Construction And Demolition Waste Research Articles

SUSTAINABLE DEVELOPMENT AND ADAPTIVE MANAGEMENT CONCEPTS IN THE CEMENT ENTERPRISES OF THE INDUSTRY 4.0

Sustainable development is one the main strategies for advanced cement enterprises in the industry 4.0. There are applied modern technologies and methods resulted in sustainable development and competitive advantage of the Holcim Group. According to the objectives of the Holcim Group it is announced to introduce a new reference for the sustainable construction industry by 2030 and 2050. These goals have been validated by the Science Based Targets initiative. [6] Therefore, managers of cement enterprises introduce new advanced methods of adaptive management to implement the above-mentioned goals to survive in the market. In order to be successful in these tasks there are applied advanced products and solutions to accelerate the transition to green building process. On the basis of these goals there are demanded the advanced techniques and technologies like Computerized Maintenance Management Systems, Fuzzy Recurrent Neural Network, Condition-Based Maintenance, online Condition Monitoring Systems in the cement enterprises of the Holcim Group. These advanced techniques and technologies will ensure successful implementation of the methods of adaptive management to achieve the sustainability. Keywords: sustainable development, adaptive management, Science Based Targets initiative (SBTi), Environmental, Social and Governance (ESG), Construction and Demolition Waste (CDW), Biodiversity Indicator Reporting System (BIRS), International Union for Conservation of Nature (IUCN), Computerized Maintenance Management Systems (CMMS), Fuzzy Recurrent Neural Network (RNN), Condition-Based Maintenance (CBM), online Condition Monitoring Systems (CMS).

Dissolved recycled expanded polystyrene as partial replacement in plaster composites

The recovery of Construction and Demolition Waste (CDW) for its reincorporation into the manufacturing process of new materials is fundamental in the fight against environmental pollution, reducing the current high consumption of raw materials and boosting energy savings. The aim of this research is the study and development of a new plaster-based material in which the conglomerating material is partially replaced by dissolved recycled expanded polystyrene. In the experimental campaign, different dosages have been used in which the plaster material has been progressively replaced by the dissolved recycled expanded polystyrene, in order to subsequently carry out a physicochemical, physical and mechanical characterisation of the composites. The results obtained show how the incorporation of expanded polystyrene in solution as a partial replacement of the binder generates a homogeneous plaster composite, favouring the total integration of the waste in the matrix of the construction material finally produced. It has been observed that this new material has, in comparison with traditional plasters, a very low density, high thermal resistance and excellent plate bending behaviour. These properties position the developed material as a viable alternative in the production of more sustainable prefabricated plates and panels through the application of circular economy criteria.

Recycled Aggregates from Ceramic and Concrete in Mortar Mixes: A Study of Their Mechanical Properties.

In recent decades, large amounts of construction and demolition waste (CDW) have been generated and accumulated throughout Europe, which is a challenge to manage and control nowadays. This work shows the results of a study carried out with samples of ceramic recycled aggregates (CRAs) and recycled concrete aggregates (RCAs) mixed with cement (C) in mortars. The main objective of this research is to demonstrate how, by adding CRAs and RCAs to a mixture of cement and natural aggregate (NA), it is possible to develop a high-strength mortar and achieve the best mixing ratio. To achieve these objectives, the characterization of the samples was initially carried out such as XRF, XRD and SEM. Next, tests were carried out on the products obtained, such as the consistency of the fresh mortar and the density of the specimens. Finally, a study of mechanical compressive strength was performed at 7, 28 and 200 days. The results show that although both CRAs and RCAs negatively affect the curing process of the specimens, it is possible to develop mortars with compressive strengths greater than 20 MPa. An obvious increase in mechanical compressive strengths was seen between 7 and 200 days of analysis. The results achieved in this research could be an important guide for the management of CDWs by local industries, thus favouring the development of the circular economy.

