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Research on the variability of the properties of recycled aggregate concrete is lacking and is necessary for the development of reliability analyses and code calibration procedures. This paper presents an experimental programme on the within-batch variability of the compressive strength, Young’s modulus, and splitting tensile strength of several recycled and natural aggregate concrete mixes. The influence of the recycled concrete aggregates on the mechanical properties and variability of concrete is analysed and discussed and benchmarks with standard predictions for the variability of natural aggregate concrete are made. It was found that full recycled aggregate concrete incorporation did not increase the variability of any of the properties tested, but intermediate ratios of recycled aggregate incorporation did. The properties of high-strength concrete mixes were more variable than that of all other mixes, irrespective of recycled aggregate incorporation. All properties of all compositions were suitably modelled by normal distributions. The coarse recycled aggregates were sourced from concrete waste.

Steel corrosion is one of the biggest threats to the service life of reinforced concrete structures and chloride penetration favours the corrosion process. Due to sustainability and environmental issues, the use of recycled aggregate in concrete production has been growing. The aim of this study is to develop analytical models that allow predicting the performance of concrete incorporating recycled aggregates regarding chloride penetration. Multiple linear regression analysis was applied to a dataset collated from the literature. The dataset comprised 942 case studies from 33 publications. The analyses allowed identifying the explanatory variables and developing two mathematical models. One of these models is intended to predict the chloride diffusion coefficient from accelerated non-steady state migration tests, while the other predicts the charge transfer in rapid chloride permeability tests. The obtained correlation coefficients and analysis of variance (ANOVA) test results evidence the adequacy of both models. Thus, it is possible to estimate the resistance to chloride penetration in concrete incorporating recycled aggregates through the proposed models.

This paper presents a literature review concerning the fresh properties of concrete containing recycled aggregates from beneficiated construction and demolition wastes. It starts with the identification of the main variables affecting the workability of concrete, such as the quality and moisture state of the recycled aggregates. The effectiveness of water-reducing admixtures and of mineral additions on the fresh properties of recycled aggregate concrete is also analysed. A brief insight is given on the influence of using recycled aggregates on the main characterizing parameters of the material’s rheological behaviour. Other properties of recycled aggregate concrete in its fresh state are also discussed, including stability (i.e., bleeding and segregation), temperature of hydration, air content, and fresh density.

External renders are the first barrier against degradation agents and their performance affects directly that of building facades. During the life cycle of renders there is a progressive reduction of their performance until they are no longer able to fulfil their required functions, such as protection of walls and finishing of surfaces. The evaluation to understand how a render performs over time is a complex activity, not only due to the multiple factors concerning its exposition, but also to the difficulty in assessing the in-service behaviour. The use of in-situ techniques gives the possibility of obtaining the information about in-service performance of renders. This paper discusses the use of ultrasound and pendulum rebound hammer techniques for assessing the mechanical performance of rendered walls under natural ageing conditions. The results of ultrasound pulse velocity and rebound hammer index, in conventional and industrial renders, allowed identifying some of the main influencing factors, related both to the rendering-wall system (characteristics and degradation) and the inspection conditions and procedures. This study has confirmed the usefulness of these in-situ tests to evaluate the mechanical performance of rendered walls, despite their variability in natural ageing conditions.

In construction, there is a need to respond to environmental challenges and implement the Circular Economy as a strategy for the sustainable growth of the sector. To eliminate the lack of confidence in the application of the waste from this sector, it is necessary to carry out research in order to achieve an effective and integral management, as well as the reuse and recycling of these materials. In this work, a detailed study of Self-Compacting Concrete (SCC) was carried out, using as filler a waste from the drying process of the aggregate used in the manufacture of hot-mix asphalt. The results showed that it is possible to obtain a high-performance SCC in terms of durability by replacing a commercial siliceous filler (SF) with this dolomitic residual powder (RF), with high performance against the attack of aggressive agents (chloride, sulphate and carbonate ions) and shrinkage. In this study the analysis of the physical parameters of the materials (density, open porosity and pore size distribution as obtained from mercury intrusion porosimetry) and water absorption (by immersion and capillarity) was fundamental. The joint analysis of all the studied parameters allowed obtaining exhaustive results about the durability of the mixes and its interrelation with the properties of the constituents.

