Evaluating the Efficiency of Municipal Solid Waste Management in China

Poor public health is always associated with the mismanagement of municipal solid waste (MSW). Many cities are besieged by MSW in the world. It is essential to do a good job in MSW management (MSWM). In order to improve the efficiency of MSWM, the Chinese government has intensively implemented relevant policies. There are still few studies on MSWM efficiency in China. The research aims to comprehensively analyze MSWM efficiency, find high-efficiency MSWM policy implementation routes and the breakthrough on improving MSWM efficiency. To measure Chinese MSWM efficiency accurately, this paper introduced the three-stage data envelopment analysis (DEA) model into the research. According to the results of DEA, Fuzzy c-Means algorithm was used to the cluster analysis of 33 typical cities. After eliminating the interference of the external environment and random disturbance, the mean value of MSWM efficiency declined from 0.575 to 0.544. The mean of pure technical efficiency (PTE) was declined from 0.966 to 0.611, while the mean of scale efficiency (SE) increased from 0.600 to 0.907. The PTE of central and northeastern cities was relatively low. The SE of western cities was comparatively high and the efficiency distribution of the eastern region was relatively scattered. In general, MSWM efficiency is low and expected to be improved. Regional differences in MSWM efficiency have been shown. The management effectiveness of eight pilot cities (MSW classification) is affirmative but not that significant. To improve MSWM efficiency, differential management for four types of cities should be carried out.

The Effect of Incorporating Silica Stone Waste on the Mechanical Properties of Sustainable Concretes

Incorporating various industrial waste materials into concrete has recently gained attention for sustainable construction. This paper, for the first time, studies the effects of silica stone waste (SSW) powder on concrete. The cement of concrete was replaced with 5, 10, 15, and 20% of the SSW powder. The mechanical properties of concrete, such as compressive and tensile strength, were studied. Furthermore, the microstructure of concrete was studied by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy analysis (EDX), Fourier transformed infrared spectroscopy (FTIR), and X-Ray diffraction (XRD) tests. Compressive and tensile strength of samples with 5% SSW powder was improved up to 18.8% and 10.46%, respectively. As can be observed in the SEM images, a reduced number of pores and higher density in the matrix can explain the better compressive strength of samples with 5% SSW powder.

Durability and Mechanical Properties of Concrete Reinforced with Basalt Fiber-Reinforced Polymer (BFRP) Bars: Towards Sustainable Infrastructure

Reducing the fingerprint of infrastructure has become and is likely to continue to be at the forefront of stakeholders' interests, including engineers and researchers. It necessary that future buildings produce minimal environmental impact during construction and remain durable for as long as practicably possible. The use of basalt fiber-reinforced polymer (BFRP) bars as a replacement for carbon steel is reviewed in this article by examining the literature from the past two decades with an emphasis on flexural strength, serviceability, and durability. The provisions of selected design and construction guides for flexural members are presented, compared, and discussed. The bond of BFRP bars to the surrounding concrete was reportedly superior to carbon steel when BFRP was helically wrapped and sand coated. Experimental studies confirmed that a bond coefficient k_b = 0.8, which is superior to carbon steel, may be assumed for sand-coated BFRP ribbed bars that are helically wrapped, as opposed to the conservative value of 1.4 suggested by ACI440.1R-15. Code-based models overestimate the cracking load for BFRP-reinforced beams, but they underestimate the ultimate load. Exposure to an alkaline environment at temperatures as high as 60 °C caused a limited reduction in bond strength of BFRP. The durability of BFRP bars is influenced by the type of resin and sizing used to produce the bars.

Mechanical Behavior of Masonry Mortars Made with Recycled Mortar Aggregate

Recycling is an important habit to avoid waste. This paper evaluates the performance of masonry mortar, elaborated by replacing natural sand with recycled fine aggregate (RFA) obtained from mortar. Five families of mixtures were prepared with different replacement proportions: 20%, 40%, 60%, and 100%. A 1:4 volumetric cement-to-aggregate ratio was used for all mixtures by experimentally adjusting the amount of water to achieve the same consistency of 175 ± 5 mm. The effects of the following procedures were analyzed: (1) the use of a deconstruction technique to collect the RFA, (2) pre-wetting of the aggregates, and (3) the use of a commercial plasticizer. Experimental results show that it is possible to use this type of recycled fine aggregate as a substitute for natural sand by up to 60% in the manufacture of masonry mortar without significantly affecting its properties.

Bridge Carbon Emissions and Driving Factors Based on a Life-Cycle Assessment Case Study: Cable-Stayed Bridge over Hun He River in Liaoning, China

Due to the rapid growth of the construction industry’s global environmental impact, especially the environmental impact contribution of bridge structures, it is necessary to study the detailed environmental impact of bridges at each stage of the full life cycle, which can provide optimal data support for sustainable development analysis. In this work, the environmental impact case of a three-tower cable-stayed bridge was analyzed through openLCA software, and more than 23,680 groups of data were analyzed using Markov chain and other research methods. It was concluded that the cable-stayed bridge contributed the most to the global warming potential value, which was mainly concentrated in the operation and maintenance phases. The conclusion shows that controlling the exhaust pollution of passing vehicles and improving the durability of building materials were the key to reducing carbon contribution and are also important directions for future research.

