Documents published in Scipedia

• Opportunity-Based Maintenance of Buildings’ Envelope

  C. Ferreira, J. de Brito, A. Silva

  DBMC 2023.

  
  

  Abstract

  More than half of the building’s life-cycle costs correspond to maintenance costs. Nevertheless, maintenance actions are, generally, conditioned by subjective criteria and carried out at inopportune times, which implies that one third of the maintenance costs are improperly incurred. Buildings are multi-component systems and, therefore, the adoption of opportunistic maintenance policies allows reducing the maintenance costs and the number of interventions, while maximizing the service life and the efficiency of the resources available. In this study, an opportunistic maintenance plan is proposed for the buildings’ envelope, combining the maintenance needs of four elements: rendered facades; ceramic claddings; window frames; and pitched roofs ceramic claddings. For this purpose, a condition-based maintenance model is used. The maintenance model is based on stochastic degradation models for the individual components of the system. The optimization of these policies will identify the best maintenance schedule and combination of maintenance activities, finding the optimal trade-off between disruption of the buildings’ use, maintenance costs and their service life. The application of these opportunistic maintenance policies in the building envelope elements allows mitigating the degradation of these elements over the buildings’ life cycle and, consequently, increasing the economy, quality, and aesthetic perception of our cities. This methodology will change the way that maintenance plans are defined, and interventions are prioritized.

  Abstract
  More than half of the building’s life-cycle costs correspond to maintenance costs. Nevertheless, maintenance actions are, generally, conditioned by subjective criteria [...]

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• Flexibility and Adaptability: A Review on Assessment Methods and Tools and Their Applicability

  G. Cignachi, P. Gaspar, H. Farias

  DBMC 2023.

  
  

  Abstract

  In this paper, the existing methods for the assessment of flexibility and adaptability in buildings are reviewed. These methods have been tentatively proposed for a number of building types / uses - notably for residential buildings - and generally propose sets of indicators, variables and weights that combine into a score of flexibility. In spite of the limited practical applicability of these methods so far, they provide a stimulating approach to greater use and incorporation of the concepts and strategies of flexibility and adaptability, aiming at an increased performance of buildings.

  Abstract
  In this paper, the existing methods for the assessment of flexibility and adaptability in buildings are reviewed. These methods have been tentatively proposed for a number [...]

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• Durability and Long-term Performance Assessment in Eco-efficient Concrete Mixtures Towards a More Sustainable Cement Industry - A Critical Review

  Z. Xia, C. Londero, S. R.A.Dantas, L. F.M.Sanchez

  DBMC 2023.

  
  

  Abstract

  In the current need to fulfill a Net-Zero goal to offset greenhouse gas emissions by 2050, the cement industry deeply needs to renovate its process and products. The amount of concrete, and consequently ordinary Portland cement (OPC) used worldwide, far exceeds other industrial materials, contributing to around 8% of global emissions. A recognized solution would be to partially replace clinker with limestone, an available material in many countries with the potential to improve the particle packing of a concrete mixture. Even though several studies have been carried out on the application of Portland limestone cement (PLC) concrete, there is a need for further investigation regarding durability performance. Problems include alkali-silica reaction (ASR), delayed ettringite formation (DEF), sulphate attack, steel corrosion, and freeze/thawing, whose deteriorating effects tend to be maximized in harsh climate countries such as Canada and should be evaluated when introducing distinct materials into concrete. Therefore, this paper aims to review previous assessment of the durability of PLC concrete mixtures. The use of an advanced mix-design method (particle packing model and mobility parameters - PPM+MPs), will also be discussed on its ability to enhance the durability performance of the mixtures. It is expected that novel guidelines to design more eco-efficient concrete mixtures using PLC can be developed to reduce concrete’s cost and carbon footprint, achieving a more sustainable industry.

  Abstract
  In the current need to fulfill a Net-Zero goal to offset greenhouse gas emissions by 2050, the cement industry deeply needs to renovate its process and products. The amount [...]

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• Changes in Educational Buildings at Very Early Stages of Their Life Cycle

  G. Cignachi, P. Gaspar, H. Farias

  DBMC 2023.

