Secondary Construction Materials Research Articles

CONSTRUCTION WASTE RECYCLING ORGANIZATION

The purpose of the article is to study the global experience of organizing the collection and processing of construction and demolition waste for their reuse in construction, to determine the possibility of applying positive practices in Ukraine. In the EU, construction waste makes up more than a third of all generated waste. The components of construction and demolition waste have different resource values, but can still be easily recycled into new products or materials. The level of recycling and disposal of waste varies significantly in EU countries, ranging from less than 10% to more than 90%. With the economic development of the country, the volume of waste increases. The main obstacles that hindered the development of sustainable waste management, for example in Germany, are the lack of nationwide regulation of secondary construction materials; lack of economic incentives, when primary raw materials are presented in large quantities in most regions of Germany, and therefore they are relatively cheap compared to secondary raw materials; sanctions for violators of waste management rules are too low and not applied regularly. Ways to ensure the need to process construction waste can be the determination at the legislative level of the volume of construction waste depending on the area of the building where construction work is performed, or the cost of construction work; establishment of a direct requirement for the use of a certain percentage of products from recycled construction waste in new construction or a direct ban on landfills for construction and demolition waste that can be processed for reuse. Economic incentives, such as tax breaks or subsidies, as well as additional taxes on the use of non-recycled materials, are used to encourage companies to use secondary materials and reduce waste. The Waste Framework Directive, adopted in 2008, aims to prevent or reduce waste generation in order to transition to a circular economy and guarantee the EU's long-term competitiveness.

Spatial optimization of circular timber hubs

In the European Union, construction is responsible for 36% of CO2 emissions and 40% energy consumption. The reuse of construction materials has been receiving increasing attention, including regulations established by the European Union, and cities establishing goals to reuse construction materials. This is the case for Amsterdam, which established the goal of reusing 50% of construction materials in new construction by 2030. Part of the challenge of reuse of construction materials in urban areas is to optimize the waste-to-resource loops: finding the optimal scale and location for circular construction hubs—facilities that collect, store, and redistribute construction waste as secondary construction materials. In this paper, we use the supply and demand of timber construction materials in Amsterdam as a case study to find the optimal scale and location for construction hubs. We used the spatial simulated annealing algorithm as an optimization method for balancing the trade-off between small and large-scale hubs, using cost-effectiveness to compare potential locations and identify the optimal solution. We found that the optimal number of hubs for our study area is 29, with an average service radius of 3 km. This study has implications for policymakers, urban planners, and companies seeking to implement circular economy principles.

PARTICLE-SIZE DISTRIBUTION ASSESSMENT OF THE RECYCLED AGGREGATES FROM CONCRETE REMAINS

The reuse of the remainders of destroyed concrete structures is becoming more and more urgent problem not only in Ukraine, but also in the whole world. According to the current strategy of secondary use of resources, concrete waste is either crushed into recycled aggregate as a substitute for natural aggregate or crushed into recycled powder as a substitute for cement in mortar and concrete. The reuse of construction waste as secondary construction materials can reduce the need for natural resources for construction and free areas from accumulated construction debris. The purpose of the work is to evaluate the particle size composition of aggregates obtained from recycled concrete of waste reinforced concrete railway sleepers. To achieve the goal, the following tasks were set: to grind of sleeper waste in various ways; to determine the granulometric composition of coarse and fine aggregates; compare the obtained data with the standard requirements for concrete aggregates. Destroyed reinforced concrete railway sleepers were used as material for research. After removing the reinforcement, the sleeper parts were first loaded into a jaw crusher with a fixed distance between the working plates at 20 mm. The obtained material was reloaded into a drum mill and grinded for 30 minutes. After that, the mixture was unloaded on a standard set of sieves to determine the particle size distribution. As a result of an experimental study of crushed waste of reinforced concrete sleepers, the following was established. The granulometric composition of particles larger than 5 mm meet the requirements for coarse aggregates to produce concrete mixtures. Fractions with particle sizes less than 5 mm are very fine with a fineness modulus at 0.9 which does not meet the requirements for fine aggregates to produce concrete mixtures. Further research will be aimed at studying other properties that determine the possibility of using aggregates for reuse in concrete mixes, namely moisture content, average density, compressive strength, etc. Also, the ways for usage of fine fractions as fillers will be search for other building materials in order to dispose of crushed concrete waste.

