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Plastic recyclates can be contaminated with a variety of impurities due to their previous life, which cannot always be perfectly separated in recycling pretrcatment steps. Hence melt filtration is an important step in reprocessing plastic rccyclates to achieve material of sufficient purity, but it also leads to more stress on the material due to higher pressures and longer processing times. In our study, we investigated the influence of typical particulate impurities as may occur in recyclate on the mechanical and rheological properties of AP.S. Even low amounts of contaminations lowered the key properties. Melt filtration of post-consumer ABS recyclate with different mesh size melt screens showed little improvement of mcchanica! properties, but longer idle times and loss of material. Damage to the material caused by finer filtration could be shown by thermal measurements. Highlights * Determination of properties of ABS contaminated with 0.5-2.0 wt.% of selected impurities (wood and rubber particles). * Melt filtration of post-consumer ABS recyclate with different melt screens. * Investigation of process and properties of filtered ABS recyclate. KEYWORDS ABS lecyclate, mechanical properties, melt titration, melt screens, particulate contaminations, 1 | INTRODUCTION Recycling post-consumer waste is challenging, but inevitable to contribute to global waste and resource problems and to establish a true circular economy. One obstruction on the path [...]

The spatial distribution of hydraulic gradients within a soil sample under cyclic flow with different frequencies was measured and compared with calculated results. The permeability within the soil before and after cyclic flow was compared. This study shows that a lower ratio of consolidation coefficient of the soil to the angular velocity of cyclic flow will result in higher hydraulic gradients at the boundaries, and lower gradients within the soil. This study suggests that besides geometrical parameters of soil and geosynthetics, the consolidation coefficient of the soil and the frequency of cyclic flow need to be considered as well in the design of filters under cyclic flow. DOI: 10.1061/(ASCE)GT. 1943-5606.0000009 CE Database subject headings: Soil water; Filtration; Hydraulic gradients; Silts.

Seepage erosion phenomena can arise when particles of soil are transported underneath any hydraulic structure by the seepage flow, as a consequence of the difference in the surface elevation upstream and downstream of the hydraulic structure. To assess the stability of hydraulic structures against seepage erosion computational models are available varying from simple empirical rules to advanced models. In this paper, the safety coefficient is assessed by comparing the exit gradient with the critical gradient: the former represents the hydraulic gradient at the exit point along the downstream ground surface, whereas the latter is the gradient at which upward drag forces on the soil particles equal the submerged weight of the soil particles and a quicksand condition originates. An experimental research was carried out to analyze different thickness sheet piles embedded in sandy soils, resulting in agreement between experimental data and theoretical values if the thickness of the sheet pile and the ground surface deformation are properly taken into account. DOI: 10.1061/(ASCE)0733-9429(2008)134:6(794) CE Database subject headings: Filtration; Seepage; Soil erosion; Heaving; Hydraulic models; Experimentation; Sand.