Storage of mine tailings and waste concrete imposes economical and environmental impacts. Researchers have attempted to reuse wastes as construction material by utilizing ordinary Portland cement (OPC) to stabilize them. This method, however, has a number of limitations related to OPC. In this research, a recent technology called geopolymerization is used to stabilize mine tailings and concrete waste so that they can be completely recycled and reused. The research includes three main parts. The first part studies the effect of different factors on the mechanical properties, micro/nano structure, and elemental and phase composition of mine tailings-based geopolymer binder. The second part investigates the feasibility of producing geopolymer bricks using mine tailings. The physical and mechanical properties, micro/nano structure, durability, and environmental performance of the produced bricks are studied in a systematic way. Moreover, the enhancement of the mine tailings-based geopolymer bricks by adding cement kiln dust (CKD) is studied. The third part of the research investigates the recycling of the fines fraction of crushed waste concrete to produce binder through geopolymerization in order to completely recycle concrete waste. The results indicate the viability of geopolymerization of mine tailings by optimizing the synthesis conditions. By properly selecting these factors, mine tailings-based geopolymer bricks can be produced to meet the ASTM standard requirements and to be environmentally safe by effectively immobilizing the heavy metals in the mine tailings. The physical and mechanical properties and durability of the mine tailings-based geopolymer bricks can be further enhanced by adding a small amount of CKD. The results also show that the fines fraction of crushed waste concrete can be used together with fly ash to produce high performance geopolymer binder. Incorporation of calcium in the geopolymer structure and coexistence of the calcium products such as CSH gel and the geopolymer gel explains the enhancement of the mine tailings-based geopolymer bricks with CKD and the high performance of geopolymer binder from the waste concrete fines and fly ash. The research contributes to sustainable development by promoting complete recycling and utilization of mine tailings and concrete waste as construction material.

This research investigates complete recycling and utilization of waste concrete to produce new structural concrete through geopolymerization. The investigation was conducted through both macro-and micro/nano-scale studies. First the geopolymer paste synthesized using a mixture of waste concrete fines (WCF) and class F fly ash (FA) as the source material and a mixture of NaOH solution (N) and Na2SiO3 solution (SS) as the alkaline activating agent was studied. Various NaOH concentrations, SS/N ratios, and WCF contents were used to produce geopolymer paste specimens in order to study their effect on the properties of the geopolymer paste. Uniaxial compression tests were conducted to measure the strength of the geopolymer paste specimens. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), and Fourier transform infrared spectroscopy (FTIR) analyses were performed to investigate the micro/nano-structure, morphology and phase/surface elemental compositions of the geopolymer paste and the effect of calcium (Ca) on them. The results indicate that by using 10 M NaOH solution, SS/N of 2 and 50% WCF, the highest geopolymer paste strength can be obtained. Second, the interfacial transition zones (ITZs) between geopolymer (GP) and recycled aggregates (RA) were studied. Considering that RA consist of the stone particles and the attached paste/mortar from the original ordinary Portland cement (OPC) concrete, both the ITZs between GP and natural aggregate (NA) and those between GP and residual OPC paste/mortar (ROPM) were studied. For comparison, the ITZs between OPC paste and NA and those between OPC paste and ROPM were also investigated. 4-point bending tests were conducted to measure the bonding strength of the different types of ITZs at water to solid (W/S) ratio of 0.30, 0.35 and 0.40 for the geopolymer and OPC pastes after 7 and 14 days curing, respectively. SEM imaging was performed to investigate the microstructure of the ITZs. The results indicate that when NA is used, the bonding strength of both the GP-NA and OPC-NA ITZs decreases with higher water to solid (W/S) ratio. When ROPM is used, higher W/S ratio leads to smaller bonding strength for the GP-ROPM ITZ but greater bonding strength for the OPC-ROPM ITZ. Based on the measured bonding strength values for NA- and ROPM-based ITZs, the bonding strength of the GP-RA and OPC-RA ITZs was estimated by considering the average area coverage of ROPM on the RA surface. The GP-RA ITZ has the highest bonding strength among the different ITZs, implying the great potential for utilizing waste concrete (both the WCF and the RA) to produce geopolymer concrete. Third, based on the studies on geopolymer paste and ITZs, geopolymer concrete (GPC) was produced and studied using WCF and FA as the cementitious material and RA as the aggregate. For comparison, GPC using NA was also produced and studied at similar conditions. Various NaOH concentrations, SS/N ratios, and cement (WCF and FA) to aggregate (C/A) ratios were used to produce GPC specimens in order to study their effect on the behavior of GPC. The effect of water content and curing temperature on the initial setting time and 7-day unconfined