RESUMO O emprego de adições minerais como substituição parcial do clínquer no cimento Portland tem sido uma das principais estratégias para redução da emissão de CO2 por parte da indústria mundial do cimento. Contudo, a disponibilidade de escórias de alto forno e cinza volante não supre a demanda. Na Amazônia, as indústrias de beneficiamento de caulim como cobertura para papel já depositaram cerca de 70 milhões de toneladas de resíduos constituídos essencialmente por caulinita extremamente fina. Uma alternativa para a região seria o emprego do cimento Portland com adições minerais de calcário e argila calcinada para a produção de um cimento de baixa emissão de CO2, o limestone calcined clay cement (LC3). O objetivo deste trabalho foi avaliar as propriedades desses cimentos a partir de elevadas incorporações de calcário e do metacaulim proveniente do resíduo calcinado do processamento da mina, o caulim flint. Os percentuais avaliados de substituição do clínquer Portland pelas adições minerais foram 45% e 60%. As variáveis investigadas foram a massa específica, a área superficial especifica Blaine, a água de consistência, os tempos de pega e a resistência à compressão. Os cimentos de metacaulim e calcário apresentaram maior demanda de água e menores de tempos de pega em razão da elevada finura da caulinita. Entretanto, os ganhos de resistência à compressão foram significativos em comparação aos obtidos com os cimentos Portland composto e comum, demonstrando a alta eficiência deste ligante. Os resultados são promissores, mas requerem estudos mais aprofundados, principalmente no que tange à durabilidade e à estabilidade dimensional de concretos e argamassas produzidos a partir destes cimentos.

ABSTRACT The use of mineral admixtures as a partial replacement of clinker in Portland cement has been one of the main strategies for reducing CO2 emissions by the global cement industry. However, the availability of ground blast furnace slag and fly ash does not supply the demand. In the Amazon region, the kaolin processing industries as a coating for paper have already deposited around 70 million tons of waste, essentially consisting of extremely fine kaolin. An alternative for the region would be the use of Portland cement with limestone and calcined clay to produce a cement with low CO2 emission, the limestone calcined clay cement (LC3). The objective of this work was to evaluate the properties of these cements from high limestone incorporations and metakaolin from the mine processing waste, the flint kaolin. The evaluated percentages of replacement of Portland clinker by mineral admixture were 45% and 60%. The variables investigated were specific mass, Blaine specific surface area, consistency water, setting times and compressive strength. The metakaolin and limestone cements showed higher water demand and shorter setting times due to the high fineness of kaolinite. However, the compressive strength gains were significant compared to ordinary and limestone Portland cements, demonstrating the high efficiency of this binder. The results are promising, but require further studies, especially with regard to the durability and dimensional stability of concrete and mor-tars produced from these cements.

ABSTRACT The use of permeable concrete pavements can mitigate flooding in densely populated areas by serving as a functional and sustainable mechanism for surface water absorption and drainage. However, it is found that the performance of the pavement is often limited to low and moderate flows and that the absorption capacity of the concrete matrix decreases as the flow rate increases. Therefore, the present study was developed aiming to evaluate the potential to reduce runoff in permeable concrete pavements subjected to simulations of successive events of heavy rainfall. For this purpose, 2 binary combinations of coarse aggregates were used, varying the cement consumption and the water/cement (w/c) ratio. The samples were submitted to simulations of heavy and sequential rainfall, with evaluation of the volume of water absorbed and the runoff. The mechanical and hydraulical properties of the permeable pavements were evaluated, as well as the characteristics of the area and volume of the internal and superficial pores. Among the results, specific weight stands out as the parameter that showed the highest linear correlation with the mechanical and hydraulic behavior of the specimens. It was also found that the runoff coefficient had a moderate negative linear correlation with the average pore size of the surface of the pavement. Finally, the permeable concrete pavements investigated were found to have the potential to reduce surface runoff in densely populated areas that are prone to frequent flooding, thus playing a critical role in mitigating the problems associated with stormwater runoff.

ABSTRACT The state of Para is one of the greatest producers of mineral substances in Brazil. Kaolin for paper coating industry and bauxite for alumina and aluminium production are amongst the most important commodities. The latter is responsible for the generation of red mud, a well-known residue from Bayer process. The kaolin processing plants are also responsible for the generation of large amounts of wastes, in this case, very fine-grained kaolinite (white mud). The research aimed to find a final destination for such residues by developing new building materials. The proposed material is a pozzolanic pigment produced through calcination and grinding of mixtures of red mud and kaolin waste. The pozzolanic pigments provided increased mechanical strength and color stability of the colored mortars relative to the inert pigment. The pozzolanic characteristics of the pigments reduced the leaching of the mortars. The new material has proven to be promising in its application as an innovative construction material, with the possibility of using these residues in a market that is little explored in Brazilian civil construction: colored mortars and concrete.