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Mine tailings (MT) waste valorization in construction materials can be one possible solution because they may allow an alternative for some applications as an important contribution for a more circular economy. The aim of this work was to study the feasibility of using a sulfidic mine tailing in the production of building materials such as ceramic roof tiles. The introduction of 5, 10 and 20% MT in ceramic roof tiles promoted an improvement on the final properties of these materials. The use of 20%MT has decreased the firing temperature from 1150º to 1050 ºC, hence promoting energy savings and lower costs. Properties as density and water absorption were improved. Firing shrinkage, many times responsible for cracking, also decrease with the use of MT and, in this way, improve the production rate. The 20% MT ceramic formulation achieved the highest value of strength with lowest firing temperature. For the effects of sulphates' emission (SO2 and SO3 gases) upon firing, a solution was proposed involving their reaction with water and, through condensation, providing afterwards sulphuric acid as a process by-product. The use of high sulphide MT in ceramic roof tiles processing could be viewed as a potential safe waste management solution for these particular mine tailings.

Considering the construction sector’s impact on the environment, it is necessary amongst other measures to change the way in which new construction or renovation projects of buildings are designed and how solutions are proposed and integrated. Nowadays, an effort is being made by designers to implement more sustainable and circular design in buildings, but because of the lack of tools that can provide designers with knowledge about the impacts of the solutions to be chosen, the sustainability factor does not enter in the decision-making process as a key factor. In this sense, the development of an eco-design tool and procedure for the decision-making process will allow designers to integrate into the design phase a circular design methodology and, in a practical way, will also promote sustainability and circularity concepts as a decision factor in the construction of buildings. The present work introduces an eco-design tool that was developed to integrate circularity and sustainability information into building-renovation projects. This tool enables the evaluation and comparison of solutions based on information provided by Environmental Product Declarations (EPD) or other LCA-based calculations as well as life cycle costing information, through the generation of radar graphics that simplify the overall analysis at the decision moment. The tool was tested in a simple case study of a building renovation process and allowed designers to understand the environmental and economic impacts that each competing solution carries, either related to the materials removed from the building or to the materials coming into the buildings being renovated. In this test application, the eco-design tool proved to be able to gather quantitative information regarding environmental and economic impacts, facilitating designers to access knowledge on the different solutions impacts and help them to make a design choice based on sustainability and circularity considerations.

This manuscript presents an experimental study on the combustion rate of biomass briquettes or logs in a domestic boiler, by monitoring the time decay of its mass and the temperature of the flame inside the boiler. Assuming close to steady state conditions, two combustion models were studied: the constant particle density-burning model and the constant particle diameter-burning model. For each model, the evolution of the global combustion resistance with the decay of the particle diameter was analyzed, and it was possible to conclude that the burning occurred approximately with constant particle size and that the heterogeneous C to CO reaction takes place at the surface of the inner carbonaceous core. The high values obtained for the Sherwood number revealed that there were significant convective effects inside the furnace and compare well with a previously developed Sherwood number correlation for a packed bed of active particles.

This work concerns the study of the combustion kinetic characteristics of chars made from three different biomass species, vine and kiwi pruning wastes, and gorse from forest cleaning process in a fluidized bed combustor, operating in the bubbling bed regime, at four bed temperatures, 750, 820, 850 and 920 °C. Batches of the original biomass pellets were carbonized in a nitrogen fluidized bed, either at 900 °C, for the kiwi and vine pellets, or at 800 °C for the gorse pellets. To acquire complete information on the combustion behaviour, different sizes of the char particles were subsequently burned in a bubbling fluidized bed. The evolution of the overall combustion resistance, and information on the combustion control were obtained. It was observed that for the kiwi and vine chars, the combustion was controlled through a combination of diffusion and kinetics, while for the gorse char the combustion was diffusionally controlled. In addition, the pre-exponential factors and activation energies were obtained for the kiwi and vine chars, by applying the Arrhenius law to the kinetic data for each char. Activation energy values of 246.16 kJ/mol for the kiwi char and of 155.02 kJ/mol for the vine char were obtained.

The radiant floor system market is growing rapidly because Europe is moving toward a low-carbon economy and increased awareness about environmental sustainability and energy efficiency, stimulated by the ambitious EU Energy Efficient Directive and nZEB challenge. The high growth rate of the market share is due to the involvement of homeowners in the specifications of their living commodities, so they are thus willing to invest more at the initial stage to obtain long-term benefits and lower energy exploration costs. We performed an experimental campaign over three slabs with a hydronic radiant floor system of equal dimensions, shape, and pipe pitch with different screed mortar formulations to assess their performance throughout a heating/cooling cycle. The temperature at different heights within the interior of the screed mortars and at the surface were monitored. The results revealed that an improved screed mortar has a relevant impact on the efficiency of the system. Moreover, a three-dimensional transient heat transfer model was validated using the experimental data. The model was used to evaluate the impact of different finishing materials, namely wood, cork, ceramic, and linoleum, on the floor surface temperatures. The results showed differences of 15% in the surface temperature when using different floor finishing solutions.

