Photocatalytic materials can minimize atmospheric pollution by decomposing certain organic and inorganic pollutants using sunlight as an energy source. In this paper, the development of a methodology to measure the photocatalytic potential of mortar containing TiO2 nanoparticles is reported. The results indicate that up to 40% of NOx can be degraded by Portland cement mortar containing 30-50% of TiO2, which validates the method developed for evaluating the photocatalytic potential of materials.

Para a caracterização, classificação e o mapeamento da corrosividade atmosférica da cidade de São Luís-MA, região costeira do Norte do Brasil, foi desenvolvida uma metodologia baseada na implantação de quinze estações de corrosão atmosférica (ACS) abrangendo diferentes ambientes corrosivos. Nestas ACS foram monitorados, mensalmente, a taxa de deposição dos principais poluentes atmosféricos (íons cloreto, Cl_; gases compostos de enxofre, expressos em SO2 e partículas sedimentáveis) e os parâmetros meteorológicos, a fim de se obter subsídios para a classificação da corrosividade atmosférica. Em quatro destas ACS foram instalados, além dos módulos de coleta de poluentes, painéis de intemperismo natural com corpos-de-prova dos materiais metálicos: aço-carbono, aço galvanizado, alumínio e cobre, metais mais utilizados no setor de distribuição e transmissão de energia elétrica local. Da classificação atmosférica foi elaborado mapa para promover a seleção dos materiais segundo seu desempenho em cada região e diminuir custos diretos e indiretos da corrosão pela extensão da sua vida-útil.

The main purpose of this study is to develop a method to characterize and classify the atmospheric corrosivity of the Sao Luis City, located at the Brazilian North coast, establishing 15 atmospheric corrosion sites (ACS), in different environments. These sites were monitored on a monthly basis to determine the deposition rates of atmospheric contaminants, such as airborne salinity, represented by chloride ions (Cl_), sulfur-containing substances, represented by SO2 and dustfall. These parameters were correlated to meteorological data and both were used to classify the atmospheric corrosivity. At the same time, metallic samples such as low carbon steel, galvanized steel, aluminum and copper, which are commonly used in transmission and distribution power lines, were exposed to the environment in four of these 15 sites, in order to qualify the environmental aggressiveness according to the corrosion rate of these materials. Based on the mapping results, it was possible to determine the materials which are more proper to be used in those specific areas, which could result in the cost reduction due to a span-life extension of such structures.

An alternative application of the humid sludge from the Passaúna WTP, located in Curitiba's metropolitan area, is proposed for concrete structures, partially replacing aggregates and cement. For the investigation, a reference concrete and four concrete mixtures with sludge were produced, and from these, two mixtures, containing 4% and 8% of sludge (m/m), were analyzed by different techniques: X ray fluorescence, X ray diffraction, thermo-gravimetric analysis, physicochemical analysis, compressive strength, etc. The properties were evaluated and the results indicate that the mixtures can be applied in different situations as cast structures for construction of concrete walls. Mixtures with more than 4% of sludge are restricted to applications where the workability of the concrete is not required, such as for residential pavements, sidewalks and stepping floors.