Marcin K. Widomski

Hydraulic Conductivity and Landfill Construction

Landfills are important engineered constructions spread all over the world. Their number is calculated in thousands as the production of wastes in Europe only, reaches each year 3000 million tones of which 14% (about 415kg per capita) is municipal waste (EEA, 2004). Of this in 1999 about 57% was landfilled, 16% was incinerated, 20% recycled and composted and 7% was treated in other way. There are numerous types of landfills from simple dumping sites to rather sophisticated constructions constituting real bioreactors. Due to uncountable biochemical reactions occurring within the waste body, landfills produce biogas and leachates which threaten the pollution of air, water and soil. The environmental impact of landfills depends, to a high extent, on a bottom liner and top capping isolating the landfill from the surrounding. The quality of this isolation is determined by the water permeability as, in fact, no constructions are completely impermeable. There are two essential types of liners i.e. mineral clay liners and synthetic liners of different geomembranes (or combination of both). As durability of synthetic liners is limited in time the mineral clay liners, which can persist thousands of years, if managed in a sophisticated way as it was proved by the countless layered natural soils worldwide, are preferred as a long term impermeable and rigid system. It is necessary to emphasize that landfill should preferably have a bottom liner and top capping. The function of bottom liner is to prevent the deeper soil layers and the groundwater from contamination with soluble substrates and irreversible pollution of the future drinking water reservoirs. The function of the top capping is to avoid infiltration of the precipitation water (from rain and from snow melting) and migration of methane and odors from the biogas to the atmosphere. However, the top capping system also has to guarantee optimal (or at least satisfactory) conditions for plant growth while the deep rooting of plants must be prevented. Thus, these conflicting requirements can be only fulfilled by special mineral soil systems which, if they are adjust, will preserve their properties for ever.

Shrink-swell potential, hydraulic conductivity and geotechnical properties of clay materials for landfill liner construction

Abstract This paper presents studies concerning the applicability of two clay materials for the construction of a sustainable landfill liner. The studies consisted in determination of basic characteristics of the materials, eg particle size distribution, bulk density, particle density, total porosity, pore size, mineralogy, specific surface area, nanoparticle size, and Atterberg limits, as well as measurements of their geotechnical and hydraulic parameters, such as in situ saturated hydraulic conductivity, modules of primary and secondary compression, cohesion, and angle of internal friction. Furthermore, the effects of compaction performed by the Proctor method at various water contents on swelling and shrinkage characteristics and saturated hydraulic conductivity were investigated in order to determine the compliance with the national requirements for selection of material for landfill liner construction. The determined characteristics and geotechnical parameters of the tested clay materials allowed qualifying them as suitable for municipal landfill construction. The shrinkage potential of the tested clays observed was rated as moderate to very high. The cyclic drying and rewetting of the clay materials performed resulted in a significant increase in saturated hydraulic conductivity. Thus, the clay sealing layers, as part of a multilayer liner, should be very carefully operated, preventing the drying out of the clay sealing and assuring the possibility of its constant saturation.

Impact of Different Binders on the Roughness, Adhesion Strength, and Other Properties of Mortars with Expanded Cork

The aim of the research that is presented in this paper was to evaluate the physical and mechanical properties of heat-insulating mortars with expanded cork aggregates and different binders. In this work, the measurements of surface roughness and adhesion strength, supported by determination of basic mechanical and physical parameters, such as density, bulk density, open porosity, total porosity, absorbability, thermal conductivity coefficient, compressive strength, flexural strength, and frost resistance of mortars containing expanded oak cork, were performed. The scanning electron microscope (SEM) investigations demonstrated the microstructure, contact zone, and distribution of pores in the heat-insulating mortars containing expanded cork. The results indicated that the addition of expanded cork and different binders in heat-insulating mortars triggers changes in their roughness and adhesion strength. The SEM research confirmed the very good adhesion of the paste to the cork aggregate.