The present study reports on the development of multifunctional plaster showing superior thermal insulation, ability to control the indoor RH and NO x photocatalytic degradation. The plaster contains TiO 2 nanoparticles (1 wt.%) and 0–4 wt.% fibers of two distinct sizes: 1 mm 1-2mm ) and 2 mm 2-4mm ). The formulations were adjusted based on flow table and rheometer tests, aiming to assure a desirable workability. Plasters with similar workability (spread on table) showed distinct yield stress values over time and Fb (1-2mm) plays an important role on the workability control. Rheological behaviour was governed by Fb (2-4mm) . Binary mixture 2.0Fb 1-2mm + 2.0Fb 2-4mm 2·0Fb 2-4mm required less water amount to show the same workability of the single formulation 4.0Fb 1-2mm . However, the control of the rheological behavior over time was found difficult. The apparent porosity, water absorption and capillary index were strongly incremented with the rise of cellulose fiber concentration. Singular and binary samples present similar results and no significant differences were observed by changing the fibers size. Plaster’s buffering capacity and NO x uptake was considerably improved by using cellulose fibers, being this increment primarily governed by the fiber concentration. Formulation containing 4.0 wt.% Fb (2-4mm) revealed the optimal performance.

The environmental performance of a combined cooling, heating, and power system is analyzed in this study at a component-level using a SPECO-based exergoenvironmental analysis. The engine consumes natural gas and produces 168.6 kW net power. The waste heat is recovered by a LiBr-H2O absorption chiller and a heat exchanger, which are used for cooling and heating purposes. The energy system is assisted by a solar field. An environmental Life Cycle Assessment quantifies the environmental impacts of the system, and these data are combined with exergy evaluations. The highest total environmental impact rate, 23,740.16 mPt/h, is related to the internal combustion engine, of which pollutant formation is the primary source of environmental impact. Compared with a non-renewable energy system, the solar-assisted trigeneration system decreased the environmental impact per exergy unit of chilled water by 10.99%. Exergoenvironmental performance can be further improved by enhancing the exergy efficiency of the solution pump and high-pressure generator (HG), and by employing a treatment to remove nitrogen oxides in the reciprocating engine.

The hollow brick masonry and reinforced concrete construction is the most common and technically known constructive system in southern European countries. However, more industrialised alternatives have arisen, such as the Light Steel Framing (LSF). Nevertheless, an important research gap concerning the performance of this constructive system and its comparison with the brick masonry buildings was found. The shortage of available experimental data hinders the optimisation of these buildings towards high energy efficiency standards and indoor comfort. In this sense, the primary aim of this research is to assess the opportunities and limitations of each constructive system in terms of minimising energy consumption and providing a comfortable indoor environment during the heating season, considering an intermittent heating pattern. The novelty of the present work is the long-term experimental campaign involving the construction and monitoring of two identical test cells, differing only in the constructive system. The test cells are located in the Aveiro district (Portugal) and were monitored over an entire year. The results revealed a lower energy consumption of LSF test cell in every monitored month. On the other hand, this test cell is more responsive to the external weather stimulus and, therefore, more susceptible to the nocturnal temperature drop and overheating during warmer conditions. The present work intends to achieve a long-term value by providing the scientific community with original data within a research scope where this information is not abundant.

This study focuses on a solar-assisted trigeneration system, designed to meet the electricity, cooling, and heat demands of a residential consumer center. This is the first study to consider different dead state temperatures in the exergy assessment (10–30 °C) of a system containing an absorption chiller. Mass, energy and exergy balances were developed, and the exergy model is based on the SPECO methodology. The COP of the absorption system increases with the temperature of the heat source of exhaust gases. The maximum cooling output is 264.15 kW, with a COP of 1.2, when the ratio exhaust gas/hot water is 0.77:1. When increasing the dead state temperature, there is a slight decrease in the exergy efficiency of the engine and solar system. The exergy efficiency of the absorption chiller is 79.75% for a dead state temperature of 10 °C, changing to 3.66% at 15 °C, 8.06% at 20 °C, 12.69% at 25 °C, and finally 17.57% at 30 °C. The behavior of the overall system is similar, and a consequence of the product and fuel definitions employed by SPECO. This analysis of dead state temperatures is useful for exergoeconomic and exergoenvironmental analyses, as it avoids inconsistencies such as negative cost rates or environmental impact rates.

Incorporation of biochar in cementitious materials is a promising solution in the mitigation of environmental pollutants by partially cutting off the consumed ordinary Portland cement and reducing the amount of waste disposal in landfills. This work studied the partial replacement of cement by biochars having a different chemical composition and its effect on the performance of cement mortars. The feedstocks for biochar production were selected from biomass wastes produced in agro-industrial and forestry sectors in Portugal. They included olive stone, rice husk and wood chips from residual forest biomass. Biochars were produced at 500 ℃ using a slow pyrolysis process. The biochars were added at different cement replacement rates; 0.5, 1, 2 and 4 wt% of cement weight. XRD and TGA were used to elaborate the effect of biochar on the hydration products. Effect of biochar addition on the capillary water absorption, compressive and flexural strength of cement mortar was analyzed. The results suggested that the biochars contributed to the promotion of hydration products. Cement replacement with 4 wt% olive stone and rice husk biochars was associated with a slight increase of 28-days compressive strength. Rice husk biochar showed the best long-term mechanical performance due to its pozzolanic reaction in the matrix. No significant changes were observed in the water absorption of cement mortar after the addition of 4 wt% biochar as cement replacement. The research outcomes suggested the beneficial effect of cement replacement with biochars from olive stone and rice husk up to 4 wt% with comparable properties.

