J. de Brito

An Expert System for Concrete Bridge Management

The importance of bridge repair versus new bridge construction has risen in recent decades due to high deterioration rates that have been observed in these structures. Budgets both for building new bridges and keeping the existing ones are always limited. To help rational decision-making, bridge management systems are presently being implemented by bridge authorities in several countries. The prototype of an expert system for concrete bridge management is presented in this paper, with its functionality relying on two modules. The inspection module relies on a periodic acquisition of field information complemented by a knowledge-based interactive system, BRIDGE-1. To optimize management strategies at the headquarters, the BRIDGE-2 module was implemented, including three submodules: inspection strategy, maintenance and repair.

Concrete with fine recycled aggregates: a review

This paper presents a review of the literature published so far on the use of fine aggregates from construction demolition waste used as a partial or total replacement of fine natural aggregates in concrete production. The review presents the initial works on this subject and an overview of the existing regulations. It goes on to describe the production, treatment and properties of the fine recycled aggregates (FRA). The most suitable mixing techniques for concrete with this type of aggregates are then discussed. The properties of these concrete mixes are analysed in detail, after which a few examples of structures with this type of concrete are described and compared. The acquisition of fine natural aggregates and the dumping of the fine fraction of construction and demolition waste are two serious environmental problems that can be solved simultaneously by using FRA in concrete production, a subject that is lagging behind the use of the corresponding coarse fraction.

Inspection and Diagnosis of Gypsum Plasterboard Walls

This paper proposes an expert system to support the inspection and diagnosis of partition walls or wall coverings mounted using the drywall (DW) construction method. This tool allows the succinct characterization of the pathological situation of each DW inspected. It also eases the systematization of the inspections included in periodic maintenance actions, thereby preventing future defects. The proposed tool includes a classification of defects in DW and their probable causes. The correlation matrices between defects and between defects and probable causes complement these classifications. Finally, the diagnosis methods and the repair techniques suitable for each DW defect are classified. All the defects, diagnosis methods, and repair techniques have individual files containing their significant information. The proposed classifications were validated via standard inspections of DW in three shopping centers, four stores, a school, three offices, a gymnasium, two condominiums, a hospital, four hotels, and two restaurants.

Inspection and Defect Diagnosis System for Natural Stone Cladding

An inspection and diagnosis support system is proposed for natural stone cladding (NSC) on walls and pavements in order to systemize inspections and make them more objective. The inclusion of this system in a maintenance plan aims at preventing degradation of this type of cladding and its substrate. The system is based initially on the identification and classification of defects and probable causes associated with NSC. These data are used to compile correlation matrices of defects/probable causes and defects/defects and create defect forms with relevant data on each defect. The appropriate diagnosis and repair methods are then identified and classified, and correlation matrices of defects and diagnosis methods and defects and repair methods are assembled. An individual form with relevant data is created for each diagnosis and repair method. The system proposed was validated through 128 inspections of NSC, which were afterwards subjected to statistical posttreatment and analysis.

Discussion of Criteria for Prioritization of Predictive Maintenance of Building Façades: Survey of 30 Experts

The practice of predictive maintenance depends significantly on the diagnosis of in-service performance and on the decision criteria for the selection of maintenance tasks. The definition of these criteria is limited because several actors are involved, each with their own perspectives of performance and maintenance needs. This paper discusses a set of 17 criteria to help the maintenance choice for building facades, from three viewpoints: physical performance, risk, and costs. A group of experts was surveyed and 30 answers were received. Therefore, each criterion will be discussed according to the answers collected. The relative importance (using quantitative weights) and subclasses for each criterion are proposed.

Effect of Water on the Degradation of Gypsum Plaster Coatings: Inspection, Diagnosis, and Repair

AbstractThis paper presents an expert system designed to support the inspection and diagnosis of gypsum plaster coatings applied to partition walls and ceilings [interior gypsum plaster (IGP)]. It includes a classification of the defects that may affect IGP and their probable causes, the correlation matrices amongst defects and between defects and probable causes, and a classification of diagnostic methods and repair techniques suitable for each type of IGP defect. This inspection system was validated through standard IGP inspections undertaken on 119 walls or ceilings in 23 buildings located throughout Portugal. A statistical analysis of the results of the inspection is given that provides details on, in particular, the pathological problems related to the action of water on IGP because the presence of moisture within or on the surface of IGP coatings was shown to affect the severity of the problems of inspected samples. The characteristics and frequency of occurrence of dampness, biodeterioration, and e...

