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Three industrial aluminosilicate wastes were studied as precursors to produce alkali-activated concrete: (i) electric arc furnace slag, (ii) municipal solid waste incineration bottom ashes, and (iii) waste glass rejects. These were characterized via X-ray diffraction and fluorescence, laser particle size distribution, thermogravimetric, and Fourier-transform infrared analyses. Distinctive combinations of anhydrous sodium hydroxide and sodium silicate solution were tried by varying the Na2O/binder ratio (8%, 10%, 12%, 14%) and SiO2/Na2O ratio (0, 0.5, 1.0, 1.5) to find the optimum solution for maximized mechanical performance. Specimens were produced and subjected to a three-step curing process: (1) 24 h thermal curing (70 °C), (2) followed by 21 days of dry curing in a climatic chamber (~21 °C, 65% RH), and (3) ending with a 7-day carbonation curing stage (5 ± 0.2% CO2; 65 ± 10% RH). Compressive and flexural strength tests were performed, to ascertain the mix with the best mechanical performance. The precursors showed reasonable bonding capabilities, thus suggesting some reactivity when alkali-activated due to the presence of amorphous phases. Mixes with slag and glass showed compressive strengths of almost 40 MPa. Most mixes required a higher Na2O/binder ratio for maximized performance, even though, contrary to expectations, the opposite was observed for the SiO2/Na2O ratio. [ABSTRACT FROM AUTHOR]

Toward a sustainable approach, concrete consumption is confronted with new challenges to developing and implementing cleaner technology. Concrete production is associated with excessive use of natural resources along with environmental pollution, which can be partially addressed through cement replacement with industrial waste. Red mud (RM), a toxic by-product of alumina refineries, is a potential supplementary cementitious material that has attracted researchers' attention in the last years. In this study, 10 mixes were prepared and tested to investigate the simultaneous application of RM (10%, 15%, and 20%) and silica fume (SF) (5% and 7.5%) as cement replacement on concrete properties. The properties of fresh and hardened concrete and its durability were investigated. Overall, the mechanical performance of mixes decreased by increasing RM incorporation, whereas the simultaneous application of 20% RM and 5% SF as cement replacement yielded the same compressive strength as the reference. Furthermore, an evaluation of global warming potential and used water as environmental impacts in addition to a simplified cost analysis was performed on all mixes. Overall, the mix made with 10% RM and 7.5% SF achieved the highest consolidated performance score. [ABSTRACT FROM AUTHOR]

Featured Application: The developed En-ActivETICS responds to the growing interest in Building Integrated Photovoltaics. Even for certain limitations, results may have practical applications and effects on the safety and durability of the installation. The proposal to improve the solution through the PCM application is one of the ways to solve the overheating problem in extreme temperatures. The main goal of the paper was to numerically analyse the risk of overheating of the Energy Activated External Thermal Insulation Composite System (En-ActivETICS) as an example of Building Integrated Photovoltaics (BIPV). The analyses were conducted with the coupled power flow method (thermal and electrical) for 20 European cities. All locations were analysed considering the local climate in the context of building performance simulation as well as electricity production. The obtained results allowed for the determination of the risk of overheating, which can influence system durability, accelerated thermal ageing, and overall performance. It was revealed that the risk of overheating above 80 °C is possible in almost all locations; however, the intensity considerably differs between southern and northern Europe. The effect of latent heat storage for better thermal stabilization and overall performance was determined numerically for all locations. Finally, the improved solution with a phase change material (PCM) layer beside the PV panel was proposed individually for specific climatic zones, considering the required heat capacity. The maximum panel temperature for improved En-ActivETICS does not exceed 85 °C for any location. [ABSTRACT FROM AUTHOR]

Acceptance by the construction industry of recycled concrete as a sustainable alternative material is contingent upon a reliable assessment of its permeability to corrosive agents. This study analyses the transport mechanisms associated with chloride (Cl−), oxygen (O2) and carbon dioxide (CO2) ions in concrete with cement made with 10% or 25% ground recycled concrete (GRC) separately or in combination with 50% mixed recycled aggregate (MRA). The findings show that, irrespective of aggregate type, concrete with GRC exhibited lower resistance to ingress than conventional concrete due to its greater porosity. Nonetheless, O2 permeability was consistently below 4.5 × 10−17 m2 and CO2 penetration, under 4 mm/year0.5, indicative of concrete with high quality. Resistance to CO2 and Cl− penetration in the materials with 10% GRC was similar to the values observed in conventional concrete. On the other hand, the incorporation of 25% GRC increased the penetration of CO2 and Cl- by 106% and 38%, respectively. Further to those findings in normal carbonation environments, reinforcement passivity would be guaranteed in such recycled materials over a 100 year service life. [ABSTRACT FROM AUTHOR]

The search for more sustainable construction materials, capable of complying with quality standards and current innovation policies, aimed at saving natural resources and reducing global pollution, is one of the greatest present societal challenges. In this study, an innovative recycled aggregate concrete (RAC) is designed and produced based on the use of a coarse recycled aggregate (CRA) crushing concrete with electric arc furnace slags as aggregate. These slags are a by-product of the steelmaking industry and their use, which avoids the use of natural aggregates, is a new trend in concrete and pavement technology. This paper has investigated the effects of incorporating this type of CRA in concrete at several replacement levels (0%, 20%, 50% and 100% by volume), by means of the physical, mechanical and durability characterization of the mixes. The analysis of the results has allowed the benefits and disadvantages of these new CRAs to be established, by comparing them with those of a natural aggregate concrete (NAC) mix (with 0% CRA incorporation) and with the data available in the literature for concrete made with more common CRA based on construction and demolition waste (CDW). Compared to NAC, similar compressive strength and tensile strength values for all replacement ratios have been obtained. The modulus of elasticity, the resistance to chloride penetration and the resistance to carbonation are less affected by these CRA than when CRA from CDW waste is used. Slight increases in bulk density over 7% were observed for total replacement. Overall, functionally good mechanical and durability properties have been obtained. [ABSTRACT FROM AUTHOR]