compressive strength (UCS) of the GPC was also studied. The results show that the GPC produced from RA has higher UCS than the GPC from NA at both room curing temperature and 35°C curing temperature. Based on this study, it can be concluded that waste concrete can be completely recycled and used to produce new structural concrete based on the geopolymerization technology. Fourth, considering that the Si/Al and Na/Al ratios have great effect on the geopolymerization process and the properties of the final geopolymer product, a study was conducted on copper mine tailings (MT)-based geopolymer containing different amount of aluminum sludge (AS). The results indicate that by including AS and utilizing appropriate amount of NaOH, the UCS can be increased significantly. The main reason is because the addition of AS along with utilization of appropriate amount of NaOH makes both the Si/Al and Na/Al ratios reach the optimum values for geopolymerization, leading to higher degree of geopolymerization and more compact geopolymer microstructure. It is noted that although this study is not directly on waste concrete, it provides useful information for optimizing the design on complete recycling and utilization of waste concrete to produce new GPC. Finally, to better understand the effect of Ca on the geopolymerization process and the properties of geopolymer, molecular dynamics (MD) simulations were performed on geopolymer at different Ca contents. The molecular models at different Ca contents were constructed and uniaxial compression test was then performed on the numerical specimens. The results indicate that MD simulation is an effective tool for studying the effect of Ca on the properties of geopolymer at nano-scale.

A utilizaÃÃo do agregado miÃdo gerado a partir da reciclagem do entulho de concreto apresenta vantagens sob o aspecto econÃmico, uma vez que a areia reciclada tem o custo menor do que a areia natural. AlÃm disso, hà um ganho ambiental devido à substituiÃÃo da areia de rio e/ou de morro pela areia reciclada, resultando uma diminuiÃÃo dos danos causados pela deposiÃÃo irregular do entulho, tais como o assoreamento de rios e cÃrregos. Avaliar argamassas de revestimento vertical quando se substitui gradativamente o cimento pela cal hidratada e agregados miÃdos naturais por agregados miÃdos reciclados de concreto nos teores de 0%, 20%, 50%, 80% e 100%, em massa, nos traÃos 1:3, 1:4, 1:5, à o objetivo deste trabalho. Foi utilizada a tÃcnica do planejamento de experimentos para minimizar os ensaios e facilitar a anÃlise dos resultados. As argamassas foram utilizadas quando atingiram um Ãndice de consistÃncia entre 260mm e 280 mm, conforme prescritos na NBR 13276 (ABNT, 2005), sendo verificada a perda da trabalhabilidade com o tempo para cada traÃo. Foram moldados seis corpos-de-prova prismÃticos 4cmx4cmx16cm, para cada traÃo, para os ensaios de resistÃncia à traÃÃo na flexÃo e à compressÃo aos 14 e 28 dias de idade, conforme a NBR 13279 (ABNT, 2005). Posteriormente, as argamassas foram aplicadas em paredes, previamente chapiscadas. Jà nos revestimentos produzidos foram realizados aos 58 dias de idade os ensaios de resistÃncia de aderÃncia à traÃÃo, conforme a NBR 15258 (ABNT, 2010), como tambÃm foram avaliados os somatÃrios dos comprimentos das fissuras. Foram analisadas as variaÃÃes dos custos das argamassas produzidas em relaÃÃo Ãs argamassas de referÃncia. Os resultados foram avaliados estatisticamente e tendo sido produzidos modelos matemÃticos para cada variÃvel analisada. Os modelos produzidos apontam que os elevados teores de cimento com agregados miÃdos reciclados influenciaram positivamente, produzindo argamassas de menor custo e de melhores desempenhos nos ensaios realizados / The utilization of fine recycled aggregate originated from concrete debris recycling presents economics advantages, once recycled fine aggregate has lower costs than natural fine aggregate. Besides, there is an environmental gain due to the replacement of natural fine aggregate by recycled aggregate resulting in a in a reduction of damage caused by irregular deposition of debris, such as siltation of rivers and streams. Evaluate vertical coating mortars when cement is gradually replaced by lime and natural fine aggregates are replaced by recycled concrete fine aggregates in the content of 0%, 20%, 50%, 80% and 100%, by weight, in mixtures 1:3, 1:4 and 1:5, is the objective of this work. The design of experiments technique was used to minimize testing and to facilitate the analysis of results. Mortars were used when reached a level of consistency between 260mm and 280 mm, as prescribed in the NBR 13276 (ABNT, 2005), being verified the loss of workability with time for each mixture. Six prismatic specimens 4cmx4cmx16cm were casted for each mixture for tensile strength in flexural tests and compressive strength tests at 14 and 28 age days, according to NBR 13279 (ABNT, 2005). Later, mortars were applied to walls, previously spatterdashed. At 58 age days, tensile bond strength tests were performed at the coated wall, according to NBR 15258 (ABNT, 2010), as were also evaluated as the sums of the lengths of the cracks. Costs variations between produced mortars and reference mortars were also analyzed. Results were statistically analyzed and mathematical models have been produced for each variable analyzed. Produced models indicate that high levels of cement with recycled aggregates influenced positively, producing mortars with lower cost and better performance in the tests.