Application of the Factor Method to the Prediction of the Service Life of Ceramic External Wall Cladding

AbstractThe main goal of this study is to use the factor method to evaluate the service life of ceramic external cladding. An interesting possibility is that a tool may be developed to aid the planning of maintenance operations, to reduce costs, and to ensure a better performance of the cladding system. The method relies on field work data on the state of repair of the facades, based on a survey of 195 facades in the Lisbon area. The factors affecting durability are singled out and quantified through several scenarios with the aim of optimizing the weighting coefficients. The degradation model has provided consistent results for most of the variables influencing the cladding’s loss of performance. Adequate knowledge on the durability of a component allows correctly designing the details and planning the maintenance operations that the component requires. These in turn are part of a broader perspective that involves reductions in costs and environmental impact, exactly the challenges that service life pred...

Mechanical Performance of Structural Concrete with the Incorporation of Coarse Recycled Concrete and Ceramic Aggregates

The paper presents the results of an experimental program to evaluate the viability of concrete made when various ratios of coarse natural aggregates (CNAs) are replaced with coarse recycled concrete aggregates (CRCAs), coarse recycled ceramic masonry and mortar aggregates (CRMMAs), or both. Results show that incorporation of CRCA and of CRCA and CRMMA simultaneously has no effect on compressive strength. However, this property decreases when only CRMMA is incorporated. A reduction of 23.6% in compressive strength was obtained when 50% of CRMMA was used. Splitting tensile strength is unaffected by incorporation of CRCA but it is affected by incorporation of CRMMA. The mixes with 50% of CRMMA showed a reduction of 20.1% in tensile strength. Every recycled aggregate concrete type suffered a linear decrease of modulus of elasticity as the replacement ratio of CNA by coarse recycled aggregates increased. The use of 100% CRCA caused a decrease in modulus of elasticity of 30%. In the mixes with 50% of CRMMA that decrease was 22.2%. Shrinkage was significantly affected by incorporation of course recycled aggregates, although the degree of shrinkage varied in accordance with their nature and incorporation ratio. For replacement ratios between 50 and 100%, the difference between a reference concrete (RC) and the mixes with CRCA remained constant, inside a 30% increase range.

Inspection and Diagnosis System for Wood Flooring

AbstractThis paper presents an expert system to support the inspection and diagnosis of wood applied as a floor covering [wood flooring (WF)]. The defects that may affect WF along with their probable causes are classified in this system. The inspection system also embraces the correlation matrices between defects and between defects and probable causes, the classification of the diagnosis methods, and the repair techniques suitable for each WF defect. This paper also includes an example of an individual defect file containing a complete characterization and the most suitable diagnosis methods and repair techniques. This inspection system was validated through standard inspections of 90 WFs applied indoors and eight applied in exterior areas, in a total of 35 buildings.

Mortars Made with Fine Granulate from Shredded Tires

Changing lifestyles over the past few decades have brought about an increase in the types and volume of waste. Nowadays, waste is considered one of the world’s main problems. The incorporation of waste in structural and nonstructural elements has therefore been studied, primarily in renders. However, data are scarce on the influence of using rubber aggregates from shredded tires in mortars. This work presents a performance-based analysis to test the viability of using these modified mortars for wall coatings. It presents unprecedented analyses of some durability-related properties and the influence of the crushing process in the overall performance of mortars incorporating rubber. Even though the results show, as expected, that the incorporation of rubber particles is detrimental to both compressive and flexural strength, those changes do not impair its use as renders under normal conditions. Furthermore, the incorporation of rubber leads to a significant reduction of the modulus of elasticity of the mortar. The added rubber also improves its impact-resistance characteristics and some other durability characteristics of these modified mortars compared with those of conventional mortars, which shows that this could be a future viable alternative for wall coatings.