Browsing by Author "Gaspar, Florindo"
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- Application of near infrared spectroscopy and multivariate data analysis for the evaluation of glue lines of untreated and copper azole treated laminated timber before and after ageingPublication . Gaspar, Florindo; Lopes, João; Cruz, Helena; Schwanninger, Manfred; Rodrigues, José; Gaspar, FlorindoThe necessity for inspection and assessment of glued laminated timber structures in service has raised interest in the evaluation of the glue lines. Glue line spectra were analysed and are discussed in detail with respect to spectral contributions from the adhesive, the hardener, the wood lamella below the adhesive, the curing temperature as well as ageing-related spectral changes. The combination of near infrared (NIR) spectroscopy and principal component analysis (PCA) allowed distinguishing between aged and non-aged samples and different copper azole preservative treatment levels of phenol-resorcinol-formaldehyde (PRF) glue lines. NIR-based partial least squares (PLS) regression modelling was performed for the glue line shear strength and for the curing temperature. These findings show that NIR spectroscopy is a fast and useful technique to evaluate the degradation on the PRF glue lines of untreated and copper azole treated laminated timber.
- A building information modeling approach to integrate geomatic data for the documentation and preservation of cultural heritagePublication . Solla, Mercedes; Gonçalves, Luisa M. S.; Gonçalves, Gil; Francisco, Carina; Puente, Iván; Providência, Paulo; Gaspar, Florindo; Rodrigues, HugoNon-destructive testing (NDT) techniques play an important role in the characterization and diagnosis of historic buildings, keeping in mind their conservation and possible rehabilitation. This paper presents a new approach that merges building information modeling (BIM) with environment geospatial data obtained by several non-destructive techniques, namely terrestrial laser scanning, ground-penetrating radar, infrared thermography, and the automatic classification of pathologies based on RGB (red, green, blue) imaging acquired with an unmanned aircraft system (UAS). This approach was applied to the inspection of the Monastery of Batalha in Leiria, Portugal, a UNESCO World Heritage Site. To assess the capabilities of each technique, different parts of the monastery were examined, namely (i) part of its west façade, including a few protruding buttresses, and (ii) the masonry vaults of the Church (nave, right-hand aisle, and transept) and the Founder’s Chapel. After describing the employed techniques, a discussion of the optimization, treatment and integration of the acquired data through the BIM approach is presented. This work intends to contribute to the application of BIM in the field of cultural heritage, aiming at its future use in different activities such as facility management, support in the restoration and rehabilitation process, and research.
- Building insulation materials based on agricultural wastesPublication . Gaspar, Florindo; Bakatovich, Aliaksandr; Davydenko, Nadezhda; Joshi, ArpanEcological insulation materials of vegetable raw materials are increasingly widespread. The agricultural wastes can have an interesting role because their use allows the revaluation of agricultural wastes, whose disposal is a serious issue. This chapter gives an overview about the use of agricultural wastes on insulating materials. The source and characteristics of various types of wastes are described. The manufacturing processes considering the types of binders, including the main parameters involved, are explained. An overview is given about the properties of the insulation materials, including thermal conductibility, density, mechanical strength , hygroscopic behavior, acoustic and fire performances, and environmental performance. Suggestions regarding the future research needs are also presented.
- Composite material for thermal insulation based on moss raw materialPublication . Bakatovich, Aliaksandr; Gaspar, FlorindoThe demand for thermal insulation materials composed of sustainable raw materials remains a challenge. The substances used in the manufacture of thermal insulation materials may also, under certain conditions, have a beneficial effect on the insulated surfaces, the environment, and the human or animal body, in particular by the ability to absorb moisture and biocidal properties. Ecological insulation materials of vegetable raw materials are increasingly widespread. Most of the time, these materials are made from flax, hemp or wood fibres, agglomerated with a binder. The objective of this work was to determine the possibility of using Sphagnum moss as a fibre in thermal insulation panels. To carry out this study, several compositions were developed for thermal insulation boards based on moss, rye straw and reed, using liquid glass as a binder. The specimens were tested for thermal conductivity, and strength to compression and bending. Best results were achieved on panels of moss and straw with thermal conductivity of 0.044–0.046 W/(m.K) at a density of 156–190 kg/m3, without shrinking during drying and a compression strength between 0.20 and 0.21 MPa. Electronic microscopy of rye straw and reed stems made it possible to examine the presence of outer and inner parts in the structure, which affect the thermal and strength characteristics. With the use of natural raw materials from plants and agricultural production residues, an effective and ecologically safe rigid board insulation was obtained, which has biocidal properties and has no analogues in the market for the construction of thermal insulation materials.
- Evaluation of glue line shear strength of laminated timber structures using block and core type specimensPublication . Gaspar, Florindo; Cruz, Helena; Gomes, AugustoMonitoring and evaluation of glued laminated timber structures in service is essential to warrant its integ rity, where non-destructive techniques play an important role. This paper describes the results obtained on glued laminated timber beams of maritime pine, with and without preservative treatment, and of spruce, exposed to natural outdoor environment as well as to artificial weathering. The assessment of glue lines’ shear strength was investigated through the extraction and testing of cores parallel and per pendicular to the glued lines and block shear specimens with 50 mm×50 mm and 20 mm×20 mm shear area. The results highlight the different performances of the various types of specimens tested, showing that the measured shear strength depends on the specimen size and that the size effect depends on the material strength giving a decreasing modification factor with the increase of strength in opposi tion to the constant factor suggested by standard EN 14080. They also show that shear testing of cores drilled perpen dicular to the glued joints may be a promising tool in the assessment of glulam structures on site.
