http://repositorio.lnec.pt:8080/jspui/handle/123456789/34 2026-04-04T21:15:23Z 2026-04-04T21:15:23Z Gullota, D. RILEM TC ASC http://repositorio.lnec.pt:8080/jspui/handle/123456789/1016908 2024-03-05T17:02:41Z 2023-09-01T00:00:00Z

The New RILEM TC 271-ASC Recommendation for the durability assessment of porous building materials against salt crystallization Gullota, D.; RILEM TC ASC Salt crystallization is among the most harmful deterioration mechanisms impacting the preservation of porous building materials worldwide. Therefore, predicting the materials’ response to salt damage is crucial in the conservation practice and building sector to guarantee adequate performance and durability. These, in turn, are instrumental to achieving sustainable interventions. Numerical models have been developed to describe salt decay susceptibility quantitatively, but the most diffused approach still relies on performing accelerated weathering tests in laboratory conditions. So far, the main limitations associated with most of the available experimental and standard accelerated weathering tests arise from the generally long time they re-quire, the lack of consensus on the methods for assessing the damage progression and extent, and the use of testing scenarios hardly representative of real-world conditions. These include simulating unrealistic accumulation and salt transport processes, which in turn significantly affect the resulting deterioration patterns and the final damage extent, and the use of remarkably high salt solution concentrations. The RILEM Technical Committee (TC) 271-ASC, active between 2016 and 2022, has pursued an innovative direction to simulate more realistic salt crystallization pathways to test single porous materials (stone and clay brick units). The TC aimed to develop a reliable accelerated aging procedure for laboratories in the architectural heritage conservation and construction sectors. The requirements for the new procedure focused on achieving realistic results in a relatively limited time, without significantly altering the deterioration process and allowing for a simple damage assessment based on readily available and non-sophisticated techniques. The test simulates the deterioration effects induced by capillary transport of sodium sulfate and sodium chloride aqueous solutions, considered as single salts, toward the evaporative surface of cylindrical specimens. Building on the experience of reinforced concrete durability research, the TC has explored the feasibility of a two-stage approach (Fig. 1) to trigger damage development and progression, only after a certain degree of pore filling – as a result of salt accumulation – is reached. The new procedure translates this theoretical assumption into two distinct testing phases: a preliminary salt accumulation phase, during which the porous substrate is contaminated with salt solution with fixed concentration, and capillary transport promotes its accumulation close to the evaporation surface without causing visible damage, followed by a propagation phase (Fig. 2). The propagation phase activates the damage development due to repeated crystallization and dissolution cycles. The testing conditions for the accumulation phase are the same for both salts. Specimens are subjected to capillary absorption of 5% and 10% concentrations of sodium sulfate and sodium chloride solutions and then dried until the evaporation of at least 80% of the absorbed water. Then the propagation phase starts, based on four 3-week cycles. Differently from the accumulation phase, the set conditions of such cycles differ (i.e., T and RH values, duration, and use of rewetting stages) depending on the type of salt employed. In brief, each single 3-week cycle of the propagation phase of NaCl employs a series of high relative humidity adsorption sub-cycles alternated with drying stages, followed by a rewetting step and a final drying (Fig. 3, above). Each Na2SO4 propagation phase starts with a cooling and rewetting sub-cycle at room conditions, followed by drying (Fig. 3, below). Two round-robin testing programs have been conducted to validate the accelerated weathering procedure, involving ten research laboratories across Europe and the US [2]. The substrates tested during the validation phase include five stones (Lecce, Massangis and Migné limestone, Tuffeau, and Mšené “Prague” sandstone) and two fired-clay bricks. The physical characteristics of such substrates cover an open po-rosity range between 13% and 50% (vol %) and a capillary water absorption inter-val between 50 and 1070 g/m2s0.5. The new accelerated aging procedure has been recently published as a RILEM recommendation [3]. The document details the two procedures for testing single porous materials and includes a simplified methodology based on visual observations, photographic documentation, and mass loss recording to guide the evaluation of the salt crystallization results. A damage glossary for identifying the deterioration patterns is also provided, derived from selected terms of the ICOMOS-ISCS Stone Deterioration Glossary [4] and the MDCS Damage Atlas [5].

2023-09-01T00:00:00Z Lubelli, B. Gonçalves, T. D. Veiga, M. R. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1016905 2024-03-05T15:25:12Z 2023-01-01T00:00:00Z

Recommendation of RILEM TC 271-ASC: New accelerated test procedure for the assessment of resistance of natural stone and fired-clay brick units against salt crystallization Lubelli, B.; Gonçalves, T. D.; Veiga, M. R. This recommendation is devoted to testing the resistance of natural stone and fired-clay brick units against salt crystallization. The procedure was developed by the RILEM TC 271-ASC to evaluate the durability of porous building materials against salt crystallization through a laboratory method that allows for accelerated testing without compromising the reliability of the results. The new procedure is designed to replicate salt damage caused by crystallization near the surface of materials as a result of capillary transport and evaporation. A new approach is proposed that considers the presence of two stages in the salt crystallization test. In the first, the accumulation stage, salts gradually accumulate on or near the surface of the material due to evaporation. In the second, the propagation stage, damage initiates and develops due to changes in moisture content and relative humidity that trigger salt dissolution and crystallization cycles. To achieve this, two types of salt were tested, namely sodium chloride and sodium sulphate, with each salt tested separately. A methodology for assessing the salt-induced damage is proposed, which includes visual and photographical observations and measurement of material loss. The procedure has been preliminarily validated in round robin tests.

