J Scheirs’s scientific contributions

As the geosynthetic installation sector attempts to manage current global challenges, it is beginning to rely on AI technology and sensor technology to ease some pressure. This white paper explains what AI technology is and outlines the business case for investing in this technology.

Thermal fusion welding plays a crucial role in ensuring the integrity and effectiveness of geomembrane liners used in geotechnical and hydraulic engineering systems. This technical paper emphasizes the importance of monitoring all welding parameters during the hot wedge or hot air combi thermal fusion welding process to achieve best practices (refer to Photo 1). The paper highlights the significance of factors influencing geomembrane fusion welding and emphasizes the need for accurate control and reproducibility of heat/energy, speed, and pressure parameters. It also discusses the importance of squeeze out and the significance of welding device design principles. The paper concludes by emphasizing the importance of adherence to testing standards and the necessity of incorporating data acquisition systems for post-welding analysis. Photo 1: Fusion (double wedge) welding of HDPE geomembrane 2

This technical note discusses the use of coupons of geomembrane to monitor the performance of geomembranes in real-time and describes how coupons are immersed into the facility, extracted periodically, and tested to determine whether any property changes or deterioration is occurring. Furthermore, the technical note explains how the coupons can be positioned at various locations to determine the effect of spatial distribution on the rate of geomembrane liner deterioration.

This technical note investigates the impact of inadequate compensation slack and point loads on the stress cracking of HDPE geomembranes. The installation of HDPE geomembranes on slopes without compensation slack to compensate for thermal contraction during cooler nights can lead to excessive strains that can cause stress cracking. The presence of underlying rocks and aggregate can exacerbate the situation by exerting point loads on the geomembrane, which can promote stress cracking. The stresses imposed by angular rocks and aggregate on the geomembrane are significant in the field situation. The concern, particularly with HDPE, is not whether the geomembrane is punctured but rather whether it is stressed sufficiently to induce stress cracking in the longer term. The technical note demonstrates that damage is done to the geomembrane well before a leak, hole, or puncture might occur in it.

High Density Polyethylene (HDPE) geomembranes contain proprietary blends of antioxidants and stabilisers (known as the additive package) to improve the service life of the polymer. The service lifetime of HDPE liners is mainly dependent on the level and permanence of the additive package. The problem is manufacturers do not disclose the mix of additives to the end-user, and they regularly engage in resin substitution, masterbatch substitution and additive substitution based on price and local availability of the raw materials. This has led to a lot of uncertainty around the consistency and quality of HDPE geomembrane products available today. The way to overcome these issues is by reverse engineering the additive package through deformulation, and performing the newly developed rapid screening procedures outlined in this paper. Although conventional long-term immersion testing is now recognized as the preferred method to assess the durability of HDPE geomembranes in specific end-use media, the protracted amount of time required to develop meaningful ageing of the geomembrane is a disadvantage. Conventional accelerated ageing tests typically require a minimum of 3 to 6 months and sometimes years to complete, while the new rapid screening procedures can be completed within 2 to 4 weeks. The additive de-formulation combined with the knowledge of the acid and alkali tolerance of each additive (known as pKa values) allows one to predict the performance of the geomembrane for a given service environment, while the rapid screening procedure can ameliorate the risk level associated with using HDPE geomembranes and provide a greater degree of comfort to designers and facility owners, particularly when project timelines are tight.