No abstract

The utilization of residual materials in the fabrication of new products has a strong impact on the preservation of non-renewable natural resources, diminishes energetic consumption and avoids the costs and problems that imply the final disposal of them. The aim of this work is to investigate the recycling of waste foundry sand coming from the process of cast iron for use as aggregate in the manufacture of red clay bricks and tiles. The raw materials, waste foundry sand and clay soil were chemically and microstructural characterized and different samples were designed. Compact bodies were prepared with 10%, 20%, 30%, 40% and 50% (wt%) of waste. They were thermally treated in the range 950-1000ºC. The experimental conditions were established taking into account those used for commercial products. The characterization of raw materials and products was carried out using various techniques. The results allow one to conclude that it is feasible to incorporate important quantities of waste foundry sand into the manufacture process of clay bricks and tiles. The best properties were obtained in samples with 30 and 40 wt% of waste added, taking into account the characteristics required for commercial applications.

The generation of industrial residues is unavoidable, but these materials may be recovered, redirecting them toward new production processes, rather than allocating them to the stream of discards. The aim of this paper is to study the feasibility of utilization of metallurgical wastes as raw material for tiles in the ceramic industry, using the residual materials as aggregates in clay based ceramics. The residues used are: sludge and slag from several metallurgical processes, Ruthner dust and foundry sand. Samples were obtained from mixtures of clay and each waste in various percentages, which were then heat treated. The pieces obtained were characterized using several techniques, with the aim of determining the properties of these materials in relation to the commercial requirements. A high feasibility of reuse of most of these wastes as raw material in the production of ceramic bodies has been established.

The air quality in urban regions is affected by the presence of pollutants, mainly coming from combustion processes. The principal source is vehicular traffic which emits nitrogen, sulfur and carbon oxides, hydrocarbons, particulate matter, etc. into the atmosphere.In this work the influence of the changes in traffic during holidays on the air quality of the centre of Mar del Plata city was analyzed. For this purpose continuous monitoring equipment with electrochemical sensor technology was installed, in order to determine the contaminant concentration. Simultaneously the vehicular density was measured. These measurements were performed during winter vacations and during a similar period of working days.The obtained results allow one to determine that the air quality in the centre of Mar del Plata is not noticeably affected by the fluency of more vehicles. This was interpreted taking into account the behaviour of the tourists and local people.The determined pollutant levels are relatively low considering the number of automobiles. This situation is usually observed in seashore cities, due to the air fluxes or "channels" formed in the street canyons, which include the street and their flanking walls [1].

Wastes from construction and demolition (C&D) are mainly composed of inert materials. A small proportion of C&D wastes contain substances which make them hazardous, for example, those wastes containing asbestos, mineral fibres, additives, some paints and resins, among others.On the other hand, in the manufacturing of several products used in the construction industry many hazardous substances are utilized. In most cases these materials are relatively safe while being used, but they become dangerous when they are broken, spilled or released in some way.There are other wastes groups which are not hazardous by themselves, but they can suffer reactions, producing toxic substances. These groups include, for example, some plastics or treated woods, which can emit toxic gases when they are burnt for energetic profit.In this work a scheme is presented for the safe management of construction and demolition wastes containing hazardous substances, starting from an inventory of hazardous wastes. This scheme takes into account different stages: i) selective extraction avoiding the mixture with no hazardous wastes, ii) characterization of hazardous substances contained in C&D, iii) feasibility evaluation of the reuse or recycle of the analyzed material and, iv) adequate treatment either for recycling or for safe final disposal.This constitutes the first step in the way of obtaining proper norms in this area, absent nowadays from the local regulations.