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2021 | Book

Proceedings of the 3rd RILEM Spring Convention and Conference (RSCC 2020)

Volume 4: Shift to a Circular Economy

Editors: Dr. Vítor M.C.F. Cunha, Dr. Mohammadali Rezazadeh, Dr. Chandan Gowda

Publisher: Springer International Publishing

Book Series : RILEM Bookseries


About this book

This book gathers peer-reviewed contributions presented at the 3rd RILEM Spring Convention and Conference, held at Guimarães and hosted by the University of Minho, Portugal, on March 9-14, 2020. The theme of the Conference was “Ambitioning a Sustainable Future for Built Environment: comprehensive strategies for unprecedented challenges”, which was aimed at discussing current challenges and impacts of the built environment on sustainability. The present volume is dedicated to the topic “Shift to a circular economy”, which is focussed on sustainability and covers the research and recent technologies on the use and development of sustainable materials and structural systems, as well as on recycling and reusing. It also covers the implementation of industrial processes leading to minimized waste, including digital fabrication and deconstruction, as well as integrative approaches that lead to the achievement of the concept of circular economy. Additionally, this topic covers research on novel or existing construction materials and systems based on local resources and regional practices. The following subtopics are included: industrialized construction systems minimizing waste; recycling and reuse of materials and components; 4Ls: local constructions with local materials through local approaches for local development; Digital Manufacturing; design for deconstruction; smart demolition techniques; timber structures; Life-Cycle Assessment of construction materials and technologies; recycling of pavements and materials in roads.

Table of Contents

Circular CO2 Utilization Strategies for More Sustainable Concrete
The sustainability goals of the cement and concrete industry cannot be met by simple improvements to process efficiencies but instead demand innovative solutions. New processes have been developed to reduce the carbon footprint of ready mixed concrete through CO2 utilization strategies concerning three components: binder, water and aggregates. The injection of an optimized dose of waste carbon dioxide into concrete reacts with the cement binder to form in-situ nanoscale calcium carbonate particles that can improve the compressive strength of the mix. The increased cement efficiency allows the concrete to be produced with less cement thereby realizing a GHG benefit through both the mineralized CO2 and the avoided cement CO2 emissions. Concrete wash water, a by-product of concrete production that is typically a waste stream and a challenge to reuse, can be treated with carbon dioxide. The CO2 is mineralized in a reaction with the waste cement suspended in the slurry. The treated slurry can more readily be used as mix water in a new concrete batch. The performance benefit of using the recycled slurry, in particular the cementitious nature of the treated wash water solids, allows for a cement reduction. Finally, the performance of recycled concrete aggregate can be improved through a carbon dioxide treatment. The carbon dioxide reacts with the hydrated cement paste component of the crushed concrete to form CaCO3. A combination of the three strategies can realize a net carbon benefit of around 76.9 kg per m3 of concrete including recycling of 50.3 kg of CO2.
Sean Monkman, Mike Thomas
Use of Waste Calcium Carbonate in Sustainable Cement
The quest for a new-generation concrete, designed to be compatible with the need of mitigating the effect of greenhouse gas emissions on the climate, has prompted applied research to define a broad range of low-CO2 cement-based materials. While minimizing CO2 emissions is a goal of the utmost importance, research into sustainable building materials must also tackle the issue of raw material depletion (including limestone, clay and aggregate deposits, as well as water resources) in favor of secondary raw materials. One possible solution is that of minimizing the impact of quarrying by a circular economy approach that envisages the reuse of waste from stone extraction and processing. It is estimated that 200 Mt waste are produced by the stone industry worldwide each year. This includes slurries obtained from the quarrying, cutting and polishing of marble, which can be used as a source of calcium carbonate, alternative to primary limestone. This contribution illustrates the use of waste calcium carbonate, obtained from marble slurry (waste marble, WM), in sustainable cement materials alternative to Portland cement. The possibility of exploiting locally available resources is explored, and the effect of WM additions up to 50% by total mass on the macroscopic properties is investigated experimentally. It is shown that binders with adequate fresh and hardened state properties can be obtained by moderate additions of WM, which greatly enhances the environmental performance by reducing the amount of primary resources used in the mix. By reducing the amount of thermally treated clay in alkali-activated blends, the use of WM also results in a net decrease of the embodied energy.
