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"recycled building materials"
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Thermal Characterization of Recycled Materials for Building Insulation
The building sector is known to have a significant environmental impact, considering that it is the largest contributor to global greenhouse gas emissions of around 36% and is also responsible for about 40% of global energy consumption. Of this, about 50% takes place during the building operational phase, while around 10–20% is consumed in materials manufacturing, transport and building construction, maintenance, and demolition. Increasing the necessity of reducing the environmental impact of buildings has led to enhancing not only the thermal performances of building materials, but also the environmental sustainability of their production chains and waste prevention. As a consequence, novel thermo-insulating building materials or products have been developed by using both locally produced natural and waste/recycled materials that are able to provide good thermal performances while also having a lower environmental impact. In this context, the aim of this work is to provide a detailed analysis for the thermal characterization of recycled materials for building insulation. To this end, the thermal behavior of different materials representing industrial residual or wastes collected or recycled using Sardinian zero-km locally available raw materials was investigated, namely: (1) plasters with recycled materials; (2) plasters with natural fibers; and (3) building insulation materials with natural fibers. Results indicate that the investigated materials were able to improve not only the energy performances but also the environmental comfort in both new and in existing buildings. In particular, plasters and mortars with recycled materials and with natural fibers showed, respectively, values of thermal conductivity (at 20 °C) lower than 0.475 and 0.272 W/(m⋅K), while that of building materials with natural fibers was always lower than 0.162 W/(m⋅K) with lower values for compounds with recycled materials (0.107 W/(m⋅K)). Further developments are underway to analyze the mechanical properties of these materials.
Journal Article
Low impact building : housing using renewable materials
\"Low Impact Building: Housing using Renewable Materials is about changing the way we build houses to reduce their 'carbon' footprint and to minimise environmental damage. One of the ways this can be done is by reducing the energy and environmental impact of the materials and resources used to construct buildings by choosing alternative products and systems. In particular, we need to recognise the potential for using natural and renewable construction materials as a way to reduce both carbon emissions but also build in a more benign and healthy way. This book is an account of some attempts to introduce this into mainstream house construction and the problems and obstacles that need to be overcome to gain wider acceptance of genuinely environmental construction methods.\"-- From publisher description.
Book
Utilization of Recycled Foam Concrete Powder with Phase-Change Material as a Cement or Sand Replacement: Impact on Mortar Properties and Superplasticizer Performance
The recycling of ultralight foam concrete (ULFC), both with and without phase-change material (PCM), involves crushing it and using the resulting recycled foam concrete powder (RFCP) as a partial substitute for cement or sand in cement composites. These recycling paths remain insufficiently explored in the literature regarding practical feasibility. Since both RFCP and PCM reduce the flowability of fresh mortars, incorporating RFCP with PCM is, in practice, only feasible with the addition of a superplasticizer (SP). The primary objectives of this study were to determine: (1) the effect of RFCP with PCM, when used to replace cement or sand, on mortar properties, and (2) its influence on the performance of the superplasticizer (SP), to assess the feasibility of using RFCP with PCM in cement composites. The addition of RFCP, both without PCM (RFCP₀) and with PCM (RFCP_(P)CM), deteriorates the properties of fresh and hardened mortars compared to reference mortars. The negative impact of RFCP is less pronounced when it replaces sand rather than cement. Compared to RFCP₀ mortars, RFCP_(P)CM mortars exhibit reduced flowability. PCM delays setting and reduces heat evolution during the first 48 h of hardening. PCM does not significantly affect strength or water absorption but increases shrinkage and lowers thermal conductivity. While RFCP_(P)CM does not impair SP efficiency, PCM causes SP to significantly retard setting and hardening.