This paper describes an experimental campaign developed with the aim of evaluating the influence of the incorporation of fine and coarse recycled aggregates (FRA and CRA, respectively) on the durability properties of self-compacting concrete (SCC). The main objective is to provide the precast industry with an alternative way of disposal and recovery of self-generated waste, minimising the consumption of natural resources and, consequently, significantly reducing the environmental impact associated with the manufacture of concrete. For this purpose, two families of concrete were produced, distinct in terms of the compressive strength of the source concrete of the recycled aggregates (45 MPa and 65 MPa), with FRA/CRA incorporation ratios of 0/0%, 25/25%, 50/50%, 0/100% and 100/0%. To evaluate the durability of the concretes, tests for water absorption, capillary absorption, oxygen permeability, electrical resistivity, chloride penetration and carbonation resistance were performed in the hardened state. The results revealed that the concrete mixes with recycled aggregate incorporated showed worse performance than the reference mixes. However, taking all the studied properties into account, it is possible to conclude that recycled aggregates from the precast concrete industry are of very good quality and can be incorporated in the production of SCC with ratios of 25/25% and 0/100% as recommended limits. [ABSTRACT FROM AUTHOR]

One of the paths taken towards the greening of concrete has been through the use of recycled aggregates as replacement of their natural counterparts. After decades of studies, the partial use of coarse recycled aggregates is considered acceptable, yet the use of fine recycled aggregates (FRAs) is highly restricted in concrete production. This restriction is based on technical concerns; for example, the presence of FRAs in concrete allegedly hinders its performance beyond acceptance. More recently, several studies seem to point to different conclusions regarding the use of FRAs in concrete: if the materials' specificities are considered during the mixing and composition design of concrete, FRAs may be considered a viable source for concrete production even if, from a durability point of view, they might still present some limitations. This paper presents some results for the durability of FRA concrete by assessing the materials' permeability properties. Different compositions were cast and tested for durability-related properties, such as water absorption by immersion, capillary absorption, carbonation, chloride penetration and electrical resistivity. The results show that the use of FRAs in concrete production is viable, meaning that it is possible to use FRAs in concrete production without neglecting the existing criteria for structural purposes. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a literature review and experimental results on the effect of high incorporation levels of fly ash (FA) and recycled concrete aggregates (RCA), individually and jointly, on the pore system of concrete that remarkably influences its durability. For that purpose, apart from an extensive literature review, three tests were performed, including electrical resistivity (ER) test, which indirectly measures the interconnected porosity of concrete, and water absorption (WA) by capillarity and immersion tests that both depend on the pores number and size but in a different way. A comparison between the experimental results and the literature is also presented to show the main findings and the research needs. The results show that WA increases and ER decreases with increasing incorporation level of RCA, and the opposite occurs with the addition of FA for both tests. The reduction percentage of WA was higher in mixes with both RCA and FA when compared to the sum of reductions in mixes with only RCA or FA. Thus, it is advisable to produce concrete with both mentioned non-traditional materials in terms of WA and ER of concrete. In addition, the benefit of incorporating of FA and RCA in concrete increased even more when superplasticizers was used. [ABSTRACT FROM AUTHOR]

This study intends to develop a methodology for service life prediction of ETICS (External Thermal Insulation Composite System), based on the factor method. The methodology adopted is based on data collected during visual inspections of buildings under current conditions of occupation and exposure, contemplating the degradation mechanisms and the characteristics of ETICS. This research can also provide a suitable tool to aid the planning, implementation and rational use of building management systems in several ways, namely: i) improvement of the materials' performance, based on the optimization of maintenance actions, use of resources and maintenance costs; ii) selection of the best constructive solution, based on the knowledge of the evolution of degradation of ETICS, according to their characteristics; iii) analysis of the economic and environmental impacts of buildings during their life cycle, based on the knowledge of the number of replacements required during this period of time. [ABSTRACT FROM AUTHOR]

• Alkali activation of municipal solid waste incinerator bottom ashes and fly ash. • Effect of recycled aggregates on the performance of alkali-activated concrete. • Reduced durability performance with inclusion of bottom ash and recycled aggregate. • Bottom ash particles presented low reactivity and acted mainly as filler. • Extensive mass loss of specimens due to ionic migration to the recycled aggregates. The increasing demand for sustainable construction materials has led to a growing interest in the use of recycled materials in concrete production. The main motivation for this research is to explore sustainable alternatives to conventional concrete mixes that can reduce the environmental impact of construction activities and address the growing issue of waste accumulation. For this reason, this study intends to evaluate the performance of alkali-activated concrete with different contents of fly ash (FA) and municipal solid waste incinerator bottom ash (MIBA). For this purpose, five compositions were considered, where the binder ratios were 100% cement, 100% FA, 75% FA/25% MIBA, 50% FA/50% MIBA and 25% FA/75% MIBA, all of which were produced with natural aggregates. Five additional mixes were produced by fully replacing the natural aggregate with recycled aggregate from mixed construction and demolition waste. A mix with 100% FA, fine natural aggregates and coarse recycled aggregates was also produced to understand the difference between the full use of recycled aggregates and their partial use. The conducted tests include compressive strength, water absorption by capillarity and immersion, chloride penetration, carbonation, and shrinkage (autogenous and total). The results showed that the substitution of FA with MIBA led to progressively worse durability-related performance, though manageable in given proportions. The incorporation of recycled aggregates led to an unexpectedly steep decline of ∼80% in compressive strength and overall durability performance in comparison with equivalent cement-based recycled aggregate concrete mixes. Nevertheless, the trend reverted in terms of shrinkage, wherein recycled aggregate-containing mixes presented the least dimensional variations. In the mechanical strength test, the curing of the alkali-activated concrete mixes in a CO 2 chamber led to a considerable improvement (i.e. 5–15 MPa) in all tested mixes. [ABSTRACT FROM AUTHOR]