Luca Valentini, Ludovico Mascarin, Hassan Ez-zaki, Mark Bediako, Joseph Mwiti Marangu, Maurizio Bellotto
Classification of Recycled Aggregates Using Deep Learning
The European Union is promoting sustainable development and circular economy by inciting its member states to recycle at least 70% of their construction and demolition waste (CDW) through the Horizon 2020 programme. CDW is crushed in order to obtain recycled aggregates (RA). The latter are a mixture of recycled concrete aggregates, natural stones, clay bricks, bituminous grains and with other materials (e.g. glass, wood and steel). The composition of RA is variable and in order to determine it, the NF EN 933-11 standard recommends manual sorting. However, it is time-consuming and it is performed only occasionally on recycling plants. Our work focuses on the development of a novel method to determine the composition of RA faster and in an automated way. It makes use of deep learning, particularly convolutional neural networks (CNN). CNNs can analyse images of RA and identify the nature of every aggregate in order to give the composition of the RA instantly. A labelled database was created for learning of the CNNs. It consists of approximately 36,000 images of individual grains classified according to their nature. The best-performing CNN is now able to identify correctly the class (i.e. the nature) of 97% of aggregates present on a picture of RA. Moreover, we proposed a method to evaluate the mass of the grains by assuming that those of a given nature have a constant form and density. We are also working on the automatic extraction of the grains from a picture of RA using Mask R-CNN.
Jean David Lau Hiu Hoong, Jérôme Lux, Pierre-Yves Mahieux, Philippe Turcry, Abdelkarim Aït-Mokhtar
Performance and Ageing Evaluation of Bituminous Mixtures with High RAP Content
The implementation of a circular economy implies turning waste into resources, avoiding its disposal in landfills and minimizing the extraction of raw materials. Every year, a considerable amount of Reclaimed Asphalt Pavement (RAP) is generated, as the road network requires pavement maintenance to ensure the safety and comfort of the users. RAP contains both constituents of a bituminous mixture (bitumen and aggregates), and is 100% recyclable, therefore being able to be re-introduced back into the cycle without its use being downgraded. However, RAP is currently being employed solely as an aggregate in unbound layers or in small percentages in new bituminous mixtures, rather than taking advantage of the aged bitumen. This paper presents a study which aimed to evaluate the performance of a surface dense-graded hot bituminous mixture before and after being subjected to an ageing procedure. The bituminous mixture containing a high RAP content—75%—was treated with a commercial vegetable rejuvenator. Short Term Oven Ageing (STOA) and Long Term Oven Ageing (LTOA) procedures were used to simulate the ageing that occurs during the mixture’s production and service life, respectively. The evaluation of the recycled bituminous mixture’s performance was based on stiffness, fatigue resistance, and permanent deformation tests carried out in the laboratory. In comparison with a conventional bituminous mixture, it was found that, in general, the recycled bituminous mixture, before and after ageing, showed higher stiffness and resistance to permanent deformation, yet had very similar fatigue resistance.
C. Santos, V. Antunes, J. Neves, A. C. Freire
Strength and Microstructure Development of Fly Ash Geopolymer Binders Using Waste Glass Powder
This study investigated the effect of using waste glass powder (GP) as partial replacement of fly ash on the strength and microstructure development of geopolmer binders. GP was used at different rates varying from 1 to 5% mass of fly ash and 8 molar NaOH solution was used as the activator. Geopolymer paste specimens of 50 mm cube were heat cured at 80 °C for the first 24 h after casting and then left in ambient conditions. The 28-day compressive strength of the fly ash geopolymer without GP was 23 MPa. The inclusion of 2% GP improved the 28-day compressive strength of heat cured fly ash geopolymer by 18%. This is attributed to the increment of soluble silica from the GP. However, compressive strength declined with further increase of GP content beyond 2%. The decline of strength is attributed to the presence of excess unreacted GP particles. X-ray diffraction (XRD) analysis indicated that the presence of higher amount of crystalline Na-type chabazite and zeolite phases for using 2% GP. Scanning electron microscopy (SEM) images showed denser microstructure of geopolymers containing 1–2% GP. The elemental composition of gel formed in these binders consisted of higher percentages of Si, Al and Na, which indicates the formation of higher amount of sodium aluminosilicate gel (N–A–S–H).
