Construction Waste Research Articles

Enhancing the physical performance of concrete containing construction and demolition waste against the effects of accelerated carbonation and chloride ingression

Enhancing the physical performance of concrete containing construction and demolition waste against the effects of accelerated carbonation and chloride ingression

Pull-out response of a geogrid buried in recycled sands

Recycled construction and demolition waste (RCDW) has demonstrated geotechnical properties that encourage it to be used in reinforced soil structures (RSS) with geosynthetics. However, the interaction between RCDW and reinforcements needs to be better understood, given its importance for design. This paper presents a qualitative study on the interaction between geogrid and recycled sands by means of pull-out tests performed on small equipment. Tests with the same degree of compaction and a geogrid buried in different types of recycled and natural sands (for comparison purposes) were performed. The characterisation of the materials was carried out in the laboratory and the variability of their geotechnical properties was evaluated. In addition, fill material moisture content was investigated as another potential factor influencing soil-geogrid interface shear. The results of the pull-out tests demonstrated the specific influences of the factors investigated. The comparative study showed that recycled sands can be suitable materials to be used as backfill in geosynthetic reinforced soil structures, meeting physical, mechanical and environmental requirements for this kind of work.

OPTIMIZATION OF ORGANIZATIONAL PROCESSES IN CIVIL ENGINEERING USING LOGISTICS MODELS

Purpose. In accordance with the analyzed problem, there is a need for a more detailed study and justification of the benefits of implementing logistics models to optimize organizational processes in civil engineering. Methodology. To achieve this goal, the article conducts a systematic analysis of organizational processes in civil engineering in terms of logistics approaches. Current trends in the industry, regulations and scientific developments are considered, risks and barriers that may arise when implementing logistics models in the construction industry are analyzed, practical examples of possible use of logistics concepts in civil engineering at different stages of work and when using specific building materials are offered, ways to overcome barriers and stimulate the implementation of logistics models are provided, and an integrated approach to optimizing organizational processes in civil engineering is proposed. Findings. The study has shown that the introduction of logistics models in civil engineering can lead to: significant efficiency improvements, shorter construction time, reduced costs for materials and transportation, improved quality of construction work, reduced environmental impact, rational use of resources, reduced construction waste, increased competitiveness, improved safety, and increased project profitability. Originality. The key principles of development and functioning of logistics models in the context of civil construction are identified: the principle of integration: combining all stages of the construction process into a single logistics system, the principle of resource optimization: minimizing the cost of materials, transport, labor, the principle of flexibility and adaptability: the ability to adapt the logistics model to changing construction conditions. Practical value. The results of the study indicate that the introduction of logistics models in civil engineering is a relevant and promising area for optimizing processes in this sector. The use of logistics can contribute to effective resource management, increase productivity and reduce costs, which is noted by the practical importance of this study.

Promoting Circular Economy of the Building Industry by the Use of Straw Bales: A Review

Over the past decade, the concept of a circular economy has increasingly gained attention as a framework for guiding businesses and policymakers. Given its significant environmental impact, the building industry plays a pivotal role in the transition toward a circular economy. To address this, our review proposes a bio-based building material, specifically straw bale, which elaborates on the circularity of bio-based buildings based on the 3R principles of a circular economy: reduce, reuse, and recycle. In terms of the “reduce” principle, straw-bale buildings can reduce construction waste, the environmental impact, energy requirements, and carbon emissions. Regarding the “reuse” principle, straw-bale buildings utilize agricultural waste resources and are easily disassembled due to their prefabrication. As for the “recycle” principle, straw-bale buildings can undergo physical, biological, and biochemical conversion processes (thermochemical conversion), yielding both wooden composite boards and potential biogas and biomass fuels for electricity and heating. This study evaluates the contribution of straw packaging construction and the use of straw as a raw material, using the 3R principles to determine future research opportunities for the construction industry to achieve a circular economy. The results of this study offer circular economy solutions and interdisciplinary research insights for researchers and practitioners interested in the building environment.

