Community-Based Participatory Workshop on Recycling Construction and Demolition Waste for the Empowerment of Women and Low-Income Communities in Colombia

Construction and demolition (C&D) waste is becoming an increasing concern worldwide due to the rise of construction practices in the face of population and urban expansion. Despite this, there has been a lack of significant advancements in community-based approaches for managing this waste. Through this research, we hope to contribute to gender equality and women empowerment by utilizing community-based research methods to analyze how women in low-income communities in Colombia can find safe and meaningful work by gaining skills in extracting value from C&D wastes, business administration, and leadership. In this presentation, we will discuss the importance of utilizing community-based research to develop just and sustainable technologies for the empowerment of women by using our research on recycling C&D waste in the context of low-income communities as a guide. It is important to note that this research is in its preliminary phases and will not be completed until March 2023, thus the final outcomes and conclusions are currently unknown.

Recycled construction and demolition waste as a possible source of materials for composite manufacturing

The recycling of construction waste is key to reducing waste generation and CO2 emissions. This study aimed to develop a quantitative model for analyzing the carbon reduction potential of recycling construction, demolition, and renovation waste (CDRW) in Jiangsu province. The waste generation rate calculation method and nonlinear autoregressive artificial neural network model were used to estimate and predict CDRW generation. The life cycle assessment was performed to calculate the carbon reduction potential of recycling CDRW. In quantifying the carbon reduction potential, not only construction and demolition waste, but also renovation waste was considered for the first time. The results showed that the total carbon reduction potential of recycling CDRW increased from 3.94 Mt CO2e in 2000 to 58.65 Mt CO2e in 2020. Steel and concrete were the main contributors. By scenario analysis, the carbon reduction potential of fully recycling CDRW in 2020 increased by 37.79 Mt CO2e, a growth rate of 64%. The study further predicts future CDRW generation and the corresponding carbon reduction potential. Our conclusions indicate that 245.45 Mt of CDRW will be generated in 2030, and carbon reduction potential may reach 82.36 Mt CO2e. These results will help the government manage construction waste better and reach early achievement of the carbon peak target.

Bangladesh is a fast-growing developing country and Buildings of Mymensingh city areas are increasing rapidly in last five years. The management of construction and demolition trash is an issue given the dramatic increase in 20-building construction. Environmental contamination has risen recently due to a lot of development and demolition trash. Building materials, collection techniques, recycling and disposal should all be evaluated to assess this problem. This article demonstrates the Reuse, Recycling and Disposal of Construction and Demolition waste as a way for environmental protection, and Construction and Demolition waste management. The investigation was based on field visits, interviews, secondary data sources, and conceptual methods. We surveyed 300 construction sites (buildings) in Mymensingh city as a new city corporation of the country. We found 31% materials are reused, 26% are recycled and rest of the materials is nominated as construction waste. This paper also examines the management practices for evaluating the result. Different methods could be used to reduce waste and increase profits through recovery, reuse, and recycling of construction and demolition waste. For proper reuse and recycling of Construction and Demolition waste, waste management strategies, reliable and tested case studies are necessary.

Estimation of construction waste generation and management in Thailand

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.

Construction and demolition waste has become a serious trouble to public administration authorities due to adoption of repeated, expensive and inefficient management solutions. These actions are generally supported by the feeling that construction and demolition wastes present a high variability in their compounds, thus being inappropriate to reuse. In considering a competent approach in engineering practice, the decisive factors for the use of recycled construction and demolition wastes are their properties as a construction material, and the fact that variability may only be assessed by the use of statistical tools. In this investigation the authors have carried out a laboratory testing program (characterization, Proctor compaction, pH and direct shear test) on RCDW sampled in different times in order to conduct statistical analyses of its chemical and geotechnical parameters. The results have shown that recycled construction and demolition waste has a low variation of its properties and high levels of confidence that justify its use in a range of geotechnical application.