This investigation intends to analyse the effects of the variation of different types of recycled concrete aggregates (RCA) on structural concrete. For this purpose, two source concrete (SC) mixes, one produced in the laboratory and another in a precasting plant, were considered. The experimental campaign included mechanical, durability and long-term tests: compressive strength in cubes; splitting tensile strength; modulus of elasticity; abrasion resistance; water absorption by immersion and by capillarity; resistance to carbonation; resistance to chloride ion penetration; shrinkage and creep. The recycled aggregate concrete (RAC) mixes were compared with a reference concrete (RC) produced solely with natural aggregates (NA). Concerning the replacement percentages for fine and coarse recycled concrete aggregates (FRCA/CRCA%), the following were considered: 25/25; 50/50; 100/0; 0/100 and 100/100%. The results show that it is possible to achieve similar performances using RCA from different SC but with similar compressive strengths. In fact, RAC mixes achieved results comparable to RC in several properties.

Most research on recycled aggregates concrete concern aggregates produced from concrete waste, rather than actual construction and demolition waste. Different investigations have assessed that sulfonated-based superplastizers are not as efficient in recycled aggregates concrete than on natural aggregates concrete, but no significant loss of polycarboxylic-based superplasticizer efficiency has been reported. This may not be valid when the aggregates are sourced from actual construction and demolition waste, due to the higher porosity, roughness, and weaker mechanical properties of aggregates produced from this source. This paper analyses the mechanical properties of superplasticized concrete with the incorporation of construction and demolition waste. Recycled aggregates produced from construction and demolition waste were taken directly from plants and used as aggregates without screening or treatment, emulating what would happen in a practical application by the concrete industry. The results of the tests and the superplasticizer’s efficiency are compared with results on natural aggregate concrete compositions and on analogue recycled concrete aggregate concrete compositions with and without superplasticizers. The composition of the different construction and demolition waste aggregates is considered during the analysis of results. Evidence was found that when recycled aggregates are sourced from construction and demolition waste, polycarboxylic-based superplasticizers perform satisfactorily but may not be as efficient as in natural aggregate concrete compositions.

This paper intends to evaluate the real influence of a commercial densified silica fume (SF) and of recycled concrete aggregates (RA) on the behaviour of high-performance concrete (HPC). For that purpose, three families of concrete with 0%, 5% and 10% silica fume (SF) of the binder’s mass were produced. In addition to the commercial silica fume, fly ash (FA) and superplasticizer (SP) were also incorporated in the concrete mixes. Each type of concrete comprises a reference concrete (RC) and three recycled aggregates concrete (RAC) mixes with replacement percentages (in volume) of fine natural aggregates (FNA) with fine recycled aggregates (FRA) and of coarse natural aggregates (CNA) with coarse recycled aggregates (CRA) of 50/50, 0/100 and 100/100, respectively. Considering the mechanical performance and durability of the concrete mixes, results show that it is possible to incorporate significant amounts of FRA and CRA. Regarding the silica fume, the densification process used in its manufacture seems to lead to the formation of agglomerates that change the real particle size of the SF, originating a loss of performance of the concrete made with them.

There is a growing awareness towards using materials with less social, economic and environmental impacts in the construction and rehabilitation of buildings. However, the evaluation of the sustainability of acoustic insulation materials in these three dimensions has not yet been presented in reference publications. This paper presents these results for the first time for materials used currently and alternative materials available in the construction market to control noise in buildings. An exhaustive review has been performed, focused on the most used insulation materials at the European level in construction and rehabilitation. The characterization at the level of embodied energy, acoustic behaviour and costs of these materials is presented, so that the most eco-efficient can be selected and applied. It is concluded that there are alternative materials that, from the acoustic behaviour, embodied energy and costs points of view, are perfectly viable to replace the currently used products.

The growing European interest on building sustainability has driven the establishment of the 2012/27/UE Directive. Mortars with thermal conductivity lower than 0.2 W/m·K (thermal mortars) can have an important role in the energy efficiency of buildings. The thermal conductivity is a fundamental parameter to characterize the hygrothermal performance of mortars. Nevertheless, its measurement is complex due to its large dependency on several factors and its dynamic behaviour. In the present paper, an experimental campaign is carried out to evaluate the influence of the moisture content on the thermal conductivity of 17 thermal mortars. Moreover, correlations between thermal conductivity analytically estimated from standards and experimentally measured are assessed. The results showed that the thermal conductivity is significantly dependent on the moisture content. However, most of the building standards use fixed conductivity values for normalized conditions. Therefore the discussion of relevant influence factors on thermal conductivity of thermal mortars can help designers and professionals to evaluate the hygrothermal performance of in-service buildings facades with thermal mortars, when subjected to real exposure conditions.