Md. Nabi Newaz Khan, Jhutan Chandra Kuri, Prabir Kumar Sarker
The Influence of Polymers Impregnation on Bending Behaviour of Phyllostachys pubescens (Mosso) Bamboo
As the consumption of natural resources in today's industrialized society is increasing and the supply of these resources tends to deplete, the search for alternative and environmentally friendly raw materials becomes mandatory. Bamboo is a very abundant resource and presents short growth, carbon sequestration ability, easy processing and good mechanical properties. However, bamboo is hygroscopic material and presents functional gradation of properties along the culm wall thickness. Cracks may occur in bamboo’s wall as a consequence of a radial moisture gradient, that generate stress perpendicularly to natural fiber alignment, and this occurrence may compromise the durability and structural performance of the material. Aiming to minimize these shortcomings and to enhance physical properties, different polymers were used to impregnate samples of Phyllostachys pubescens bamboo through immersion: styrene butadiene rubber (SBR), carboxylated styrene butadiene rubber (XSBR) and polyvinyl alcohol (PVOH). Three temperatures of impregnation were investigated (23, 60 and 100 ºC, and the most effective in relation to polymer penetration and retention was identified. Results of water absorption tests showed that PVOH resulted in better physical behaviour and smaller water absorption values, compared with non impregnated samples. Three-points bending test was carried out employing samples with 20 × 2 × 0.5 cm. The samples were extracted from the internodes of the middle portion of a 3 years old culms. The obtained parameters (bending strength, stiffness and toughness) were compared among the 4 conditions (plain, SBR, XSBR, PVOH) in order to understand how the impregnation process affected the mechanical performance under bending loads.
Lucas Muniz Valani, Fabrício de Campos Vitorino, Adriana Paiva de Souza Martins, Romildo Dias Toledo Filho
Recovering of Clinker Minerals from Hydrated Portland Cement Paste
Recycling of concrete construction and demolition waste is necessary for the increase of sustainability and reducing the environmental impact of concrete construction because of the increasing rate of such waste production and its accumulation. Coarse aggregates can be partially recovered from concrete waste. However, it is not clear whether hydrated cement paste can be converted back to clinker. However, concrete waste fines, which are a mix of fine aggregates, coarse aggregate debris, and the hydrated cement paste, are currently not a part of the recycling process. The ability of hydrated cement paste to be recovered back to clinker minerals that have binder properties has not been studied systematically. In the current research, the phase transitions in hydrated cement paste heated to a temperature in the range from 600 and 1450 °C were investigated by means of X-ray diffractometry and thermal analysis. The experimental results demonstrate that hydrated Portland cement paste can be recovered back to clinker minerals. The recovered cement paste contains all the main clinker minerals similarly to the initial cement. The results provide evidence for the possibility of recycling hydrated cement and concrete into the cement clinker. The recycled clinker will potentially have a lower carbon footprint in comparison to original Portland cement.
Semion Zhutovsky, Andrei Shishkin
Recycling of Slightly Contaminated Demolition Waste—Part 2: PAH
For the purposes of environmental protection, resource efficiency and to foster a sustainable development it is advisable to recycle also slightly contaminated CDW and keep it from ending up in landfills. A high-quality option is the use as aggregate for concretes (RCA). In doing so, it must be guaranteed, that no harms for health and environment are caused by potential emissions. The use of crushed demolition waste as a concrete aggregate is technically state-of-the-art. Investigations on the leaching behaviour of recycled concrete showed a good integration of inorganic contaminants. However, PAH were found to be leached in noticeable amounts even for moderately contaminated CDW, complying with the German threshold of 25 mg/kg for RCA. For this contribution different test specimens, containing moderately PAH-contaminated aggregates, were tested in leaching tests following DIN CEN/TS 16637-2. The results were evaluated according to the current German evaluation procedure and compared to limit values for PAH in groundwater. PAH leaching from concrete proved to be a relevant issue, the permitted release of 0.22 mg/m2 and therefore the threshold for groundwater was exceeded in many cases. The PAH content of the recycled aggregate was no suitable indicator for an environmental compatible concrete, the most determining factor, besides the total aggregate amount added, is the contaminated fines share.
Lia Weiler, Anya Vollpracht
Recycling of Slightly Contaminated Demolition Waste—Part 1: Inorganic Constituents
Due to the high amount of construction and demolition waste (CDW) generated, the recycling and reuse of these materials is an important factor for the sustainability of the whole building sector. The use of CDW as recycled aggregate is a high-quality recovery; however, contaminations that may emerge during the service life of a building, have to be considered. Part 1 of this publication deals with inorganic contaminants. Within a large research project numerous CDW samples from a commercial recycling plant were investigated in granular form. Selected samples were used as aggregates and the leaching of the resulting concretes was tested. In addition a doped concrete was tested to simulate a higher degree of contamination. The results show, that inorganic compounds are well bound in the concrete. The German limit values for the leaching of unbound CDW guaranty a save use, however there is no direct correlation between the leaching of unbound CDW and concrete with CDW aggregate, because the leaching of concrete is dominated by the binder.