Rheological property and extrudability performance assessment of construction and demolition waste-based geopolymer mortars with varied testing protocols

This study investigated fresh properties of 100% construction and demolition waste (CDW)-based geopolymer mortars providing innovative solutions for waste upcycling in favor of continuously transforming sustainable construction applications. Mortars were produced by utilizing hollow brick, red clay brick, roof tile, glass and concrete wastes as precursors and crushed concrete waste as aggregates. For activation, different combinations of NaOH-(molar concentrations of 7.5-10-12.5-15) and Ca(OH)2-(0-4-8%, by weight of binder) were used. For rheological assessments, different protocols including flow curve, constant shear rate, varied shear rate and three interval thixotropy testing (3ITT) were implemented. Ram extrusion was performed to investigate the extrudability performance of the mixtures. The study showed that the mortars’ rheological properties can be driven by arranging alkaline activator content. Although empirical approaches of flow curve, constant shear rate, and varied shear rate were able to verify the existence of thixotropy behavior, they were not capable of quantifying the viscosity recovery level of the mixtures, as opposed to 3ITT method. The 3ITT results showed that the viscosity recovery performances of geopolymers with varying activator content were between 65 and 82%. Ram extrusion demonstrated that mixtures were extruded without showing any types of failures, although some of them had different types of failures on the extruded specimen with the increased resting time beyond 60 min. However, except for 15M-activated mixtures, each mixture was extrudable even after 120 min. In general, this study presents a comprehensive investigation of assessing the rheological properties and extrudability performance of the CDW-based geopolymers via performing various testing methods.

Bonding of Carbon Steel Bars in Concrete Produced with Recycled Aggregates: A Systematic Review of the Literature

Civil construction is essential for the world economy and the largest generator of construction and demolition waste (CDW), mainly due to a lack of planning, technological control, and restoration execution, among other factors. While efforts are made to minimize this waste generation, one possible application for CDW is its incorporation into Portland cement-based materials as recycled aggregates, in partial or total replacement of natural aggregates. However, for CDW use to be feasible, the structure performance and safety must be assured, and the adherence between concrete and reinforcement bars, in this context, is a fundamental mechanism. With this perspective, this paper aims to investigate the influence of recycled aggregate on steel–concrete bonding. To this end, the SREE (Systematic Review for Engineering and Experiments) method was employed as a novelty, including a methodology quality analysis, to search and analyze relevant scientific articles published in the last ten years. The results revealed that the use of CDW as recycled aggregates in concrete worsens the steel–concrete bonding, and that ribbed steel bar seems to be the best option when employed in RC structures built with CDW-concrete, although the bar diameter and the anchorage length still need further investigations, and that CDW-concrete’s use can significantly contribute to reducing the emission of greenhouse gases and to capturing CO2 from the atmosphere. Therefore, further investigations should focus on the real influence of recycled aggregate type and replacement content, bar diameter, anchorage length, and CDW’s potential to capture CO2.

Assessing the construction and demolition waste volume for a typical Mediterranean residential building

Construction and Demolition Waste (CDW) effective management is of vital importance, especially regarding the climate-neutral economy target set for 2050. The common practice of landfilling them during the past decades and ignoring the environmental impacts is now obsolete, with countries around the world adopting national regulations for their proper treatment. The lack of data on the CDW volume produced every year both in the European region and at the Greek national level is evident, in contrast with Asian or American regions, and introduces a great uncertainty in the field. This study aims at estimating the CDW quantities produced by a typical multi-storey residential building in Greece, built in the mid-20th century, made of reinforced concrete and filling masonry walls. The subsidized renovation programs by the European Union, which have a great impact on the Greek domain, are also considered, so two renovation procedures are considered during the building’s lifespan, resulting in an extended lifetime of the building along with additional CDW quantities produced on each renovation procedure. Challenges regarding the disposal, recycling and reuse potential and alternatives of the distinct CDW types produced are presented, based on the international literature available data.

Barriers to the Adoption of Reverse Logistics in the Construction Industry: A Combined ISM and MICMAC Approach

With growing environmental concerns, reverse logistics (RL) assumes a significant role in the sustainability of the construction industry to the extent that it can contribute to mitigating some of the negative environmental impacts related to its activity. However, despite the benefits that can be attributed to RL, its implementation level in the construction industry is still very low. This research determines the root barriers to adopting RL in construction (ARLC) using the case of the Portuguese construction market. The methodology involved focus groups and a combined Interpretive Structural Modelling (ISM) and Matrices d’Impacts cross-multiplication appliqúe a classmate (MICMAC) approach. The root barriers that have been identified by the application of the methodology to the ARLC are: lack of financial incentives to incorporate recycled materials, lack of knowledge about RL, lack of technical support, standard codes and regulations in favor of using recycled materials, lack of information sharing, cooperation and coordination among entities of the supply chain, current buildings have not been designed for deconstruction, and lack of construction and demolition waste (CDW) management and recycling infrastructures and markets for the materials resulting from CDW. The highest hierarchical level includes barrier B10 (lack of financial incentives to incorporate recycled materials into the construction); this barrier influences all the other barriers and, as such, it is considered the key barrier to the ARLC in Portugal. The research has also identified 17 different mitigation measures to tackle these barriers, with different natures: fiscal, regulatory, financial, etc.