The aim of this paper is to assess the feasibility of the use of a fine grain waste generated in hot-mix asphalt plants (HMA), namely recovery filler (RF), as filler materials in self-compacting concrete (SCC) production. A comparative study of two types of SCC was performed. The first concrete type was made incorporating recovery filler (SCC-RF) of a dolomitic nature and the second was made with commercial siliceous filler (SCC-SF), the latter used as reference. Good results of self-compatibility were obtained using RF. The thermogravimetric study showed that in SCC-SF the higher loss weight occurs in the dehydration zone (0–400 °C) and in SCC-RF it occurs in the decarbonation area (550–735 °C). The aging mechanism of both concrete types (SCC-SF and SCC-RF) was different. In the SCC-SF mixes, portlandite undergoes carbonation processes and pozzolanic reactions and in the SCC-RF mixes it only undergoes carbonation processes. The experimental results (splitting tensile strength, flexural strength and static modulus of elasticity) show the validity of using EHE-08, initially proposed for NVC (Normally Vibrated Concrete), in SCC. The ultrasonic pulse velocity values for SCC-SF was greater than for SCC-RF, which can be attributed to compacity and compressive strength. The shrinkage behaviour was better in SCC-RF than SCC-SF, mainly due to the greater particle size of recovery filler (RF), although the SCC-RF mixes showed lower density and mechanical strength than SCC-SF. In short, the SCC manufactured with recovery filler from plants manufacturing hot-mix asphalt (HMA) – SCC-RF – is expected to have better features than SCC-SF in relation to shrinkage and early appearance of cracks.

The water vapour permeability of renders is related with the greater or lesser drying ability of this coating mortar system. Easy drying of an applied render allows a better water resistance and consequently its greater durability versus the physical degradation mechanisms in real in-service conditions. Presently this standard characteristic is not measured on site, and neither are there consensual in situ methods that allow an indirect relationship with this property. This paper presents two experimental programs, in laboratory and in situ, which studied various drying parameters (drying rate and drying resistance index) and the corresponding relationships with hardened physical characteristics (water vapour permeability, open porosity and bulk density) relevant to characterize the in-service performance of mortars. Based on the experimental results, it is concluded that the drying resistance index (D i ) is a good indirect measure of the in-service water vapour permeability of renders applied on building facades.

The main goal of this study was to characterize, using the slant shear test, the bond strength of the interface between recycled aggregates concrete (RAC) and natural aggregates concrete (NAC). This can be relevant in the case of new construction, if precast NAC members with cast-in-place RAC parts are adopted, as well as in the case of rehabilitation of existing NAC structures if strengthened using an RAC overlay. Four replacement rates of natural coarse aggregates by recycled coarse aggregates obtained from concrete blocks, 0% (NAC, to serve as reference), 20%, 50% and 100%, were considered. The following substrate roughness conditions were produced: smooth interface – cast against wood formwork (CAW) without any further treatment; slightly rough interface – produced with a steel brush (SB); and rough surface – treated with a needle gun (NG). A total of 12 tests were performed regarding the four replacement rates and the three substrate roughness conditions. The assessment of the roughness parameters was performed using the 2D-LRA method. It was concluded that RAC exhibits adequate mechanical properties for structural use, although declining with the increase of the replacement rate. Regarding roughness, results corroborated previous studies, since an increase of strength for rougher substrates was observed. Finally, it is found that the values obtained by the codes are very conservative for all types of tested concrete, including for RAC100 despite their low concrete strengths.

This paper presents a step-by-step design of a structural concrete element containing recycled aggregates in accordance with Eurocode 2 (EC2). The design of a reinforced concrete beam was made as one would normally do for conventional concrete, by using practical performance-based rules based on a wide literature review to predict the mechanical and durability-related performance of recycled aggregate concrete. This design is based on adjusting the cross-section’s geometry of the reinforced recycled aggregate concrete beam in a way that it is capable of withstanding the same durability-related service life, similar load bearing capacity and within the same limits for deflection according to the serviceability limit state as per EC2. In most of the scenarios considered in this study, the results showed that a slight increase to the nominal cover of reinforced recycled aggregate concrete was required to exhibit the same service-life as that of a conventional concrete beam subjected to the same environment. Furthermore, although no fundamental alterations were required to the amount of reinforcement, the cross-section’s height was increased to maintain the maximum deflection within the limitations imposed by EC2.

This paper presents a systematic literature review of 114 publications published over a period of 39 years from 1977 to 2015, alongside a meta-analysis of collated data sourced from publications concerning the effect of incorporating recycled aggregates, from treated construction and demolition wastes, on the performance of cementitious renderings and masonry mortars. Several of the most relevant properties were evaluated regarding the mortars’ fresh state and their mechanical, physical and durability-related performance. The results suggest that an increasing content of recycled aggregates may reduce the performance of some of the masonry mortars, which can nonetheless be easily compensated, but most recycled aggregates mortars for rendering applications have shown comparable performance to that of conventional mortars and complied with the requirements of the European Standardization.

