite, the primary natural source of aluminum, is carried out. The tests were performed with a textured geomembrane with different asperity heights, and two soil types representative of the site (in saturated and dry conditions). The results showed similar values for peak resistance and residual resistance. No influence of the asperity height on the interface parameters was observed, which suggests the need to evaluate other texture characteristics. The need to perform geomembrane-soil interface tests for any liner project, especially for mining, stands out.
... Furthermore, chloride mobility in leachate is one of the highest [75], and 100-150 years are needed before chloride in MSW leachate can be directly released without attenuation to the environment [76]). Consequently, a highdensity polyethylene (HDPE) geomembrane base liner shall be implemented in MSW landfills in Cairo because the non-polar matrix of polyethylene reduces the diffusibility of inorganic salts into the geomembrane [67,77,78]. Specifically, the diffusion of chloride into the HDPE geomembrane is extremely low [75]. ...
The composition of municipal solid waste (MSW) in the Cairo metropolitan area is investigated. The outputs of MSW sorting analysis at various locations in Cairo with different waste management schemes are presented. Organics (58–75%) and plastic waste (19–28%) are the main components of MSW in Cairo with a higher percentage of organics in landfills compared to dumpsites. The leachate quality is analyzed, and the analysis results indicate that the concentration of macro inorganic pollutants (NH4+, Na+, Ca2+, and Cl−) and heavy metals (e.g., Cd2+ and Zn2+) are exceeding the majority of values reported in the literature in various cities all over the world. There was no evidence of an effect of the recycling process on chloride concentration in leachate, while the concentration of iron was reduced. The variation of leachate quality with time for two samples collected from the same municipal solid waste landfill is presented. The first leachate sample is a two-year-old, and the second sample is a sixteen-year-old. There was a significant increase in the concentration of chloride, sodium, chromium, calcium, and magnesium. The implications of the leachate quality in Cairo on the longevity of barrier systems in an MSW landfill are discussed.
... Teknologi geomembrane pada meja kristalisasi diklaim mampu meningkatkan kualitas garam yang dihasilkan menjadi lebih bersih dan homogen sehingga garam tersebut memenuhi syarat SNI langsung dari lahan penggaraman, yakni dengan kadar iodium 30-80 ppm (Assadad & Utomo, 2011). Teknologi geomembrane memiliki beberapa kelebihan yaitu tahan terhadap sinar ultraviolet dan bahan kimia (Scheirs, 2009) serta berfungsi untuk mencegah susutnya air laut yang menjadi bahan baku garam, mempercepat proses kristalisasi, sehingga garam yang dihasilkan lebih putih dan bersih karena tidak berinteraksi langsung dengan tanah (Suhendra, 2016). Banyaknya petambak garam di Kabupaten Sumenep masih menggunakan metode tradisional maduris untuk produksi garam, karena bagi petambak garam teknologi geomembrane dan teknologi rumah garam adalah suatu inovasi baru bagi petambak garam di Kabupaten Sumenep. ...
Saluran komunikasi adalah media untuk pembangunan pertanian berkelanjutan serta pemanfaatan inovasi dan teknologi bagi peningkatan kesejahteraan masyarakat tanpa mengabaikan kelestarian sumber daya alam dan lingkungan. Pemerintah mendorong aplikasi inovasi teknologi geomembrane pada produksi garam dengan tujuan untuk meningkatkan produktivitas dan kualitas garam yang dihasilkan. Tujuan penelitian ini adalah mendeskripsikan saluran komunikasi dan persepsi petambak garam rakyat terhadap inovasi teknologi geomembrane, serta menganalisis hubungan antara saluran komunikasi dengan persepsi inovasi teknologi tambak garam. Unit analisis adalah petambak garam rakyat di Desa Gersik Putih dan Desa Sentol Daya Kabupaten Sumenep sebanyak 68 responden. Data dianalisis menggunakan metode korelasi pearson. Hasil analisis menunjukkan bawah petambak garam rakyat menggunakan seluruh saluran komunikasi kecuali media hibrida internet. Persepsi terendah adalah kerumitan dan persepsi tertinggi adalah tingkat trialabilitas pada teknologi geomembrane. Saluran komunikasi interpersonal berhubungan dengan persepsi inovasi pada karakteristik tingkat keuntungan relatif, tingkat kompabilitas, dan tingkat observabilitas, sedangkan komunikasi kelompok berhubungan negatif pada tingkat trialabilitas.
This study investigates the degradation of colored (white and black, green on both sides and black on both sides) textured high-density polyethylene (HDPE) geomembranes with a nominal thickness of 1.00 mm, subjected to fluorescent UV chamber exposure under controlled cycles of radiation and condensation for durations of 500, 1000, and 2000 h. The geomembranes were manufactured using flat-die fabrication, a less common process. Degradation was evaluated by analyzing the retained Melt Flow Index (MFI) under high load (HLMI) and low load (LLMI), tensile properties including strength and strain at yield (elastic deformation limit) and at break (end of plastic deformation), and secant rigidity modulus (Js). Antioxidant depletion was assessed using Standard Oxidation Induction Time (Std-OIT) tests. Exponential decay models, including first-order and second-order equations, were applied to describe antioxidant depletion during stage I of oxidation. The first-order decay model, considering retained Std-OIT values, provided the best overall fit for the three geomembranes. The results showed that colored geomembranes exhibited faster antioxidant depletion rates than conventional black HDPE geomembranes.