The use of thermal insulation materials is regarded as the most effective passive measure of energy savings in buildings. Rigid polyurethane foams (RPU) are commonly used as the insulation layers of opaque building envelope solutions, as well as for other applications in field of transportation, textile industry and electrical appliances, accounting for almost one-third of the polyurethane market. In the assessment of the energy performance of buildings, insulation materials, such as RPU foams have good insulating properties – low thermal conductivity – however their thermal regulation capacity can be enhanced by the incorporation of phase change materials (PCMs). In this paper, three different approaches (flux meter approach, the guarded hot plate approach and the transient plane source approach) are presented to determine the thermal conductivity of RPU foams with and without the incorporation of PCMs based on steady state method and transient method. In addition, this work presents and discusses the comparison between measurements amongst the three approaches revealing the important factors that should be considered to determinate the thermal conductivity of the RPU foams with PCMs, particularly in the temperature range during PCMs phase change transition (solid/liquid state).

Using a simple experimental layout, some results on the evolution of global heat transfer coefficient for two phase change materials (PCM), during fusion and solidification processes, were determined. To do this, a system using commercially available thermal oil as the heat transfer carrier was used and the phase change material being tested operated in a fusion and solidification cycle. The heat transfer oil transferred heat to the phase change material during the fusion step and carried heat away from the phase change material during the solidification step. The influence of the mass flow rate of the heat transfer fluid, as well as of its temperature, in the evolution of the overall heat transfer coefficient from the thermal oil to the PCM during its fusion and in the opposite direction during the PCM solidification, for a given experimental set-up, was studied. One of the tested phase change materials was a salt while the other was a paraffin.

Several types of industrial solid waste have been used as byproducts in the construction and materials industries. Some of the applications seem to be required from the environmental point of view as a contribution to circular economy. Nevertheless, durability of materials should be assessed to avoid future problems. This work evaluated the fly ash from forest biomass combustion as a potential additive replacing calcite in Portland cement-based mortars. Cement-based mortar formulations were prepared and characterized in the fresh and hardened states. In particular, the durability of samples cured for 1 year was assessed based on sulfate attack. Mortars cured for 360 days were pre-weighted and then totally immersed in a solution containing a well-defined concentration of sulfate. Seven-day immersion + drying cycles were carried out, and weight was determined after each cycle. Liquid solutions containing sulfate were renewed every 14 days. One set sample was kept soaked in tap water to be used as reference. The results revealed that replacing 20% of calcite by fly ash seems to be a suitable alternative concerning mechanical strength. However, sulfate attack tests showed that strength rapidly deteriorates using fly ashes as a replacement raw material.

The homogeneous state of the concrete in the fresh state has consequences on their properties in the hardened state. The use of pozzolanic concrete must be carefully evaluated, because the physical and chemical differences of each pozzolan have consequences on concrete hardened state properties. In this work, two physical and chemically different pozzolans were used to evaluate the effect on concrete microstructure and its basic hardened state properties. Scanning electron microscopy (SEM) was used and can be an effective tool in the analysis of the microstructure allowing a better understanding of the properties of concrete in hardened state. It allows showing that the differences in the two pozzolans (metakaolin and diatomite) promote different microstructures as well as different final properties of pozzolanic concrete. Moreover, it was also shown that the use of a water reducing agent, to adjust workability instead of water, promotes an improvement in both the microstructure and the hardened state features such as porosity and mechanical strength.

Waste recycling is part of the circular economy concept that goes from the redesign of processes, products, business models with resource efficiency. Bituminous mixtures were developed with paper and pulp industry wastes (dregs and grits). These mixtures will be used as a surface course in a pilot large-scale demonstrator of an on-going European Circular Economy project (Paperchain). To scale up from laboratory to the industrial level, mix designs were designed, tested, technical and legal constraints were assessed in order to carry on the pilot test. This paper discusses relevant results so that the pilot test can be carried out with success in an environmentally safe way. Results show mix designs that have the possibility to be scaled up with success, using dregs and grits as alternative raw materials of natural filler and fine aggregates present in traditional bituminous mixtures for road construction.

Atualmente, a indústria da construção é um dos principais setores europeus responsáveis pelos elevados níveis de consumo de energia, extração de matérias-primas e produção de resíduos. Cada vez mais o consumo de energia proveniente de fontes renováveis e a reutilização de resíduos industriais constituem a única maneira de minimizar este problema para o meio ambiente e sociedade. A incorporação simultânea de materiais de mudança de fase (PCM) e cinzas volantes (FA) em argamassas permite aumentar a eficiência energética nos edifícios e diminuir a quantidade de extração de matérias-primas e de resíduos depositados em aterro. O desenvolvimento de argamassas com incorporação de PCM e cinzas volantes contribui para uma melhoria significativa dos parâmetros de conforto no interior de edifícios e do meio ambiente. O PCM permite regular a temperatura no interior dos edifícios utilizando como recurso apenas energia solar, diminuindo as necessidades de utilização de equipamentos de climatização. O PCM possui a capacidade de absorver e liberar energia para o meio ambiente. O principal objetivo deste trabalho consistiu na caracterização física, mecânica e térmica de argamassas com incorporação de PCM e FA. Foi possível concluir que a incorporação simultânea de PCM e FA permitiu obter argamassas homogêneas e adequadas, com boas propriedades físicas e mecânicas e um comportamento térmico melhorado quando comparadas às argamassas sem incorporação e apenas com incorporação de PCM., Nowadays, the construction industry is the one of the main European sector responsible for the higher levels of energy consumption, raw materials extraction and waste production. Increasingly the consumption of energy from renewable sources and reusing industrial wastes is the only way to minimize this problem for the environment and society. The simultaneous incorporation of phase change materials (PCM) and fly ash (FA) in mortars allow increase the energy efficiency in buildings and decrease the amount of the raw materials extraction and waste materials landfilled. The development of mortars with incorporation of PCM and fly ash contributes to a significant improvement of the comfort parameters inside buildings and in the environment. The PCM allow regulating the temperature inside buildings using only solar energy as a resource, decreasing the air conditioning needs. The PCM has the capability to absorb and release energy for the environment. The main purpose of this study was the physical, mechanical and thermal characterization of mortars with incorporation of PCM and FA. It was concluded that the simultaneous incorporation of PCM and FA leads to homogenous and suitable mortars, with good physical and mechanical properties and an increased thermal behavior when compared to the mortars without incorporation of PCM and only with incorporation of PCM., Os autores desejam expressar os seus agradecimentos à Fundação para a Ciência e Tecnologia (FCT) pelo financiamento deste trabalho no âmbito do projeto UID/ECI/04047/2013-UM., info:eu-repo/semantics/publishedVersion