- Experimental study on 3D printing of concrete with overhangsPublication . Brun, Francis; Gaspar, Florindo; Mateus, Artur; Vitorino, João; Diz, FranciscoThe construction industry has been receiving in the recent past years the 3D printing technology as an emerging technology. Several researchers and companies have been reporting a number of case studies that show the possibilities of this technology regarding the dimensions, shape, building time, finishing and the material characteristics. It is commonly accepted that one of the big advantages of 3D printing is its possibility regarding the shape of the printed object since it can be easily changed each time a new piece is printed. This possibility raises some challenges regarding the printing limits, that are needed to the project design, such as to create overhangs. In this sense, a work was carried out to evaluate and optimize concrete printing mixtures and assess the 3D concrete printing of elements with overhangs. This paper presents the work carried out, showing the optimization of mixture composition for the binder/aggregate ratio, cement/fly ash ratio, and amount of superplasticizer and hardening accelerator, and evaluating their printing performance and mechanical properties. Printing of overhangs was possible for angles with the vertical direction till 17.5º.
- John Dunning’s influence in International business/strategy research: a bibliometric study in the Strategic Management JournalPublication . Ferreira, Manuel Portugal; Pinto, Cláudia Frias; Serra, Fernando A. Ribeiro; Gaspar, FlorindoIn this paper we undertake a literature review analyzing John Dunning’s contribution for international business and strategy research. We examine Dunning’s articles and other works and carry out a bibliometric study in the Strategic Management Journal, in the period from 1980 to 2009, a thirty years period. We conclude that beyond the more obvious contribution to the international business discipline with the Eclectic paradigm (OLI – Ownership, Location, Internalization), Dunning’s influence extends to other theories and concepts. Specifically, we observe connections to the resource-based view, transaction costs theory, the evolutionary theory and more broadly to the theory of the multinational enterprise.
- Modeling the influence of delamination on the mechanical performance of straight glued laminated timber beamsPublication . Gaspar, Florindo; Cruz, Helena; Gomes, AugustoDelamination at the glue lines is a key factor to take into account when assessing glued laminated timber members in service. In order to gain a more objective and wide knowledge about the importance of delamination in relation to its type and extension, a numerical study was developed. Finite element modeling (FEM) was used to evaluate the influence of delamination – near the surface, on the vertical faces and ends – on the mechanic performance of straight glued laminated timber beams. The FEM was validated by comparing stresses and deformations obtained with the model and with the application of the beam theory, showing satisfactory results. Results show that when delamination is non-symmetric regarding the member’s cross section, it can cause the member’s lateral instability, thus increasing its stresses and deformations. Delamination is not a problem when it occurs in members or member areas with low shear stresses, particularly when it is symmetric and does not reach the whole width of the beam. The stresses corresponding to the bending or deformation limit-states get near the elastic limit only for very important delamination. Moreover, delamination depth higher than 60% of the cross section width may be regarded as a turn point beyond which the structural integrity may be at risk.
- NonDestructive Techniques for the Assessment and Preservation of Historic StructuresPublication . Gonçalves, Luísa M. S.; Rodrigues, Hugo; Gaspar, FlorindoThe preservation of the built heritage has long been a public concern, mainly due to fears about the loss of identity, history and heritage of populations. The main concerns are the conservation and restoration of monuments that usually represent important events in the history of a city or a country. More recently, urban residents and policymakers have become aware of the abandonment or degradation of old city cores, leading to mischaracterisation of the buildings and ways of living. To preserve history and promote building and urban renewal, considering the basic principles of the preservation process, it is important to introduce the least possible disturbance. To start with, the diagnostic process is a key aspect, especially to investigate the construction characteristics and the damage to materials, and to find structural and nonstructural problems. To start any process, a visual inspection, a study and knowledge of the original construction methods and materials and historical repair techniques can help but may not be sufficient, and the use of conventional techniques to complement the information needed can result in an insufficient understanding or in extensive and unnecessary intrusions in the construction. In recent years, the rapid growth of science and research, combined with the industry and the need to gather more and accurate information, have led to the fast development of nondestructive testing methodologies that allow the architectural archaeology to be studied, the structural assessment to be supported and information to be given about the material properties. Each technique can be used for a specific purpose, but, in some cases, only a combination of techniques is reliable and gives an accurate interpretation of the data acquired. The fundamental contribution and aim of this book is to give a full overview of several case studies where different nondestructive techniques have been applied, in several cases using multidisciplinary approaches, which aim to highlight the importance of the information acquired and encourage the use of these techniques in future studies. The book brings together 16 chapters focused on nondestructive testing techniques applied at the urban building level and also applied to monumental buildings, archaeology and cultural heritage, bringing together more than 40 international researchers and experts in the field, who are the source of practical case studies supported by a theoretical background.
- Pathology of Stone Masonry Buildings: A Case Study at the Batalha MonasteryPublication . Gaspar, Florindo; Rodrigues, Hugo; Zhgun, AnnaThe Batalha Monastery is not only historical, but also an architectural and construction masterpiece of Portugal and has been listed on the Unesco World Heritage list. The quality of a monument varies depending on the construction techniques, the architecture and the materials used, as well as the interventions and conservation actions taken over the years. All these factors are decisive for the durability and state ofconservation. A visual survey of the facade pathologies of the Chapel of the Monastery of Batalha was made. The main construction materials of the monastery have been subjected to significant changes over the years. Moreover, with the growing amount of pollution in the environment and the rate of deterioration is increasing significantly.