This diploma thesis deals with the issue of using fine powder of concrete recyclate. In this thesis, the theoretical expectations of milling are summarized as well as high energy milling. Afterwards professional articles, in which fine powder of concrete recyclate is successfully activated, are described and commented on. In the experimental part, there are 11 recipes of cement mortar and 3 recipes of concrete mixed. The benefit of using fine powder of concrete recyclate as a possible substitute for part of the cement is evaluated.

A cadeia produtiva da construção civil exerce grande influência na macroeconomia de um país. Em contrapartida, este setor destaca-se pelo consumo indiscriminado de matérias-primas não renováveis, processos produtivos ineficientes, além de uma grande quantidade de resíduos gerados. A reciclagem de materiais de construção desempenha um papel importante para a sustentabilidade visto que se tem a conservação dos recursos naturais e a redução de áreas para aterro. O foco principal dessa pesquisa é o estudo de resíduos de construção e demolição, mais especificamente os agregados graúdos reciclados de concreto (AGRC). O objetivo principal desta tese foi analisar a influência dos principais parâmetros que regem a variabilidade de concretos produzidos com agregados graúdos reciclados de concreto (AGRC), visando a transferência tecnológica. O programa experimental foi dividido em seis etapas. Nas etapas iniciais, estudou-se o resíduo de concreto, analisando a sua origem, os métodos de ensaios, para por fim realizar a caracterização dos materiais. Nas etapas intermediárias, fez-se um estudo para entender o efeito da variação granulométrica durante o processo de produção do concreto com fins estruturais. E nas etapas finais foram feitos estudos quanto à condição de saturação do AGRC. Com os resultados pode-se concluir que com um eficiente controle dos parâmetros de variabilidade do AGRC é possível produzir concretos com fins estruturais, visando dessa forma a transferência tecnológica. / The construction industry supply chain has a great influence on country macro economy. In contrast, there is the indiscriminate consumption of non-renewable raw materials, production processes inefficient, plus a large amount of waste generated. The construction materials recycling plays an important role for the sustainability since it is the conservation of natural resources and reducing landfill areas. The main focus of this research is the study of construction and demolition waste, specifically recycled coarse aggregate concrete (AGRC). The main objective of this thesis is to analyze the influence of the main parameters governing the variability of concrete made with recycled coarse aggregate concrete (AGRC), aiming at technology transfer. The experimental program was divided into nine steps. In the early stages, concrete residue was studied, their origin and test methods were analyzed, and to end materials were characterized. In the intermediate stages, a study was made to understand the effect of varying particle size during the production process of structural concrete. And in the final stages studies were made in AGRC saturation condition. With the results it can be concluded that with an efficient control of AGRC variability parameter it is possible to produce concrete with structural objectives, aiming thereby to technology transfer.