This paper presents an overview of the previous studies carried out on the combined effects of incorporating high contents of fly ash (FA) and recycled concrete aggregates (RCA) in concrete. The focus is on the fresh and hardened properties of concrete where fine and coarse RCA were used as partial or total replacement of fine and coarse natural aggregates (NA), respectively, and where high contents of FA are incorporated as binder or filler. In order to understand the combined effects of both FA and RCA, the values of some properties of the concrete mixes made with incorporation of FA and RCA relative to the reference concrete are plotted in 3D surfaces. The results of this study show that, due to chemical reaction between FA and RCA, using FA in RCA concrete production is advisable, especially for percentages of FA exceeding the standard limit, some of the particles of FA work as a pozzolanic binder instead of a filler. [ABSTRACT FROM AUTHOR]

In this study, a methodology for the service life prediction of architectural concrete facades is proposed, following a research line previously developed for other types of claddings, to evaluate their durability. The methodology developed is based on the collection of data in visual inspections. In this study, 174 facades were analysed, during the fieldwork phase, through a survey of the different degradation phenomena. This information is used to define degradation curves, which graphically express the loss of performance of architectural concrete facades over time, evaluating the influence of the degradation agents, allowing estimating a reference service life for this type of coating. The model proposed in this study leads to acceptable and consistent results, adequately translating the degradation observed in reality. However, for some characteristics of architectural concrete facades, it is not possible to obtain unequivocal conclusions, which reveals the high susceptibility of these coatings to the aggressive environmental agents, e.g. sea salts, which act simultaneously on the facade, hindering the determination of the separate influence of these characteristics on the degradation found. This study intends to give a contribution to the service life prediction of exterior facades, allowing defining rational maintenance plans and reducing the costs associated to the buildings refurbishment during their life cycle. [ABSTRACT FROM AUTHOR]

This paper evaluates the influence of two superplasticizers (SP) on the durability properties of concrete made with fine recycled concrete aggregate (FRCA). For this purpose, three families of concrete were tested: concrete without SP, concrete made with a regular superplasticizer and concrete made with a high-performance superplasticizer. Five volumetric replacement ratios of natural sand by FRCA were tested: 0%, 10%, 30%, 50% and 100%. Two natural gravels were used as coarse aggregates. All mixes had the same particle size distribution, cement content and amount of superplasticizer. The w/c ratio was calibrated to obtain similar slump. The results showed that the incorporation of FRCA increased the water absorption by immersion, the water absorption by capillary action, the carbonation depth and the chloride migration coefficient, while the use of superplasticizers highly improved these properties. The incorporation of FRCA jeopardized the SP's effectiveness. This research demonstrated that, from a durability point of view, the simultaneous incorporation of FRCA and high-performance SP is a viable sustainable solution for structural concrete production. [ABSTRACT FROM AUTHOR]

The last few years have seen expressions of concern about the sustainability of construction from all actors in the sector. The durability of the materials used has, in particular, been mentioned as a determining factor in increasing the service life of structures and consequently in reducing energy consumption and environmental impacts as a whole. With the introduction of new products and/or the adoption of new constructive techniques it has become necessary to develop the fields of durability and service life prediction of construction products, with the purpose of evaluating their performance throughout their life cycle. A model to estimate the service life of natural stone claddings is put forward, based on the factor method initially proposed by the Architectural Institute of Japan. This method involves the appraisal of the degradation phenomena in stone claddings under real use conditions, through a field survey. 269 stone claddings located in Portugal were analysed. The factors that affect the durability of natural stone claddings were examined. The quantification of the factors affecting the durability of stone claddings is affected by some subjectivity. Therefore it does not seem viable to propose standard values that can be applied in all circumstances. Analysis of the scenarios proposed for that quantification shows that the use of generic values for durability factors, such as those in ISO 15686:2000, does not lead to the best results. The best solution is to adopt durability factors adjusted to the reality of the phenomenon to be modelled at a regional or local scale. This is a first approach to applying the factor method to estimate the service life of natural stone cladding. It is considered that the method proposed shows very promising results, though it still needs to be supplemented, particularly in terms of the comprehensiveness of the sample. [ABSTRACT FROM AUTHOR]