Journal Article
Rheology, Strength, and Durability of Concrete and Mortar Made of Recycled Calcium Silicate Masonry
Selective demolition of building components and recycling construction demolition waste is a growing tendency as we move towards a circular construction. This study investigates the feasibility of using demolition waste from calcium silicate brick masonry as an aggregate in concrete and mortar. The purpose is to assess its impact on concrete and mortar properties, including compressive strength, durability, and workability. Silicate bricks from two demolished buildings were processed into aggregate, and laboratory experiments were conducted to evaluate concrete and mortar made with varying proportions of recycled aggregate. Results indicate that replacing natural aggregate (limestone rubble and sand) with recycled silicate brick aggregate up to 50% does not significantly compromise concrete performance, with no significant decrease in compressive strength observed. Frost resistance of the concrete made with recycled aggregate even surpasses that of reference concrete, possibly due to the lower density and higher (closed) porosity of the recycled aggregate. However, challenges such as increased water demand and loss of workability over time are noted with higher proportions of recycled aggregate. Further research is recommended to explore strategies for mitigating these challenges and to assess the effects of chemical admixtures on concrete properties. Overall, the findings suggest that recycled calcium silicate brick holds promise as a sustainable alternative for aggregate in concrete production.
Journal Article
Economical Assessment of Recycled Asphalt Pavement (RAP) Aggregate for Structural Concrete Production in Italy
Structural concrete aggregate can be substituted with sustainable alternatives from construction and demolition waste, such as reclaimed asphalt pavement (RAP). This contribution assesses the RAP aggregate production chain and aims to investigate the economic aspect of RAP aggregate, evaluating the costs associated with its production and comparing them with the ones necessary to produce NA and recycled concrete aggregate (RCA). This analysis aims to provide additional information on the possible advantages of RAP aggregate use in order to promote sustainable construction. The evaluation was developed using a four-step methodology consisting of (i) determining the RAP aggregate production procedure; (ii) selecting a case study; (iii) defining the mix design; and (iv) performing a cost evaluation and comparing it to the cost of NA and RCA production. The results of the cost analysis of three concretes containing different RAP percentages (0%, 30%, and 45%) demonstrated that RAP’s presence led to more expensive admixtures, with the RAP unit cost being higher than NA (+155.39%). Some strategies were proposed to diminish RAP’s cost, resulting in a reduction of −39.64% with respect to NA’s cost and ranging from 45.13% to 67.30% when compared to RCA’s cost.
Journal Article
Untersuchung der Nährstoffauswaschung unter Schotterrasenflächen an einem inneralpinen Standort
Zusammenfassung
Schotterrasenflächen als umweltschonende Alternative zu asphaltierten Parkplätzen tragen zu einer guten Versickerung nach Starkniederschlagsereignissen bei. Die Nährstoffkonzentrationen des Sickerwassers und die damit verbundenen Nährstoffauswaschungen von Schotterrasenflächen wurden in einem zweijährigen Feldversuch an der HBLFA Raumberg-Gumpenstein durch Anlegung einer Versuchseinheit anhand von sechs Schwerkraftlysimetern analysiert. Zwei unterschiedliche regionale Materialien (Kalkschotter mit 10 % Humus und Baustoffrecyclingmaterial mit 10 % Kompost) wurden auf jeweils drei Lysimeterkammern eingebaut.
Die Sickerwassermengenbestimmungen ergaben, dass Kalkschottermaterial eine bessere Versickerungsleistung als Baustoffrecyclingmaterial erzielt. Die Nährstoffkonzentrationen und Nährstoffauswaschungen weisen im Anlagejahr als auch im Folgejahr signifikant höhere Werte im Baustoffrecyclingmaterial auf. Beide Materialien zeigen im Anlagejahr einen höheren Nährstoffkonzentrations- und Auswaschungswert als im Folgejahr an.
Der in der Trinkwasserverordnung (BGBI. I Nr. 21/2001) bestehende Nitratgrenzwert von 50 ppm wird im Kalkschottermaterial eingehalten, im Baustoffrecyclingmaterial jedoch im Anlagejahr um das Dreifache überschritten. Im Sinne des Grundwasserschutzes sollte daher beim Einbau von Baustoffrecyclingmaterial das erhöhte Auswaschungsrisiko in der Anlagephase berücksichtigt werden.