Using dynamic-locational material flow analysis to model the development of urban stock

ABSTRACT Construction and demolition waste (CDW) constitutes the biggest share of all waste generated. In addition to the environmental advantages, CDW recycling provides also high resource conservation benefits if used as recycled aggregates. Integrated forecasting of demolition and construction activities is crucial for quantifying and reconciling future supply and demand. While spatial characteristics are significant to minimize transportation costs, temporal aspects and material characteristic are important to regard for the development of the urban stock over time. This paper presents a Dynamic-Locational MFA as a model that integrates spatial, temporal and CDW material characteristics into material flow analysis at the demand and supply side. The relevant drivers of construction and demolition activities are defined in order to derive the required equations. Also, the empirical analysis is used to conclude the parameters and demonstrate the model on a real case study. Hence, the synergies between the recycling and construction activities are identified and the supply and demand of materials can be reconciled. The outcomes are not only important in terms of resource efficiency, but also help in anticipating and planning the restructuring of the value chain of the construction sector, such as the locations and capacities of concrete and recycling plants.

Construction and demolition waste recycling in developing cities: management and cost analysis

In Bolivia, construction and demolition waste (CDW) is unmanaged. The current research implemented a CDW flow analysis and a cost assessment in the city of La Paz, aiming to compare future recycling scenarios. Lack of data is challenging; therefore, a review of 31 international studies has been conducted. Results report that the waste generation rate (WGR) of concrete residential buildings can be of about 91.9–113.3 kg m−2 for construction and about 867.2–1064.8 kg m−2 for demolition. In addition, positive correlation was found in national WGR with number of inhabitants and the GDP. By these results, it was estimated that about 271,051–349,418 tonnes of CDW are potentially generated yearly in La Paz, about two times more than the CDW projected by local authorities. By the scenarios analysis, it was estimated that 56.1–71.1% of the inert aggregates can be recycled. The cost of the system is estimated between 7.8 and 31.1 USD tCDW−1, for a total annual cost (20 years horizon) of about 2.3–9 million USD y−1 depending on the management scenario. In the best scenario, an average fee of less than 1% of the current costs of a flat in La Paz can be required, potentially affordable for the local economy. The most attractive scenario involves the source separation of recyclable materials and the hybrid organization of stationary and mobile recycling facilities. Results show that a CDW management can be implemented in La Paz to foster a circular economy in developing cities.

Diagnosis of construction and demolition waste management (CDW) in the city of Caruaru, Pernambuco

The management of construction and demolition waste (CDW) is the main tool for construction housing sustainably. This article presents a diagnosis of the management of CDW and their environmental impacts in the municipality of Caruaru, Pernambuco. The construction and demolition waste management Index (CDWMI) was calculated. This index uses the environmental sustainability indicators: management instruments, management programs, collection and screening, and treatment and disposition of the CDW. The results of this research were compared with the results of six municipalities in the metropolitan region of Recife (MRR). The evaluation of the management of the municipality of Caruaru regarding the CDW indicated the low performance of the municipality since, of the four groups of instruments used, three of them were low grades, and only in the indicators of instruments for policies obtained the average grade. With the diagnosis of a low degree of sustainability in relation to the management of CDW, it is evident that there must be a restructuring in the management of the municipality so that what is established and agreed upon in the Municipal Solid Waste Plan (MSWP) is commenced.