Abstract: The quarrying of marble, a well-known ornamental stone, has a substantial positive impact on Portugal's economy, but it also generates large environmental impacts. The amount of waste produced during quarrying can be as much as 80% of all stone/soil extracted. That waste is then dumped near the quarry, where it accumulates indiscriminately because a viable alternative for its disposal has not yet been found. In this context, solutions must be found that can transform this waste into a by-product and restore some of its economic value. The main goal of this study was to evaluate the influence of the replacement of primary aggregates (PA) with marble aggregates. No additions or admixtures were used, as those could change the fresh or hardened properties of the resulting concrete and disguise the influence of the replacement under study. This evaluation required the production of three concrete families. The conventional primary aggregates (PA; basalt, granite and limestone) were replaced in the three families by coarse marble aggregates (CMA) at ratios of 20%, 50% and 100% of the total volume of aggregates. These mixes were tested in the concrete's fresh state for workability and density and in its hardened state for compressive strength, water absorption by capillarity and immersion, carbonation and chloride penetration. The results indicate that there are no significant differences between a concrete produced using CMA and one made with PA in terms of durability, making the use of this waste as concrete aggregate perfectly feasible. The mechanical properties of the concrete made with CMA were assessed in the scope of concurrent work also performed at the Instituto Superior Técnico (Lisbon, Portugal). [Copyright &y& Elsevier]

Abstract: Contrasting with previous studies that aimed to evaluate the mechanical properties of concrete made with glass, this one focuses on their durability performance. For this, water absorption by capillarity and immersion, carbonation resistance, chloride penetration and shrinkage tests were performed. Mixes containing 0%, 5%, 10% and 20% of glass aggregates (GA) as replacement of natural aggregates (NA) were prepared. Also analysed is the influence of the size of the replaced aggregates (fine and coarse, separately or simultaneously), in a total of 10 concrete mixes. It was found that the particle size strongly affects the workability of concrete. Due to the lower density of the glass aggregates, the mixes made with glass had a lighter fresh density than the reference concrete. Although there is a decrease in the compressive strength as the replacement rate increases, mixes with GA are totally feasible, even though there are some differences in performance as a function of the particle size of the GA used to replace the NA. It was found that in most cases the GA do not significantly alter the durability-related properties of concrete. In a few instances there is a variation from the reference concrete of ±15%, which is well within the expectable scatter of the results from experimental research. [Copyright &y& Elsevier]

Abstract: A substantial growth in the consumption of plastic is observed all over the world in recent years, which has led to huge quantities of plastic-related waste. Recycling of plastic waste to produce new materials like concrete or mortar appears as one of the best solution for disposing of plastic waste, due to its economic and ecological advantages. Several works have been performed or are under way to evaluate the properties of cement-composites containing various types of plastic waste as aggregate, filler or fibre. This paper presents a review on the recycling plastic waste as aggregate in cement mortar and concrete productions. For better presentation, the paper is divided into four different sections along with introduction and conclusion sections. In the first section, types of plastics and types of methods used to prepare plastic aggregate as well as the methods of evaluation of various properties of aggregate and concrete were briefly discussed. In the next two sections, the properties of plastic aggregates and the various fresh and hardened concrete properties of cement mortar and concrete in presence of plastic aggregate are discussed. The fourth section focus on the practical implications of the use of plastic waste in concrete production and future research needs. [Copyright &y& Elsevier]

Abstract: The many problems related to dumping used tyres have led to the development of various uses for this industrial waste. The performance of concrete that contains rubber aggregate made from used tyres (CTA) has been studied since the early 1990s. Past research has dealt mainly with the mechanical characteristics of this type of concrete. This research, however, has assessed the performance of CTA in terms of durability. Tests for shrinkage, water absorption by immersion and capillarity, carbonation and chlorides penetration resistance were performed. Concrete mixes were produced in which 5%, 10% and 15% of the volume of natural aggregate (NA) were replaced by aggregate derived from used tyres (TA). The fine and coarse aggregate were replaced both separately and simultaneously. This research also examined the influence of the rubber grinding process. Some concrete mixes were therefore made with mechanically ground aggregate and others with aggregate produced by cryogenic technology. [Copyright &y& Elsevier]

Although ceramic tiling on building facades has a history of long durability and service life, a number of service life anomalies in modern buildings have occurred. To identify the factors and address this problem, a method is developed for the service life prediction of adhesive ceramic tiling systems based on a successful model for render and natural stone cladding. The focus is on the applicability of an empirical method of field data collection to this type of cladding that recognizes the complexity of ceramic tiling systems. A hierarchy of defects is defined to establish levels of degradation and identify the susceptibility to errors in design, execution and selection of materials. Results were validated using in-situ visual inspections of 117 tiling systems in Lisbon, Portugal. The aim is to provide a preliminary tool to estimate the durability of ceramic tiling systems and identify influencing factors. Ceramic tiling systems are particularly sensitive to the inadequacy of the materials as well as execution and design errors. Although 42% of the variance of the severity of degradation indicator can be explained by environmental agents, a larger 58% is attributed to design and installation errors. Bien que les revetements en carreaux de ceramique sur les facades de batiments presentent des antecedents de durabilite et de duree de vie etendues, un certain nombre d'anomalies relatives a la duree de vie sont survenues dans des batiments modernes. Afin de s'attaquer a ce probleme et d'en identifier les facteurs, il a ete mis au point une methode permettant de prevoir la duree de vie des systemes d'adherence des revetements en carreaux de ceramique, qui est basee sur un modele probant pour les revetements en crepis et en pierre naturelle. L'accent est mis sur l'applicabilite a ce type de revetement d'une methode empirique de collecte des donnees de terrain, capable de reconnaitre la complexite des systemes de revetement en carreaux de ceramique. Il est defini une hierarchie des defauts afin d'etablir des niveaux de degradation et d'identifier la sensibilite aux erreurs en matiere de conception, d'execution et de choix des materiaux. Les resultats ont ete valides en recourant a des controles visuels in situ de 117 systemes de carrelage a Lisbonne, au Portugal. L'objectif est de fournir un outil preliminaire permettant d'estimer la durabilite des systemes de revetement en carreaux de ceramique et d'identifier les facteurs d'influence. Les systemes de revetement en carreaux de ceramique sont particulierement sensibles a l'inadaptation des materiaux aussi bien qu'aux erreurs d'execution et de conception. Bien que 42 % des variations de l'indicateur du degre de gravite des degradations puissent s'expliquer par des agents environnementaux, 58 %, soit une proportion plus importante, sont attribuees a des erreurs de conception et d'installation. Mots cles: systemes d'adherence des revetements en carreaux de ceramique, pathologie des batiments, defauts, degradation, durabilite, facades, prediction de la duree de vie [ABSTRACT FROM AUTHOR]