In the past few decades, the construction industry has been increasingly using fibre reinforced polymer (FRP) materials, due to their advantages in comparison with traditional materials, especially in aggressive environments. However, the information regarding the long-term behaviour of FRP constructions under real service conditions is limited and scattered. In this paper, a system for the inspection, diagnosis and rehabilitation of FRP constructions is presented and validated, providing a standardized and systematic tool for the maintenance of these constructions during their service life. A classification system for the anomalies and most probable causes is first presented. To assist the diagnosis of the anomalies, several in situ non-destructive methods are included in the system, as well as various rehabilitation techniques, able to maintain and/or restore the functionality of FRP elements. Several correlation matrices are proposed, interrelating different anomalies, and relating them with probable causes, and diagnosis and rehabilitation techniques. The system is validated and calibrated through an extensive field campaign of inspections of 410 substructures in 31 facilities. Although developed for FRP profiles and moulded gratings of all-FRP constructions, the system can also be used to inspect FRP components of sandwich or hybrid structures. The implementation of this system supports the inspection activities of a proactive maintenance strategy and, at the same time, the standardization of inspections, resulting in an increase of the effectiveness and objectivity of the actions to be taken upon the occurrence of anomalies in FRP constructions.

This investigation intends to characterize the fresh state behaviour of concrete produced with coarse recycled aggregates (CRA). The concrete mixes were produced with different CRA crushing levels (primary crushing or primary and secondary crushing), water to cement (w/c) ratios (0.35, 0.45, 0.55), and paste volumes (±1.25%, ±2.5%). The fresh concrete mixes were tested for slump, flow table, inverted cone, and Vebe. In addition, the workability loss over time was assessed after 0, 30, 60 and 90 min of mixing. The compressive strength of concrete mixes produced after 0 and 90 min of mixing was also related to the workability loss of concrete. The experimental results showed that mixes with CRA and w/c 0.55 tend to have a similar behaviour. This is mainly because in this type of concrete the cement paste plays the dominant role in terms of workability. In mixes with lower w/c (0.35 and 0.45), the shape and texture of CRA became more relevant, leading to less fluidity and consistency. The mixes also showed small scatter of their fresh-state properties for small variations of cement paste volume. For mixes produced with CRA that underwent primary crushing only, the conclusions presented before are valid but the differences are greater.

In order to study the behaviour of concrete structures made with coarse crushed concrete aggregates recycled from discarded elements from the precasting industry, extensive testing was performed in four full-scale structures with varying recycled aggregate (RA) ratios. This paper describes and analyses the results of vertical load tests on each slab of these double-floor structures. The Young’s modulus ( E ) of the concrete mixes was estimated by finite element model calibration using deflection data from the tests. The response pattern of the various structures was the same and the aggregates used had a small influence on E , even smaller than the execution conditions. One of the concrete mixes included a superplasticizer (SP) and this product more than offset the loss of stiffness due to RA use. To the authors’ best knowledge this is the first study ever concerning the behaviour of full-scale recycled aggregate concrete (RAC) structures subjected to vertical loading and the behaviour of slabs with significant replacement of conventional aggregates by RA.

Self-compacting concrete (SCC) can soon be expected to replace conventional concrete due to its many advantages. Its main characteristics in the fresh state are achieved essentially by a higher volume of mortar (more ultrafine material) and a decrease of the coarse-aggregates. The use of over-large volumes of additions such as fly ash (FA) and/or limestone filler (LF) can substantially affect the concrete’s pore structure and consequently its durability. In this context, an experimental programme was conducted to evaluate the effect on the concrete’s porosity and microstructure of incorporating FA and LF in binary and ternary mixes of SCC. For this, a total of 11 SCC mixes were produced: 1 with cement only (C); 3 with C + FA in 30%, 60% and 70% substitution ( f ad ); 3 with C + LF in 30%, 60% and 70% f ad ; 4 with C + FA + LF in combinations of 10–20%, 20–10%, 20–40% and 40–20% f ad , respectively. The results enabled conclusions to be established regarding the SCC’s durability, based on its permeability and the microstructure of its pore structure. The properties studied are strongly affected by the type and quantity of additions. The use of ternary mixes also proves to be extremely favourable, confirming the beneficial effect of the synergy between these additions.