  
  

  Abstract

  Changes always occur in buildings at any stage of their life cycle. In this paper, particular attention is paid to changes that occur very early on this process, sometimes between bidding and very initial construction stages, in the context of public procurement and building. The research is based on the total building stock of the Federal Institute Sul-rio-grandense, in Brazil, which holds presently 14 campuses and more than 120 buildings. Accumulated experience has demonstrated that the prototypical buildings - educational or administrative - designed to be repeated often undergo alterations. The reasons for such changes are identified, along with their impact on the functionality, service life and future maintenance of such assets.

  Abstract
  Changes always occur in buildings at any stage of their life cycle. In this paper, particular attention is paid to changes that occur very early on this process, sometimes [...]

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• Analysis of the Repassivation of Corroded Bars in Cementitious Materials Subjected to Realkalisation

  G. R. Meira, P. R. R. Ferreira, A. A. Meira

  DBMC 2023.

  
  

  Abstract

  The effect of concrete realkalinisation on reinforcement repassivation was evaluated by means of electrochemical measurements considering different previous corrosion degrees of reinforcements and different environmental conditions. Reinforcements obtained from a real concrete structure which were activated due to concrete carbonation were used for this purpose. Five different corrosion degrees were considered. All these reinforcements after being classified, were embedded in fresh mortar specimens and were cured in wet chamber for 7 days. After that, they were sequentially subjected to two different environmental conditions; laboratory environment (65% of relative humidity) and 80 % of relative humidity environment. Along all the testing period, reinforcements were monitored on corrosion potential and instantaneous corrosion current density by linear polarisation measurements. Results show that as the previous corrosion degree increases it becomes harder to reach the repassivation condition for reinforcements. This shows that the effectiveness of concrete realkalisation on reinforcement repassivation depends on the previous corrosion degree of reinforcements. The influence of the relative humidity was not significant under the experimental conditions adopted in this work.

  Abstract
  The effect of concrete realkalinisation on reinforcement repassivation was evaluated by means of electrochemical measurements considering different previous corrosion degrees [...]

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• Durability Assessment and Maintenance Planning of Concrete Structures in Ningbo-Zhoushan Port Main Channel Sea Link Project

  L. Li, K. Li

  DBMC 2023.

  
  

  Abstract

  This paper performs the durability assessment and maintenance planning of concrete structures during construction phase in the ongoing Ningbo-Zhoushan Port Main Channel (NZPMC) sea link project with a service life of 100 years. The background of this project is first introduced and the durability design at preliminary study phase is recalled; the chloride-induced corrosion of reinforcement steel was considered as the most critical process that controls the design. Then, the durability model for assessment is established for this durability limit state and the statistical properties of the model parameters are given. From the collected data on the concrete cover thickness and modified chloride diffusion coefficients, the statistical properties of these parameters are updated. With the design options adopted in design phase and the updated parameter properties, taking one non-navigable bridge as an example, the achieved reliability levels and failure probabilities are calculated for structural elements under different exposure conditions by using full probabilistic approach. On the basis of the achieved reliability level of durability, a preliminary maintenance planning is performed for the concrete elements in the concrete structures, and the corresponding recommendations are given.

  Abstract
  This paper performs the durability assessment and maintenance planning of concrete structures during construction phase in the ongoing Ningbo-Zhoushan Port Main Channel (NZPMC) [...]

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• Damaged Swedish Buildings

  P. Wallentén, S. Olof Mundt-Petersen, K. O. Anders Joelsson, M. Kläth

  DBMC 2023.

  
  

  Abstract

  Damages with a negative influence on the indoor environment often become linked to high costs. Detailed facts about buildings with damages need to be collected and analyzed in order to be able to reduce the number of damages. This paper presents basic facts, such as design, property ownership and year of construction in buildings where 1105 damages were found. In general, the study gives qualitative indications and cross-comparing to other parameters considering damages and causes of damages needs to be done to obtain better results. Buildings with indoor air ventilated or heated crawlspaces have less damages compare to non- or outdoor ventilated crawl spaces. Damages are more common in buildings with poor exterior insulation in the foundation or a no-drainage and poorly ventilated cladding. In the buildings in the study, schools and local authority owned buildings have a high frequency of damages. A higher number of damages were also found in condominium association owned multi-family houses compared to public tenancy owned multi-family houses.

