Environmental issues have been at the center of society's concerns for a long time. Recently, this kind of concern is growing even more due to the damage caused to the environment by electrical and electronic product waste. Based on this same concern, this work aimed to analyze, through a literature review, the production and treatment of electronic waste in today's world, with an emphasis on Brazil and China. The articles reviewed point to an increase in the production of this type of waste, in both Brazil and China, and reveal that the current processes of treatment of electronic waste mostly aim to obtain profit through the recovery of precious metals such as copper. This paper concluded that although Brazil is one of the major producers of e-waste, more than 90% of its e-waste has not had a proper final destination. This deficiency in e-waste treatment in Brazil is mainly due to financial factors and the lack of a robust educational policy focused on the environment. Thus, this work suggests the implementation of an effective educational policy aimed at environmental conservation, as well as investments in research on recycling methods in Brazil, especially on the use of e-waste as an aggregate in the manufacture of concrete.

The inadequate disposal of household appliances by consumers and industries have annually been generating enormous amounts of polymeric waste (PW). So, the interest in reuse of PW in civil construction has increased. The production of new cementitious materials, such as concrete with PW, proves to be a promising solution to inappropriate disposal of this waste. In this study, self-compacting concrete (SCC) was developed with partial replacement of the coarse aggregates by polymeric waste (PW) from the recycling of refrigerators. In the SCC reference mixture, Portland cement, silica fume, sand, gravel and superplasticizer were used. The study also grouped the gravel as replaced by 5%, 10%, 15% and 20% of PW. In order to analyze the samples, the following tests were used: spreading, viscosity, passing ability, compressive strength, tensile strength, microstructure, modulus of elasticity, specific gravity, absorption, voids index and electrical resistivity. The SCC found showed adequate homogeneity and viscosity, staying within the normative parameters. The mechanical resistance was above 20 MPa; specific mass between 1870 to 2260 kg/m3; modulus of elasticity ranged from 34 to 14 GPa; and electrical resistivity between 319 to 420 ohm.m. Due to the mechanical resistance, the SCC with PW can be used for structural purposes and densely reinforced structures such as pillars, beams and foundation elements.

Recebido em 16/3/05; aceito m 28/7/05; publicado na web em 20/1/06 TiO 2 IMMOBILIZATION ONTO CONCRETE: CHLOROFORM AND PHENOL PHOTODEGRADATION. TiO 2 immobilization on concrete was studied using mixtures with cement, varnish and resin. The UV radiation sources were a germicide UV lamp and solar light. Aqueous solutions of chloroform (CHCl 3 ) and of phenol were prepared and recirculated over the TiO 2 immobilized surfaces. The immobilized TiO 2 surfaces showed better photocatalytic efficiency for phenol degradation compared to the control. For CHCl 3 , the presence or absence of the catalyst did not cause any significant difference to its degradation efficiency. The micrographic results showed a more homogeneous surface for TiO 2 immobilized in resin and varnish.Keywords: titanium dioxide; immobilization; degradation. INTRODUÇÃOInúmeros trabalhos envolvendo os Processos Oxidativos Avançados (POA) têm sido desenvolvidos visando principalmente a mineralização completa de poluentes orgânicos [1][2][3] . Dentre estes trabalhos os mais investigados são os que empregam o sistema dióxido de titânio e irradiação UV (TiO 2 /UV). O TiO 2 é um semicondutor que sob irradiação, de energia mínima de 3,2 eV, promove os elé-trons da banda de valência para a banda de condução, formando sítios oxidantes e redutores capazes de catalisar reações químicas, oxidando os compostos orgânicos à CO 2 e H 2 O e reduzindo metais dissolvidos ou outras espécies presentes [4][5][6][7] . Elétrons na banda de condução e buracos na banda de valência representam cargas móveis que interagem umas com as outras. O tempo de vida deste estado excitado é de nanosegundos, uma vez que os elétrons e os buracos irão se recombinar ao se reencontrarem, e a energia dissipada será na forma de calor ou outra forma de radiação 8 . Este sistema foi primeiramente utilizado em suspensão aquosa, degradando inúmeros compostos orgânicos [9][10][11] . Entretanto, existe a necessidade de se separar o TiO 2 da água após o tratamento, acarretando uma etapa adicional e, conseqüentemente, um aumento no custo do processo 12,13 . Pela necessidade deste processo adicional, vários pesquisadores vêm estudando tipos de imobilização para o TiO 2 .Rachel e colaboradores 14 investigaram a imobilização de TiO 2 em vários substratos, tais como vidro, cimento branco, tijolo vermelho e fibra inorgânica, utilizando técnicas como spray, sol-gel e um método já patenteado para imobilização em fibras inorgânicas. O processo de cloração é muito utilizado na maioria dos paí-ses, por ser um método eficaz e econômico de desinfecção de água para consumo humano. Uma desvantagem deste processo é que o cloro reage com substâncias húmicas, resultantes da degradação de matéria orgânica, originando compostos organoclorados, principalmente os trialometanos (THM). Dentre os THM, o clorofór-mio é o composto que se forma em maior quantidade, sendo comprovadamente cancerígeno 17 . Uma vez que a cloração é o processo empregado no Brasil, uma alternativa para evitar que o THM, formado durante o processo de trat...

Superabsorbent polymers (SAP) have gained the attention of the engineering field for applications in cementitious composites. Recently, many studies have addressed using these materials as an alternative to controlling recurrent pathologies, especially retraction in the hardening stage. This study conducted a literature review in the Scopus and Web of Science databases to identify relevant studies for future research in this area. Analyses were performed using the RStudio software program, where data on the number of publications, the main authors and journals, the most used keywords, and most common countries of publication were analyzed. Furthermore, bibliographic coupling and co-citation analyses were carried out. The results indicate that the most published authors were De Belie, Snoeck and Liu J., and the most cited authors were Jensen, Schrofl and Snoeck. Although Brazil is among the fifteen most published countries, it was not among the most cited, showing lacks in studies. In total, 343 articles were found in the Scopus database and 369 in the Web of Science.

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