Now more than ever, the construction sector is aiming to adopt more sustainable solutions. To achieve this purpose, more durable solutions must be adopted, making rational decisions at the design and maintenance stages regarding the conditions of environmental exposure and use. In this sense, knowledge regarding the service life of building components is crucial. This knowledge should not be a general concept, or a standard value, and adapting practices from one country to another is extremely challenging. In this sense, this study analyses the service life of natural stone claddings. We adopt a methodology initially proposed for Lisbon (Portugal), intending to evaluate its applicability to other geographical contexts, in order to perform a more reliable service life prediction of stone claddings located in Tehran (Iran). An estimated service life of 65 years was obtained for a sample of 162 stone claddings directly adhered to the substrate, located in Tehran, which were analysed by in situ inspections. The impact of different conditions (e.g., type of stone and environmental exposure conditions) on the service life of stone claddings in Tehran was quantified, which revealed that the exposure to environmental agents, such as wind, rain and pollutants, is the main cause of degradation of the natural stone claddings. [ABSTRACT FROM AUTHOR]

The increase of awareness with sustainability and the desire of reducing the energy consumption in the construction sector haved increased the application of External Thermal Insulation Composite Systems (ETICS) across Europe in the last decades. Nevertheless, the implementation of appropriate maintenance strategies is still neglected. The aim of this study is to analyse the impact of different maintenance strategies. For that purpose, a condition-based maintenance model, based on Petri nets, is used to evaluate three maintenance strategies: MS1—total replacement only; MS2—combination of minor intervention and total replacement; and MS3—combination of cleaning operations, minor intervention, and total replacement. In the end, a multi-criteria analysis is used to discuss the impact of the three maintenance strategies proposed, evaluating the remaining service life, the global costs over time, the ETICS' degradation condition, and the number of replacements (end of service life) over the time horizon. For this purpose, a sample of 378 ETICS was analysed, based on in situ visual inspections, carried out in Portugal. The results from this study reveal that maintenance plays an important role to increase the durability of ETICS, and therefore their sustainability. Regular maintenance can promote the extension of the ETICS's service life between 88% and 159% (between 15 to 27 years), improve the global degradation condition of the ETICS, and reduce the impact on users by reducing the number of deeper interventions. Further research is essential to optimise the maintenance strategies (time interval between inspections, stakeholders' performance criteria, and environmental exposure). [ABSTRACT FROM AUTHOR]

The concrete industry is under increasing pressure to reduce greenhouse gas emissions. An immediate solution is to minimize the amount of Portland cement used by partially substituting other supplementary cementitious materials. This article presents the results of an experimental campaign on the influence of replacing Portland cement with both calcined and uncalcined diatomites from the filtration of beer and wine in the production of elements made of vibro-pressed pre-cast concrete, such as pipes. Additionally, a natural diatomite is used. The mechanical properties, capillary water absorption, carbonation, and chloride ingress are tested. The results obtained show the possibility of using natural and recycled diatomites on an industrial scale, which can improve even the long term properties of prepared precast concrete. [ABSTRACT FROM AUTHOR]

Wood is a natural, sustainable, and renewable material, which has been used as flooring for centuries, but not enough is known about its durability and performance over time when subjected to different degradation agents. This study proposes a methodology for the service life prediction of wood flooring systems, considering the impact of different factors that influence the floors' durability. For that purpose, a fieldwork survey is performed to evaluate the degradation phenomena of 96 indoor wood floorings in-use conditions, located in Portugal. The data collected are converted into degradation patterns that graphically illustrate the loss of performance of wood floorings over time. An estimated service life of 44 years is obtained. This study thus allows quantifying the impact of various characteristics on the indoor wood floorings' service life. The results reveal the high importance of the type of protection, the type of wood, and the type of floor (with a range of estimated service life values of around 18, 17 and 16 years, respectively). This study is a first step to understanding the degradation mechanisms of the wood flooring systems, in order to extend their service life, while allowing optimising of maintenance actions, thus promoting the durability and sustainability of these floorings. [ABSTRACT FROM AUTHOR]

• Alkali-silica reaction was analysed through expansion evolution in concrete mixes. • Different replacement levels of coarse natural aggregates. • Reactive and non-reactive coarse recycled aggregates. • The influence of cement type was also evaluated. The incorporation of recycled aggregate (RA) in structural concrete requires deep knowledge of this material's potential and limitations by assessing its effect on the concrete properties. Alkali-silica reaction (ASR) is one of the most concerning degradation agents in concrete produced with natural aggregates, and more expectedly in recycled aggregate concrete (RAC), which motivated this study. ASR was analysed through expansion evolution in concrete mixes produced with different replacement levels of coarse natural aggregates (CNA) with reactive and non-reactive coarse recycled aggregates (CRA). In addition, concrete mixes were naturally and artificially aged to simulate the reaction at different ages. The influence of cement type on ASR development in RAC was also evaluated. The results showed that the incorporation of 20% of reactive RA did not affect concrete's expansion behaviour. The highest expansions were obtained when 100% of reactive RA and a higher strength class cement were used. [ABSTRACT FROM AUTHOR]