Anya Vollpracht, Lia Weiler
Processed Municipal Solid Waste Incineration Ashes as Sustainable Binder for Concrete Products
After proper pre-treatment procedures, Municipal Solid Waste Incineration (MSWI) bottom ashes show all needed characteristics to substitute part of the Portland clinker in concrete. The use of these ashes greatly contributes to the establishment of a circular economy. As a by-product of waste-to-energy plants, they are abundantly and locally available. Ashes currently available after proprietary pre-treatment procedures contain elemental aluminium that deters their usability as supplementary cementitious material. An efficient pre-treatment option that is low-cost and avoids secondary pollution was recently proposed to remove elemental aluminium from ashes. This method consists of slow grinding and sieving, resulting in aluminium and other metals remaining in the coarse fraction facilitating their removal. In this research, the use of pre-treated Processed Incineration Ashes (PIA) in concrete was investigated. A concrete mix with replacement of 20% of the Portland cement CEM I 52.5 R by PIA was optimised to show similar compressive strength at 28 days to the CEM I 52.5 N reference, and even at 90 days compressive strength was 20% higher than for the CEM I reference concrete. Furthermore, equivalent performance with the benchmark concrete was found for the tested durability properties (open porosity, carbonation). Also leaching tests were performed to assess the potential use of PIA in the construction industry. Results provide evidence of the good overall performance of the PIA concrete.
Aneeta Mary Joseph, Natalia Alderete, Stijn Matthys, Nele De Belie
Autogenous Shrinkage in Structural Concrete Made with Recycled Concrete Aggregates
Sustainable alternatives should be employed in the construction industry to minimize environmental impacts, including high consumption of natural resources and high waste generation. The recycling of waste to be used as aggregates for concrete is an alternative with great potential. Although many studies have been carried out to investigate the influence of the use of Recycled Concrete Aggregates (RCAs) on the mechanical properties of concrete, the relationship between the intrinsic properties of aggregates and the main types of long-term deformation of Recycled Aggregate Concrete (RAC) still needs to be better understood. As a matter of the principle, autogenous shrinkage can cause significant damage to concrete structures, mainly due to the induction of cracking that can impair the durability of the structure. In this context, the present paper presents the preliminary results of an experimental investigation aimed at evaluating the influence of RCAs on the autogenous shrinkage of normal and high strength RACs (35 and 60 MPa). The RCA were derived from demolition concrete waste and used in a 9.5–19 mm particle size fraction. In addition, the concepts of scientific mix-design for the optimization of dry granular mixture were utilized through the Compressible Packing Model (CPM).
Mayara Amario, Caroline S. Rangel, Marco Pepe, Enzo Martinelli, Romildo D. Toledo Filho
Circular Economic Modelling—Barriers and Challenges Throughout the Value Circle
The transition from a linear to a circular economy is a process that has already started throughout our societies as one important strategy to reduce CO2 emissions and by decoupling the use of natural resources, materials and fossil fuels from economic activity. Using examples from the Construction Industry, this paper argues that key premises must be present for circularity to happen. The business case at each level of the value circle must be viable. New building standards backed up by adequate policy measures, e.g. green public procurement, CO2 and virgin materials taxation is likely to be required. Finally, securing future supply of secondary raw materials (SRM) must be demonstrated and adequate supply chains of SRM to emerge.
Birgitte Holt Andersen, Giovanni Salvetti, Anastasija Komkova
Development of Sustainable Perspective of Carbon Fibers Recycling and Reusing for Construction Materials
The development of sustainable methods is a demanding challenge posed by Global civilizations for improving the life quality in many ways. A key role in achieving sustainability goals could be the implementation of the new building materials models for the future environmental requirements. The presented process deals with the recycling of carbon fibers wastes deriving from automotive industry and the reusing within a building system, increasing in value the approach of circular economy and providing a solution to many negative economic and environmental impacts. To quantify potential benefits, in this work the behavior of cement-matrix composites containing short carbon fibers is described. An experimental campaign, starting from a specific surface treatment of the “pre peg” composite material sheets and an accurate study of the dimensional distribution of the carbon fibers, is presented. The aim is the evaluation of the influence of the percentage and length of fibers usage on the mechanical performance of cement based carbon fibers-reinforced mortars, following different approaches of mixture. The results show a good increase in stiffness and in flexural strength up to 11% and 20% respectively, for the samples characterized by fibers in percentage of 6.4% by volume of mixture and of 2–5 mm length and by a reduced amount of cement. A strong connection between the mixture workability and fibers size is observed. Finally, the assessment of the entire life cycle of the product is discussed for quantifying effective environmental impacts.