Integrating bottom-up building stock model with logistics networks to support the site selection of circular construction hub

The circular construction hub is a logistics point for the storage, processing, and distribution of secondary construction materials. However, its site selection is dampened by the lack of detailed spatial information on material flows. In this study, the quantities and the spatial distribution of material flows are projected using a bottom-up building stock model. The material flows are integrated with logistics networks to assess the environmental impact of transporting materials between the building stock and the circular construction hub. The model is demonstrated on the building stock of Leiden, a municipality in the Netherlands. The results show that the location of future construction and demolition activities has a major impact on transportation carbon emissions. As construction decreases and demolition increases, the relative share of transportation carbon emissions from recycling will increase. The comparison between the two candidate sites for the circular construction hub is made to select the site with lower total transportation carbon emissions. By considering the evolution of building stock, the model can help urban planners make a more comprehensive decision on the location of the circular construction hub.

Blockchain Enhanced Construction Waste Information Management: A Conceptual Framework

Despite the large quantities of secondary materials flowing within the built environment, their actual volume and respective waste management processes are not accurately known and recorded. Consequently, various sustainability and material efficiency policies are not supported by accurate data and information-reporting associated with secondary materials’ availability and sourcing. Many recent studies have shown that the integration of digital technologies such as city information management (CIM), building information modeling (BIM), and blockchain have the potential to enhance construction waste management (CWM) by classifying recycled materials and creating value from waste. However, there is insufficient guidance to address the challenges during the process of CWM. Therefore, the research reported in this paper aims to develop a blockchain-enhanced construction waste information management conceptual framework (BeCW). This paper is the first attempt to apply the strengths of integrated information-management modeling with blockchain to optimize the process of CWM, which includes a WasteChain for providing a unified and trustworthy credit system for evaluating construction-waste-recyclability to stakeholders. This is enabled through the use of blockchain and self-executing smart contracts to clarify the responsibility and ownership of the relevant stakeholders. As a result, this study provides a unified and explicit framework for referencing which quantifies the value-contribution of stakeholders to waste-recovery and the optimization of secondary construction materials for reuse and recycling. It also addresses the issue of sustainable CWM through information exchange at four levels: user, application, service, and infrastructure data levels.

The use of urban biowaste and excavated soil in the construction sector: A literature review

Soil has been used as building material for thousands of years with a decrease in popularity after the industrial revolution. Nowadays, there is a growing interest in the implementation of unfired soil-based building solutions for their low environmental impact, performances and availability. Traditional soil construction techniques have recurrently included vegetal fibres to enhance soil performance and recent studies highlight a predominant use of agro- and non-agro-waste for unfired soil construction. The article reviews the state-of-the-art of the use of excavated soil and biowaste in the construction industry including a novel focus on urban-only waste and on building technologies using the integration of these two secondary construction material flows. Our literature review highlights a lack of references about the joint use of these secondary resources. Finally, future research orientations are suggested to promote their implementation in the building sector, which could improve urban waste management.

Stocks and flows of buildings: Analysis of existing, demolished, and constructed buildings in Tampere, Finland, 2000–2018

AbstractResearch has identified cities as potential urban mines for recovering secondary construction materials. Studies typically focus on stocks or flows of bulk materials on high abstraction levels. To enable a shift of focus toward higher levels of circular economy, such as waste minimization, there is a need for a more detailed understanding of the dynamics that contribute to the waste flows, building replacement in particular. This paper examines the characteristics and location of the stocks and flows of buildings, both residential and non‐residential, in the city of Tampere, Finland, over the last 20 years. Statistical and geographical analyses are performed on the building stock, new construction, and demolition in Tampere to unveil patterns pertaining to stock change and building replacement. The study shows that these patterns vary significantly between buildings of different function. Spatially confined redevelopment areas within the city structure, that is, brownfields and grayfields, whose industrial and commercial functions yield to housing and mixed residential–commercial use, make up major arenas for replacement. Policy‐making should acknowledge that urban planning stirs these waste flows and incorporate their conscious prevention and management on its agenda.