Development of sustainable alkali-activated slag bricks with high content of carbonated recycled concrete fines: Strength, microstructure and environmental benefit

This research presents a novel method of recycling construction waste while capturing CO2 through the formation of mineral carbon. The technology uses carbonated recycled concrete fines (CRCF) as the primary raw material to produce sustainable, high-performance alkali bricks with high replacement rates. Firstly, a general assessment of the physical and chemical properties of CRCF was carried out, which revealed the formation of silica gel encapsulating the surface of CRCF during carbonation. Subsequently, alkali bricks were prepared utilizing CRCF. The study investigated the impact of various mix proportions, water-to-cement ratios, and manufacturing process parameters on brick strength. Additionally, an in-depth analysis of reaction products and brick microstructures was carried out. The results showed that the bricks produced from CRCF were stronger than those from RCF, indicating enhanced reactivity after carbonation. Finally, an analysis demonstrated that utilizing RCF from construction waste can significantly reduce carbon dioxide emissions, thereby mitigating the environmental impact associated with cement production.

Mechanics and permeability properties of ecological concrete mixed with recycled engineering muck particles

The excavation of construction foundation pits, tunnels, channels, and other projects generates a significant volume of engineering muck, posing challenges in management. Prolonged accumulation of this muck can lead to environmental pollution. The effective recycling of this type of construction waste is crucial for the advancement of a circular economy, necessitating immediate attention to research and solutions. In this study, a novel method is introduced for the preparation of low-carbon and environmentally friendly ecological concrete. This method involves the utilization of recycled engineering muck particles to substitute a portion of the natural aggregate and enables the comprehensive recycling of engineering muck. Subsequently, the mechanical and permeability properties of ecological concrete under varying muck particle content and porosity conditions are analyzed through experiments, taking into account the impact of relative average pore diameter and pore tortuosity. A predictive model has been developed for the tortuosity of pore channels in ecological concrete, taking into account effective porosity and average pore diameter. The enhanced Kozney-Carman model is employed to describe the correlation between pore properties and hydraulic conductivity. The findings indicate that a composite curing agent is formed by combining ordinary Portland cement with a hydrophilic polyurethane solution. This composite curing agent demonstrates superior performance compared to pure cement in the solidification of engineering muck. As the replacement rate of unsintered recycled residue particles increases, the porosity of concrete may increase by up to 29.7 %. This results in enhanced permeability characteristics but a decrease in compressive strength. In contrast to lightweight aggregates manufactured through the sintering process, the carbon emissions of unsintered recycled residue particles are reduced by 57.7 %. This study provides suggestions for the repurposing of construction waste and contributes to the advancement of sustainable practices within the concrete production sector.

Prediction of properties of recycled aggregate concrete using machine learning models: A critical review

Recycled aggregate concrete (RAC) not only alleviates the shortage of natural aggregates but also promotes the recycling of construction and demolition waste, contributing to sustainable development. Traditional empirical and statistical formulas have limited applicability and perform poorly when dealing with complex relationships. Therefore, machine learning has been widely used to predict the performance of RAC. In this paper, an overview is provided of the current research examining the impact of various parameters on the workability, mechanical properties and durability of RAC. The discussion and evaluation are focused on the applicability, accuracy, hyper-parameter selection, and input variables of machine learning algorithms that are employed to predict the performance of RAC. The advantages and disadvantages of different algorithms are compared, and the practical suggestions are given based on their performance. Additionally, the limitations of current research are discussed, and the perspectives for the prediction of RAC's performance based on the machine learning models are proposed.

Analysis of road construction waste generation in developing economies: A focus on surfacing and sub-base construction projects in Sri Lanka

The motivation for this study was to develop simplified tools to estimate material wastage during road construction projects. In developing countries, there is a lack of information about material wastage factors (MWFs) in road construction projects. The purpose of this study is to reveal the MWFs of materials used in road construction. To investigate MWFs, statistics were collected from a sample of 58 road contracts concluded in the southern province of Sri Lanka, comprising 245 road construction projects. Of the selected sample, 80% of the road projects utilized wearing course (asphalt concrete), aggregate base course (ABC), cationic slow setting emulsion 1 (CSS1) and sand. The mean MWFs were calculated only for ABC, wearing course and CSS1 as 8.69%, 5.21% and 6.8%, respectively, because the authors could only achieve acceptable precision levels for these three types of materials. The coefficient of variation (CV) for all these three types of materials ranged from 25% to 3%. Based on collected data, this study proposes equations to predict waste generation for CSS1 and wearing course. Implementing the derived equations to predict waste generation can aid in efficient planning and help construction companies to move towards more sustainable practices.