Journal Article
A Review of Carbon Footprint Reduction in Construction Industry, from Design to Operation
Construction is among the leading industries/activities contributing the largest carbon footprint. This review paper aims to promote awareness of the sources of carbon footprint in the construction industry, from design to operation and management during manufacturing, transportation, construction, operations, maintenance and management, and end-of-life deconstruction phases. In addition, it summarizes the latest studies on carbon footprint reduction strategies in different phases of construction by the use of alternative additives in building materials, improvements in design, recycling construction waste, promoting the utility of alternative water resources, and increasing efficiencies of water technologies and other building systems. It was reported that the application of alternative additives/materials or techniques/systems can reduce up to 90% of CO2 emissions at different stages in the construction and building operations. Therefore, this review can be beneficial at the stage of conceptualization, design, and construction to assist clients and stakeholders in selecting materials and systems; consequently, it promotes consciousness of the environmental impacts of fabrication, transportation, and operation.
Journal Article
Shrinkage of recycled aggregate concrete: experimental database and application of fib Model Code 2010
This paper describes a meta-analysis of previously published studies on the shrinkage strain of recycled aggregate concrete (RAC). The study aims at providing an analytic expression for the shrinkage strain of RAC to be used in conjunction with the existing fib Model Code 2010 shrinkage prediction model. For this purpose, a database of experimental results on the shrinkage of RAC and companion natural aggregate concrete (NAC), produced with the same water-cement ratio, was compiled using strict selection criteria. Results from 19 studies entered into the database, consisting of 125 shrinkage curves (39 NAC and 86 RAC) with a total of 424 data points. A comparison of RAC and companion NAC revealed that, on average, RAC displays a larger shrinkage strain. This difference increases with increasing recycled concrete aggregate (RCA) content and with decreasing compressive strength. Applying the fib Model Code 2010 shrinkage prediction model revealed that, relative to its performance on NAC, the shrinkage strain of RAC is underestimated. Finally, a correction coefficient for the shrinkage strain of RAC, \\[\\xi _{{\\mathrm{cs}},{\\mathrm{RAC}}}\\], to be used in conjunction with the fib Model Code 2010 model, was proposed in the form of a bivariate power function with RAC compressive strength and RCA replacement ratio as variables.
Journal Article
Carbon Sequestration by Preparing Recycled Cement, Recycled Aggregates, and Recycled Concrete from Construction and Demolition (C&D) Wastes
As the world’s largest producer of construction waste, China’s recycling and related policies are of the biggest concern to the world. However, the effective disposal and reuse of this waste has become an important issue since currently China still has a very low recycling ratio compared to developed countries, and most of the waste concrete was only simply broken and used as low-grade recycled aggregates for subgrade cushion, cement stabilized crushed stone, and filler wall. In this paper, a concrete cycle model focusing on how to effectively recycle and utilize waste concrete is put forward to prepare high quality recycled concrete, especially through a series of technical means, such as effective separation, carbon sequestration, and reactivation. Producing high quality recycled concrete can not only replace traditional concrete but also effectively reduce the consumption and waste of raw materials. What’s more, the calculation results show a potential of significantly carbon sink; for every ton of recycled cement produced, the CO2 emission could be reduced by 0.35–0.77 tons compared to ordinary Portland cement, corresponding to a reduction of 47%–94%; and for every ton of recycled concrete produced, the CO2 emission could be reduced by 0.186 tons compared to normal concrete. A yearly CO2 sequestration of 1.4–3.08 gigatonnes could happen if the ordinary Portland cement could be replaced by the recycled cement around the world. Taking the currently accumulated construction and demolition (C&D) wastes globally, the production of recycled cement, recycled aggregates, and recycled concrete could induce a significant carbon sink in the world.
Journal Article