2023-01-01T00:00:00Z Gonçalves, T. D. Saporiti Machado, J. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1016904 2024-03-05T15:25:26Z 2023-01-01T00:00:00Z

Sustainability: Conceptual Origins, Evolution and Current Challenges in the Construction Sector Gonçalves, T. D.; Saporiti Machado, J. Sustainability is the desirable attribute of an ideal economic system, where development stems from a balanced integration of economic factors, namely economic growth, with considerations for environmental preservation and social fairness. This sort of development is called sustainable. The idea is frequently illustrated through diagrams such as the well-known three overlapping circles (Figure 1). The concept arose largely in response to questioning of the prevailing economic order, which prioritizes economic growth while treating environmental and social issues as externalities. Opposition to that economic model intensified in the 1960s, led by civil movements concerned with environmental problems, as well as with social issues. One of the first documents to appear as a response, in the early 1970s, was MIT's report The Limits to Growth [1]. This proposed to replace the economic concept of growth with that of equilibrium, in a new type of economic system that was coined as "sustainable". The idea of sustainable development was popularized fifteen years later, in 1987, through the United Nations (UN) report Our Common Future [2]. While considering economic growth a necessary driver to development, the report emphasizes the need to manage growth to avoid excessive pressure on environmental resources, the biosphere, and social equity, that is, to achieve sustainability. Since then, several initiatives have been launched to implement the concept. In 1992, a global plan of action for sustainable development, known as Agenda 21, was put forward at the United Nations Rio 92 Conference [3]. Agenda 21 emphasizes the social and environmental dimensions of sustainable development and reiterates they should be considered alongside purely economic issues. Nine years, later, in 2011, the UN report Towards a Green Economy introduces the concept of a so-called Green Economy [4]. This was intended as a reaction to the recurrent market crises and the increasing disillusionment with an economic system that continued to favour growth at the expense of social disparities and environmental destruction. The construction sector is considered one of those with the greatest potential for change. Finally, in 2015, the United Nations launched the Agenda 2030 for Sustainable Development, which introduced 17 sustainable development goals (SDG) to be achieved by 2030 [5]. The SDGs address pressing environmental, economic, and social issues, from poverty and inequality to protection of the planet. These initiatives, among others, created the backdrop for several developments at European level. Still in 2015, the European Commission (EC) released the concept of a Circular Economy, a model of production and consumption that promotes sharing, leasing, reusing, repairing, refurbishing and recycling [6]. In 2019, a strategic plan entitled the European Green Deal was launched by the EC, which is aimed at making the EU climate neutral by 2050 while promoting a circular economy to reduce both resource usage and energy dependency [7]. Recently, the EC decided to take action to address the problem of greenwashing too, through an update to EU consumer rules. Greenwashing is a concept that gained popularity in the early 1990's and occurs when organizations falsely project an image of environmental friendliness for their products or practices [8]. This deceptive behaviour misleads people and undermines efforts to protect the environment. In the European Union, the translation of sustainability principles into the construction sector is also underway. At first, it was largely based on the set of standards produced by CEN/TC 350 [9]. Then, the EC launched Level(s), a simplified framework for assessing the sustainability of buildings, their parts and materials, which is still partially under development [10]. Another important step is the revision of the Construction Products Regulation, which establishes the requirements for construction products to circulate freely within the European Single Market. This is currently ongoing and will incorporate sustainability criteria. In addition, the EC is proposing a new Ecodesign for Sustainable Products Regulation, aimed at making sustainable products the norm in the EU market. In this presentation, we will take an integrated approach to analysing the concept of sustainability and the evolution it has undergone over time and in its application to the construction sector in the European Union. We will also discuss the internal consistency of the concept, as well as chief distortions that may arise, such as greenwashing.

2023-01-01T00:00:00Z Gonçalves, T. D. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1016903 2024-03-05T15:25:21Z 2023-01-01T00:00:00Z

On the Inconsistency between Practice and Reporting in Science: The Genesis of Scientific Articles Gonçalves, T. D. Scientific publications depict science as an orderly endeavour and the epitome of rationality. In contrast, scientific practice is messy and not strictly rational. Here, I analyze this inconsistency, which is recurrent, and try to clarify its meaning for the functioning of science. The discussion is based on a review of relevant literature and detailed analysis of the role of each of the three intervening elements, the scientist, his/her practice and the scientific publication, with an emphasis on the circular mode of the latter’s creation. This way, I will discuss the nature, causes and relevance of the inconsistency. That corresponds to answering three questions, respectively: ‘what are the characteristics of the inconsistency?’, ‘what are its origins?’ and ‘how could it be interpreted within a model for the structure and functioning of science?’ From this discussion it is concluded that, contrary to the negative character generally attributed to it, the inconsistency between practice and reporting is part of the production mechanism of science.

2023-01-01T00:00:00Z