This paper analyses the behaviour of cement mortars with addition of grinded fine sanitary ware (GSWF) aggregates, in percentages of 0%, 10%, 15% and 20% of the natural aggregates’ volume, to be used as renderings. The effect of these recycled materials was studied in an experimental programme through several tests. The performance of these modified mortars was evaluated in terms of strength, water absorption, water retention, dimensional instability and water permeability. Some extra tests were also formulated to understand the microstructure of these mortars such as open porosity and magnifying glass observation. The research results were very positive since the modified mortars had, in the most tests, better performance than the reference mortar (0% of GSWF addition). The modified mortar with 20% addition of GSWF was the one with the best performance of all the modified mortars, in particular in terms of higher strength and lower water absorption.

Performance-based design and specification of concrete for durability is the most efficient way to achieve the intended service life; its use has been increasing. However, to have a consistent approach, the durability related properties must be assessed onsite. This assessment can provide useful and realistic information to estimate the service life of newly built concrete structures. Thus, this work aims at evaluating the suitability of a non-destructive onsite test method to provide such information. A preliminary study, comprising tests on air permeability and carbonation resistance of several concrete mixes and an analysis of its results, was carried out. The analysis allowed proposing an analytical model, based on the calibration of a theoretical model, correlating air permeability with resistance to carbonation. This allows estimating reliably carbonation resistance through air permeability results. Although further research is needed, to provide more data, the results encourage the use of a simple test method that operates on a completely non-destructive basis. Thus, a contribution to a more consistent approach towards the achievement of durable concrete structures and of the associated positive environmental impacts is provided.

This paper provides a systematic literature review, based on the identification, appraisal, selection and synthesis of publications relating to the effect of incorporating recycled aggregates, sourced from construction and demolition wastes, on the tensile strength of concrete. It identifies various influencing aspects related to the use of recycled aggregates such as replacement level, size and origin, as well as mixing procedure, chemical admixtures, additions and strength development over time. In this paper, estimated values, using the Eurocode 2 method to determine the tensile strength over time, were compared with the actual measured values, showing little correlation and therefore new coefficients are proposed. This paper also presents the relationship between the tensile and compressive strengths according to Eurocode 2. The results suggest that, regardless of the replacement level, type, and quality of the recycled aggregate used, the resulting recycled concrete tends to exhibit a similar relationship to that of the corresponding natural aggregate concrete.

This paper provides a systematic literature review, based on the identification, appraisal, selection and synthesis of publications relating to the effect of incorporating recycled aggregates, sourced from construction and demolition waste, on the shrinkage of concrete. It identifies various influencing aspects related to the use of recycled aggregates such as replacement level, size and origin, as well as mixing procedure, curing conditions, and use of chemical admixtures and additions. A comparison between the shrinkage strain obtained experimentally and that calculated using existing models for predicting shrinkage is also presented. The results show that all prediction models analyzed in this paper tend to overestimate the shrinkage strain of concrete and would benefit from calibration in the form of short-term testing of an actual concrete to be used in a given project.

Building facades are significantly influenced by the wall renders’ performance, since they are the first protection layer against degradation agents. During their service life, facades undergo a continuous performance reduction until they are unable to meet their demanded functions, such as protecting and waterproofing the facade. Therefore, the application of in-situ testing has great importance to evaluate in-service performance of wall renders under natural conditions. This study focuses on testing the physical and mechanical behaviour of rendered facades, taking into account different render colourings and roughness and natural exposure conditions according to the wall orientation. Physical (Karsten tube and moisture meter) and mechanical in-situ tests (pendulum rebound hammer and ultrasound pulse velocity) were performed on eight walls at a natural ageing station. The in-situ tests were used to detect the factors affecting the results of these techniques, and the evolution of the rendered walls’ performance over time was investigated. The relationships between the testing techniques were also assessed.

This research aims at evaluating the effect of the replacement ratio of natural course aggregates (NCA) by recycled concrete coarse aggregates (RCCA) on the anchorage strength of ribbed steel rebars to concrete. To accomplish this purpose, four concrete mixes were designed: a conventional NCA concrete (NCA by RCCA replacement ratio of 0%) to serve as reference and three recycled aggregates concrete (RAC) with 20%, 50% and 100% NCA by RCCA replacement ratios. Besides this parameter, all the remaining ones were kept constant. An effective water/cement ratio of 0.53 and a slump of 125 ± 10 mm were adopted. The mechanical properties of the considered mixes were characterized in terms of compressive strength, splitting tensile strength, and Young’s modulus. The anchorage strength of ribbed steel rebars to RAC was assessed for each of the four concrete mixes using pull-out tests. In addition to the NCA by RCCA replacement ratio, two other variables were evaluated: the diameter (12 and 16 mm) and the anchorage length (5 ϕ , 10 ϕ and 15 ϕ ) of the steel rebars. The combination of these three variables led to 24 different testing conditions. For each of these, three equal specimens were produced, corresponding to a total of 72 pull-out tests performed. As main conclusions of this research study, it can be stated that NCA by RCCA replacement ratio has a negative impact on the mechanical properties of concrete, presenting an approximately linear correlation. Only for lower replacement ratios, namely 20%, there are not any clear changes in concrete mechanical properties, and a slight increase can even occur. Regarding the anchorage strength of ribbed steel rebars to concrete, the incorporation of RCCA has a similar effect: the increase of the NCA by RCCA replacement ratio leads to a decrease of this parameter. This effect can be well explained analysing the stress distribution inside the pull-out specimens using a finite-element model developed with this aim, also presented herein.