Effect of Construction Wastes as Coarse Aggregates in Cement Concrete: A Review

The global economy depends on the building industry. Rapid building growth creates global worries about waste. Construction and demolition waste (CDW) negatively affect costs, energy, productivity, the environment, and society. Planning and storing building trash may reduce these harmful consequences. On local construction sites, waste, poor site management, and resource loss are common. The way a structure is built, how materials and equipment are transported, how employees behave, how a firm is handled, how the site is set up, and how resources are procured all contribute to construction waste, which in turn contributes significantly to the degradation of the environment due to indiscriminate disposals. This study takes a look at the mechanical properties of CDW while conducting the research, credible academic sources were located on Google Scholar, SCOPUS, the Web of Science, IEEE Xplore, and Science Direct. The publications were narrowed down to only those that were most relevant to the study's aims. After reviewing these, the authors focused on just the 49 journal articles, 15 related books, and 7 government publications that were most relevant to the research.

Blockchain-based framework for improving waste management and circular economy in construction

There is a current lack of management tools that guarantee control and traceability of actions taken by the generator of construction and demolition waste (CDW). Furthermore, the reinsertion of recycled CDW into productive cycle is necessary to foster a circular economy in construction sector. To address these challenges, this study builds a novel blockchain-based information management framework for CDW management in construction, which extends the applications of blockchain for improving circular economy in the sector. Using design science research as a methodological research strategy, this study presents and analyses a blockchain framework and its development processes. The framework performance was evaluated through simulation and quantitative and qualitative indicators. Through a SaaS (Software as a Service) concept, the system allows strengthens the connection between stakeholders looking for sustainable solutions for CDW management. These solutions are independent of the size or segment of the company and allow the creation of business opportunities within the industry itself that provide expertise to foster the circular economy such as reverse logistics, servitization, and industrial symbiosis.

Energy-environmental performance assessment and cleaner energy solutions for a novel Construction and Demolition Waste-based geopolymer binder production process

Construction and Demolition Waste (CDW)-based geopolymers are expected to lower the construction sector’s environmental impacts by reducing the use of ordinary cement and reusing waste materials and are considered a substantial step toward a circular economy and environmental sustainability in the long run. However, due to the energy-intensive mechanical, thermal, and chemical processes involved in preparing the CDW-based geopolymers, it is essential to quantify their environmental implications in the early stages of development. The objective of the study is to analyze the environmental sustainability of newly developed geopolymers containing CDWs, i.e., roof tile (RT), hollow brick (HB), red clay brick (RCB), and glass waste (G) based geopolymer binder materials. The study aims to identify the environmental impact of their critical process parameters using Life Cycle Assessment (LCA) approach and evaluate their production feasibility at a location with completely different energy and water scenarios. According to the results of the study, compared to Ordinary Portland Cement (OPC), all the CDW-based geopolymers had lower environmental impacts. G-based geopolymer binder resulted in the lowest Global Warming Potential (GWP) with a 38% reduction, followed by RT and HB with 35.3% and 34.8%, respectively. However, due to the energy-intensive processes of crushing and grinding CDWs, electrical energy is identified as a hotspot with significant environmental impacts. The replacement of mix-grid energy with hydropower reduced GWP by 63.3%, Eutrophication (EP) by 52.5%, Acidification potential (AP) by 86.4%, and fossil fuel deposition (FFD) by 74%. The highest environmental performance is calculated for electricity produced from hydropower, wind, and photovoltaics, then geothermal and biomass resources.

Stackelberg game model for construction waste disposal network design

Governments and contractors have different goals in handling construction and demolition waste (CDW), which makes it challenging to design CDW recycling networks. This paper develops a Stackelberg game model that governments can use to decide the optimal locations and types of CDW disposal facilities by considering the interests of both the government and contractors. The proposed model is proven to be efficient and practical through a series of real-world case studies. The findings elucidate and manage the different goals of governments and contractors and can help government design an optimal CDW recycling network in practice. Future research could tackle the problem of designing a multiperiod recycling network for managing CDW.