The demand for low environmental impact of materials in our habitat is one of the current societal challenges. Along with other solutions of waste valorisation, alkali activation as geopolymers can be one possible solution of waste valorisation because they may allow, for instance, an alternative solution for cement-based materials in some applications and it is one contribution for circular economy. This work has focused on the development and processing of geopolymers that incorporates as a fine aggregate a high-sulfidic mining waste (mine tailing), a difficult waste to process. Rheology analysis was applied as an important step to understand not only the geopolymers behaviour but also its transition from the fresh to the hardened state. The effect of precursor binder type (metakaolin or blast furnace slag), of mine tailing content and also the effect of temperature and curing conditions of different formulations were studied in this solution. It was possible to conclude that although this particular mine tailing is not a geopolymer binder precursor, it may be incorporated as an alternative fine aggregate in construction products. Furthermore, rheology could be used to follow up the geopolymer alkali-activation process and even to setup proper curing conditions and components contents in order to optimize the final mechanical strength of this material as a waste management solution. The final properties of these geopolymers compositions were adequate and after 28 days of curing, these geopolymers exhibit significant chemical resistance under severe test conditions.

Increasing cement production in construction sector and waste generation in industrial sectors are of the major sources of CO2 emission. For decades, it has been the concern of environmentalists to convince constructors and researchers to find sustainable solutions targeting aforementioned problems. The attempts focused on identification of wastes to be successfully complied with construction materials. Biochar has recently received attention due to several environmental and technological advantages, shortly include carbon sequestration, low thermal conductivity, chemical stability and low flammability. For this reason, biochar is recognized as an efficient candidate for cement or lightweight aggregates replacement in building materials. Biochar addition could result in a reduction of capillary absorption in mortar paste. Besides, its addition accelerates cement hydration and restricts shrinkage cracking in cement mortar. The present review categorizes all the biochar critical features affecting the performance of cementitious materials. The effect of biochar addition as filler and cement replacement on the workability, hydration, mechanical and transfer properties of cement paste/composites is reviewed in this paper. From the data collection, an optimum biochar content around 2% is shown to contribute to the improvement of mechanical properties. The gaps in the literature are identified and the future research plans are proposed.

Rheological behavior of concrete is closely related to the rheology of its mortar. This paper aims to study the relation between the rheological parameters of mortars and its corresponding concretes. The correlation between the compressive strength of mortars and the corresponding concretes is also considered. Workability of mortars and concretes, prepared with different amounts of metakaolin and diatomite, were controlled either with water or a water reducing admixture. A direct relationship was observed between the rheological parameters of mortars and its corresponding concretes. Formulations with metakaolin show a linear correlation between the mortars and the corresponding concretes compressive strength. Values of the mortars’s compressive strength was 84% of the ones of corresponding concretes. Although without a linear correlation, in compositions with diatomite where the workability adjustment was done with a water reducing agent, the values of mortars’s compressive strength were also 85% of the values of corresponding concretes.

The European Green Deal defined by the European Commission on December 2019 presents an ambitious set of measures for the European Union and its citizens to accomplish the challenge of climate change, making Europe until 2050 the first neutral continent, where there are no net emissions of greenhouse gases. The Passive House (PH) concept has the same ambitious goal, targeting the reduction of the carbon footprint while promoting a construction design that gives primacy to the optimum energy balance, assuring comfort and quality with a minimum impact on the final building cost and operation. However, the PH concept is still not an easy process to implement in the traditional construction sector, especially in South European territory, as is the case of Portugal. Contextually, the present study through the discussion of a case study research method applied to European PH successful experience, has defined guidelines for the implementation of this concept within sustainable development principles. The methodology strategy starts with the information collection from Hanover, Brussels, and Tyrol case studies. Then, a statement regarding the current situation of Portugal in respect of the PH numbers and policies was performed. Moreover, the information gathered, as well as the experience of learnt lessons, were compared to the Portuguese reality. As a final procedure, barriers and obstacles for the Portuguese case have been identified through the analysis and understanding of the country&rsquo, s social dynamics, and also with the crossing of sustainable development principles. Thus, the present research enables us to propose guidelines to increase the PH implementation in Portugal.