Performance of Construction and Demolition Waste Coupled with Selected Vascular Plants to Treat Gray Water in Nature-Based Solutions

Performance of Construction and Demolition Waste Coupled with Selected Vascular Plants to Treat Gray Water in Nature-Based Solutions

Construction and Demolition Waste as a Sustainable Backfill for Geosynthetic-Reinforced MSE Walls

Construction and Demolition Waste as a Sustainable Backfill for Geosynthetic-Reinforced MSE Walls

The Uncertainty of Reusable Building Components/Materials A Subsidiary of Circular Economy in the Africa Construction Sector: The Issue of Affordable Housing in Kenya

There is growing interest in the adaptation of circular economy approaches in the construction sector, for developing African countries like Kenya with an increase in construction activities leading to more generation of construction wastes. The approach of circularity presents an alternative to reuse these construction or demolition wastes thereby lowering environmental risks and providing for a lower price for building components/materials required for affordable building projects. However, there is little, or no information on these reusable building components/materials, which lowers the confidence by construction stakeholders in using them. No information on its possible new life longevity (durability), its possible maintenance budget, and no means of enabling a design team to plan for its acquisition (accessibility) in a design project. This paper adopted a review of previous literature on these topics to search for possible solutions to the research questions, of which some literature provided only a list of requirements needed to give a level of information to reusable building elements. The paper went further to provide proposals for an information catalogue that would enable the insertion of reusable building elements’ Indicators of service (availability, reliability, and maintainability) obtainable from experience with the elements. Also, a format for a maintenance budget plan would be required during the new service life of the reused element. And a means of simulation using the Monte Carlo simulation tool to obtain reliable viability of access to reusable building elements in a transitional building in its design stage. These proposals would have to be put into practice to ascertain their effectiveness, meanwhile, other areas of further studies are provided in the paper.

Recycling of mineral wool waste as supplementary cementitious material through thermochemical treatment.

Mineral wool is commonly used in construction as thermal insulation material. After the product's lifetime, it is classified as hazardous waste if no trademark of the European Certification Board for Mineral Wool Products (EUCEB) or the German Institute for Quality Assurance and Labelling (RAL) exists. Mineral Wool Waste (MWW) is typically landfilled in Europe, which is challenging due to its low bulk density and dimensional stability. This circumstance highlights the need for alternative recycling methods that increase the recycling rate of construction and demolition (C&D) waste. This article outlines the recycling opportunities of MWW and focuses on the use of thermochemical treatment of different mixtures of input materials to produce a supplementary cementitious material (SCM). The material characterisation results and investigations on the binder suitability demonstrate that the slag fractions after the thermochemical treatment are well-qualified to be used as reactive binder components. Additionally, a material flow analysis was conducted to estimate the substitution potential of MWW as SCM in the Austrian cement industry.

Decarbonizing prefabricated building waste: Scenario simulation of policies in China

Compared to cast-in-situ construction, prefabricated construction reduces the generation of construction waste; however, construction waste cannot be entirely eliminated through prefabrication and can be generated at each stage of its life cycle. This paper generates a system dynamics model, comprising two causal-loop diagrams and one stock-flow diagram, to simulate the effectiveness of policies on decarbonizing prefabricated concrete building waste. The model can predict the annual and total construction waste, along with the associated carbon emissions, under different policy scenarios in China by 2030. This paper focuses on prefabricated concrete buildings in China, with specific attention to the wastage of concrete, bricks, mortar, and metal. In single-factor scenario simulations, increasing landfilling fee is the most effective policy for waste decarbonization, potentially reducing carbon emissions by 31%. Increasing prefabrication rate and enhancing regulation degree at the design phase of prefabrication can directly reduce prefabricated building waste generation, subsequently resulting in an 18% and 7% carbon emissions reduction. Multi-factor scenario simulations demonstrate that the simultaneous application of all four policies is most effective, achieving a 44% reduction in carbon emissions. This research establishes a theoretical framework for prefabricated concrete building waste management and provides the Chinese government with practical insights on optimizing policies for waste decarbonization in the dynamic landscape of prefabrication.