Eco-, economic- and mechanical- efficiencies of using precast rejects as coarse aggregates in self-compacting concrete

This paper investigates the eco-, economic- and mechanical- properties of self-compacting concrete (SCC) containing recycled coarse aggregates generated from prefabricated concrete rejects (PRA) or construction and demolition wastes (CRA). A total of 720 specimens from 36 unique SCC mixes are prepared and tested. The effects of the key parameters including, water-to-binder ratio (w/b), fly ash replacing ordinary Portland cement weight ratio, recycled coarse aggregate replacing natural coarse aggregate volume ratio, heat curing temperature, mixing method or the addition of steel fibers, on the fresh and hardened properties of SCC are experimentally explored. In addition to the experimental study, cradle-to-gate life cycle cost (LCC) analysis and life cycle assessment (LCA) of the SCC are carried out, where these are done through considering different levels of functional units. Based on the results of the experimental work, LCA and LCC, it is found that the PRA based concrete shows ecological-, environmental- and economic- benefits over conventional SCC with slightly compromised rheological and mechanical properties. When considering only the volumetric equivalence, it is observed that a higher w/b, the inclusion of higher amount of recycled coarse aggregate (RCA), or fly ash, or using a lower curing temperature can efficiently reduce the cost and environmental impacts of SCC with PRA. PRA concrete products are more eco-friendly and less cost intensive than those associated with the CRA ones due mainly to the shorter distance to transport PRA compared to CRA. Beyond the volumetric functional unit, the results of LCC and LCA show that, as indicated by carbon dioxide equivalent-, embodied energy- or cost- intensity, a higher w/b, the incorporation of higher content of RCA or fly ash, and using a lower curing temperature no longer benefit the eco-, environmental and mechanical performance of recycled coarse aggregate SCC (RCASCC) and the effect of curing temperature becomes ambiguous.

Performance evaluation of reinforced earth walls with sustainable backfills subjected to railway loading

The concept of using Reinforced Earth (RE) walls for rail corridors is gaining popularity. As of now, very few nations have successfully adopted the RE walls for Railway infrastructure. These structures require good quality granular materials like sand for backfilling. However, due to the scarcity of good quality natural sand, research efforts are being made to look for cost effective alternatives to sand in backfill applications. The present study examines the possibilities of using the two sustainable materials, namely steel slag and construction and demolition waste (CDW), as backfills in RE walls subjected to harmonic train-induced load. In total, 63 separate full-scale numerical models of RE walls have been analyzed to understand the wall behavior with sustainable backfills subjected to different train speeds. The backfill materials were simulated with three different material models, namely, linear elastic, Mohr-Coulomb and Hardening Soil, for comparison. The results showed that the RE wall behavior is highly frequency-dependent. RE walls with steel slag and CDW backfills have shown 25% and 12% lesser deformations, respectively as compared to the sand backfill. Furthermore, reinforcement tensile forces in walls with sustainable backfills were found to be comparable to those of sand. The maximum deformation of the wall was observed when the fill materials were simulated with the Hardening Soil model. In overall, satisfactory performance of the RE wall was observed in the presence of sustainable backfill materials under Railway loading.

Mechanical anisotropy evaluation and bonding properties of 3D-printable construction and demolition waste-based geopolymer mortars

This work aims at evaluating the anisotropy (direction-dependency) in terms of mechanical performance and bonding properties of entirely construction and demolition waste (CDW)-based geopolymer mortars fabricated by 3D-additive manufacturing (3D-AM) technique. In the study, a combination of hollow brick (HB), red clay brick (RCB), roof tile (RT), concrete waste (CW) and glass waste (GW) obtained from various demolition sites and different combinations of alkaline activators including sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2) were used for geopolymerization. CW was also used as fine aggregate in geopolymer mortar production. Specimens were subjected to ambient curing conditions until testing ages. Direction-dependent mechanical performance of printed specimens was evaluated at 7-, 28- and 90-day via compressive strength test in three different loading directions of perpendicular, parallel, and lateral to the printing path and flexural strength test in two different loading directions of perpendicular and lateral to the printing path. Moreover, bond strength between the consecutive printed layers were tested through direct and splitting tensile strength tests at the end of 7-, 28- and 90-day ambient curing and used to compare the directional performance of tested mixtures. In addition, compressive and flexural strength test results of printed specimens were compared with those of conventional mold-casted specimens. Results showed that alkaline activator content affects the mechanical properties considerably. According to compressive and flexural strength test results, 3D-printed geopolymer mortar specimens have anisotropic behavior and the bond performance between consecutive layers is one of the main influencing parameters for the anisotropic behavior of 3D-printed structures. However, perpendicular-loaded 3D-printed specimens showed similar or slightly better performance compared to the mold-casted ones, indicating that the bond zone had little influence on the performance of specimens loaded in perpendicular loading direction. This study pointed out that the anisotropic performance of printed structures can be diminished with the enhanced bond adhesion between consecutive layers and the adhesion can be improved by optimizing the rheological properties and matrix performance of the mixtures.