This study deals with the problem of consumption of construction waste and shortage of traditional construction materials, offering a technical and environmental basis for the recycling and utilization of construction and demolition waste (CDW). Using waste concrete and waste bricks as recycled aggregates for pavement base materials, and cement, lime and fly ash as stabilizers, this study systematically explores the feasibility of stabilizing recycled aggregate-based materials for road use. The basic physical properties and macro-mechanical properties are analyzed, and the effects of stabilizer dosage (ESR), recycled aggregate dosage (RASR), and brick-concrete ratio (BCR) on the roadability of stabilized recycled aggregate materials are investigated. Revealing the significance and critical effects of multi-factors of strength development. Life cycle assessment (LCA) method is employed to measure the carbon emissions of different materials used as road pavement sub-base and compare them with those of natural aggregates. The results show that stabilized construction waste recycled aggregate is suitable for road subgrade. ESR, RASR and BCR have a significant effect on it with the order of BCR > RASR > ESR. The optimum ratio exists at 30% ~ 45% recycled aggregate blending and 1:2 of BCR. The carbon emission of cement stabilized class can be reduced from 60,789.66 to 48,117.03 kgCO2eq by using recycled construction waste aggregate instead of natural aggregate during construction period based on the base unit (a flow section length of 500m as the basic unit), which is 19.2% reduction in carbon emission. For the lime fly ash stabilized category, the carbon emission is reduced from 53,246.65 to 41,734.03 kgCO2eq, which is 21.6% reduction in carbon emission. Recycled aggregates alone can achieve carbon emission reductions of 82.27%, 81.23%, and 78.02%, demonstrating a substantial environmental benefit in carbon reduction.

Characterising the resilient behaviour of pavement subgrade with construction and demolition waste under Freeze–Thaw cycles

The volumetric deviations in montmorillonite-rich clays like bentonite render such soils unsuitable to support overlying pavement and foundation structures. Moreover, green construction and sustainable waste management practices have adapted use of waste recycled materials for engineering purposes. This study explores the feasibility of using recycled construction and demolition waste and ground granulated blast furnace slag for developing shear strength properties of bentonite clay. Direct shear tests were performed on specimens from bentonite and bentonite-stabiliser composites to evaluate the effect of both stabilisers under different curing times and percentages. Microanalyses were conducted to obtain microstructural, mineralogical and elemental composition of the stabilised and unstabilised samples. Results exhibit that shear strength increased with increasing stabiliser percentages and curing time, and the effects were more enhanced on higher stabiliser dosages and curing periods. Sample cohesion value increased from 58.90 kPa for pure bentonite sample to 67.26 kPa for the maximum additive percentages of 5% slag and 20%construction waste (sample S3G5), after 28 days of curing. The internal friction angle also increased by 7.3° from the pure sample to the S3G5 bentonite-stabilisers composite specimen. Peak shear stress values also showed a development of 55.95 kPa after additive induction and 28 days curing, for 200 kPa of normal stress. Curing period also affected the development of cohesion and peak shear strength of the stabilised samples. Internal frictional angle for sample S3G5 also escalated by 2.3°, after 28 days, from the 25.0° value after sample curing of 1 day. Scanning Electron Microscopy (SEM) micrographs and Energy Dispersive Spectroscopy (EDS) spectra show that stabilisers occupied vesicles and cracks found in construction waste particles, resulting in better particle interlocking mechanism and greater shear strength.

For environment protection in the European Union (EU) it is very important the construction waste to be recycled and reused. The potential for the construction waste recycling and reuse is high, as their components have high cost. There is an opportunity for re-use of such materials in road construction, for drainage systems, for outdoor sports grounds and other construction sites. In 2012 a regulation on the management of construction waste and on the use of recycled building materials was adopted in Bulgaria, aiming to introduce a new model for the management of construction waste. This would guarantee: creation of favorable legislative and economic conditions for implementation of technologies ensuring the achievement of recycling and recovery targets but which are also financially viable in line with the country's incomes; identifying the persons responsible for covering the costs of building waste management and achieving the recycling and recovery targets; creating conditions for the production and marketing of materials from recycling of construction waste at a price that is competitive with the same new raw materials used in construction. The main effect expected from this normative document is to contribute to Bulgaria's development towards European trends, environmental protection through an integrated framework for the management of construction and demolition waste that will reduce the harmful impacts on it caused by construction waste, improving the efficiency of resource use, increasing the responsibilities of pollutants and stimulating investment in waste management.