Aiming for life cycle sustainability assessment of cement‐based composites: A trend study for wall systems of carbon concrete: Dresden Nexus Conference 2020—Session 4—Circular economy for building with secondary construction materials to minimise resource use and land use

AbstractThe narrative sustainable building is core message of European politics. Strategies discussed in this regard concern above all material minimization by using new more efficient manufacturing technologies, new form finding approaches for load‐bearing structures or new high‐performance materials. The goal of the research project V2.10, funded by the German Federal Ministry of Education and Research, refers to the latter by assessing the sustainability potential of building components made of innovative textile reinforced concrete. We conceptualized a life cycle sustainability assessment framework and applied it to variants of sandwich wall systems made of carbon concrete composites and steel‐reinforced concrete. Results indicate hotspots in technology and material choices that could be addressed by circular strategies, for example, refuse, reduce or recycling. Overall, one design variant made of carbon concrete composites is the best performing with respect to all dimensions of sustainability.

Identification and Quantification of Chemical Forms of Cu and Zn in MSWI Ashes Using XANES

Incineration is in many countries a common treatment method for municipal solid waste, and utilization of the ash residues has attracted significant interest. The bottom ash is best suited as a secondary construction material, whereas the fly ash is being investigated as a secondary raw material for recovery of, for example, Zn, Cu, and salts. For both types of application, knowledge about the chemical speciation of Zn and Cu in the ashes is valuable. The present work focuses on identifying and quantifying the chemical species of Zn and Cu in 12 samples of fly ash and bottom ash from three waste-to-energy plants using X-ray absorption near edge structure (XANES). The XANES spectra of the ash samples showed similar distinctive features, and both in the bottom and fly ash samples, the same chemical forms were identified but in various ratios. Cu and Zn occurred in several chemical forms, with typically 5-7 forms present in the same sample. For Cu, the XANES spectra of the fly ash samples were nearly identical, indicating very similar chemical speciation (same chemical forms and similar ratios). Cu was found to exist in various oxide, hydroxide, chloride, silicate, and metallic forms. The most commonly occurring Zn compounds were the aluminate, ferrite, silicate, and oxide along with chloride, basic carbonate (hydrozincite), and occasionally metallic forms, probably alloyed with Cu in brass. Cu occurred in different oxidation states from zero to +II, with a higher prevalence of the lower oxidation states in bottom ash than in fly ash. Zn occurred mainly in oxidation state +II in all ashes analyzed. Finally, we showed that during outdoor storage of bottom ash, levels of Cu and Zn hydroxycarbonates were increased compared to fresh bottom ash. This carbonate formation aims to make Cu and Zn less leachable.

Influence of water and frost on the performance of natural and recycled materials used in unpaved roads and road shoulders

Abstract In recent years, recycled materials from construction and demolition waste (C&D materials) have gained ever more importance as secondary construction materials in civil engineering, especially for road construction purposes. Their use in high-grade applications is an important contribution to a circular economy. However, from a technical viewpoint, reservations remain about the use of such materials. Such reservations typically concern their performance when exposed to water and frost. The aim of this study was to evaluate the field performance of unbound mixed C&D materials used in surface applications like road shoulders or unpaved roads and exposed to the weather conditions of central Europe and to compare the mixed C&D material with two natural reference materials. Two mixed C&D materials and two natural reference materials were field compacted and exposed to the weather during the winter of 2017/2018 and early summer of 2018. The parameters monitored during the period of observation were dry density, stiffness and particle breakdown due to weathering. The results highlight the possible technical benefits of using C&D materials derived from construction and demolition waste instead of natural raw materials in applications such as road shoulders or unpaved roads.