Aiming at characterizing the behaviour of concrete structures made with coarse aggregates recycled from crushing concrete elements from the precast industry, extensive testing was performed in four full-scale recycled concrete structures, made with various recycled aggregate ratios. This paper concerns the in situ concrete characterization tests carried out. The purpose was to study the use of the coarse fraction of the recycled aggregates (RCA) at different replacement ratios and the possibility of including a superplastizer (SP) in concrete mixes, as a means of replicating the properties of a conventional concrete (RC) mix. The results showed that the behaviour of the concrete mixes produced with these aggregates, originated from the precasting industry, i.e. with high quality, is almost unaffected by their incorporation. Only the results of the ultrasonic pulse velocity (UPV) tests were affected by RCA incorporation, but the loss was lower than the one reported in the literature. This study concluded that these RCA have, in fact, high quality and are suitable for the production of recycled aggregate concrete to be used in structural elements. The SP more than offset the effects of RCA incorporation on the concrete mixes. To the authors’ best knowledge this is the first investigation concerning the in situ concrete properties of full-scale recycled aggregate concrete structures.

This paper presents the results of an experimental campaign developed with the aim of evaluating the effect of the incorporation in concrete of recycled aggregates from crushed elements produced by the precasting concrete industry. The specific purpose was to study the use of the coarse fraction of these aggregates. This was done by studying various replacement ratios of the coarse fraction of the aggregates. The possibility/need to correct the composition of concrete mixes with recycled aggregates was also investigated, by testing various contents of a superplasticizer, intending to replicate the characteristics of a reference concrete, i.e. a mix with an analogous composition but where all aggregates are natural. An extensive set of tests was performed to evaluate the mechanical and durability properties of all concrete mixes. The results prove that the concrete mixes with recycled aggregates have an equivalent performance to that of the reference concrete in most of the properties. In the others, where a performance loss was registered, that loss was lower than the one reported in the literature review performed. This was expected since the quality of the coarse aggregates recycled from precast elements is very good and totally fit for the production of new concrete, originating concrete compositions with good quality, namely in terms of hardened state properties. As expected the use of a superplasticizer is beneficial for concrete performance in all properties analysed.

In recent years the interest on the durability of buildings and their materials has been increasing. The reasons behind that attention are mainly economic and environmental. Service life prediction methods are an essential tool to support decision-making during the building’s life cycle. Service life prediction must be used to estimate the duration of a building component and allows a more rational definition of the maintenance operations, reducing unnecessary costs. However, service life prediction can be a complex issue. The results obtained are closely related to the quality of data used to define these models. In this study, the influence of the sample on the results of a service life prediction model applied to ceramic external walls is analysed. The methodology adopted is based on field work data collection, concerning the state of degradation of the facades. Two samples were used: the initial one, composed of 117 case studies, without a pre-selection of the cases analysed, and an improved sample, composed of 195 claddings, with more complete and reliable data. The results obtained confirm that more and better data conducts to more reliable results.

In this paper some of the main long-term properties of concrete produced with recycled aggregates obtained from crushing both structural and non-structural lightweight concrete (LWC) are analysed. The properties studied are drying shrinkage, capillary and immersion absorption, and carbonation and chloride penetration resistance. A comprehensive experimental study was carried out on a series of concrete mixes in which ratios of 20%, 50% and 100% of two types of coarse lightweight aggregates (LWA) were replaced with two types of recycled lightweight concrete aggregates (RLCA). Long-term shrinkage is affected by the paste adhered to LWA and increases as the replacement ratio of LWA with RLCA goes up. However, the internal curing promoted by RLCA reduces the early shrinkage. In terms of durability, the experimental results show that generally all the properties studied decay due to the progressive replacement of structural LWA with RLCA. However, despite the general reduction of long-term properties, recycled lightweight concrete (RLWC) can be also durable, regardless of the type of RLCA. Moreover, it is shown that even for low to moderate strength RLWC the mechanism of carbonation is not a determinant factor for durability. On the other hand, the carbonation and chloride penetration resistance of concrete with non-structural LWA tends to improve with the incorporation of RLCA. It can thus be concluded that RLWC may be a viable and more cost-effective alternative solution, especially given its higher structural efficiency. In addition, RLCA obtained from non-structural LWC can be incorporated in concrete without significantly compromising its durability.