In the light of one of the most common waste management issues in urban areas, namely the elimination of municipal solid waste (MSW; about 486 kg of the waste per capita were generated in the EU in 2017), this study discusses one technique as an outlet in the construction industry for the by-product of the waste's incineration in energy recovery facilities (i.e., MSW incinerator bottom ash—MIBA). There have been some investigations on the use of MIBA as partial replacement of cement to be used in cementitious composites, such as concrete and mortars. However, the waste's incorporation ratio is limited since further products of hydration may not be produced after a given replacement level and can lead to an unsustainable decline in performance. In order to maximize the incorporation of MIBA, some research studies have been conducted on the alkali activation of the waste as precursor. Thus, this study presents an extensive literature review of the most relevant investigations on the matter to understand the material's applicability in construction. It analyses the performance of the alkali-activated MIBA as paste, mortar, and concrete from different perspectives. This literature review was made using search engines of several databases. In each database, the same search options were repeated using combinations of various representative keywords. Furthermore, several boundaries were made to find the most relevant studies for further inspection. The main findings of this review have shown that the chemical composition and reactivity of MIBA vary considerably, which may compromise performance comparison, standardization and commercialization. There are several factors that affect the performance of the material that need to be considered, e.g., type and content of precursor, alkaline activator, curing temperature and time, liquid to solid ratio, among others. MIBA-based alkali-activated materials (AAM) can be produced with a very wide range of compressive strength (0.3–160 MPa). The main factor affecting the performance of this precursor is the existence of metallic aluminum (Al), which leads to damaging expansive reactions and an increase in porosity due to hydrogen gas generation stemming from the reaction with the alkaline activator. Several approaches have been proposed to eliminate this issue. The most effective solution was found to be the removal of Al by means of eddy current electromagnetic separation. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to provide the industry with a simple and practical way of disposing and recovering recycled waste from precast reinforced concrete elements rejected during the quality control process, while minimizing the consumption of natural resources in the production of concrete and, consequently, significantly reducing the environmental impact of both (construction and demolition waste and extracting natural aggregates). In other words, with this work, the intention is to evaluate the feasibility of producing high-performance self-compacting concrete with a less environmental impact, by replacing natural aggregates (NA) with fine and coarse recycled aggregates resulting from the precast industry, which allows the future use of this type of aggregates in the industrial process without reservations concerning the expected durability performance. To achieve these objectives, six types of self-compacting concrete (SCC) were produced incorporating different amounts of recycled aggregates. Six replacement ratios for fine recycled aggregates (FRA) and coarse recycled aggregates (CRA) were considered: (FRA/CRA) 0/0; 25/25; 50/50; 100/100; 0/100 and 100/0%. Six different tests were carried out to characterize both the main concrete transport mechanisms and the main concrete degradation mechanisms, namely: the immersion water absorption test, capillary water absorption test, oxygen permeability test, chloride migration test, electrical resistivity test and carbonation test. The obtained results clearly demonstrate that, despite the negative influence of the inclusion of recycled aggregates, it is still possible to produce high-performance self-compacting concrete with perfectly acceptable durability properties. [ABSTRACT FROM AUTHOR]

Abstract This study analyses the feasibility of incorporating electric arc furnace dust (EAFD) in the production of self-compacting mortars from the point of view of durability. Two types of EAFD, previously characterized and classified as hazardous waste, were used. Siliceous filler (powder) was replaced at different ratios (25%, 50%, and 100%, by volume). The following self-compacting mortar properties were measured at different curing times: total heat of hydration, compressive strength, ultrasonic pulse velocity, pore size distribution through mercury intrusion porosimetry, shrinkage and mass loss, water absorption by capillary, water absorption capacity, bulk density, skeletal density, open porosity for water, wettability by contact angle measurement, electrical resistivity, and carbonation depth. Although some of properties linked to the durability of the mortars, such as water absorption by capillarity, wettability or carbonation, were negatively affected by the incorporation of the EAFD, the results show the feasibility of replacing siliceous filler at up to 25% and the valorisation of EAFD as a secondary raw material (SRM). This research demonstrated that EAFD can be used as SRM as an alternative to landfills, thereby contributing to the promotion of the new circular economic model pursued by the European Union. Highlights • Contribution to the circular economy paradigm in the construction industry. • Electric arc furnace dust (EAFD) management to avoid its deposition in landfills. • EAFD valorisation as a secondary raw material in self-compacting mortar production. • Feasibility of using EAFD up to 25% as a filler from a durability point of view. [ABSTRACT FROM AUTHOR]