  Abstract
  Damages with a negative influence on the indoor environment often become linked to high costs. Detailed facts about buildings with damages need to be collected and analyzed [...]

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• Classification Systems for the Built Environment: A Cornerstone for the Long-term Performance Analysis

  C. Serrat, V. Royano, V. Gibert, J. Rapinski

  DBMC 2023.

  
  

  Abstract

  In the long-term performance analysis of the built environment, classification systems are seen as a key consideration. When classifying residential building objects, characteristics such as accuracy, exhaustivity, and consistency are required. It is noticeable that while organizations around the world are working to develop an internationally agreed standard classifier, the use of national classification systems remains widespread. Therefore, this paper focuses on reviewing the most popular classification systems such as CoClass, Uniclass 2015 and OmniClass®, among others, and discusses their strengths and weaknesses, in order to be useful both to the research and technical communities. Based on this, two main contributions are derived. On the one hand, the paper points out that there is no international consensus to use a common classification system. On the other hand, some recommendations are given and illustrated to meet the challenges of classifying existing buildings, in particular under a functional assessment approach.

  Abstract
  In the long-term performance analysis of the built environment, classification systems are seen as a key consideration. When classifying residential building objects, characteristics [...]

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• Causes of Damages in Swedish Buildings

  S. Olof Mundt-Petersen, P. Wallentén, I. J. Edskär, K. O. Anders Joelsson

  DBMC 2023.

  
  

  Abstract

  Damages, failures and functional defects in buildings create high cost for the owner and the society. It is important to determinate the causes of damages in order to limit the costs. This paper presents the causes of 1105 different damages from a technical perspective from 265 real damage investigations. In general, the results show that; 1. Rain and snow was the most common moisture source cause damages, 2. The number of damages caused by wet concrete and PVC or linoleum flooring may be overestimated. 3. A significant number of damages were caused in details where different materials connect to each other, 4. A high number of damages were linked to wear and tear and poor maintenance. 5. Causes of damages occurs in all phases of the building process but most of them were deemed to occur in the management and on-site construction phase. 6. Most of the damages were caused by building owner or their facility trustees.

  Abstract
  Damages, failures and functional defects in buildings create high cost for the owner and the society. It is important to determinate the causes of damages in order to limit [...]

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• Assessment of the Impressed Current Cathodic Protection System after 4 Years Operation: Evolution Over Temperature and Time of the Applied Current and Tension on Anodic Zones of the Saint-Cloud Viaduct (France)

  J. Ducasse-Lapeyrusse, V. Bouteiller, O. Lesieutre, E. Marie-Victoire, M. Bouichou, G. Damien, V. Martinet, C. Annede-Villeau

  DBMC 2023.

  
  

  Abstract

  This paper presents the feedback of the Impressed Current Cathodic Protection (ICCP) system implemented on a road bridge, the Viaduct of Saint-Cloud, constructed in the 1970s in France. After a test trial in 2012, the full-scale ICCP system was energized in 2018. It consisted of 44359 discrete titanium anodes implemented on the lateral segment webs on both sides of the Viaduct, distributed in 212 anodic zones on one side and 153 anodic zones on the other side. The four years monitoring data include the variations of the applied current and tension on anodic zones, their polarization, etc. This paper focus on the global resistance of the circuit for the different anodic zones. The circuit resistance shows first the influence of the temperature. The differences between anodic zones and their evolution over time also bring more information about the environment of the anodes and the reinforcements. The analysis of the response of the circuit reveals the heterogeneity of an actual and large-scale ICCP system and provides important feedback to an appropriate ICCP design for durable cathodic protection.

  Abstract
  This paper presents the feedback of the Impressed Current Cathodic Protection (ICCP) system implemented on a road bridge, the Viaduct of Saint-Cloud, constructed in the 1970s [...]

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