In concrete manufacture, cement (Portland type is the most used), water and aggregates (classified into coarse and fine) are used. With the use of several raw materials the generation of waste is inevitable, both in construction and in other sectors, such as the industries producing ceramic materials. Among the types of waste from such industries, can be mentioned the ceramic scrap (from the sanitary ware industry). According to the above, the aim of this research was to study the addition of ceramic scrap as a coarse aggregate in different proportions in the concrete formulation. In order to do this, was select wastes from an industry in the south of Minas Gerais (Brazil), and prepare specimens to determine the fresh (slump test, adhesiveness and porosity) and hardened (compression strength) of concrete. Were fabricated five concrete formulations, one reference (RC) and four with ceramic scrap substituted for coarse aggregate in the proportions of 25% (CSC-I), 50% (CSC-II), 75% (CSC-III) and 100% (CSC -IV). Fresh concretes, two formulations did not show adhesiveness (CSC-III and CSC-IV) and two a small water runoff (CSC-I and CSC-II), however, without compromising the concrete’s workability. Regarding the compression strength, the average values presented were very good, including the formulation with 100% ceramic scrap (fc = 47.78 MPa). Another important aspect observed in the rupture modes was the small adhesion between the ceramic scrap and the mortar due to the glazing in the contour of the waste. As for the porosity of the concretes, those with 25%, 75% and 100% of ceramic scrap in their composition presented lower values than the reference concrete.
Water-reducing additives for concretes are high efficiency dispersants that promote reduction of viscosity in suspensions, minimizing the amount of water used to hydrate the cement, thus enabling the fabrication of concrete with excellent properties. However, different forms of interaction between cement and additives are observed. In this work the properties of concrete formulated with three dosages of a polycarboxylate-based water-reducing additive and cement type CPII E-32 from two distinct manufacturers were investigated. In the experimental part, we verified the importance to use this technology justified by excellent results obtained for mechanical resistance and plasticity properties of the concretes. Through statistical analysis it was possible to point a discrete superiority in compositions using Holcim cement in function of its physical and chemical characteristics, in which the interaction process showed to be more efficient.
ResumoEste trabalho apresenta uma simulação das possíveis reduções de emissões de gases de efeito estufa geradas pela substituição parcial de cimento Portland por cinza de bagaço de cana-de-açúcar (CBCA) em habitações de interesse social. Para isso, foi analisado o uso da CBCA nas construções do Programa "Minha Casa Minha Vida" em Minas Gerais e foram mensuradas as reduções pelo Método QE-CO 2 . As emissões de CO 2 de dois cenários hipotéticos foram avaliadas com base na metodologia QE-CO 2 , nível básico. Os resultados demonstram que a substituição do cimento Portland pela CBCA pode gerar reduções de custos e, sobretudo, dos patamares de emissões de CO 2, em ambos os cená-rios, evidenciando, dessa forma, a possibilidade de utilização da cinza de bagaço da cana-de-açúcar em habitações de interesse social. Palavras-chave: Pozolana. Pegada de carbono. Mecanismo de desenvolvimento limpo. Sustentabilidade. IntroduçãoA oferta de ambiente construído com maior número de unidades residenciais de melhor qualidade, principalmente nos países em desenvolvimento, é condição indispensável para a melhoria da qualidade de vida da população. Como consequência, espera-se que a indústria de materiais de construção cresça mundialmente duas vezes e meia entre os anos de 2010 e 2050. No Brasil, a expectativa é que o setor da construção civil, devido aos serviços vinculados às políticas públicas, duplique seu tamanho até o ano 2022 (FUNDAÇÃO GETÚLIO VARGAS -FGV, 2010), devido a programas governamentais como o "Minha Casa Minha Vida".A cadeia produtiva da construção civil e os órgãos governamentais, inclusive em nível internacional, demoraram a perceber o impacto do crescimento desse setor e, atualmente, são forçados a mudanças culturais, tecnológicas e de comportamento para atender à demanda crescente de uma
Concrete used in civil engineering is a composite obtained from the combination of coarse and fine aggregates, cement and water, and its cost and quality are normally associated to the proportion of its constituents (ceramic formulation), as well as the reduction of water consumption. The aggregates used in concrete may have diverse origins, and the syenite extracted at Pedra Branca Alkaline Massif is one of the materials that can be used for this substitution. In order to do so, a reference formulation of concrete was calculated and optimized using the mathematical models of Andreasen, and syenite was added substituting 25, 50, 75 and 100% of the fine aggregate. In order to maintain the original granulometric distribution, an algorithm was developed to compensate the different particle size distributions. The grain size correction guaranteed the maintenance of the original properties of the concrete, reaching values of mechanical strength above 35 MPa.
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