Influence of aggregate type and chemical admixtures on frost resistance of lightweight mortars

The aim of studies presented in this paper covered analyses of type of lightweight aggregate as well as aeration and hydrophobic admixtures influence on absorbability and frost resistance of heat-insulating mortars applied in the energy-efficient construction. In the presented research, expanded perlite (EP) and expanded clay aggregate (ceramsite) were used as lightweight aggregates. The measurements of the basic mechanical and physical characteristics of tested mortars were performed, including, inter alia, compressive and flexural tensile strength, density, effective (open) and total porosity, absorbability, thermal conductivity as well as frost resistance after 25 cycles of freezing and thawing. Substitution of some part of sand fraction by the lightweight aggregates, expanded clay aggregate or perlite, resulted in changes in physical properties of the tested mortars. The observed decrease in density (specific weight), coefficient of heat transport and strength parameters were simultaneously accompanied by the increase in absorbability. Researches concerning frost resistance of mortars containing ceramsite and perlite showed the improved frost resistance of mortar utilizing perlite. Most of the tested mortars shoved satisfactory frost resistance, only samples of mortar containing ceramsite and aeration admixture were destroyed. The significant influence of aerating admixture on frost resistance of mortars was determined. Hydrophobic siloxanes addition failed to adequately protect the mortars against frost erosion, regardless the type of applied aggregate.The aim of studies presented in this paper covered analyses of type of lightweight aggregate as well as aeration and hydrophobic admixtures influence on absorbability and frost resistance of heat-insulating mortars applied in the energy-efficient construction. In the presented research, expanded perlite (EP) and expanded clay aggregate (ceramsite) were used as lightweight aggregates. The measurements of the basic mechanical and physical characteristics of tested mortars were performed, including, inter alia, compressive and flexural tensile strength, density, effective (open) and total porosity, absorbability, thermal conductivity as well as frost resistance after 25 cycles of freezing and thawing. Substitution of some part of sand fraction by the lightweight aggregates, expanded clay aggregate or perlite, resulted in changes in physical properties of the tested mortars. The observed decrease in density (specific weight), coefficient of heat transport and strength parameters were simultaneously accompanie...

Methodology of Moisture Measurement in Porous Materials Using Time Domain Reflectometry / Metodyka Prowadzenia Badań Wilgotności W Ośrodkach Porowatych Za Pomocą Reflektometrii W Domenie Czasu

Abstract The article presents the description of measurement methodology of moisture transport in unsaturated porous materials using Time Domain Reflectometry (TDR) technique on the example of measurement of capillary uptake phenomenon in the sample of autoclaved aerated concrete (AAC). In the paper there are presented basic principles of the TDR method as a technique applied in metrology, its potential for measurement of moisture in porous materials like soils and porous building materials. Second part of the article presents the experiment of capillary rise process in the sample of AAC. Within the experiment moisture content was monitored in the sample exposed on water influence. Monitoring was conducted using TDR FP/mts probes. Preparation of the measuring setup was presented in detail. The TDR readouts post-processing, graphical presentations of the obtained results, short discussion and comparison of TDR readouts to gravimetric measurement were also presented. Abstrakt W artykule przedstawiono opis metodyki pomiaru transportu wilgoci w nienasyconych porowatych materiałach przy wykorzystaniu techniki Time Domain Reflectometry (TDR) na przykładzie pomiarów zjawiska podciągania kapilarnego przez próbkę autoklawizowanego betonu komórkowego. Zaprezentowano podstawowe informacje na temat metody TDR jako techniki stosowanej w metrologii. Omówiono jej potencjał do pomiarów wilgoci w takich ośrodkach porowatych, jak gleby i porowate materiały budowlane. Druga część artykułu przedstawia eksperyment podciągania kapilarnego przez próbkę autoklawizowanego betonu komórkowego. W trakcie trwania eksperymentu monitorowano zmiany wilgotności w próbce wystawionej na oddziaływaniewody. Monitoring realizowano za pomocą sond TDR FP/mts. Rozdział „Materials and Methods” przedstawia szczegółowo przygotowanie stanowiska pomiarowego. W rozdziale „Results” podano odczyty miernika TDR przeliczone na wilgotność oraz zaprezentowano uzyskane wyniki w postaci graficznej. Zawarto w nim również krótką dyskusję wyników i porównanie odczytów TDR z pomiarami grawimetrycznymi.

Influence of Treated Sewage Discharge on the Benthos Ciliate Assembly in the Lowland River

Abstract This paper presents results of the studies of ciliate assemblage in benthos of lowland river influenced by sewage discharged from the municipal wastewater treatment plant. During the presented research the 47 ciliate species, including 45 species from the benthos of the river and 18 from the activated sludge of aeration chamber were identified. Only two species registered in the activated sludge were not observed in the river. Against the background of the lowest number of species in the point located in the distance of 50 m below the discharge of sewage the maximum amount and biomass of these species were observed. Whereas, 200 m below the discharge the decrease in number and biomass of ciliate to the level noted for location before the discharge was observed. Thus, generalizing, one may state that influence of municipal WWTP sewage discharge for ciliate assemblage in the river’s benthos was clearly visible but local.