Rehabilitation of renders of old buildings in Portugal: survey, supporting methodology proposal and case study

The main purpose of the research is to present a proposal for a methodology to support the rehabilitation project of renders of old buildings in Portugal. To achieve the objective it was considered essential to define the main types of participants and aspects to integrate the proposal. The research methodology consists in an inquiry presented to professional participants in rehabilitation, a market study of materials and products available in Portugal, the design of a methodology proposal and its application to a case study. The inquiry sample totals 24 answers from the targeted professionals. A sequence of relevant supporting procedures consists in the proposal, which aims to provide a supporting methodology to decide and project in this context and also to be tested with its application to the building. This proposal was applied to an old building with load-bearing stone masonry walls and air-lime based renders. It was concluded that the assessment of the building and external renderings’ condition, its diagnosis and of the supporting walls, the definition of intervention, the specification of materials to be used and performance requirements to comply, and also plans for conservation and periodic maintenance, are crucial. From the inquiry, compatibility between materials and complementary roles and points of view of different types of participants in rehabilitation must be highlighted. A proposal for a methodology to support the project could provide useful guidance particularly for architects and construction engineers, and improve the understanding of direct participants on site, therefore contributing for the correct implementation of intervention

Reliability of in-situ diagnosis in external wall renders

This study focuses on the reliability of in-situ diagnosis performed on external rendered façades. This analysis was based on a set of parameters drawn from different visual observation, in-situ and laboratory testing techniques. The results were collected based on the previous inspections of 98 rendered façades of buildings and individual testing walls with different components, ages and degradation types. For that purpose, a reliability indicator was proposed and applied for better results interpretation of multiple testing techniques. In each case study, the parameters with higher reliability are defined. The final reliability indicator was established based on the average of three partial indicators, namely a reliability indicator for the established base criteria' uncertainty in laboratory testing (reference reliability indicator); a reliability indicator for the assessment techniques' uncertainty (verification method reliability indicator); and a reliability indicator for the results' uncertainty (number of the tests and their accuracy; reliability indicator of results obtained in-service). The reference parameters for each testing technique were synthesised. The relevant aspects, such as uncertainty associated with the reference parameter and type of verification method (quantitative, qualitative, and intervals), were defined. The analysis of the relationships between the parameters (exemplified for mechanical properties) and their correlation coefficients were assessed. Selection matrices were proposed that qualitatively identify the set of parameters that contribute to indirectly analyse the characteristics and performance relevant to the behaviour of the renders applied on façades. (c) 2020 Elsevier Lt

Multivariate Data Analysis of the Thermal Performance of Portuguese Residential Building Stock

The purpose of this study is to explore the relationship between solar orientation, age (constructive characterization) and energy performance of Portuguese residential building stock and to assess the usefulness of exploring the Portuguese National System for Energy and Indoor Air Quality Certification of Buildings (SCE) database through multivariate analysis techniques. By using principal components technique, it was possible to condense the residential units’ features to only four principal components (PC): solar orientation; constructive characterization; geometry and energy performance, making information more workable. Grouping the entities into Clusters with favourable and unfavourable solar orientation and old buildings allowed to dilute the particularities of each entity, facilitating the interpretation of the data through generalization. A regression model was generated in order to explore/confirm which factors influence summer comfort the most. Using this approach, it was illustrated that the exploration of the SCE database through multivariate data analyses has an enormous potential to convert data into knowledge

Argamassa industrial para a reabilitação de rebocos antigos

Argamassas 2014 - I Simpósio de Argamassas e Soluções Térmicas de Revestimento, 5-6 Junho, ITeCons, Universidade de CoimbraA crescente procura de argamassas técnicas que satisfaçam os requisitos impostos pelos edifícios antigos tem conduzido a indústria das argamassas a desenvolver e apresentar várias soluções para a área da reabilitação. Contudo este trabalho ainda se encontra num patamar em que é importante continuar a aprofundar e sedimentar conhecimentos nesta área. Concretamente o estudo do comportamento de argamassas com materiais mais sustentáveis que possam oferecer ao mercado produtos adequados, compatíveis com os edifícios em questão e economicamente viáveis, tem todo o interesse. Neste sentido, neste trabalho de investigação estudaram-se várias formulações industriais baseadas em cal aérea CL 90-S e em cais hidráulicas natural (NHL5 ou NHL3.5), com base num traço volumétrico 1:3 (ligante: agregado). Partindo de argamassas só de um desses ligantes (aéreo ou hidráulico), procedeu-se a substituições parciais pelo outro ligante, em teores de 25%, 50% e 75%, nas condições de cura preconizadas na norma EN 998-1. Era expectável que a cais hidráulicas naturais permitisse que as argamassas adquirissem valores de resistências mecânicas mais elevados nas primeiras idades, 28 dias, comparativamente às argamassas de cal aérea, de forma a adequar as características das argamassas aos prazos atuais de obra. Todas as formulações foram caracterizadas em termos de resistências mecânicas (28, 90 e 180 dias), aderência, massa volúmica, capilaridade e permeabilidade ao vapor de água. Verificou-se que, em termos de comportamento mecânico, algumas das as argamassas apresentaram valores satisfatórios. O mesmo se observa em termos de valores de aderência, comparativamente aos requisitos definidos na bibliografia e na norma EN 998-1. No entanto, argamassas com cais hidráulicas naturais e elevados teores de cal aérea parecem menos interessantes. Relativamente ao seu comportamento face à água observa-se que todas as formulações apresentam baixos valores de coeficiente de capilaridade e permeabilidade, o que demostra um bom desempenho, cumprindo plenamente os requisitos impostos. Considera-se que argamassas de NHL3.5 e baixos teores de cal aérea, a otimizar industrialmente, podem ser particularmente adequadas para aplicação em edifícios antigos