Highlights • Using up to 20% GWD as cement replacement does not significantly affect the mechanical properties of concrete. • Chloride attack, unlike acid attack, does not degrade the mechanical properties of concrete. • Using 20% GWD as cement replacement showed the least mass loss. • Using 10% and 20% GWD as cement replacement led to higher values of OCP and corrosion resistance. • The H 2 SO 4 solution is less aggressive than the NaCl solution in terms of corrosion behavior. Abstract In this research, the effect of granite waste dust (GWD) as partial replacement of cement (up to 20%) on the mechanical and durability behaviour of concrete mixes under adverse exposure conditions was investigated. The specimens were tested after 28 days of curing in lime-saturated water and 91 days of exposure to 5% by weight of NaCl and H 2 SO 4 solutions. Compressive and splitting tensile strength, resistance to acid attack, water absorption, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests and Scanning Electron Microscopy (SEM) analysis were performed. The compressive and tensile strength results showed that using up to 20% GWD as cement replacement does not significantly affect the mechanical properties of concrete mixes. However, the concrete mix with 10% GWD displayed the highest strength of all. It was also revealed that the concrete mix with 20% GWD showed a higher resistance to acid and chloride attack than the others. GWD did not have a significant effect on the water absorption of the concrete mixes. OCP and EIS measurements revealed that 10% and 20% GWD as cement replacement significantly improved the corrosion resistance of concrete. [ABSTRACT FROM AUTHOR]

The objective of this research is to enhance concrete produced with high content of fly ash (FA) and recycled concrete aggregates (RCA), individually and jointly, with low (with superplasticizer) and high (without superplasticizer) water to binder ratio (w/b), according to their chloride ion penetration resistance (CIPR)-related service life and embodied energy (EE). For that purpose, the EE was determined for the production of 1 m 3 (declared unit) of concrete considering the primary energy, non-renewable (PE-NRe) of the “Cumulative Energy Demand” environmental impact assessment method, and the CIPR of concrete are considered the conditioning factors. The environmental assessment of the mixes was evaluated by considering the Life Cycle Assessment (LCA) standardized methodology. In addition, the assessment was mostly made either according to the local Life cycle inventory (LCI) data or environmental product declaration (EPD) report and selected according to NativeLCA methodology on typical conditions in Portugal. Generally, the CIPR of concrete decreases when the RCA content increases, and the opposite occurs by replacing cement with FA. After 28 days, the rate of CIPR development of the concrete made with incorporating both FA and RCA is higher than that of concrete containing either FA or RCA. Therefore, it is positive to use simultaneously RCA and FA in concrete. This rate increased even more when SP was used. Furthermore, the EE significantly reduced with increasing replacement level of cement and coarse natural aggregates (NA) with FA and coarse RCA, respectively. Nonetheless, the changes in EE caused by the incorporation of SP and fine RCA are small. In term of the influence of combining FA and RCA in low and high w/b concrete, the EE linearly changed with each individual effect. Nevertheless, the optimal solution of mixes by means of both EE and CIPR (measured by the yearly EE of the mixes relative to the reference concrete) does not necessarily consider the one that requires less EE or that has higher CIPR. According to this parameter, the best-case scenario is always the low w/b mixes with high volumes of RCA and FA, followed by the corresponding high w/b mixes. [ABSTRACT FROM AUTHOR]

Currently, the built heritage presents clear signs of degradation, requiring in some situations an urgent intervention. The majority of defects can be avoided or mitigated at the design and execution stages, but the designers and stakeholders often neglect the maintainability of the buildings and components, thus compromising their performance and durability. It is thus necessary to adopt an integrated approach during the buildings life cycle, evaluating their performance over time, the influence of the degradation agents and mechanisms on their durability and service life, and the adoption of cost-effective maintenance strategies. In this sense, it is crucial to use quantitative information related with the performance of building components over time. This study intends to respond to this need by proposing a methodology for the service life prediction of pitched roofs’ ceramic claddings, which are the most common type of roofing system adopted in Portugal and in many countries around the world. These elements are one of the most vulnerable in a building, more exposed to the degradation agents, and with a higher incidence of defects. The method proposed is validated based on a visual inspection campaign, performed in 85 buildings and 146 claddings located in Portugal, with a total area of 43,991.6 m 2 . Various degradation patterns are established based on the roofs’ characteristics, evaluating their influence on the roof claddings’ service life. The proposed methodology allows obtaining coherent results, providing relevant information regarding the pitched roofs ceramic claddings’ service life, aiding the adoption of rational and integrated maintenance strategies. [ABSTRACT FROM AUTHOR]

Buildings' façades play an important role in the protection of buildings and, therefore, their envelope system must comply with its function, fulfilling the performance requirements and withstanding the external environmental agents during the buildings' life cycle. Although the degradation of buildings is a natural process, there are various factors that influence their durability. The assessment of the buildings' durability and service life is a research field that brings together several knowledge areas, e.g. construction technology, building physics and meteorology. This paper intends to identify the main factors that influence the durability of adhesive ceramic external wall claddings, developing models to predict their service life that involve these variables. The service life prediction models proposed in this study are defined based on simple and multiple regression analysis, both linear and nonlinear. The proposed models are defined based on the in situ evaluation of the degradation condition of 96 ceramic claddings of residential buildings in Brasília. The methodology led to coherent results and its applicability and adequacy to predict the service life of ceramic claddings in Brasília is demonstrated. The knowledge regarding the influence of the façades' characteristics on their durability is extremely useful to designers, in order to improve the selection of a given cladding for a specific situation, and to managers and stakeholders, allowing the optimization of maintenance policies and thus increasing the sustainability of the solutions adopted during the buildings' life cycle. [ABSTRACT FROM AUTHOR]

