Artigos de Revista

The paper focuses on the study of barium hydroxide applied to two high porosity limestones from Portugal (Ançã stone, with 27% porosity) and Italy (Lecce stone, with 37% porosity), both in the laboratory and onsite. The results show that barium hydroxide acts both through carbonation with atmospheric CO2 and by replacing calcium for barium in the calcite lattice followed by carbonation of the released calcium hydroxide. This double mechanism proved to be particularly efficient in the Ançã limestone, possibly due to a higher reactivity linked to its smaller grain size. The mechanism is far slower than simple carbonation and has a better outcome when the stone can be totally immersed in the solution. Onsite experiments on the Ançã stone were less striking than in the laboratory, possibly due to the insufficient amount of product made available for reaction, but a positive outcome was visible after six years of natural exposure.

Knowledge of current conservation materials and methods together with those adopted in the past is essential to aid research and improve or develop better conservation options. The infill and painting of tile lacunae are subjected to special requirements mainly when used in outdoor settings. A selection of the most commonly used materials was undertaken and performed based on inquiries to practitioners working in the field. The infill pastes comprised organic (epoxy, polyester), inorganic (slaked lime, hydraulic lime and zinc hydroxychloride) and mixed organic–inorganic (slaked lime mixed with a vinylic resin) binders. The selected aggregates were those most commonly used or those already present in the commercially formulated products. The infill pastes were characterised by SEM, MIP, open porosity, water absorption by capillarity, water vapour permeability, thermal and hydric expansibilities and adhesion to the ceramic body. Their performance was assessed after curing, artificial ageing (salt ageing and UV–Temp–RH cycles) and natural ageing. The results were interpreted in terms of their significance as indicators of effectiveness, compatibility and durability.

Em Portugal, os interiores de igrejas, espaços conventuais e palácios estão frequentemente decorados com revestimentos azulejares desde finais do séc. XVI. Mas nem todos chegaram aos nossos dias em boas condições. O presente estudo teve como objetivo levantar formas de degradação in situ e eventualmente relacioná-las com a ocorrência de sais solúveis. Pretendia-se também identificar os sais correlacionando-os com a forma de degradação. Analisaram-se eflorescências e pequenos fragmentos de chacota e vidrado colhidos em obra, utilizando o microscópio eletrónico de varrimento com unidade de microanálise associada (SEM-EDS), para a identificação de espécies salinas.

Differential erosion is a deterioration pattern common in stone and mortars exposed to environmental agents. The differential morphology is usually determined by specific intrinsic characteristics. The case analysed here corresponds to a peculiar situation of rhythmic precipitation inside lime mortars following a physical process designated as Liesegang phenomenon. The rhythmic reaction occurs between calcium hydroxide and carbon dioxide in the early steps of the carbonation process, and when appropriate boundary conditions are met, a more or less “perfect” sequence of higher and lower concentration of the carbonated lime (calcite) is formed. This sequence is called a series of Liesegang rings. The rings have distinct hardness and, when exposed to erosion agents, a differential pattern may be formed. In certain regions, this differential erosion pattern was given the name of Flos tectorii

The present work aims to develop the Life Cycle Assessment study of thermo-modifiedAtlanticwood® pine boards based on real data provided by Santos & Santos Madeirascompany. Atlanticwood® pine boards are used mainly for exterior decking and claddingfacades of buildings. The LCA study is elaborated based on ISO 14040/44 standard and Product Category Rules for preparing an environmental product declaration for Construction Products and Construction Services. The inventory analysis and, subsequently, the impact analysis have been performed using the LCA software SimaPro8.0.4. The method chosen for impact assessment was EPD (2013) V1.01. The results show that more than ¾ of

Within the framework of the activities of the working group GT1 of the Portuguese Commission onTransportation Geotechnics

Wave-induced flow velocity and turbulence may cause scouring in the seabed around coastal structures depending on the wave climate and tidal water depth. A 3-D physical modelling study was conducted to investigate the possible causes of the sinking of two submerged coastal structures on the Santa Maria del Mar (SMM) beach, Spain. The experimental investigation was conducted by employing a Froude similarity law with a geometric scale of 1:20, and the submerged modular structure was subjected to different wave climates and tidal water levels. The combinations of the significant wave height and peak period were chosen from in-situ real wave conditions thatwere monitored during the sinking of the prototype structures. Linking and unlinking conditions for the modules in the structure were investigated in this study. The results show that the modules sank to approximately 48% of their height at the end of the tests with storm waves and semi-linking conditions of low water depth. Most of the experimental results were compatible with the prototype monitoring results. Tests with proper linking among themodules and testswith an appropriate gravel foundation resulted in a sustainable solution because they presented much less or almost no scouring and sinking.

This paper intends to analyze the microstructure of concrete with recycled aggregates (RA) from construction and demolition waste from various Portuguese recycling plants. To that effect, several scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed. Various concrete mixes were evaluated in order to analyze the influence of the RA’s collection point and consequently of their composition on the mixes’ characteristics. Afterward all the mixes were subjected to the capillary water absorption test in order to quantitatively evaluate their porosity. Results from the SEM/EDS analysis were compared with those from capillary water absorption test. The SEM/EDS analysis showed that the bond capacity of aggregates to the new cement paste is greatly influenced by the RA’s nature. On the other hand, there was an increase in porosity with the incorporation of RA.

This work investigates tensile crack propagation in concrete gravity dams by using some recently developed numerical techniques (crack-path field and strain injection techniques). The work carefully addresses aspects related to mesh independence, robustness and computational cost, which are the main issues in fracture modeling. The novel technique consists of a procedure to insert, in the selected domain areas, specific strain fields for enhancing the performance of the underlying finite elements in modeling fracture. Representative numerical simulations of concrete dams show the accuracy and robustness of the methodology.

The current paper is aimed at studying the influence of weather conditions on urban water consumption using available continuous flow measurements from existing district metered areas (DMA), belonging to different Portuguese water distribution systems. A three-step methodology was followed: Data processing; DMA segmentation in terms of billed consumption and socio-demographic characteristics; and demand modeling. Cluster analysis was carried out to segment the different DMA with similar billed consumption, and multiple linear regression analysis was used to describe the effect of weather variables (temperature and rainfall) on water consumption. Three well-defined DMA clusters were identified and the respective demand models were obtained for each group. Results have shown that temperature has a significant influence on water consumption, particularly in DMA in which the public billed consumption (29%) and the domestic billed consumption in the third and fourth tariff levels (10.7 and 10.1%, respectively) are relevant. The relationship between consumption and rainfall is not as evident as the relationship with temperature; however, the rainfall variable is equally important in the construction of demand models. These results allow improving of monthly and seasonal network operation, since these allow a more robust profiling of the water uses as well as modeling demand for different weather conditions.