Properties of Inorganic Polymers Produced from Brick Waste and Metallurgical Slag

This paper explores the alkali activation potential of brick wastes and metallurgical slags. Inorganic polymers (IPs) were produced using an alkaline medium consisting of sodium hydroxide and sodium silicate solutions and the optimum synthesis conditions were determined. In this context, the variable parameters, such as solid to liquid (S/L) ratio, curing temperature (60, 80 and 90 °C) and ageing time (7 and 28 days) on the compressive strength and the morphology of the produced IPs were investigated. Specimens produced under the optimum synthesis conditions were subjected to high temperature firing and immersed in distilled water and acidic solutions for various periods of time, in order to assess their durability and structural integrity. The results showed that the IPs produced using a mix ratio of 50 wt % metallurgical slag and 50 wt % brick wastes, cured at 90 °C and aged for 7 days obtained the highest compressive strength (48.9 MPa). X-ray fluorescence analysis (XRF), particle size analysis, Fourier transform infrared spectroscopy (FTIR), mineralogical analysis (XRD), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and thermogravimetric (TG) analysis also confirmed the optimum microstructural characteristics and the chemical reactions that took place during synthesis. The overall results of this study indicate that the co-valorization of different waste streams, which are produced in large quantities and cause environmental problems if not properly managed, is a viable alternative for the production of binders or secondary construction materials with higher added value.

Man-Made Waste as a Raw Material Base for the Production of Modern Construction Composites

The results of tests of secondary construction materials derived from man-made materials are presented. The granulometric and chemical compositions of secondary products from technogenic raw materials are investigated. The analysis of local natural and man-made raw materials base of the Chechen Republic. The possibilities of using local natural raw materials (crushed stone from gravel, natural sand, gravel, gypsum, cement, etc.) in the technology of building composite materials are shown. The suitability and efficiency of the use of technogenic raw materials in concrete and mortar technology, justified by the complex economic and environmental effect of its use in the practice of building materials science, have been experimentally proved. It has been established that with the introduction of advanced innovations in the field of concrete science it is possible to produce competitive products that are not inferior to foreign analogues.

Detailed characterization of particle size fractions of municipal solid waste incineration bottom ash

Municipal Solid Waste Incineration Bottom Ash (MSWI BA) is of increasing interest as a secondary construction material worldwide. In most cases, MSWI BA is used in isolated conditions. However, according to the Dutch Green Deal B-076 in 2012, by 2020 all MSWI BA should be used in a non-sealed environment in the Netherlands. However, freshly produced. MSWI BA normally does not match environmental legislation due to high leaching of chlorides, sulfates, and potentially toxic elements. Because different particle size fractions of MSWI BA are of interest for designing optimized concrete recipes, it is beneficial to analyze the whole range of MSWI BA fractions in detail. In this study, 14 size fractions of MSWI BA were analyzed to determine the total elemental composition and leaching capacity, mineralogical composition, and shape variety of fine particles. From the point of view of mineralogical composition, 6 particle size fractions (<180 μm, 180–500 μm, 0.5–1 mm, 1–4 mm, 4–22 mm, > 22 mm) can be distinguished. All together the analyses showed that almost all fractions of the investigated MSWI BA can be used as secondary building materials. However, because the leaching of fine fractions is 5–10 times higher than of coarse fractions, all these fractions must undergo various treatments to allow them to match the environmental legislation. Thus, to decontaminate MSWI BA from potentially toxic elements, a division into three size groups is suggested: fine (<125 μm), medium (125 μm - 1 mm), and coarse fractions (over 1 mm).