Performance of foam concrete developed from construction and demolition waste

Unconscious industrialization, urbanization and consumption of natural resources pose a serious threat to the environment. The threat can be reduced by upcycling construction and demolition waste (CDW) in the production of foam concrete, which is a special type of concrete used especially for thermal insulation purposes. This study aims to use of CDW as a source of fine aggregate (0-4 mm) in the production of foam concrete mixtures. A series of mixtures with target density values between 500 and 900 kg/m3 were designed with various recycled aggregate and foam contents to investigate the physical, mechanical and thermal properties of the mixtures. Findings of the study reveal that mixtures with an elevated foam content possess a greater number of larger pores, which, as observed through microscopy, form interconnected structures that are porous. On the other hand, adding more fine recycled material (FRM) makes the matrix denser, which reduces the overall porosity and increases the packing density. In contrast to increased content of FRM, correlation coefficient of (-0.77) reveal a more powerful inverse relationship between risen level of foam content (-0.67) and the reduction ratio of fresh-to-dry density and the increase in compressive strength from 7 to 28 days. It is also known that mixes with more foam have better thermal insulation because they trap more air, while mixes with more FRM show an increase in thermal conductivity. The sensitivity analysis showed that changes in thermal conductivity are almost three times as sensitive for FRM content, which means they have a bigger effect than changes in foam content. Employing the Taguchi method, (R_0.714) emerges as the most efficient tested combination indicative of superior overall performance. Notably, the Taguchi method predicts the untested combination (0.100-F/C ratio + 0.714-R/C ratio) as potentially more efficient, suggesting avenues for further exploration and optimization. This study furnishes valuable insights into sustainable construction practices by reutilizing CDW in foam concrete production, thereby contributing to both environmental conservation and enhanced structural outcomes.

Rheological properties of high-performance SCC using recycled marble powder

Due to the impacts of cement manufacturing and depletion of the natural aggregates for concrete production, recycling of construction and demolition waste materials has become an alternative replacement to natural materials that lower their consumption and satisfy the environment. One of these alternatives is replacing cement with recycled materials from marble, ceramic, granite, and concrete wastes or even replacing the coarse aggregate with crushed marble and other stone wastes. Marble, granite, and natural stone wastes rapidly increase each year due to unmanaged waste disposal processes and the incremental increase in construction potential. Marble slurry, which comes from washing and cleaning marble surfaces, shows a filler effect by giving the concrete a denser and homogenous structure. This study evaluates the marble filler effects on the rheology in the fresh state of self-compacting concrete (SCC) through four SCC mixes by incorporating 10% marble powder (MP) and 33% fly ash (FA) as a partial ordinary Portland cement (OPC) replacement. Tests on paste and mortar were conducted to assess the suitability of the marble dosage on the water content and the superplasticizer amount. Spread flow and V-funnel tests were assessed. The results showed that mixes with MP required additional mixing water to ensure the same workability. Regardless of the high viscosity and air content, the overall developed marble SCC mixes reduced the cement quantity by up to 11% and provided excellent rheological properties like that of the reference mix. Besides the economic benefits, this transformation of waste to valuable materials involves environmental advantages and sustainability promotion.

Micromechanical Modeling of Cement-Treated Base Materials Considering Recycled Crushed Aggregate Morphology from Construction and Demolition Waste Using Three-Dimensional Discrete Element Method

Micromechanical Modeling of Cement-Treated Base Materials Considering Recycled Crushed Aggregate Morphology from Construction and Demolition Waste Using Three-Dimensional Discrete Element Method

Combined Application of CDWs as Precursors and Aggregates in Geopolymer Composites: A Comprehensive Rheological Analysis

The study of rheological characterization of construction and demolition waste (CDW)-based geopolymeric materials has gained interest due to digital innovation in construction and the increased focus on sustainable materials. Understanding the rheological behavior of these materials is essential due to their rapid geopolymeric reaction kinetics and viscosity behavior. This study investigated the impact of various CDW-based fine recycled aggregates, including crushed concrete aggregates (CRC), crushed ceramic-tile aggregates (CTA), and crushed brick aggregates (CBA), on the rheological behavior of geopolymer mortars (GPMs). Natural sand (NSA) was utilized as a reference for comparison purposes. In addition to CDW-aggregates, the GPMs were also made from optimized CDW-based precursors of brick waste powder (BP), ceramic-tile waste powder (TP), or concrete waste powder (CP). As a result, twelve different GPMs were considered, each containing 100% individual CRC, CTA, and CBA fine aggregates, blended with BP, TP, and CP precursors. The study evaluated the relationship between the design variable of SiO2/Al2O3 molar ratio as well as the packing densities (PD) of GPM systems and their rheological characteristics, such as flow, apparent and plastic viscosity, yield and shear stresses, thixotropy and shear strains employing the compressible packing method. The results indicate that all GPMs possess shear-thinning or pseudoplastic characteristics. Enhanced SiO2/Al2O3 molar ratio generally resulted in increased rheological parameters. However, using TP as a precursor and CBA as fine aggregates in GPM matrices led to significant enhancement in rheological parameters due to the higher specific surface area of TP and the greater irregularity, convexity, and absorption capacity of CBA particles. Notably, although the enhanced non-colloidal frictional interactions and colloidal flocculation of CRC, CTA, and CBA resulted in reduced flow tendency of GPMs, they have been found to improve the thixotropy during the initial geopolymeric gelation stage.