Nowadays, the construction is one of the main European sectors responsible for the high levels of energy consumption and raw material extraction. Increasingly, the energy consumption from renewable sources and industrial waste reuse are the only ways to minimize these environmental and societal problems. Simultaneous incorporation of phase change materials and fly ash in the mortars increases the energy efficiency and decreases the waste materials landfilled. The development of mortars with phase change materials and fly ash incorporation contributes to a significant improvement of the building comfort parameters and the environmental quality. The phase change materials possess the capability to normalize the temperature flux inside the buildings, using the solar energy as resource. The main purposes of this study were the physical, mechanical, and thermal characterization of mortars with phase change materials and fly ash incorporation. It was concluded that the phase change materials and fly ash simultaneous incorporation leads to homogeneous and suitable mortars with increased thermal behavior compared with the phase change material addition alone., info:eu-repo/semantics/publishedVersion

The rapid world economic growth has led to an increase in the energy consumption. So, the energy efficiency of buildings is very important because this is one of the leading sectors in energy consumption, in developed countries. The phase change materials (PCM) have the ability to reduce the temperature variation, due to their capability of absorbing and releasing energy to the environment. The PCM can be incorporated into building materials using different methods, such as encapsulation, shape-stabilization, direct incorporation and immersion. The most common form of this material utilization is through encapsulation. It should be noted that, currently, there are still high production costs involved with PCM encapsulation. Thus, it is imperative to develop mortars with PCM incorporation based on inexpensive raw materials (PCM direct incorporation), to address the high production costs of macro or microencapsulated PCM. The main objective of this work was the study of the physical and mechanical properties of cement mortars with direct incorporation of PCM, with a melting temperature of about 22 ºC. Based on the results obtained, it can be concluded that the addition of this material caused some changes in the fresh and hardened properties of cement mortars., info:eu-repo/semantics/publishedVersion

The construction industry is responsible for high energy and raw materials consumption. Thus, it is important to minimize the high energy consumption by taking advantage of renewable energy sources and reusing industrial waste, decreasing the extraction of natural materials. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing to the thermal comfort and reduction of the use of heating and cooling equipment, using only the energy supplied by the sun. The simultaneous incorporation of PCM and fly ash (FA) can reduce the energetic consumption and the amount of materials landfilled. However, the addition of these materials in mortars modifies its characteristics. The main purpose of this study was the production and characterization in the fresh and hardened state of mortars with incorporation of different contents of PCM and FA. The binders studied were aerial lime, hydraulic lime, gypsum and cement. The proportion of PCM studied was 0%, 20%, 40% and 60% of the mass of the sand. The content of fly ash added to the mortars was 0%, 20%, 40% and 60% of the mass of the binder. It was possible to observe that the incorporation of PCM and fly ash in mortars caused differences in properties such as workability, microstructure, water absorption, compressive strength, flexural strength and adhesion.

Cement pastes and mortars were prepared by replacing ordinary Portland cement with different dosages of biomass fly ashes (0, 10, 20 and 30% BFA) whilst in dry condition. The effect of BFA on the flow behaviour (spread on table and rheology), setting time, temperature of hydration and electrical resistivity was studied in this experimental research. Increasing the amount of BFA in the compositions required extra dosage of water, as a result of particles fineness, tendency for agglomeration and retention/absorption of water molecules. As a consequence, the relative amount of free water diminishes and the flowability is poorer. The introduction of BFA also led to an increase in setting time, while the resistivity obtained from the impedance measurements tends to be lower than the reference paste (ash-free). The higher concentration of mobile species in the pore solution, namely sodium ions introduced by the ash, explains that tendency. The hydration temperature of cement pastes tends to decrease with the level of cement to ash replacement. Between the two tested ashes (from grate and fluidized sand bed furnaces), differences in particle size and shape, in the amount of residual organic matter and concentration of inorganic components define minor changes in the workability and setting behaviour. Therefore, the introduction of biomass fly ashes affects the hardened state features but do not compromise them. (C) 2015 Elsevier Ltd. All rights reserved.

O despertar da consciência ambiental pela sociedade, tem levantado problemas até então ignorados tais como os consumos energéticos. Numa sociedade com um elevado ritmo de crescimento e padrões de conforto cada vez maiores, surge a necessidade de minimizar os elevados consumos energéticos, tirando partido de fontes de energia renováveis. As argamassas com incorporação de materiais de mudança de fase (PCM) possuem a capacidade de regular a temperatura no interior dos edifícios, contribuindo desta forma para o aumento do nível de conforto térmico e diminuição do recurso a equipamentos de climatização, apenas com recurso à energia solar. Contudo, a incorporação de materiais de mudança de fase em argamassas modifica algumas das suas principais características. Portanto, o principal objetivo deste estudo consistiu na caracterização física e mecânica de argamassas aditivadas com PCM, assim como na avaliação da sua durabilidade. Para tal foram desenvolvidas 12 composições distintas, à base de diferentes ligantes e dopadas com 40% de PCM. Tendo sido possível observar que a incorporação de PCM provoca diferenças significativas em propriedades tais como a trabalhabilidade, resistência à compressão, resistência à flexão, aderência, absorção de água por capilaridade, absorção de água por imersão e resistência a ações de gelo-degelo. Contudo, foi possível concluir que a incorporação de PCM nas argamassas pode ser realizada com sucesso. Sendo que, as alterações verificadas nas argamassas podem ser contornadas através da incorporação de uma maior dosagem de ligante, superplastificante e até mesmo a inclusão de fibras. Apesar dos resultados desta investigação serem promissores é importante referir que outras investigações devem ser realizadas com o intuito de observar a influência do PCM em argamassas constituídas por outros materiais., The awakening of environmental awareness by society has raised issues previously ignored such as energy consumption. In a society with a high growth rate and increased standards of comfort arises the need to minimize the currently high energy consumption by taking advantage of renewable energy sources. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing to the thermal comfort and reduction of the use of heating and cooling equipment, using only the energy supplied by the sun. However, the incorporation of phase change materials in mortars modifies its characteristics. The main purpose of this study was the physical and mechanical characterization, as well the evaluation of the durability. Twelve compositions were developed, based in different binders and doped with 40% of PCM. It was possible to observe that the incorporation of PCM in mortars caused significant differences in properties, such as workability, compression strength, flexural strength, adhesion, water absorption by capillarity, water absorption by immersion and degradation after freeze-thaw cycles. However, it was concluded that the incorporation of PCM in mortars can be performed successfully. Being that the changes in mortars can be solved by incorporating a higher content of binder, superplasticizer and the inclusion of fibers. Although the results of this investigation are promising it is important to note that further investigations should be performed aiming to observe the influence of PCM in mortars composed by other materials., Fundação para a Ciência e Tecnologia pelo financiamento deste trabalho de investigação desenvolvido no âmbito do projeto “ Contribuição de Argamassas Térmicas Ativas para a Eficiência Energética dos Edifícios” (PTDC/ECM/102154/2008) e à atribuição da bolsa individual de doutoramento com referência SFRH/BD/95611/2013.