This study evaluated the performance over time of Self-Compacting Mortars (SC mortars) with different industrial by-products simultaneously; Electric Arc Furnace Dust (EAFD) and fly ash, conforming (FA) or not conforming (NcFA), from coal-fired power plant or recovery filler from hot-mix asphalt plant (RF). Different SC mortars mixes were produced; three mixes with different EAFD ratio incorporation (0 %, 10 %and 20 %) for each the other industrial by-products (FA, NcFA and RF) substituted of cement at 30 %; and additional three mixes with 60 % of cement replacement by FA and the same EAFD incorporation ratios. To study the performance over time of these SC mortars, tests such as electrical resistivity, ultrasonic pulse velocity, drying shrinkage, capillarity, compressive and flexural strength were carried out up to 91 days of curing. The SC mortar compositions was evaluated by TGA/DTA and DRX analysis. Previously, the by-products used were characterized. The EAFD incorporation showed a strong influence in SC mortars, independently of the industrial by-product used. The initial inhibition of development of hardening in SC mortars due to the presence of ZnO in EAFD was lifted over time up to some extent. The simultaneous use of different industrial-by products in SC mortars in high volume content walks towards the sustainability in the construction sector. [Display omitted] • EAFD with other industrial by-products are a viable alternative to produce SC mortars. • 20 and 40 MPa reached in compressive strength at 28 and 91 days in SC mortars with EAFD. • Durability worsening of SC mortars when EAFD incorporated occurred but reduced over time. [ABSTRACT FROM AUTHOR]

• A higher number of recycling cycles generates RCA with higher adhered mortar content; • The increase of adhered mortar present in the constitution of RCA tends to stabilize given enough recycling cycles. • Three recycling cycles were not enough to achieve a stabilization of the aggregates properties. Since construction is one of the most environmental impacting activities in existence, it is important to study and develop solutions to make its processes more efficient. Thus, multiple-recycling of concrete presents itself as a possible alternative for the reutilization of construction and demolition waste (CDW) over a large period of time. This paper presents the results and conclusions obtained from an extensive experimental campaign intended to study the durability performance of concrete made with aggregates resulting from multiple recycling cycles. Concrete mixes with 25% and 100% of substitution of natural coarse aggregates with recycled coarse concrete aggregates obtained from one, two and three recycling cycles were produced. Tests such as sieve analysis, water absorption, particle density, shape index, particle bulk density and Los Angeles abrasion were made to study the recycled coarse aggregates properties. Additionally, the workability and bulk density of fresh concrete were measured, and water absorption by immersion and capillarity, carbonation and chloride penetration were assessed to evaluate the durability performance of hardened concrete, as well as shrinkage. The results obtained in the various tests show that, with the increase of recycling cycles, the recycled coarse aggregates demonstrate a quality decrease in their properties, resulting in a worse durability and shrinkage performance of the resulting concrete. Furthermore, it is shown that the decrease in performance tends to slow down with the increase of the recycling cycles, thus presenting an asymptotic behaviour. However, in most cases, it was not possible to establish that three recycling cycles were enough to stabilize the properties. [ABSTRACT FROM AUTHOR]

• Effect of steel fibres on the mechanical and durability properties of rubberised concrete. • Effect of rubber waste aggregates on the compressive and splitting tensile strength, fracture energy, ultrasonic pulse velocity, drying shrinkage, bulk electrical resistivity, dynamic modulus of elasticity and resonance frequency of concrete. • 15 concrete mixes containing various steel fibres and rubber aggregates were manufactured and examined. • Some correlations are proposed to predict compressive-tensile behaviour, flexural strength-fracture energy performance and flexural-compressive strength relationships of rubberised concrete with various contents of steel fibres. This study intends to assess the mechanical and durability behaviour of steel fibres (SF) concrete containing rubber waste. For this purpose, 16 concrete mixes were manufactured to produce test specimens. Rubber waste was used at five volume ratios of 0%, 5%, 10%, 15% and 20%. Moreover, SF were added at three mass ratios (0%, 1% and 2%). Subsequently, the slump, compressive and splitting tensile strength, fracture energy, ultrasonic pulse velocity, drying shrinkage length changes, bulk electrical resistivity, dynamic modulus of elasticity and resonance frequencies of all specimens were measured. One mix with no SF and rubber was used as control. The results showed that shrinkage deformation increased with the rubber waste content; however, and adding SF reduced shrinkage deformation, as expected. Moreover, using 2% SF with 5%, 10%, 15% and 20% rubber tire waste raised the flexural strength of the specimens by 23%, 16%, 7% and 1%, respectively, relative to the control mix. Moreover, rubber waste improved the fracture energy of specimens particularly when both rubber and SF are used. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental investigation of durability properties carried out on 16 concrete mixes containing marble waste powder and silica fume as partial replacement of ordinary Portland cement. The latter was partially replaced at different ratios of silica fume (0%, 2.5%, 5%, 10%) and marble waste powder (0%, 5%, 10%, 20%). In all concrete mixes, constant water/binder ratio of 0.45 and target initial slump of S2 class (50–90 mm) were used. Workability and bulk density tests were carried out on fresh concrete, while compressive strength, electrical resistivity, water absorption, durability to sodium sulphate, magnesium sulphate and sulphuric acid attack tests were performed to evaluate some relevant properties of concrete in the hardened state. It was found that the strength and durability of concrete containing marble waste powder tend to decline for replacement ratios over 10% but satisfactory results were obtained below that level of replacement. Regarding the use of silica fume, it was observed that it improves the strength and durability of concrete with marble waste powder by offsetting the decline of its properties relative to conventional concrete. In addition to obtaining approximately the same results as the original concrete mix, using 20% marble waste powder and 10% silica fume as partial replacement of cement resulted in a 30% cement reduction which decreases the harmful effects of cement industry on the environment. [ABSTRACT FROM AUTHOR]