R. Napolitano, P. Vitale, C. Menna, D. Asprone
Optimization of Alkali-Activated Mineral Wool Mixture for Panel Production
A significant amount of mineral wool waste is generated during the construction and demolition of buildings. At the moment, most of this material ends up in a landfill without further utilization. Alkali activation is one technology already recognized to produce low carbon dioxide binders and other products/materials from several industrial by-products, and could also be employed to recycle mineral wool waste. This study shows the result of milling and homogenization of different types of wool waste and their subsequent use as precursors in the alkali-activation process. Two different types of mineral wool waste were taken from the mining company Termit (Slovenia). Stone and glass wool were milled, pulverized and sieved below 63 μm. After homogenization, different alkali-activated pastes were prepared using two different alkali activators (NaOH and/or Na–water glass). The compressive and flexural strength of each alkali-activated material was measured, showing higher values for glass wool in comparison to stone wool. In addition, different curing temperatures were assessed (room temperature and 40 °C). The compressive and flexural strength of glass wool after three days at 40 °C was 34.7 and 8.7 MPa respectively, compared to values of 29.1 and 9.3 MPa for stone wool. After 3 days at room temperature, the strengths were not measurable, however, after 28 days the respective compressive and flexural strength were 29.9 and 14.4 MPa in the case of glass wool, and 40.6 and 14.9 MPa for stone wool.
Majda Pavlin, Ana Frankovič, Barbara Horvat, Vilma Ducman
Suitability of Different Stabilizing Agents in Alkali-Activated Fly-Ash Based Foams
Alkali-activated foams (AAFs) are inorganic materials produced from aluminosilicate sources, such as fly-ash and metallurgical slag or clay, which contain air voids in their matrices. One possible route to the pore-forming process is chemical foaming through the use of a blowing agent such as hydrogen peroxide. Gaseous products (e.g. O2) are formed during this process and then become trapped in a solidified structure during the hardening stage. In order to avoid the collapse of pores during this process various stabilizing agents (surfactants), such as sodium oleate, sodium dodecyl sulfate (both anionic surfactants), and Triton X 100 (nonionic surfactant), are also added to the mixture. In the present study, the AAFs were formed using fly-ash from a Slovenian thermal plant and H2O2 as a foaming agent. The air voids were stabilized through the addition of three different surfactants: sodium oleate, sodium dodecyl sulfate, and Triton. The effects of different quantities of foaming and stabilizing agents and different types of stabilizing agents on the mechanical properties and microstructure of foams were investigated.
Katja Traven, Mark Češnovar, Vilma Ducman
Influence of Specific SCM on Microstructure and Early Strength of Sustainable Cement Blends
Blended binders combining different hydraulically active materials and inert fillers, have a high potential to improve sustainability of cement and concrete. In this study a portion of ordinary Portland cement (OPC) up to 40 wt.% was replaced by supplementary cementitious material (SCM): two limestone powders (LSP) of different fineness and ground granulated blast furnace slag (GGBFS). Their influence on microstructure and strength development and of blended formulations is presented. While strength development was assessed by compressive strength measurements up to three months, the effects on microstructure were investigated by Mercury intrusion porosimetry and air permeability measurements. The results show that refinement of pore size distribution and altered capillary porosity is strongly influenced by both, the ratio of water to total binder content (w/b) and of water to hydraulically effective portion of binder (w/bhy) related to the effects of combined SCMs. Significantly higher strength gains (between 1st to 28th and 1st to 91st day) of blended mixes were found due to joint contribution of latent-hydraulic reaction of GGBFS and strength accelerating “filler-effect” of inert LSP. Sole influence of inert fillers was found to be significantly higher in case of lower w/b (water content per volume) due to increased packing density.