Bottom bed ash (BA) from forest biomass residue combustion generated in bubbling fluidized bed combustor (BFBC) was chemically, mineralogically and physically characterized and evaluated according to Decision 2003/33/CE and its landfill classification was determined based on criteria established by European and Portuguese legislations. Aiming to investigate its potential for being used as alternative aggregate in cementitious-adhesive mortar (CAM), formulations were produced by replacing commercial sand by an equivalent mass of 25,50 and 100 wt.% of bottom ash. CAM properties were measured in fresh and hardened conditions. The bottom ash effect on the tensile adhesion strength (TAS) was investigated on samples cured under four distinct conditions. Macro and microstructural analyses were carried out to identify the influence of wetting capability and transference area in the TAS. Results revealed that high ash levels cause relevant changes in TAS, particularly those evaluated after 30 min of open time. However, within reasonable limits, the effects are minor and acceptable. This recycling route seems feasible, since it combines environmental benefits with economic advantages for the adhesive mortar producers in the sense that they can use BA as raw material, saving a natural resource; this recycling option is also important since one can avoid waste landfilling. (C) 2014 Elsevier B.V. All rights reserved.

In a society with a high growth rate and increased standards of comfort arises the need to minimize the currently high energy consumption by taking advantage of renewable energy sources. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing to the thermal comfort and reduction of the use of heating and cooling equipment, using only the energy supplied by the sun. However, the incorporation of phase change materials in mortars modifies its characteristics. The main purpose of this study was the production and characterization in the fresh and hardened state of mortars with incorporation of different contents of PCM in mortars based in different binders. The binders studied were aerial lime, hydraulic lime, gypsum and cement. For each type of binder, different mortars were developed with different content of PCM. The proportion of PCM studied was 0%, 20%, 40% and 60% of the mass of the sand. It was possible to observe that the incorporation of PCM in mortars caused differences in properties such as workability, microstructure, compressive strength, flexural strength and adhesion., (undefined)

The thermal rehabilitation is an opportunity to reach higher levels of energetic performance, reducing the high energetic dependence of the countries. Rehabilitation operations based in the utilization of materials with the capability to store and release energy contribute to obtain more energy efficient buildings. Combining the use of smart materials with temperature control capability and renewable energy sources, it is possible to increase the thermal comfort inside the buildings. The main purpose of this study was the physical, mechanical, and thermal characterization of mortars based in specific binders for rehabilitation with incorporation of phase change materials (PCM). Mortars without and with incorporation of PCM were studied. It was observed that the incorporation of PCM in mortars caused differences in the physical and mechanical properties and improved their thermal behavior, reducing the extreme temperatures and decreasing the heating and cooling needs., Portuguese Foundation for Science and Technology (FCT), info:eu-repo/semantics/publishedVersion

Bottom bed waste (BBW) from combustion of forest biomass residues was characterized aiming its use as partial substitute of fresh bed sand (FBS) in industrial bubbling fluidized bed combustors (BFBC). BBW particle size distribution, elemental composition (mainly Si, Ca, Al, Na, K, P and Mg) and mineralogy were evaluated considering also the influence of the characteristics of the biomass used as fuel. Biomass combustion experiments were developed using a pilot-scale bubbling fluidized bed combustor. The operating conditions during the experiments were monitored, namely the flue gas composition (CO 2 , O 2 and CO), temperature and pressure, and compared with data collected from BFBC located in two industrial biomass thermal power plants. Physical, chemical and mineralogical characteristics of the FBS and BBW revealed that practices related with biomass handling at the forest strongly influence the BBW properties, in terms of not only coarse soil particle addition (> 1.0 mm) but also mineralogically. However, the results obtained here indicate that by sieving of BBW it is possible to recover almost 60% of the original BBW particles (size between 0.3 and 1.0 mm), which have properties that allow its reuse as substitute of FBS for bed make-up in industrial BFBC.