Reduction of Natural Resource Use by Improving Resource Efficiency

In 2011, the German Association of Engineers (VDI) started working on a set of guidelines dealing with the improvement of resource efficiency. These guidelines represent a framework that defines resource efficiency and outlines proposals for the producing industry. A special guideline for small and medium-sized enterprises (SMEs) is included as well as guidelines on methodologies for evaluating resource use indicators, such as the cumulative raw material demand of products and production systems. The work on resource use indicators is still in progress. The evaluation of raw materials expenditure will include water, soil and land use. The model will include the availability of raw materials (criticality). Improving resource efficiency at the end-of-life stage is illustrated in this paper by the example of materials recovery from waste, here from residues out of municipal solid waste incineration (MSWI). With mechanical treatment valuable materials like ferrous and non-ferrous metals and secondary construction material can be extracted from MSWI bottom ash. The potential contribution on the resource efficiency is discussed.

Development of drainage water quality from a landfill cover built with secondary construction materials

The aim of this study was to evaluate the drainage water quality from a landfill cover built with secondary construction materials (SCM), fly ash (FA), bottom ash (BA) sewage sludge, compost and its changes over time. Column tests, physical simulation models and a full scale field test were conducted. While the laboratory tests showed a clear trend for all studied constituents towards reduced concentrations over time, the concentrations in the field fluctuated considerably. The primary contaminants in the drainage water were Cl−, N, dissolved organic matter and Cd, Cu, Ni, Zn with initial concentrations one to three orders of magnitude above the discharge values to the local recipient. Using a sludge/FA mixture in the protection layer resulted in less contaminated drainage water compared to a sludge/BA mixture. If the leaching conditions in the landfill cover change from reduced to oxidized, the release of trace elements from ashes is expected to last about one decade longer while the release of N and organic matter from the sludge can be shortened with about two–three decades. The observed concentration levels and their expected development over time require drainage water treatment for at least three to four decades before the water can be discharged directly to the recipient.

Beyond the material grave: Life Cycle Impact Assessment of leaching from secondary materials in road and earth constructions

In industrialized countries, large amounts of mineral wastes are produced. They are re-used in various ways, particularly in road and earth constructions, substituting primary resources such as gravel. However, they may also contain pollutants, such as heavy metals, which may be leached to the groundwater. The toxic impacts of these emissions are so far often neglected within Life Cycle Assessments (LCA) of products or waste treatment services and thus, potentially large environmental impacts are currently missed. This study aims at closing this gap by assessing the ecotoxic impacts of heavy metal leaching from industrial mineral wastes in road and earth constructions. The flows of metals such as Sb, As, Pb, Cd, Cr, Cu, Mo, Ni, V and Zn originating from three typical constructions to the environment are quantified, their fate in the environment is assessed and potential ecotoxic effects evaluated. For our reference country, Germany, the industrial wastes that are applied as Granular Secondary Construction Material (GSCM) carry more than 45,000t of diverse heavy metals per year. Depending on the material quality and construction type applied, up to 150t of heavy metals may leach to the environment within the first 100years after construction. Heavy metal retardation in subsoil can potentially reduce the fate to groundwater by up to 100%. One major challenge of integrating leaching from constructions into macro-scale LCA frameworks is the high variability in micro-scale technical and geographical factors, such as material qualities, construction types and soil types. In our work, we consider a broad range of parameter values in the modeling of leaching and fate. This allows distinguishing between the impacts of various road constructions, as well as sites with different soil properties. The findings of this study promote the quantitative consideration of environmental impacts of long-term leaching in Life Cycle Assessment, complementing site-specific risk assessment, for the design of waste management strategies, particularly in the construction sector.

Water-Washing of Iron-Ore Sintering Gas Cleaning Residue for Beneficial Reutilization as Secondary Construction Material

Abstract Iron-ore sintering gas cleaning residue is an emerging type of hazardous waste due to its enrichment of heavy metals. Beneficial reutilization as secondary construction material is supposed to be a possible solution, if volatile components, mainly K and Na chlorides could be removed to acceptable level. This study investigated the effects of water-washing process on the removal of alkali chlorides, as well as heavy metal. The water-washing condition was optimized as L/S=10, t=10∼30 min. 95% of Cl and 90% of K and Na could be removed, meanwhile most of the eluted heavy metals were satisfied to the relevant discharge standard. The washed residue could be reutilized in cement production as alternative raw calcareous material or retarder.