O. Rudic, J. Juhart, J. Tritthart, M. Krüger
Affecting Factors in Rehabilitating Water Distribution Networks
High levels of non-revenue water (NRW) reflect that an area’s water distribution networks (WDN) are losing vast volumes of clean water. Therefore, reducing NRW is crucial for sustainable water management. NRW levels in most developing countries are high, ranging between 35 and 50%. While one of the significant causes of NRW is difficulties in rehabilitating old piping networks, studies on factors that are influencing WDN rehabilitation in practice is limited. This study aims to identify affecting factors for WDN rehabilitation. To achieve that objective, a series of individual interviews with industry practitioners that manage WDN are analyzed using the thematic analysis. The major findings from the analysis are: (1) internal and external factors are influencing WDN rehabilitation; (2) internal factors are related to cost, location, and design; and (3) external factors are related to local authorities and surrounding communities. This research adds to the body of knowledge by providing a set of affecting factors for rehabilitating WDN, which can assist researchers and practitioners in developing strategies to reduce NRW for achieving sustainable water management.
Rahimi A. Rahman, Noor Suraya Romali, Siti Sarah Sufian, Mazlan Abu Seman
Success Factors for Construction Waste Recycling in Developing Countries: A Project Management Perspective
Construction industries around the world are generating a large number of wastes that end at landfills every year, and recycling is one of the approaches for minimizing that amount. While various strategies have been adopted in practice, recycling rates of construction projects are still at a low level in numerous countries. Therefore, identifying factors that influence the successful recycling of construction waste is crucial. This study identifies the success factors for recycling construction waste from industry practitioners’ perspectives. To achieve this objective, interview data with project managers are analyzed using the thematic analysis. The major findings from the analysis are: (1) the success factors relate to both people or process; (2) people-related factors involve having individuals that are highly competent, aware on construction waste recycling, and knowledgeable; (3) process-related factors include having a detailed project planning, adequate education and training programs, clear project scope and design, effective procurement system, and consistent monitoring of the construction waste recycling system; and (4) the criticality of the success factors differs between developing countries. This research adds to the body of knowledge by providing a set of success factors for recycling construction waste, which can assist researchers and practitioners in developing strategies to increase recycling rates of construction projects.
Rahimi A. Rahman, Abdulmalek K. Badraddin, Muzamir Hasan, Nor’Aini Yusof
A Proposed Methodology of Life Cycle Assessment for Hot Water Building Systems
Population growth and technological development in recent decades have made human activities largely responsible for structural changes in the built environment at regional and global levels. Civil construction, as an integral part of the chain of industrial activities, is also one of the segments responsible for energy consumption and potential greenhouse gas emissions throughout its life cycle. The building materials and their systems have a direct influence on energy consumption and impact assessment, both in the pre-operational, use and end-of-life and disposal phases. In this context, Hot Water Building Systems (HWBS) are included. The variability of possibilities available with regard to the choice of energy sources, water reserve and distribution systems and the selection of materials used in these building systems allows empowering the decision-making in the designing phase. The definition of the type of installation to be used in a building is defined by technical and/or economic requirements. However, the spectrum of possibilities should consider resource consumption and generation of environmental impacts throughout the life cycle. This research proposes a novel application of an environmental management method to empower the decision-making process and encourage the selection course of HWBS. This work insights a Life Cycle Assessment (LCA) methodology to compare a specific the environmental performance of two distinct HWBS (i.e. Natural Gas Heating System and Solar Heating System) for multi-family residential developments.
Arthur B. Silva, Mohammad K. Najjar, Ahmed W. A. Hammad, Assed N. Haddad, Elaine G. Vazquez
Screening Regionally Available Natural Resources and Waste Streams as Potential Supplementary Cementitious Material
The usage of industrial by-products and natural resources has already been acknowledged as a viable option for lowering the CO2 emissions in cement production. The utilization of locally available materials as supplementary cementitious material (SCM) presents an opportunity to produce more sustainable cements that could satisfy the growing concrete demand. However, the composition of these materials is origin related and can differ from region to region. For that reason, this study correlates the physical and chemical properties of local materials with their mechanical performance when used as SCM. Twelve different samples were collected: three slags, two fly ashes, one silica fume, and six clays. The R3 reactivity test was performed together with compressive strength tests on mortars after 2, 7 and 28 days. Finally, the paper presents the most suitable materials prioritising the results according to the obtained data. With the screening approach, this research brings attention to the key parameters that are vital for preliminary SCM identification.