How to promote sustainable development of construction and demolition waste recycling systems: Production subsidies or consumption subsidies?

In the paper a preliminary analysis of Construction and Demolition Waste (CDW) management in Bulgaria is presented, using official data from Bulgarian National statistical institute [2] and European Union [6].In Bulgaria for the period 2013 - 2017, there is an almost threefold decrease in the amount of non-hazardous construction waste generated. During the same period, hazardous construction waste also decreased by over 50%. In 2016, 54% recycling of construction and demolition waste (CDW) was achieved with the aim of achieving a minimum of 70% by 2020 according to the Waste Management Framework Directive (Directive 2008/98/EC [9]). On this basis, amendments to the Waste Management Act (WMA) were introduced and the Ordinance on construction waste management and input of recycled construction materials (NUSOVRM) was prepared. New standards for the quality of construction materials used have been modified and introduced. In order to reduce landfill recycling, financial incentives are provided by municipalities. Some of the public-funded construction sites require a mandatory percentage of recycled waste, depending on the type of site. Specific targets (for construction waste codes) introduced for recovery for each construction - for example 85% for concrete and reinforced concrete waste, 90% for metals.

Using recycled construction and demolition waste (RCDW) in geosynthetic reinforced soil (GRS) structures presents attractive environmental and economic aspects. However, bearing in mind installation damage can be responsible for significant changes in geosynthetic tensile-strain behavior, the damage caused by the RCDW must be assessed and quantified. This study aims to investigate the occurrence of mechanical damage during the installation of geogrids with RCDW backfill material using an in-field test facility. In order to understand the mechanisms related to the damage, the influences of the dropping height and compaction method were investigated. Statistical analysis using the Student's t-distribution was carried out to validate the occurrence of damage and calculate reduction factors for geogrids’ tensile strengths. Results revealed that dropping processes reduced the geogrid ultimate tensile strengths, but the compaction methods caused the highest reductions. The reduction factor values encourage the design of GRS structures with RCDW, an interesting option to satisfy the technical and economic aspects required for these structures in agreement with the environmental concerns.

Currently, a number of disadvantages hampers the use of recycled concrete aggregates (RCA). The current review proves that concretes made with complete replacement of natural aggregate with RCA allow the production of high-quality concrete. One of the possibilities for improving concrete properties with RCA is the use of extended curing and pozzolanic materials with varying cement ratios. The potential use of RCA concretes is in the production of high-value materials that increase environmental and financial benefits. RCA have strong potential in the development of a new generation of concrete and stimulate economic activity in many countries in addition to optimizing natural resources. Economic benefits include minimal travel costs; cheaper sources of concrete than newly mined aggregates; reduction of the landfill area required for the placement of concrete waste; the use of RCA minimizes the need for gravel extraction, etc. The proposed strategy could be to sequentially separate demolition waste such as roof finishes, waterproof materials, interior and exterior materials, etc. Closing life cycles is the main approach used for efficient structures for the recycling and reuse of construction and demolition waste in the production and recovery of materials, especially when recycling and reusing materials. In the life cycle, the recycling of recovered materials allows them to be used for new construction purposes, avoiding the use of natural concrete aggregates. Government, design institutes, construction departments and project managers should be involved in the creation and use of RCA. In demolition and construction, the main players are the project owners. Their obligations, expectations and responsibilities must be properly aligned. For the past 20 years, recycled concrete aggregate from demolition and construction waste has been considered as an alternative to pure concrete in structural concrete to minimize the environmental impact of construction waste and demolition waste and the conversion of natural aggregate resources. It is now recognized that the use of RCA for the generations of concrete is a promising and very attractive technology for reducing the environmental impact of the construction sector and conserving natural resources. In the market, the selling price is not an obstacle for market applications of RCA, as there are scenarios in which their cost is lower than the cost of products made from conventional building materials. This is more of an acceptance factor in the market for recycled concrete aggregates. In this sector, the lack of identification, accreditation and uniform quality certification systems and their narrow application cause some marketing problems. With proper RCA preparation, concrete with standard physical and mechanical properties and performance characteristics can be obtained.