Investigation of Cu leaching from municipal solid waste incinerator bottom ash with a comprehensive approach

Municipal solid waste incinerator (MSWI) bottom ash is often reused as a secondary construction material. This study used a comprehensive approach to characterize the leaching behavior of copper (Cu) from the MSWI bottom ash. The batch titration procedure was used to determine the acid neutralizing capacity and Cu leaching as a function of pH. The sequential extraction procedure (SEP) was adopted to analyze the speciation of Cu in the MSWI bottom ash. The metal speciation equilibrium model for surface and ground water (Visual MINTEQ) was used to evaluate the equilibrium of the leachates with the relative minerals, and to determine the speciation of the aqueous Cu in the leachates. Based on the multi-analysis of the results, Cu would be significantly released from the MSWI bottom ash when it is acidic. The Cu leaching pattern was not only affected by dissolved organic carbon, it was also limited by its speciation in the MSWI bottom ash. Furthermore, almost 100% of the aqueous Cu in the leachate was bound to organic matter in basic and neutral conditions, but mostly existed as Cu2+ in an acidic condition. These findings provide an important insight into predicting the leaching behavior of Cu from the MSWI bottom ash, as well as its impact on the environment.

Environmental impacts of reconstruction activities: A case of Lebanon

Significant damages incurred across Lebanon during the July 2006 war encompassing the destruction of road networks, bridges and overpasses as well as a vast number of dwelling units. It is anticipated that reconstruction works after the war shall unavoidably create a newly founded demand for natural resources, most notably primary and secondary construction material. This paper assesses the war-related impacts of the construction sector on the environment coupled with recommendations for controlling and mitigating these impacts. A cost benefit analysis of four different scenarios for supplying construction material was conducted based on their environmental and fiscal costs as well as their economic benefits and government returns. The Fixed Box Model was applied to estimate air pollutants concentration. Results indicated that the preferred alternative for the supply of cement primarily consists of local manufacturing of 100 percent of the required quantities. With regards to sand and aggregates, the analysis indicated that the preferred alternatives are to either rely on local production or import 25 percent of the required material. The predicted average concentration of Total Suspended Particulates at the southern suburb of Beirut site exceeded the recommended values of the Lebanese, EU, USEPA, and WHO standards.

Artificial carbonation for controlling the mobility of critical elements in bottom ash

In municipal solid waste incineration (MSWI), bottom ash, generated at a stoker grate type incinerator, the critical elements were identified in terms of EU regulation. The stabilizing effect of moderate carbonation (pH 8.28 ± 0.03) on critical contaminants was studied through availability and diffusion leaching protocols. Data from the performed tests were evaluated with the goal of reusing MSWI bottom ash as secondary construction material. To investigate the mobilizing effect of CO2, suspended MSWI bottom ash was severely carbonated (pH 6.40 ± 0.07). The effect of CO2 and its interaction with other leaching factors, such as liquid/solid (L/S) ratio, leaching time, pH, ultrasound treatment, and leaching temperature, were examined using a reduced 26-1 experimental design. Contaminants identified as critical were Cr, Cu, Mo, Sb, Cl−, and SO42−. Although moderate carbonation decreased the release of Cr, Cu, Mo, and Sb from compacted bottom ash, the main disadvantage remains its inability to demobilize Cl− and SO42−. The hypothesized mobilizing effect of severe carbonation was proven. The treatment enhanced the separation of critical components (α = 0.05) (except for Cl−), i.e., about fivefold for Sb and about twofold for Cr, Cu, and S. Nevertheless, the prospect is good that severe carbonation could constitute the deciding key parameter to facilitate the technical feasibility of a future washing process for MSWI bottom ash.