This study investigates the degradation of textured High-Density Polyethene (HDPE) geomembranes (GMs) subjected to natural weathering for 8.5 to 10.5 years. The GMs, denoted as GM-W/B (white and black), GM-G (green) and GM-B (black), had a nominal thickness of 1.00 mm and were manufactured using a flat die process with texture on both surfaces. Standard Oxidation Induction Time (Std-OIT) tests and Thermogravimetric Analysis (TG/DTG) were performed to assess the antioxidant depletion and thermal decomposition. Additionally, degradation due to Ultraviolet (UV) radiation and environmental agents was assessed through retained physical and mechanical properties, including the Melt Flow Index (MFI) measured under various loading conditions. Antioxidant depletion and TG/DTG analyses indicated that environmental exposure compromised the thermal stability of these GMs. Among the tested GMs, GM-W/B exhibited the greatest reduction in both Std-OIT and MFI, followed by GM-G and GM-B, suggesting a direct correlation between these properties. While GM-B appeared to be still in the antioxidant depletion stage (Stage I), GM-W/B and GM-G showed signs of degradation beyond Stage I. This study provides insights into the degradation of textured HDPE GMs in the face of weathering exposure effects and the durability of colored HDPE GMs.
High Density Polyethylene (HDPE) Geomembranes have been used in containment applications for the past 50 years. Over this period, Polyethylene Geomembrane formulations have changed markedly with a design need to contain higher risk contaminants stored in more challenging environments. One of the major product developments has seen the emergence of “White Top Layer” Geomembranes. Atarfil would concur, and our most recent immersion and exposure data is compelling. It is not simply the thermal behavior that is beneficial, the additive types required to meet the challenges of stabilizing white layers, also serve significantly better protection when subjected to UV and Immersion Testing. This is translating to significantly longer predictions of Geomembrane performance life.
The depletion of antioxidants from a 2 mm high-density polyethylene geomembrane immersed in brine at seven temperatures (95, 85, 75, 65, 55, 40, and 25°C) for 28 months is reported. An Arrhenius model is used to predict the performance of the geomembrane at low site-specific temperatures. The antioxidant depletion times are reported for temperatures between 20 and 95 o C. The solubility of the antioxidant and stabilizer packages, the oxidation by-products, and their susceptibility to hydrolysis are discussed. After 28 months of incubation, no oxidative degradation was observed for samples in the full brine solution even at 95 o C. Morphological changes reduced the stress-crack resistance to a stable representative value without a reduction in the tensile elongation at break. The effect of the brine solution concentration on the depletion of antioxidants and stabilizers was investigated at 85°C. It was found that the depletion rate decreases with the increasing brine concentration.
This paper is a summary of many of the key findings on the application of geosynthetics in tailings storage facilities. Topics include the compressibility and permeability of tailings, the equations predicting leakage through circular and non-circular geomembrane holes, the effect of the subgrade permeability, and the effect of a lateral drainage system within tailings on leakage predictions. Two commonly encountered engineering problems relating to the piping through circular geomembrane holes and the opening width of non-circular defective geomembrane seams are given to demonstrate the potential application of leakage prediction equations. Meanwhile, issues related to the subgrade imperfection and the long-term performance of both high-density polyethylene (HDPE) and bituminous geomembranes in tailings storage applications are addressed. The research highlights that an appropriate HDPE geomembrane liner can be expected to perform very well for an extremely long time, limiting leakage and contaminant migration from the facility into the surrounding environment if the liner is well constructed on a suitable subgrade.
The tensile shear strength, break location, and constant tensile load failure times are examined for seams made from one 4 mm-thick bituminous geomembrane (BGM) product, with corresponding observations specific to that material. In short-term tests, failure is observed within the sheet material once the seam strength exceeded 0.8 times that of the sheet material. The effects of seam thickness reduction and overlap width on seam strength are examined for two methods of seaming. Seams with a short-term strength meeting or exceeding 80% of the sheet strength are subjected to constant tensile loads between 18 and 55% of sheet ultimate strength and the time to failure is reported. The relationship between short-term seam strength and time to failure under sustained load and thickness reduction and squeeze-out is investigated. Constant tensile load testing is proposed as a construction quality assurance procedure to assess the degree of geotextile engagement of field seams.
Chapter 17 provides an introduction to geosynthetics. The description begins with definitions of the term, including those from ASTM and EN ISO standards, and the reasons for the explosion of geosynthetic materials in the civil engineering market. The next heading discusses the raw materials used in manufacturing geosynthetics, polypropylene (PP), polyethylene (PE), poly(vinyl chloride) (PVC), and polyester (polyethylene terephthalate—PET) being the most commonly used polymers. In specific applications, some geotextiles can incorporate natural biodegradable fibers. Manufacturing processes of geosynthetics are then discussed, including nonwoven, woven, and knitting methods. Subsequently, geosynthetic functions are described; hydraulic functions include filtration, drainage, and fluid(gas) barrier while mechanical functions are mainly separation, reinforcement, and protection. The next topic covers description of the most commonly available geosynthetics, i.e., geotextiles, geomembranes, geogrids, geonets, geocells, geofoams, geomats, geosynthetic clay liners, and geocomposites. At the end of the chapter, geosynthetics applications are kept in mind, including embankments on soft soils, erosion control, hydraulic landfills, railroads, roadways, and retaining walls. To finish the chapter, geosynthetic standards are very briefly discussed.
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