Synergistic effect of fibres on the physical, mechanical, and microstructural properties of aerogel-based thermal insulating renders

There is an increasing demand for highly efficient thermal insulating materials in buildings. This study presents a novel solution incorporating nanomaterials, such as silica aerogel, which can achieve low thermal conductivity values (below 0.030 W m-1 K-1) in renders. A key challenge of using aerogels is their low mechanical strength and high capillary water absorption. Here we describe a novel approach employing fibres which mitigates against some key properties which are decreased as a consequence of using aerogel. The incorporation of aramid (0.50%), sisal (0.10%), and biomass (0.10%) fibres (by total volume) was evaluated experimentally in terms of physical, mechanical, and microstructural properties. A synergistic effect between the fibres and aerogel increased mechanical resistance and a reduction in the capillary water absorption, when compared to the reference render (without fibres), whilst maintaining the low thermal conductivity. However, these properties depended significantly on whether the fibres were synthetic or organic. This study is important as it demonstrates that aerogel-based fibre-enhanced thermal renders can contribute to higher energy efficiency in both new construction and retrofitting. The use of these materials will have a direct positive impact on addressing the climate crisis

Vinyl and Linoleum Floorings in Health Infrastructures: Maintenance Recommendations Based on Fieldwork Data

Resilient flooring is a popular choice in healthcare facilities, given its durability, comfort, low maintenance and cost. However, anomalies that occur in vinyl and linoleum floorings (VLF) often do not fulfil the expectations of a flooring with good performance and durability. In fact, studies show that pathological phenomena in VLF occur more often in the first years in service, indicating a probable connection with the design and execution stages. These stages are crucial to the quality of VLF, since, if not given adequate attention, pathological symptoms are likely to increase, hence decreasing service life.The authors developed an inspection, diagnosis and rehabilitation system for VLF in healthcare facilities, including: the classification of anomalies, their probable causes, in situ diagnosis methods and repair techniques; anomalies - causes, inter-anomalies, anomalies - diagnosis methods, and anomalies - repair techniques correlation matrices. The same system was validated through the visual inspection of 101 compartments in six health infrastructures in Lisbon, Portugal, and the respective descriptive statistics analysis of the collected data. That analysis showed, for instance, that the summed contribution of "design errors" and "execution errors" to "faulty welding joints" was 59%. Making an effort to change the situation diagnosed in the mentioned inspection sample, some design and application stages‘ recommendations are highlighted, according to the main sensitive issues of the flooring system during its service life. The sensitiveness of VLF highlights the importance of a suitable maintenance plan to minimise susceptibility to various degradation mechanisms

Natural Ageing Tests to Study In-service Different Façade Solutions—ETICS and Premixed One-Coat Rendered Walls

In situ testing provides accurate characterization of existing degradation mechanisms of materials and building systems which helps reducing the subjectivity of visual inspections especially when ageing under natural ageing conditions is carried out over significant periods of time. In this work, data collected from field experimental campaigns over 10 years after construction using several premixed one-coat rendered walls and over 4 and 6 years after construction in the case of ETICS (external thermal insulation composite systems) are presented and discussed. The influence of hydrophobic agents on the performance of both types of façades in terms of surface condition and water penetration was assessed by visual inspections, Karsten test and capillary tests. Additionally, adhesion tests and subsequent evaluation of porosity were also carried out for premixed one-coat mortars. The results obtained have shown that ageing of the rendering solutions, especially after 5 or 6 years in-service, results from the loss of resistance to liquid water penetration, especially at the surface. Yet, additional mechanisms such as leaching of hydrophobic agents and photochemical degradation are thought to be involved, too. Moreover, the results obtained using the Karsten test proved to be the most reliable method to determine the loss of water penetration resistance and predict the ageing of façade solutions. The information collected and the correlations established can help developing solutions to prevent early ageing and implement appropriate maintenance plans to delay their effect