This paper reports on the use of nanoparticles of titania (nT), superabsorbent polymer (SA) and phase-change material (PCM) in order to obtain the functionalization of mortars. Single, binary and ternary mixtures with 0-1 wt.% nT, 0-1 wt.% SA, 0-20 wt.% PCM were based on flow table measurements (similar to 140 mm) to estimate the individual and interactive effect between the additives. In general, the mentioned additives showed distinct behaviors, but the PCM particles predominate on most of properties and also on the performance of others additives. SA particles exhibited quite different rheological behavior if compared with other additions, due to high affinity with the water and stronger absorption levels. The PCM-containing mortars attenuate and delayed the temperature changes, while 1SA particles resulted in higher hygroscopic capacity. Moreover, the photocatalytic degradation of NOx reached 40-45%. In addition, the moisture buffering value of 1SA, 1nT and 20PCM mortars were classified as good according to the Nordtest method. (C) 2013 Elsevier B.V. All rights reserved.

A study was conducted on the development of lime based grouts for consolidation of renders and plasters detached from the support. The aim is to develop grouts that should be compatible with the preexisting materials and allow the restoring of the adherence of coatings to the background. Special attention was paid to the rheological behaviour of the grouts and to other features of the fresh state. The role of components such as binders, aggregates and admixtures used in the formulations was tested through an outlined series of mechanical and physical tests. In terms of hardened state properties, a set of basic requirements (related to strength and capillarity) were evaluated and a test for adhesion loss measurement was developed in order to test the ability of developed grouts to restore adhesion of coating layers. The rheological behaviour was evaluated through a distinct procedure, which involved the test with a specific speed profile (dwell profile). The dwell profile allows studying the rheological behaviour along measuring time, making possible to observe changes in rheological parameters in mortar suspensions, through the measurement of flow curves along the time test. The dwell profile allowed obtaining the rheological parameters (viscosity and yield stress) according to the Bingham model. Grouts based on lime, fine sand and metakaolin together with the right amount of water and admixtures were developed and adjusted in order to be used in consolidation works of old renders. (C) 2013 Elsevier Ltd. All rights reserved.

Disposal of mine tailings is one of the most important environmental issues during the mining lifetime. Especially sulphidic tailings can cause environmental and ecological risks because of their tendency to oxidize in the presence of water or air. Because of small particle size and harmful chemical properties, utilization possibilities of sulphidic mine tailings are limited. The aim of the present study was to develop technologies to utilize sulphidic mine tailings in alkali activated materials. Alkali-activated materials also known as geopolymers are nanosized zeolite type or slightly amorphous materials comparable to traditional Portland cement concrete, which can physically encapsulate or chemically stabilize the hazardous elements such as heavy metals into the 3D structure. Mine tailing based geopolymer aggregates were successfully produced from sulphidic mine tailings with good physical properties. The geopolymer aggregates performed as a concrete aggregate comparable to commercial lightweight aggregates. In addition, geopolymer mortars were prepared from mine tailings. In mortar application, there is a need to add some co-binder such as blast furnace slag in order to achieve high strength for the material. The mine tailing based geopolymer structure has an ability to stabilize a large number of cationic species into the structure while some anionic species were not able to immobilize by alkaline activation.

In a society with a high growth rate and increased standards of comfort arises the need to minimize the currently high energy consumption by taking advantage of renewable energy sources. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing to the thermal comfort and reduction of the use of heating and cooling equipment, using only the energy supplied by the sun. However, the incorporation of PCMs in mortars modifies its characteristics. The main purpose of this study was the production and characterization of mortars with incorporation of two different PCMs. Specific properties of two PCMs, such as particle size, shape, and enthalpy, were determined, as well as the properties of the fresh and hardened state of the mortars. The proportion of PCM was 0, 10, 20, and 30% of the total mass of the solid particles. In order to minimize some problems associated with shrinkage and consequent cracking of the mortars, the incorporation of polyamide fibers and superplasticizer was tested. It was possible to observe that the incorporation of PCMs in mortars caused differences in properties such as compressive strength, flexural strength, and shrinkage. Even though the incorporation of PCM microcapsules resulted in an increase in the shrinkage, it was possible observe a significant improvement in mechanical properties.

The environmental pollution in urban areas is one of the causes for poor indoor air quality in buildings, particularly in suburban areas. The development of photocatalytic construction materials can contribute to clean the air and improve sustainability levels. Previous studies have focused mainly in cement and concrete materials, disregarding the potential application in historic buildings. In this work, a photocatalytic additive (titanium dioxide) was added to mortars prepared with aerial lime, cement and gypsum binders. The main goal was to study the way that microstructural changes affect the photocatalytic efficiency. The photocatalytic activity was determined using a reactor developed to assess the degradation rate with a common urban pollutant, NOx. The laboratory results show that all the compositions tested exhibited high photocatalytic efficiency. It was demonstrated that photocatalytic mortars can be applied in new and old buildings, because the nanoadditives do not compromise the mortar hardened state properties., The authors acknowledge the Foundation for Science and Technology (FCT) for the financial support (PTDC/ECM/72104/2006).

