Key Engineering Materials Vol. 919

Abstract: Hysteresis is observed in various mechanical systems. For structural elements, cyclic loads cause deterioration of their characteristics due to cracks opening, yielding and buckling of metal­lic elements, etc. This contribution presents a smooth hysteresis model for reinforced concrete (RC) structural elements that accounts for both damage and pinching effects. The model is based on the Bouc­-Wen differential equation. Deterioration of the mechanical properties is introduced through a damage index that includes energy dissipation and ductility. Pinching is simulated by acting directlyon the stiffness of the system. The parameters of the model have clear physical meanings, which helps in the identification and interpretation of the results. Applications to RC elements show that the model is suitable for describing complex cyclic behaviours involving effects of damage. Being defined by a smooth hysteresis law, the model is a computationally-­effective tool useful for dynamic and stochastic simulations.

Abstract: In the field of sustainable construction materials, the production of eco-friendly concretes, obtained by the addition of waste products such as biochar and recycled polymer particles, offers interesting alternatives to traditional materials. Biochar is a carbonaceous solid by-product obtained from the thermo-chemical conversion of biomass and its addition into concrete admixtures can offer an eco-friendly carbon sequestration solution, capable to slightly improve concrete properties. Recycled polymer materials can be used to partially replace conventional aggregates with the aim of obtaining lighter concretes that help to face the disposal challenge presented by this non-degradable plastic waste. However, the influence of these waste additions on the corrosion behavior of steel rebars embedded in these “eco-concretes” is still unexplored. Within this context, this work presents some results of an extensive study dealing with the concrete mechanical and physical properties and the rebar corrosion resistance during cyclic exposures to chloride-containing solutions.

Abstract: Buildings are one of the largest contributors to negative environmental impacts because of the high consumption of energy and materials during their life cycle. The present work proposes a framework, able to make available information, both of general materials and specific commercial solutions; moreover, it overcomes the current state of the art, since, although focused on environmental sustainability, provides the opportunity to compare simultaneously several choices, also considering their properties and characteristics. Based on the proposed methodology, a tool structure and workflow are presented. The main potentiality is represented by the possibility of executing sustainability assessment already in the early stages of building design using the proposed tool when design choices significantly contribute to the global environmental impact of solutions. A validation procedure to quantitatively evaluate the main tool's limits and potentialities is proposed.

Abstract: The awareness of environmental protection, with the conservation of resources and the efficient use of industrial waste, has attracted the attention in recent decades as both the overexploitation of natural resources and the disposal of industrial waste have a negative impact on the environment and sustainability [1]. Under such circumstances, replacing ordinary Portland cement (OPC) with industrial waste has been shown as a sustainable and practical way to reduce the use of natural resources, as well as landfill waste and pollution [2]. The discussion of this issue is part of a path, which sees as its starting point the design of a hydraulic pipeline prototype (Figure 1) made of geopolymer mortar instead of conventional concrete pipes. The environmental sustainability of geopolymer mortars was demonstrated through the Life Cycle Assessment (LCA) methodology. Analysis results indicate that the use of eco-friendly materials contributes to minimizing the environmental impact of new technologies for engineering sector.

Abstract: Forced by environmental implications and by legislation requirements, the cement sector is moving towards more circular economy practices, with the primary aim to enhance the sector sustainability. This commitment translates into product technology innovation, but also into innovative development perspectives for the industries involved in the supply chain. Moreover, dealing with recycled materials can modify the interaction among stakeholders from a conventional supply chain to an industrial symbiosis approach, where companies mutually exchange products and by-products into circular interactions. The purpose of this article is to investigate the circularity performances deriving from the production of a cement mortar reinforced with recycled synthetic fibers coming from artificial turf carpets. From the collection of artificial turf carpets at the end-of-life stage it is possible to recover several materials: plastic fibers used in the cement mortar, and in addition, silica sand, rubber, and bituminous membrane. The production of the innovative reinforced cement mortar leads to the connection between industries belonging to different sectors and consequently to uneven economic and environmental implications. Starting from the available literature, this study aims at evaluating the circularity potential of the unusual interactions among companies to support the development of an effective strategy, reducing environmental and economic pressures.