Matea Flegar, Marijana Serdar, Diana Londono-Zuluaga, Karen Scrivener
Thermal Performance of Compressed Blocks Made from Construction and Polyurethane Foam Waste
It is intended with the research work here presented to contribute to the scientific knowledge regarding the incorporation of C&D and polyurethane foam wastes in compressed blocks. Two mixtures were defined considering the percentages of 2.5 and 5% of polyurethane foam waste. Fly ash was used as a precursor and the two mixtures were activated with a solution based on sodium hydroxide and sodium silicate. Experimental work was carried out to assess the blocks thermal performance. Experimental measurements allowed determining indoor and outdoor temperatures, heat flux and inner surface temperatures. The data acquired allowed to estimate the values of the thermal transmission coefficient. It was concluded that an increase in the percentage of polyurethane foam waste in the composition leads to an improvement of the thermal behaviour. Values of 2.93 and 2.57 W/m2 °C were estimated for the percentages of 2.5 and 5%, respectively, presenting higher values of thermal resistance when compared with a common solution of ceramic solid block with the same dimensions.
A. Briga-Sá, V. Neiva, D. Leitão, T. Miranda, N. Cristelo
A Short Review of Researches on Mechanical Properties of Traditional Chinese Timber Joints: From Experimental Aspect
Mortise-tenon joints play important roles in Chinese traditional timber structures. In fact, all the researchers in the field of timber building heritage protection have ever conducted investigations to acquire the mechanical properties. However, the seemingly overwhelming FE simulation and theoretical methods are ideal calculations, depending highly on many assumptions and the reliability of the adopted material model, which make them hard to consider the real configurations and stress state of the joints in tests and practical timber engineering. The other hand, most tests were carried out by different researchers according to various standards, with many uncertain factors, which makes the results loss their mutual comparability. Thus related testing and analytical results are merely limited in the research stage, and cannot be smoothly put into application. This dilemma faced in this field must be broken to favor further researches and applications. Some resent voice comes towards a more comprehensive and accurate testing protocols of timber joints, which would definitely be helpful to reach a mutually obeyed standard. In this paper, the authors attempt from experimental aspect to discuss part of the existing investigations conducted on traditional Chinese mortise-tenon joints. Useful information such as adopted wood materials (species, density, moisture content, etc.), model dimensions (size effects), test measuring setups, loading methods and related operations, testing results analysis methods, etc. are summarized and compared. Some future research efforts are proposed. Related content will provide favorable reference for the future researching and testing activities of both traditional and modern type timber joints.
Lipeng Zhang, Qifang Xie
The Effect of Recycled Fine Aggregate Sourced from Construction and Demolition Waste on the Properties of Epoxy Resin Coatings
Worldwide development is currently accompanied with a fast growing construction industry that is responsible for generating the highest amount of wastes in the European Union (EU). On the other hand, the extraction of natural aggregate is also high, with sand and gravel extraction coming out on top, generating a huge amount of pollutants. This extraction has a negative influence on the environment and does not provide a renewable material. In some countries, this resource is almost finished. By 2020 the majority of the EU countries want to achieve at least 50% recycling of construction and demolition waste due to its negative impact on the environment. Thus, the main aim of this article is to analyze the impact of sustainable utilization of the recycled fine aggregate (RFA), as a substitute for ordinary fine aggregate (OFA; river sand), which was used as an extender in epoxy resin coatings, on the properties of the epoxy resin coating. For that purpose, samples with different partial substitution of the OFA with RFA: 0, 20, 40, 60, 80 and 100% were prepared and macro tests for pull-off strength were performed. Based on the obtained results, it can be concluded that RFA has a beneficial impact on the pull-off strength of the epoxy resin coating. The summary evaluation of mechanical performance shows that substitution of RFA by OFA in epoxy resin coatings has visible impact on reduction of dispersion of strength results. The coating modified with RFA wastes become more homogenous material in comparison to the specimens with OFA.
Kamil Krzywiński, Łukasz Sadowski
Performance Evaluation of Warm Recycled Surface Mixtures with Steel Slag
Development of sustainable asphalt mixtures for implementation during the life cycle stages of road pavements is of supreme importance for minimizing the environmental burdens. To this aim, recycling and reuse techniques offer significant benefits in terms of resource conservation and emission reduction. Also, reduction in production temperature of asphalt mixtures by means of warm mix asphalt (WMA) technology results in reduced emissions, fuel usage and binder oxidation, and hence may boost further the environmental but also economic benefits. This study investigates the performance of surface course mixtures designed with various contents of reclaimed asphalt (RA) and EAF steel slag aggregates, and produced at reduced temperatures by using organic additives. Performance evaluation of warm recycled surface mixtures focused on stiffness and durability. The test results are discussed to address whether the concurrent use of WMA and recycled/solid waste materials is feasible in developing asphalt mixtures with high level of performance.