The durability of concrete structures is an important issue nowadays. Specifically in the case of reinforced concrete bridges or other infrastructures one of the main form of environmental attack is the penetration of chloride ions, which leads to corrosion of concrete steel reinforcement. This study aims to evaluate the effect of the introduction of metakaolin and diatomite, two chemically and physically different pozzolans, on the resistance of concrete to the penetration of chlorides but also the effect on other properties of concrete, namely, its compressive strength and its porosity distribution. The results of this study show that the pozzolans physical and chemical characteristics have a strong influence on the pozzolans behavior and, consequently, on the concrete properties. La durabilidad de las estructuras de hormigón es un tema importante hoy en día. En concreto, en el caso de los puentes de hormigón armado u otras infraestructuras, el principal factor de agresión medioambiental es la penetración de iones cloruro, lo que conduce a la corrosion del acero de refuerzo del hormigón. Este estudio tiene como objetivo evaluar el efecto de la introducción de metacaolín y diatomita, dos puzolanas química y físicamente diferentes, sobre la resistencia del hormigón a la penetración de cloruros, y también sobre otras de sus propiedades como la distribución de su porosidad o su resistencia a compresión. Los resultados de este estudio muestran que las características fisicoquímicas de las puzolanas tienen una fuerte influencia en su comportamiento y en consecuencia, en las propiedades del hormigón.

The mining industry produces a large quantity of sulphidic mine tailings, which cause several environmental issues during waste management. Currently, there is increasing interest in new technologies to recycle and utilize mine tailings more effectively in the future. In this present study, the geopolymerization of mine tailings has been studied. Suiphidic mine tailings from a gold mining site were activated with a NaOH solution and commercial ground granulated blast furnace slag (GGBFS) was used as a co-binder. Characterization of the mine tailings and the mechanical strength of the specimens produced were investigated. In addition, the effects of different NaOH concentrations and the amount of co-binder materials on a matrix were tested. The porosity of the specimens produced was evaluated using water absorption tests, the microstructure of the fractures was analyzed with field emission scanning electron microscope (FESEM), and the crystalline phases were identified by X-ray diffraction. The results show that the unconfined compressive strength (UCS) of the specimens produced from pure mine tailings was in the range of 13-3.5 MPa. The UCS increased and water permeability decreased with 5% GGBFS content in the mixture. By optimizing the NaOH concentration and GGBFS content, the UCS of the specimens varied from 1.8 MPa to 25 MPa. The alkali-activation of mine tailings allows binders to be made with sufficient compressive strength, which can be used as a backfill in mining sites or raw material in the construction industry. (C) 2016 Elsevier B.V. All rights reserved.

This article reports an investigation on the development of multifunctional mortars with enhanced potential to passively adjust indoor RH levels and thermal conductivity, while reducing aerial pollutants (NOx) through photocatalysis. Superabsorbent polymer (SAP), Vermiculite (VER) and TiO2 nanoparticles (nT) were used as functional additives for mortars. Single and binary mixtures with 0-0.9 wt.% SAP and 0-15 wt.% VER were established based on flow table measurements (165-180 mm), while 1.0 wt.% nT remained invariable in all tested samples. In addition, the workability was adjusted by distinct amounts of water in the mixtures. In general, the effect of the VER particles predominated for most of the properties. SAP-single mixtures with similar workability showed distinct rheological behavior over time, while the yield stress represented better the continuous absorption of water molecules by SAP. VER single mixtures imposed deeper changes on the flow, hindering the rheological features. Changes on the apparent porosity, water absorption and capillarity limited the admissible VER level, but for SAP the compositional range is less restricted. In fact, no adverse effect or gain on the flexural strength was observed on SAP-containing mixtures. The internal pores created by VER reduced in 50% the thermal conductivity of 0.9SAP + 10VER in comparison to 0.9SAP + OVER. In addition, a significant increment of moisture buffering value in VER-containing mortars was also reached by using SAP particles. Finally, all samples were photocatalytically active against NOx, reaching up to 80% reduction of its initial concentration, after 60 min, regardless the concentration of additives. (C) 2016 Elsevier B.V. All rights reserved.

In this paper alkali activation of biomass fly ash – an industrial waste and biomass fly ash–metakaolin blends is investigated. Mixtures of biomass fly ash and commercially available metakaolin ARGICAL 1200 were used as solid components. Different molar volumes of NaOH and sodium silicate solutions were used for the preparation of alkali activators. The mechanical strength was determined after 10 days of curing. The concentration of alkali solution and the mix compositions were optimised for the preparation of mortar samples. The mineral and microstructural properties of the alkali activated binders were carried out by X-ray diffraction (XRD), Thermogravimetric/Differential thermal analysis (TG/DTA) and Scanning electron microscopy (SEM) methods. The mortar samples of biomass fly ashes gave a compressive strength of 18 MPa. The metakaolin incorporated samples showed a higher strength. The highest value was obtained for 40% metakaolin incorporated mortars for around 38 MPa. The biomass fly ash metakaolin blend is working well in the alkali activation application resulting in the contribution of both aluminosilicates and hydrated phases formation.

Presently the essential research trend for sustainable buildings is the use of renewable energy sources and the development of new techniques of energy storage. Phase change materials (PCMs) may store latent heat energy in addition to the typical sensible energy capacity of current building materials, allowing to store significantly more energy during the phase change process (solid to liquid and vice versa). The incorporation of PCMs into building envelope solutions takes advantage of solar energy, contributing to the overall reduction of energy consumption associated to use of the air conditioning systems. This paper presents and discusses research developed in two main components: experimental testing and numerical simulation of a building component with PCM incorporation. The main goal of the experimental testing carried out was to evaluate the effect of the incorporation of PCM macro encapsulated into a typical Portuguese clay brick masonry enclosure wall. It is evaluated the influence of the phase change process of the PCM over the attenuation and time delay of the temperature fluctuations for indoor spaces. The experimental results allowed the calibration and validation of the numerical model, enabling to carry out parametric studies with different PCMs quantity analysing consequent temperature damping and time delay.