TECHNOLOGY OF OBTAINING LARGE AND SMALL AGGREGATE FROM CONCRETE SCRAP

В работе представлены эффективные технологические мероприятия по получению крупного и мелкого заполнителя из бетонного лома. Приводится фракционный состав заполнителя из некондиционных бетонных и железобетонных изделий, классификация его в зависимости от гранулометрии и рекомендации использования вторичного заполнителя в производстве строительных материалов. The paper presents effective technological measures for obtaining large and small aggregate from concrete scrap. The fractional composition of the aggregate from substandard concrete and reinforced concrete products, its classification depending on granulometry and recommendations for the use of secondary aggregate in the production of building materials is given.

Waste of Civil Construction for Use in Mortar and Production of Structural Concrete

Civil construction is a sector of extreme impact on the Brazilian economy, both in terms of jobs as well as consumption of raw material and waste generation. Civil construction waste (CCW) represents a large part of the total mass of municipal solid waste in a medium and large city. An alternative to diminish these released wastes is to reuse them. In this work, a study was carried out using CCW both to produce concrete with sand substitution and as a small aggregate for use in mortar. The compression strength of structural concrete and mortar, with total and partial replacement of sand, was analyzed. In addition, the consistency of mortar with the replacing was also studied. The results of the compression test indicate superior quality for concretes (75wt% CCW) and mortar with CCW incorporation. The required amount of water for good workability in the modified mortar is 310 g, against 270 g for the reference mortar.

Waste tires and the burning of sugarcane bagasse in the manufacture of concrete pavers (pavers)

The research developed has the purpose of analyzing the potential utilization of sugarcane bagasse ash and tire residue in the construction of pavers in replacement of the small aggregate, the natural sand. In order to achieve this objective, the methodology adopted includes steps such as: characterization of the residues to be used, preparation of pavers with different contents of partial replacement of small aggregates, determination of the main pavers characteristics (compressive strength, water absorption, abrasion resistance) . The results proved the viability of the substitution, and the optimum content for the manufacturing of the parts is 27%, being 25% of BCC and 2% of tires. The contribution of the research is focused on reducing the consumption of natural resources and the correct disposal of the residues studied.

Reuse of glass in concrete: a study of the production and mechanical performance of resistance

The glass incorporated into the concrete contributes to the conservation of the environment, as it will have a correct destination and is an easily found material. This work had the objective of analyzing the mechanical performance of the concrete produced with glass waste from non-returnable packaging. Since glass is a residue that is easily found, it is justified to incorporate it into concrete in partial replacement of small aggregates, thus avoiding its disposal inlandfills and also in an irregular way. The concrete produced was made with the addition of “51” and “Long Neck” ground glass. A standard trace of 25 MPa was defined, with partial substitutions of 5%, 15%, 25% and 35% in the small aggregate. The individual strengths of the test specimens were submitted to the Tukey test for statistical analysis and it was verified that the trait with the percentage of 35% substitution is statistically different from the other traits. The concrete had a mean Fck of 32,37 MPa, higher than the established minimum of 25 MPa. It can be concluded that theconcrete with the use of ground glass presents technical feasibility for execution and contributes to the preservation of the environment.

Behavior of the self-compacting mortar with sugarcane bagasse ash in the fresh and hardened state

Self-compacting concrete (SCC) is a material with high workability and moderate viscosity when compared to conventional concrete. Due to its advantages, the SCC has been investigated in the last decades and the research studies the use of new components in its structure and the search for the improvement of its performance, both in the fluid and in the hardened state. The goal of this study was to evaluate the behavior of self-compacting mortars with limestone filler and with the addition of sugarcane bagasse ash (SBA) partially replacing the small aggregate. To reach this goal, initially, a rate of replacement of natural sand by SBA was set. Afterwards, slump-flow and funnel-V tests were carried out in order to check the behavior of the mortars in the fresh state. After checking the behavior of the mortars in their fresh state, the different mix proportions that achieved the best aspects of fluidity and viscosity was selected, and, for self-compacting mortars, specimens were molded to determine tensile strength at 28 days, and compressive strength at 7 and 28 days. The experimental analyses demonstrated an increase in viscosity and reduction in fluidity with increasing content of limestone filler, facilitating the obtaining of self-compacting mortars. Regarding the performance of the material in the hardened state, the mortars showed a slight increase in tensile and compressive strength due to the filler effect of fines. It was possible to replace 40% of the small aggregate with SBA.