Arising from a systematic, as opposed to narrative, literature review of 236 publications published over a period of 38 years from 1977 to 2014, the paper examines the factors affecting the physical, chemical, mechanical, permeation and compositional properties of recycled aggregates sourced from construction and demolition waste, intended for concrete production. Classifications based on their composition and contaminants have been studied. The data were collectively subjected to statistical analysis and a performance-based classification, mainly for use in concrete construction, is proposed. The results allowed producing a practical means of measuring the quality of recycled aggregates, which can be used to produce concrete with predictable performance.

The objective of this research is to evaluate the effect of the incorporation of recycled ceramic fine aggregates, obtained from crushed bricks and crushed sanitary ware, on the mechanical properties of concrete. The effects of such incorporation on properties such as compressive strength, splitting tensile strength, modulus of elasticity and abrasion resistance were investigated and are discussed. Seven different concrete mixes were cast to test these hardened properties: a conventional reference concrete and six concrete mixes with replacement ratios of 20%, 50% and 100% of natural fine aggregates by either fine recycled brick aggregates or fine recycled sanitary ware aggregates. All mixes were prepared with the same workability and the same aggregates’ size gradation to allow for a valid comparison of results. Results obtained show that concrete with recycled crushed bricks exhibits adequate structural performance. Conversely, concrete with recycled sanitary ware performed poorly compared to the reference concrete, even though this limitation may be offset by the use of superplasticizers.

The importance of the refurbishment market in the construction industry has grown considerably in recent decades, especially in developed countries, where it sometimes represents nearly 50% of the market. At the same time, sustainability has become an imperative target for development, and therefore sustainable principles will have to be an integral part of refurbishment projects in the near future. However, financial resources are very limited and the ability of decision-support tools to embrace all these aspects needs urgent assessment. The aim of this paper is to review what has been done in terms of refurbishment decision support tools, from a user’s perspective. Thus, it first reviews the objectives and criteria of each tool to help users (architects, engineers and owners) to select the most suitable method for each particular situation. Their approaches and applicability are also discussed and classified on a simple scale to help users to choose the best algorithm from those tools whose objectives and criteria might meet their expectations. A complementary review is reported on what has been started in Portugal. Finally, the paper considers the likely options in terms of the main needs and areas of future research.

Waste management has become vitally important since the demand for natural resources and the amount of construction and demolition waste have greatly increased, putting huge pressure on the environment. The main goal of this study is to evaluate the effects of the introduction of superplasticizers on some mechanical properties of concrete with recycled concrete aggregates and compare them with the corresponding properties of conventional concrete made with natural aggregates. The experimental program is described and the results of workability, specific density, compressive strength, splitting tensile strength and abrasion resistance tests carried out on concrete are presented. Two different crushing processes and their effects on aggregate properties were tested. By varying the replacement percentage of natural by recycled aggregates, with or without the addition of superplasticizers, it was possible to identify some weaknesses and strengths of the recycled aggregates concrete which can contribute to developing the more widespread use of this material.

This paper presents a viability study of the use of cementitious renderings with incorporation of very fine recycled aggregates with the intention of improving their performance. An experimental programme was therefore designed with a series of tests being performed with the objective of characterizing the behaviour of such renderings at several levels: mechanical strength, water-related behaviour, durability and other properties. Even though several studies report using various materials as filler in mortars, glass has seldom been studied in that role. The results were very positive, with most properties improving with the incorporation of up to 20% of fine glass aggregate.

This paper evaluates the performance of fresh and hardened masonry mortar manufactured using fine recycled aggregate from ceramic partition wall rubble. Five mortars were prepared replacing 0%, 5%, 10%, 20%, and 40% of the natural sand by fine recycled aggregate. A 1:7 volumetric cement-to-aggregate ratio was used. The data were analysed using a one-way analysis of variance and the results showed that replacement ratios of up to 40% by volume did not significantly affect the properties of fresh and hardened mortar, with the exception of density and workability. Therefore, the use of fine recycled aggregates in masonry mortar manufacturing could be a viable alternative that would help increase the recycling rate of construction and demolition waste and support sustainable development in the building sector.