Development of a sustainable binder made of recycled high-performance concrete (HPC)

The high consumption of ordinary Portland cement (OPC) in high-performance concrete (HPC), combined with the growing accumulation of construction and demolition wastes (CDW), raises severe environmental and economic concerns. This study addresses both issues by proposing a novel sustainable binder made of milled recycled HPC (mRHPC). A series of HPC mix designs (R-HPC) was developed replacing OPC by mRHPC (0–100%), and characterized in fresh and hardened states. The residual reactivity of mRHPC was detected using X-ray diffraction, calorimetry, and rheological oscillatory measurements (SAOS). Replacement up to 30% resulted in comparable 28-day compressive and flexural strengths to that of the OPC reference specimen while slightly improving fresh properties. Furthermore, the performance of steel fiber reinforced R-HPC overlays was investigated in repair application, and 30% replacement ratio enhanced the tensile bond strength by a factor of 2.4. The measured improved flow properties and reduced drying shrinkage can explain this remarkable result.

The Impact Resistance and Mechanical Properties of Recycled Aggregate Concrete with Hooked-End and Crimped Steel Fiber.

The utilization of recycled coarse aggregate (RCA) from construction and demolition waste (CDW) is a sustainable solution to protect the fragile natural environment and save the diminishing natural resources. The current study was aimed at exploring the impact resistance and mechanical properties of recycled aggregate concrete (RAC) affected by hooked-end steel fiber (HF) and crimped steel fiber (CF). Fifteen concrete mixtures considering different RCA substitution ratio, steel fiber dosage, and steel fiber shapes were designed. Meanwhile, a statistical analysis method-based Weibull distribution was introduced to evaluate the variations of impact test results, presented using a reliability function. Lastly, the microstructural morphologies of interfacial transition zones at the cement paste/aggregate and cement paste/fiber interfaces were observed using a scanning electron microscope (SEM). The experimental results showed that the impact resistance and mechanical properties mildly decreased with the increase in substitution ratio of RCA, whereas they conclusively increased with the increase in steel fiber content. Steel fiber recycled aggregate concrete (SFRAC) with 1.5% steel fiber content had the best impact resistance, and its initial cracking times and final failure times were 3.25–4.75 and 8.78–29.08 times those of plain RAC, respectively. HF has better impact resistance than CF. The SEM observations of microstructures indicated that the hardened cement paste of natural aggregate concrete (NAC) was more compact than that of RAC. Steel fiber had a better connection with the cement paste interface than that of aggregate and cement paste owing to better thermal conductivity. This research could be a guide for SFRAC as a structural material in practical engineering, steering the construction industry toward the circular economy.

Sustainable 3D printed mortar with CO2 pretreated recycled fine aggregates

Recycling of construction and demolition wastes (CDW) for the development of intelligent construction materials has the potential to lower the environmental burden and promote the development of intelligent construction. Herein, CO2 pretreatment to a type of recycled fine aggregate (RFA) was employed to upcycle the waste for developing 3D printable mortar (3DPM). The replacement ratios of natural fine aggregates (NFA) by recycled fine aggregates (RFA) and carbonated recycled fine aggregates (CRFA) up to 100% were designed, and the engineering properties, including compressive strength, flexural strength and interlayer bonding strength, of 3DPM were investigated. Comprehensive microscopic tests with X-ray diffraction (XRD), scanning electron microscopy-backscattered electrons (SEM-BSE), and X-ray computed tomography (X-CT), were used to demonstrate the microstructure mechanism of the 3DPM specimens with upcycled fine aggregates at the microscopic level. Systematical enhancements in engineering properties of 3DPM with CRFA were reported when compared with those of 3DPM with RFA. The compressive strength at 28 days was noticeably enhanced by 68.5% for the 3DPM with 100% upcycled fine aggregates. Carbonation enables significant calcite precipitates in the adhered cement paste area and formation of cement hydrates in the new cement paste area. The findings of the present work not only deepen the understandings in the microstructure alterations of RFA by CO2 pretreatments, but also pave a path towards the upcycling of CDW towards sustainable intelligent constructions.