Filamentous aggregates are fragmented by the proteasome holoenzyme

Filamentous aggregates (fibrils) are regarded as the final stage in the assembly of amyloidogenic proteins and are formed in many neurodegenerative diseases. Accumulation of aggregates occurs as a result of an imbalance between their formation and removal. Although there have been numerous studies of the aggregation process in vitro, far fewer studies of aggregate disassembly and degradation are available. Here we use single-aggregate imaging to show that large fibrils assembled from full-length tau are substrates of the 26S proteasome holoenzyme, which fragments them into small aggregates. TEM further revealed that these small aggregate species had no distinct structure. The intact proteasome holoenzyme is required to effectively target fibrils. Interestingly, while degradation of monomeric tau was not inhibited by ATPγS, fibril fragmentation was predominantly dependent on the ATPase activity of the proteasome. The proteasome holoenzyme was also found to target fibrils assembled from α-synuclein (αS), suggesting that its fibril fragmenting function may be a general mechanism. The fragmented species produced by the proteasome showed significant toxicity to human cell lines compared to intact fibrils. Together, our results indicate that the proteasome holoenzyme possesses a novel fragmentation function that disassembles large fibrils into smaller and more cytotoxic species.

ESTUDO DO TEOR DE SUBSTITUIÇÃO DE AGREGADO MIÚDO POR RESÍDUO DE BORRACHA EM ARGAMASSA DE CIMENTO E CAL [ Study of the replacement content of small aggregate by rubber residue in cement and lime mortar ]

RESUMO: O setor da construção civil vem absorvendo resíduos e transformando-os em componentes para utilização nas construções, especialmente através da incorporação em materiais como argamassas e concretos. Com o crescente número de veículos automotivos, ocorreu um aumento na produção de pneus e, consequentemente, de seus resíduos. Portanto, o presente estudo tem o objetivo de avaliar o melhor teor de substituição de agregado miúdo por resíduo de borracha em argamassa de cimento e cal, a partir da comparação com uma argamassa de referência, analisando o comportamento físico e mecânico. Para verificar a melhor relação de substituição, os ensaios foram realizados em argamassa referência (traço 1:2:9) e em argamassas com resíduos nas proporções de 2,5%, 5%, 10% e 15% de substituição de areia por borracha. Para caracterização das argamassas foram realizados ensaios de índice de consistência, resistência à compressão axial, resistência à tração por compressão diametral, absorção por capilaridade e absorção por imersão. Os resultados indicam que nas argamassas com resíduo ocorreu um aumento na relação a/c para se manter a trabalhabilidade e um decréscimo nas resistências. Além de, uma diminuição na absorção por capilaridade e um aumento na absorção por imersão. Apesar de provocar mudanças no comportamento da argamassa, aponta-se o uso desse resíduo como alternativa viável, tanto ambiental quanto de desempenho.ABSTRACT: The construction industry has been absorbing and transforming them into components for use in construction, especially through the incorporation of materials such as mortars and concretes. With the increasing number of automotive vehicles, there has been an increase in the production of tires and, consequently, of their waste. Therefore, the present study has the objective of evaluating the best content of substitution of small aggregate by rubber residue in cement and lime mortar, from the comparison with a reference mortar, analyzing the physical and mechanical behavior. To verify the best substitution ratio, the tests were performed in reference mortar (trace 1:2:9) and mortar with residuals in the proportions of 2.5%, 5%, 10% and 15% of Sand for rubber. To characterize the mortars, tests of consistency index, axial compression strength, tensile strength by diametrical compression, capillary absorption and immersion absorption were performed. The results indicate that in the mortars with residue an increase in the w/c ratio was observed to maintain the workability and a decrease in the resistances. In addition to, a decrease in capillary absorption and an increase in absorption by immersion. Although it causes changes in mortar behavior, the use of this residue is indicated as a viable alternative, both environmental and performance.