Abstract: Sustainability and environmental impact assessment are essential to orient new generation of materials for building and construction. In this study, life cycle assessment was applied to a set of 21 mural paints produced by a paint factory in Italy. Data collection covered upstream processes (i.e., raw materials extraction and supply), the core process (i.e., paint manufacture and packaging) and downstream processes (i.e., transport to retailers). Material and energy inputs and outputs for the main components employed in paint manufacturing (e.g., antifoaming agents, dispersants, coalescing agents, additives, biocides and similar) were gathered from primary and secondary data sources. Life cycle impact assessment results were estimated for global warming potential (on average, 1.03 ± 0.60 kg CO₂/kg paint), photochemical oxidation (0.60 ± 0.46 g C₂H₄/kg paint), abiotic depletion (1.94 ± 1.58 g Sb/kg paint), acidification (6.80 ± 6.64 g SO₂/kg paint), and eutrophication (1.96 ± 1.47 g PO₄/kg paint). Overall, upstream processes are responsible for the greatest environmental impact (on average, more than 70% for global warming potential), with titanium rutile from sulfates being the most impacting raw material. The results informed decision makers and provided a basis for achieving improvement and greener production strategies in paint manufacturing.

Abstract: The construction sector is a major contributor to total energy consumption, therefore, it is crucial to adopt energy efficiency strategies capable of reducing energy impact in buildings. Among these strategies, exterior wall insulation is one of the most cost-effective options to achieve energy savings for both newly constructed and renovated buildings. In this paper, based on an economic analysis, we aim to determine the economically optimal thickness of insulation material to be used for retrofit interventions of masonry structures. The study analyzes 10 different insulating materials and 5 masonry structures widespread in Italy. The results show that each masonry structure requires a careful evaluation of the thickness of the insulating material to be applied in retrofit operations. Moreover, varying the type of insulating material used, even if applied to the same wall structure, there are different levels of thickness to be applied in order to optimize the performance of the structure.

Abstract: The present study explores the environmental quality (natural and recycled content, recyclability, life cycle method) of a sample of certified construction products available in different database in Italy (Remade in Italy, Atlante dell’Economia Circolare, Observatory Recycle-Legambiente Report, Accredia). The results evidence the identification of a wide range of construction products with different certified recycled contents and Italian origin under the certification standard “Remade in Italy”. Moreover, 42% of the certified products rely on the use of LCA for the assessment of the environmental impacts, while 22% of certified products integrate the features of recycled content with the recyclability at the end-of-life. Overall, results show the role certifications may have in increasing the information available on products and their environmental quality, including their traceability in the reverse supply chain, becoming a potential driver for CE adoption and a wider development for such products.

Abstract: Construction and demolition waste (CDW) is very high in quantity, 30% - 40% of total solid waste and their management is inadequate and lack the integration of sustainability concepts. This situation leads to severe environmental effects, which are mainly associated with the production of new building materials due to the low recovery rate. In fact some studies show that 5-10% of total energy consumption across the EU is related to the manufacture of construction products. For this reason, CDW is a priority for many policies globally. For several years, a growing trend towards more sustainable construction processes has been taking place with a focus on secondary raw materials with lower environmental impacts on the entire life cycle. For this reason, this paper intends to contribute to increasing knowledge in this field through a review article. The review has the aim to evaluate the research gap, strategies to reduce construction waste and to promote the recycled materials use for a circular economy in construction sector. The results of the study showed that interest in this field of research has grown strongly over the years: the most publications on the subject relate to the last five years. On the other hand, issues relating to the topic did not attract particular interest in the range 2010-2016, in fact the number of publications in this period did not exceed 4%. The research showed that Europe is among the communities most sensitive to the issue and it has clearly revealed that there are still many barriers and research gaps to be overcome on this issue and the study has tried to identify the main ones.

Abstract: The present Life Cycle Analysis (LCA) intends to investigate the environmental benefit of using natural fibres and/or recyclable epoxy resins for future manufacturing of small/medium wind turbine blades to handle thermoset polymer composites that are designed to be recyclable at the end of life”). LCA comparison of a modelled blade based on flax fibres reinforced recyclable epoxy resin and a traditional blade made of glass fibres and non recyclable epoxy resin is presented. In the production phase the environmental impacts of the flax fibre reinforced recyclable epoxy resin composite blade are higher than the blade based on glass fibre epoxy composite mainly due to the higher amount of epoxy resin necessary to satisfy the design criteria of the blade e.g. fatigue and deflection. The end of life is significative as the environmental impacts are reduced by the recycling and recovery of the fibres and the resin, being the resin more significative.