Carbonation is a major cause of concrete structures deterioration leading to expensive maintenance and conservation operations. The eco-efficient construction agenda favours the increase of the use of supplementary cementing materials (SCMs) to reduce Portland cement’s consumption and also the use of recycled aggregates concrete (RAC) in order to reduce the consumption of primary aggregates and to avoid landfill disposal of concrete waste. There is a wide range of literature published on the field of concrete carbonation related to the use of SCMs and/or RCA. However, the different conditions used by different authors limit comparison and in some cases contradictory findings are noticed. Besides, since most investigations are based on the use of the phenolphthalein indicator, which provides a poor estimate of the real concrete carbonation depth, there is a high probability that past researches could have underestimate the corrosion potential associated to concrete carbonation. This paper reviews current knowledge on concrete carbonation addressing carbonation depth’s measurement, the use of SCMs and or RAC.

This work aims to provide a simple semi-probabilistic approach to the service life design of reinforced concrete structures with respect to reinforcement corrosion induced by concrete carbonation. This paper presents an analytical model for the initiation period, calibrated with long-term carbonation results, which uses the accelerated carbonation resistance and the environmental class as input parameters. The issue of defining a limit for deterioration is discussed and a maximum accepted level of deterioration and reliability indexes are defined. The corresponding partial safety factors are derived from a full probabilistic approach. The performance of the proposed method is compared with that proposed on the fib Model Code for Service Life Design.

This paper presents an expert-knowledge inspection and diagnosis system for pitched roofs with ceramic tiles and reports a statistical characterisation of the pathology of 62 roofs. It also identifies the diagnosis methods that may be used to characterise the anomalies and confirm their most probable causes, as well as the best repair techniques. A detailed correlation between anomalies and causes is also established. For the first time in the literature the pathologies of ceramic tile pitched roofs are characterised using quantitative indicators based on a statistically significant sample.

In recent years, the number of reinforced concrete structures with anomalies associated with reinforcement corrosion problems has significantly increased. One of the causes is concrete carbonation which occurs when carbon dioxide (CO 2 ) penetrates the concrete’s porous system to create an environment with lower pH around the reinforcement in which corrosion can proceed. Several analytical models describe the relationship between carbonation depth and concrete age, of which the most frequently used results from Fick’s first law: x = K t , where K is the carbonation coefficient. This coefficient depends on environmental conditions such as CO 2 concentration and humidity and concrete characteristics like w / c ratio, type of cement, and so it varies significantly from one structure to another. A statistical study is presented in this paper to enable a better evaluation of K in open air concrete structures. The study is based on the results of over 100 measurements taken on existing structures up to 99 years old. The results were statistically analysed to obtain correlations between K and factors such as structure age, the effect of painting, concrete compressive strength and exposure conditions. This analysis allowed recommendations for the covering of reinforcing bars to be made at design level.

This paper aims at establishing a model for the service life prediction of natural stone wall claddings directly adhered to the substrate, based on a survey of the degradation state of 142 buildings in the Lisbon area. The state of degradation is evaluated through visual inspections that allow the description of the extent of the cladding area affected by the different anomalies, thereby enabling the level of severity of the anomalies detected to be established. A numerical index of the degradation severity of stone claddings (Sw,rp) is established; this is intended to express the global degradation level of these claddings, thus allowing the study of the evolution of their degradation with time in order to estimate a reference service life for this type of cladding.

This paper presents an expert system to support the inspection and diagnosis of gypsum plasters applied to partition walls and ceilings (inner gypsum plasters – IGP). This system includes the classification of the defects that may affect IGP and their probable causes, which is complemented by the correlation matrices between defects, and between defects and probable causes. It is completed by a classification of the diagnosis methods and the repair techniques suitable for each IGP defect. Individual files containing a complete characterization of defects, diagnosis methods and repair techniques are also exemplified. This inspection system was validated through standard inspections of 119 IGP applied in walls or ceilings in 23 buildings.

In this paper a classification system of the anomalies in ceramic tiling applied to building facades and their most probable causes is proposed and a field data analysis is presented. The field work included the observation of 85 ceramic tiling systems in facades via standardized inspections. A statistical analysis of the anomalies observed during these inspections and their most probable causes is presented and the main ceramic tiling anomalies are evaluated for area affected, user disturbance and most probable causes. The interpretation of this data allowed the creation of an inventory of the measures to be implemented in the design, execution and maintenance phases, in order to prevent the occurrence of anomalies, helping the practicing engineer in his daily activity.