Numatsmail
Numatsmail
Autor(a/res): M.C. Serpa, Ana Catarina J. Evangelista, Marcelo G. Miguez, Romildo D. Toledo Filho, Daniel Barroso
Resumo: A report about the current industry standards of technological, economic and legal development for the recycling and reuse of civil construction waste (CCW). The use of CCW, such as recycled aggregate inserted into concrete, is still in its initial stages in Brazil [. This paper's main objective was to evaluate the quality of concrete produced using different amounts, or fractions, of recycled concrete aggregate RCA from the residues of demolition wastes RDW from UFRJ's university hospital, located at its Rio de Janeiro campus. These residues had the dimensions of crushed gravel, and were inserted into a mix of conventional concrete for making interlocking concrete paving, based on the characterization of the recycled aggregates and mechanical tests, carried out on laboratory produced cylindrical specimens of concrete, contributing to the increase in the recycling of cement and concrete in Brazil.
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Autor(a/res): MEA Fidelis; TVC Pereira; OFM Gomes; FA Silva; RD Toledo Filho
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Autor(a/res): Anne N. M. Lopes, Eugenia F. Silva, Denise C. C. Dal Molin, Romildo D. Toledo Filho
Resumo: Shrinkage-reducing admixture (SRA) is a mitigation strategy against autogenous shrinkage in high-strength concrete (HSC). It acts by reducing the surface tension of the fluid in the pore system of the cement paste. An experimental program was carried out to investigate the influence of SRA on concrete durability, as few studies about this subject have been developed. Its effectiveness in reducing autogenous shrinkage and its influence on compressive strength were also evaluated. The results showed a substantial reduction of autogenous shrinkage due to the presence of the SRA, with a slight reduction on compressive strength (up to 5%). Overall, concrete durability under the action of aggressive agents (such as water, CO2, and chloride ingress) was not influenced by SRA, as verified in the results of chloride penetration, natural carbonation, water permeability, capillary absorption of water, and absorption of water tests.
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Autor(a/res): E. Bacarji, R.D. Toledo Filho, E.A.B. Koenders, E.P. Figueiredo, J.L.M.P. Lopes
Resumo: Huge amounts of mud and other residues are yearly being produced by various countries as a waste product by the marble and granite (MGR) industry, causing serious threats to the environment, polluting soil and water, and when dry, turning into a fine dust that is harmful to the population. At this moment, most of the MGR waste is landfilled and alternative solutions are being explored in many countries with the aim to turn MGR waste into a sustainable material. In this article, the applicability of MGR as a sustainable alternative for cement replacement is investigated, specifically for such residues created in Brazil. Compressive strength, elastic modulus and water absorption tests are conducted to examine the mechanical performance of concrete containing MGR. Chemical analysis and particle size distribution showed that MGR is a non-reactive material and may act as a filler. A numerical analysis has been performed with the objective to calculate the contact area between the expanding outer shell of the hydrating cement particles and the surface of the MGR fillers. The analysis showed a strong correlation with the contact area and also confirmed that MGR can be used as a sustainable replacement for cement.
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Autor(a/res): Romildo Dias Toledo Filho, Eduard Koenders, Marco Pepe, Guilherme Chagas Cordeiro, Eduardo Fairbairn, Enzo Martinelli
Resumo: The Brazilian construction industry is committed to delivering the venues and infrastructure of the Rio 2016 Olympic and Paralympic Games with zero increase in carbon dioxide emissions, reduced consumption of raw materials, increased use of renewable materials and 100% local recycling of construction waste. This in turn has led to significant research and development into using cement replacements – particularly sugar-cane ash from local ethanol production – and recycled aggregates in concrete production. This paper reports on the initial and promising results for ecological concrete mixes using up to 20% sugar-cane ash and 50% cleaned recycled aggregates from demolition waste.
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