A cadeia produtiva da construção civil exerce grande influência na macroeconomia de um país. Em contrapartida, este setor destaca-se pelo consumo indiscriminado de matérias-primas não renováveis, processos produtivos ineficientes, além de uma grande quantidade de resíduos gerados. A reciclagem de materiais de construção desempenha um papel importante para a sustentabilidade visto que se tem a conservação dos recursos naturais e a redução de áreas para aterro. O foco principal dessa pesquisa é o estudo de resíduos de construção e demolição, mais especificamente os agregados graúdos reciclados de concreto (AGRC). O objetivo principal desta tese foi analisar a influência dos principais parâmetros que regem a variabilidade de concretos produzidos com agregados graúdos reciclados de concreto (AGRC), visando a transferência tecnológica. O programa experimental foi dividido em seis etapas. Nas etapas iniciais, estudou-se o resíduo de concreto, analisando a sua origem, os métodos de ensaios, para por fim realizar a caracterização dos materiais. Nas etapas intermediárias, fez-se um estudo para entender o efeito da variação granulométrica durante o processo de produção do concreto com fins estruturais. E nas etapas finais foram feitos estudos quanto à condição de saturação do AGRC. Com os resultados pode-se concluir que com um eficiente controle dos parâmetros de variabilidade do AGRC é possível produzir concretos com fins estruturais, visando dessa forma a transferência tecnológica. / The construction industry supply chain has a great influence on country macro economy. In contrast, there is the indiscriminate consumption of non-renewable raw materials, production processes inefficient, plus a large amount of waste generated. The construction materials recycling plays an important role for the sustainability since it is the conservation of natural resources and reducing landfill areas. The main focus of this research is the study of construction and demolition waste, specifically recycled coarse aggregate concrete (AGRC). The main objective of this thesis is to analyze the influence of the main parameters governing the variability of concrete made with recycled coarse aggregate concrete (AGRC), aiming at technology transfer. The experimental program was divided into nine steps. In the early stages, concrete residue was studied, their origin and test methods were analyzed, and to end materials were characterized. In the intermediate stages, a study was made to understand the effect of varying particle size during the production process of structural concrete. And in the final stages studies were made in AGRC saturation condition. With the results it can be concluded that with an efficient control of AGRC variability parameter it is possible to produce concrete with structural objectives, aiming thereby to technology transfer.

A cadeia produtiva da construção civil exerce grande influência na macroeconomia de um país. Em contrapartida, este setor destaca-se pelo consumo indiscriminado de matérias-primas não renováveis, processos produtivos ineficientes, além de uma grande quantidade de resíduos gerados. A reciclagem de materiais de construção desempenha um papel importante para a sustentabilidade visto que se tem a conservação dos recursos naturais e a redução de áreas para aterro. O foco principal dessa pesquisa é o estudo de resíduos de construção e demolição, mais especificamente os agregados graúdos reciclados de concreto (AGRC). O objetivo principal desta tese foi analisar a influência dos principais parâmetros que regem a variabilidade de concretos produzidos com agregados graúdos reciclados de concreto (AGRC), visando a transferência tecnológica. O programa experimental foi dividido em seis etapas. Nas etapas iniciais, estudou-se o resíduo de concreto, analisando a sua origem, os métodos de ensaios, para por fim realizar a caracterização dos materiais. Nas etapas intermediárias, fez-se um estudo para entender o efeito da variação granulométrica durante o processo de produção do concreto com fins estruturais. E nas etapas finais foram feitos estudos quanto à condição de saturação do AGRC. Com os resultados pode-se concluir que com um eficiente controle dos parâmetros de variabilidade do AGRC é possível produzir concretos com fins estruturais, visando dessa forma a transferência tecnológica. / The construction industry supply chain has a great influence on country macro economy. In contrast, there is the indiscriminate consumption of non-renewable raw materials, production processes inefficient, plus a large amount of waste generated. The construction materials recycling plays an important role for the sustainability since it is the conservation of natural resources and reducing landfill areas. The main focus of this research is the study of construction and demolition waste, specifically recycled coarse aggregate concrete (AGRC). The main objective of this thesis is to analyze the influence of the main parameters governing the variability of concrete made with recycled coarse aggregate concrete (AGRC), aiming at technology transfer. The experimental program was divided into nine steps. In the early stages, concrete residue was studied, their origin and test methods were analyzed, and to end materials were characterized. In the intermediate stages, a study was made to understand the effect of varying particle size during the production process of structural concrete. And in the final stages studies were made in AGRC saturation condition. With the results it can be concluded that with an efficient control of AGRC variability parameter it is possible to produce concrete with structural objectives, aiming thereby to technology transfer.