P. Georgiou, A. Loizos
Sustainable Polyurethane Plasterboard for Construction
The introduction of polyurethane waste from the production of cars into gypsum plasterboards in its matrix is studied. This new plasterboard is compared to commercial gypsum plasterboard; therefore, the doses and the uses of both materials are the same. The prefabricated material is entirely characterized under the Standard EN 520:2005+A1 by the following tests: bulk density, maximum breaking load under flexion stress, total water absorption and surface hardness. The results indicate that the use of polyurethane waste makes the plasterboard lighter as the density of the polyurethane is lower than the gypsum one. The water absorption increased when the amount of residue increased. The lower density leads to a higher porosity, what permits a higher absorption of water and much better thermal isolation. It also reduces its mechanical performance while preventing the board from breaking since only small cracks appear. Besides, the elastic properties of the polyurethane make the surface hardness decrease. With respect to mechanical properties, plasterboard is susceptible to the mechanical impact damage. Although the flexural strength of the plaster specimens decrease as the amount of the waste increase, it remains within the minimum reference value required by standard. Non-combustibility test is determinate on the basis of experimental data obtained according to Standard EN 13501-1. Turning waste into a resource is one key to a circular economy, the employ of this polyurethane waste for the fabrication of plasterboards could contribute to maximize the reuse of this kind of waste.
Víctor Miguel, Carlos Junco, Sara Gutiérrez, Lourdes Alameda, Alba Rodrigo
Treated Municipal Solid Waste (Biomass) Based Concrete Properties—Part II: Experimental Program
Municipal Solid Waste (MSW) management is a worldwide problem growing proportionally the earth human population. The practice of incinerating garbage has ceased in some parts of the world because of air contamination and other public health issues. Environmental impact of landfilling is ever increasing. There is clearly a need to adopt cost-effective alternatives to treat MSW. This paper is a part of a major work that considers MSW based biomass as a partial replacement of sand in concrete. The product is an exciting and eco-friendly alternative for the building industry. Here, in this paper, compressive and flexural tests are conducted on samples containing 5, 10 and 15% replacement of sand by biomass. Results are presented and discussed in a view to include biomass in concrete intended for certain type applications in the construction industry such as temporary works.
Massoud Sofi, Lino Maia, Junli Liu, Ylias Sabri, Annie Zhou, Tawab Frahmand, Priyan Mendis
Treated Municipal Solid Waste (Biomass) Based Concrete Properties—Part I: State of the Art
Municipal Solid Waste (MSW) management is a worldwide problem growing with the increase of global human population. The practice of incinerating garbage has ceased in some parts of the world because of air contamination and other public health issues. Environmental impact of landfilling is ever increasing. There is clearly a need to adopt cost-effective alternatives to treat MSW. This paper is a part of a major work that considers MSW based biomass as a partial replacement of sand in concrete. The product of the global work is an exciting and eco-friendly alternative for the building industry, especially concrete intended for certain types of applications in the construction industry such as temporary works. Here, in this paper, an overview of the state of the art on the topic is presented.
Massoud Sofi, Lino Maia, Junli Liu, Ylias Sabri, Zhiyuan Zhou, Tawab Frahmand, Priyan Mendis
Recovery of Phosphorous from Sewage Sludge Ash Prior to Utilization as Secondary Resource in Concrete and Bricks
Sewage sludge ash (SSA), which today is residual waste, can be separated into two resources, phosphorous and a particulate material for use in production of concrete or brick, by electrodialytic separation (EDS). Three SSAs from different sewage sludge mono-incineration plants were included in this investigation. Overall they had similar characteristics, but still the differences meant that the EDS process needs optimization for each ash type. Under the same experimental conditions, 80% P was recovered from two of the SSAs whereas only 65% was recovered from the third SSA. After EDS, the investigation points at a decrease in Ca and P may be beneficial if using the SSA-EDS in concrete. The investigation also showed that the investigated SSAs had high Fe contents, which may be problematic if used in brick production. In conclusion, the investigation points at a potential for SSA to be considered as secondary resource in the construction materials after EDS.
Lisbeth M. Ottosen, Gunvor M. Kirkelund, Pernille E. Jensen
Proceedings of the 3rd RILEM Spring Convention and Conference (RSCC 2020)
Dr. Vítor M.C.F. Cunha
Dr. Mohammadali Rezazadeh
Dr. Chandan Gowda
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