Preface

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Durability assessment of consolidation effect on sandstone monuments

Trabalho apresentado no 41th IAHS World Congress, 13-16 de setembro de 2016, Albufeira, Portuga

Prediction of stress-strain curves based on hydric non-destructive tests on sandstones

This research received no external funding.The study of the mechanical behavior of building stones is traditionally supported by destructive compression tests carried out on representative specimens. However, in order to respect the monuments' integrity, the study of the mechanical behavior of stones can be based mostly on physical properties obtained from non-destructive tests (NDT). For this study, a simple and cheap NDT-water absorption under low pressure-was used to carry out fast surveys and to predict the most important design parameters of loadbearing masonry, among which are the compressive strength, strain at failure, and even elastic modulus on monument blocks. The paper presents the results of the experimental work conducted to obtain the physical properties and stress-strain curves of the sandstones tested. Supported by these results, it was possible to correlate the various parameters and develop an analytical model that predicts the stress-strain curve of the sandstones based on water absorption under low pressure tests. A good agreement is observed between the analytical model and the experimental tests.publishersversionpublishe

Onset of Alveolization Processes in Sandstones Exposed to Salt Weathering

Publisher Copyright: © 2024 by the authors. This research received no external funding.Sandstones of the Lourinhã Formation were studied. Alveolization is the major form of weathering on the façades of monuments near Peniche in the western region of Portugal. Salt weathering is an important cause of this degradation form. Stones of specimens, similar to those found in these ancient buildings, were used for an experimental program of artificial salt ageing through the use of sodium chloride, calcium chloride, and sodium sulfate solutions, all at 10% (w/w). Salt weathering follow-up was carried out viz. the assessment of the degradation effect on these specimens of lower values of porosity under crystallization–dissolution cycles. Sodium chloride and sodium chloride with calcium sulfate were the more deleterious solutions, causing failure of the specimens after at least 40 cycles of immersion/drying. Surfaces of the sandstone specimens of variety A showed the onset of the alveolization form due to the use of a saline solution of sodium chloride with calcium sulfate.publishersversionpublishe

Conservation of sandstone monuments: a new approach in consolidation treatments

Trabalho apresentado no 40th IAHS World Congress on Housing, 16-19 dezembro de 2014, Funchal, Madeira, PortugalN/

Effect of salt crystallization ageing on the compressive behavior of sandstone blocks in historical buildings

info:eu-repo/semantics/publishedVersio

Development of an injectable grout for concrete repair and strengthening

This paper deals with the coupled effect of temperature and silica fume addition on rheological, mechanical behaviour and porosity of grouts based on CEMI 42.5R, proportioned with a polycarboxylate-based high range water reducer. Preliminary tests were conducted to focus on the grout best able to fill a fibrous network since the goal of this study was to develop an optimized grout able to be injected in a mat of steel fibers for concrete strengthening. The grout composition was developed based on criteria for fresh state and hardened state properties. For a CEMI 42.5R based grout different high range water reducer dosages (0%, 0.2%, 0.4%, 0.5%, 0.7%) and silica fume (SF) dosages (0%, 2%, 4%) were tested (as replacement of cement by mass). Rheological measurements were used to investigate the effect of polycarboxylates (PCEs) and SF dosage on grout properties, particularly its workability loss, as the mix was to be injected in a matrix of steel fibers for concrete jacketing. The workability behaviour was characterized by the rheological parameters yield stress and plastic viscosity (for different grout temperatures and resting times), as well as the procedures of mini slump cone and funnel flow time. Then, further development focused only on the best grout compositions. The cement substitution by 2% of SF exhibited the best overall behaviour and was considered as the most promising compared to the others compositions tested. Concerning the fresh state analysis, a significant workability loss was detected if grout temperature increased above 35 degrees C. Below this temperature the grout presented a self-levelling behaviour and a life time equal to 45 min. In the hardened state, silica fumes increased not only the grout's porosity but also the grout's compressive strength at later ages, since the pozzolanic contribution to the compressive strength does not occur until 28 d and beyond. (C) 2012 Elsevier Ltd. All rights reserved

Consideration of Critical Parameters for Improving the Efficiency of Concrete Structures Reinforced with FRP

Funding Information: This research was supported by the Polish National Agency for Academic Exchange no.: PPN/IWA/2019/1/00155/U/00001 (Iwanowska programme). Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Fibre-reinforced polymer materials (FRP) are increasingly used to reinforce structural elements. Due to this, it is possible to increase the load-bearing capacity of polymer, wooden, concrete, and metal structures. In this article, the authors collected all the crucial aspects that influence the behaviour of concrete elements reinforced with FRP. The main types of FRP, their characterization, and their impact on the load-carrying capacity of a composite structure are discussed. The most significant aspects, such as type, number of FRP layers including fibre orientation, type of matrix, reinforcement of concrete columns, preparation of a concrete surface, fire-resistance aspects, recommended conditions for the lamination process, FRP laying methods, and design aspects were considered. Attention and special emphasis were focused on the description of the current research results related to various types of concrete reinforced with FRP composites. To understand which aspects should be taken into account when designing concrete reinforcement with composite materials, the main guidelines are presented in tabular form.publishersversionpublishe

Visão integrada da reabilitação

A reabilitação de um edifício tem muitas vezes de ser analisada e efetuada tendo em conta os edifícios vizinhos e a envolvente. No caso particular da reabilitação de um edifício, à partida devem considerar-se, de forma integrada, todos os requisitos que não são cumpridos face aos padrões atuais. Com base nessa análise, e tendo em conta muitas vezes condicionantes vários, que vão desde estéticos, técnicos, culturais a económicos, e que dependem em larga medida das tipologias construtivas, a intervenção tem de ser cuidadosamente concebida, preparada e executada. Apresentam-se sinteticamente as tipologias construtivas mais correntes, o contexto legislativo português da construção e específico da reabilitação. Efetua-se uma análise à legislação vigente, detalhando com maior detalhe o Regime Especial da Reabilitação Urbana, que possibilita dispensas de cumprimentos regulamentares mas apenas relativos a aspetos construtivos. Por esse motivo apresenta-se também uma síntese de aspetos relativos à segurança estrutural na reabilitação de edifícios com tipologias correntes. Pretende-se, através desta síntese, contribuir para uma visão mais integrada da reabilitação

Degradation of gfrp-plates bonded to concrete: An experimental approach based on mohr-coulomb failure criterion

The authors are grateful to Fundação para a Ciência e Tecnologia for partial financing of thework under Project PTDC/ECM/100538/2008. The authors would like to thank for the helpof Prof. Vladimir Cervenka and Ing. Dobromil Pryl, with ATENA.publishersversionpublishe