Mechanical properties of recycled aggregate concrete reinforced with steel fibers under triaxial loading

The use of steel fiber reinforced recycled concrete (SFRAC) can help achieve resourceful reuse of construction waste and environmental sustainability. However, SFRAC structural members may experience complex stress states. Therefore, triaxial compression tests were conducted on 168 cylindrical SFRAC specimens to investigate their mechanical properties. The failure modes, stress-strain behavior, strength, and deformation of SFRAC under triaxial compression were observed. The effects of lateral confining pressure, steel fiber (SF) content, and recycled coarse aggregate (RA) replacement rate on these properties were analyzed. The internal micro-morphology of SFRAC was analyzed using SEM to better understand its failure mechanism under compression. The result shows that an increase in lateral confining pressure alters the failure mode of SFRAC specimens, resulting in a significant increase in peak strength and ductility. The enhancement of the elastic modulus by steel fibers decreases as the lateral confining pressure increases, suggesting a coupling effect between the two parameters. The inclusion of steel fibers in SFRAC did not have a significant impact on its failure mode or compressive strength. And yet, it did increase the ductility and toughness of the material, with an optimal steel fiber content of 1% (by volume). On the other hand, the addition of recycled coarse aggregate resulted in a significant reduction in the concrete's compressive strength, by almost 17%. Finally, several common material failure criteria for concrete were used to evaluate the impact of RA substitution rate and SF content on the strength of SFRAC. The Willam-Warnke failure criterion showed a higher strength. These findings provide a theoretical basis for future engineering applications of SFRAC.

Supporting zero-waste building: A novel spatial explicit material flow analysis model for construction waste

The accurate quantification of construction waste (CW) is prerequisite for achieving zero-waste in the building sector. This study employs a Spatial Material Flow Analysis model considering building life cycle to estimate the spatio-temporal dynamics of CW in Nanjing, China, over two decades. Additionally, it employs an ARIMA model for forecasting CW generation over the forthcoming decade. During 2000 to 2020, Nanjing's CW witnessed a CW increase from 0.8 to 59.0 Tg, predominantly comprising non-metallic materials. Meanwhile, the spatial distribution of CW has widened, accompanied by the emergence of numerous CW hotspots, in parallel with economic and population growth. Future projections suggest a continuous yet decelerating increase in CW generation, highlighting a significant opportunity for resource recovery. The application of this hybrid approach not only enhances CW management accuracy but also supports the broader goal of fostering sustainable building practices. This research expects to enlighten the stakeholders committed to advancing sustainable construction and waste management strategies in the context of zero-waste buildings.

An evaluation model for city-scale construction and demolition waste management effectiveness: A case study in China

The growing generation of construction and demolition waste (CDW) has emerged as a prominent challenge on global environmental agendas. However, the effectiveness of CDW management (CDWM) strategies varies among cities. Existing literature predominantly evaluates the effectiveness of CDWM at the project level, offering a localized perspective that fails to capture a city’s comprehensive CDWM profile. This localized focus has certain limitations. To fill this gap in city-scale evaluations, this study introduces a novel model for assessing CDWM effectiveness at the municipal level. An empirical investigation was conducted across 11 cities within the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) to operationalize this model. The model defines five distinct levels of CDWM effectiveness. Findings indicate that Hong Kong consistently achieves the highest level (level I), while the majority of cities fall within levels III and IV. This pattern suggests that CDWM effectiveness in the GBA is moderately developed, with uneven progress in CDW management outcomes and supporting systems. Essentially, there is a lack of synchronous development of CDWM results and guarantee systems. The proposed evaluation model enriches existing CDWM research field and offers a framework that may inform future studies in other countries.