Nicoleta Sporea

The paper addresses the methodology for obtaining biocomposite structures from waste, with sound-absorbing properties, such as: thuja shells, walnut shells, pistachio shells, beech sawdust, pumpkin seeds shells and sunflower seeds shells. The experimental analysis carried out considers the study of the sound-absorbing properties held by the proposed new biocomposite materials, by determining the value of the sound absorption coefficient, reflection coefficient, impedance ratio, using the Kundt tube. The interpretation of the results obtained from the evaluation of biocomposites shows that they have sound-absorbing properties. Consequently, sound-absorbing panels with soundproofing properties can be made from these materials, which can be used in industry, transportation, construction, etc. as well as for decorative purposes in spaces such as cinemas, malls, spas, etc.

The paper presents an environmental impact study in a real case: a landfill containing hazardous substances, held by an economic operator in an area near a city. The sludge storage was monitored taking into account three main impact factors: soil, groundwater and leachate. The actual environmental status of the storage area is assessed by calculating these impact factors before and during ten years of storage and the global pollution index.

The paper aims to present research on the determination of the coefficient of acoustic absorption as a function of frequency, for composite monolayer plates (made of: MDF - wooden dried agglomerated fibres with medium density, RWB - rebated wood from dried beech, PS - extruded polystyrene) and multilayer (with outer coatings of: MDF, RWB and polymeric core of extruded polystyrene). The sound-absorbing behavior of such plates is highlighted in the cabins made of multilayer structures.