Mechanical Characterization of Gypsum Composites Containing Inert and Insulation Materials from Construction and Demolition Waste and Further Application as A Gypsum Block

This article analyzes the feasibility of using construction and demolition waste (expanded polystyrene, ceramic, and concrete waste) in a gypsum matrix to manufacture plaster for interior coatings or for prefabricated elements for interior partitions. To do this, several gypsum specimens were prepared (4 × 4 × 16 cm) incorporating different percentages of waste based on the weight of the gypsum (25%, 50%, and 75% of ceramic, concrete, and a mixture of both). Reference samples were also produced (without additions) to compare the results obtained. The compounds with the best performance were selected and lightened by preparing other samples in which 1/3 and 2/3 of the volume of ceramic, concrete, and mixed waste were replaced with expanded polystyrene (EPS). All samples were tested in the laboratory and the following physical and mechanical characteristics were determined: density, surface hardness, flexural strength, compressive strength, capillary water absorption, and thermal conductivity. Several applications were proposed for the selected compounds. A gypsum block with a sandwich configuration was obtained (40 × 20 × 10 cm) using the optimum compound. The block was further tested regarding its density and compression strength. A comparative analysis showed that it is possible to produce materials with a gypsum matrix by adding ceramic, concrete, and EPS waste, improving the behavior of the traditional gypsum and enabling them to be applied in various construction applications. These applications have a lower environmental impact than ordinary ones because they use less primary raw material, due to the reuse of waste.

Eco-House Prototype Constructed with Alkali-Activated Blocks: Material Production, Characterization, Design, Construction, and Environmental Impact

The interest of the construction industry in alkali-activated materials has increased to the extent that these materials are recognized as alternatives to ordinary Portland cement-based materials in the quest for sustainable construction. This article presents the design and construction of a prototype of an eco-friendly house built from concrete blocks produced using alkali activation technology or geopolymerization. The prototype meets the requirements of the current Colombian Regulations for Earthquake Resistant Buildings (NSR-10) and includes standards related to the performance of the materials, design, and construction method for earthquake-resistant confined masonry of one- or two-story buildings. The alkali-activated blocks were obtained from different precursors (aluminosilicates), including a natural volcanic pozzolan, ground granulated blast furnace slag, fly ash, construction and demolition waste (concrete, ceramic, brick, and mortar), and red clay brick waste. The physical-mechanical characterization of the alkali-activated blocks allowed their classification according to the structural specifications of the Colombian Technical Standard NTC 4026 (equivalent to ASTM C90). The global warming potential (GWP) or “carbon footprint” attributed to the raw materials of alkali-activated blocks was lower (25.4–54.7%) than that of the reference blocks (ordinary Portland cement concrete blocks). These results demonstrate the potential of alkali-activated materials for application in the construction of eco-friendly houses.

Behavior of a Two-Way Lightweight Steel-Concrete Composite Slab Voided with Thin-Walled Core Boxes towards Sustainable Construction

High-performance engineered structural systems are crucial for sustainable development in the field of construction. In our previous research, a novel steel-concrete composite beam with transverse and longitudinal hidden girders exhibited good flexural behavior and desirable ductility. However, there is a dearth of studies on the flexural response of a steel-concrete composite slab voided with thin-walled core boxes. Therefore, in this study, we investigated the overarching flexural mechanism of the proposed structure when subjected to uniform vertical loads. The experimental detection results illustrated that the deflection value of the composite beam was 95.75% less than the GB/T 50152-2012 recommendation. Numerical results further validated this observation. The recorded data from the strain profile at the mid-span of the frame girder indicated that there was a considerable membrane effect, which delayed the strain growth of rebars, yielding appreciable bearing capacity. Thus, two original approaches to predicting the ultimate load of this novel structure are proposed, considering limit analysis using the upper-bound method and the membrane effect, with the latter closely linked to the experimental results. The findings can promote the extensive application of similar sustainable systems and inspire further advancements in advanced engineering structures.

Second-Generation Implants for Load Introduction into Thin-Walled CFRP-Reinforced UHPC Beams: Implant Optimisation and Investigations of Production Technologies

Combining two high-performance materials—ultra-high-performance concrete (UHPC) as the matrix and carbon-fibre-reinforced composites (CFRP) as the reinforcement—opens up new possibilities for achieving very lightweight thin-walled concrete elements. This strategy, however, leads to a higher degree of material utilisation, resulting in the generation of higher forces around load introduction points and supports. The authors present a solution for increasing the performance of supports of very slender CFRP-reinforced UHPC beams by using metal implants. Implants are used in place of concrete in regions of stress concentrations and significant deviation forces. These are able to transfer high stresses and forces efficiently due to their ability to sustain both tension and compression in equal measure. A key issue in their development is the interface between the reinforced concrete and metal implant. Building on previous research, this paper deals with the conceptual design of three types of implants manufactured from different metals and with three different types of automated production technologies (water-jet cutting, metal casting with a 3D-printed plastic formwork and binder jetting of steel components). For this paper, tests were carried out to determine the load-bearing behaviour of beams with the three different types of support implants used for load introduction at the supports. A carbon rod served as bending reinforcement and a pre-formed textile reinforcement cage served as shear and constructive reinforcement.

Determination of the Chemical, Physical and Mechanical Characteristics of Electric Arc Furnace Slags and Environmental Evaluation of the Process for Their Utilization as an Aggregate in Bituminous Mixtures

Road construction is an activity that demands a significant amount of aggregates for bituminous mixtures. In addition, these aggregates must be of a suitable quality for use, even more so on high traffic roads. In response to this problem, and in order to avoid the extraction of new raw materials, research is being carried out using industrial waste as a substitute for conventional aggregates. In this way, the extraction of raw materials is reduced and landfilling of waste is avoided. However, these wastes must have certain properties and environmental advantages over natural aggregates. Otherwise, the use of waste would not be environmentally beneficial but would be more damaging to the environment. For this reason, this research evaluates the viability of using electric arc furnace slag as aggregates for bituminous mixtures, the main objectives being the determination of the characteristics of the by-product, the particularities and the critical points to be taken into account for its subsequent use in mixtures. At the same time, the environmental advantages of treating this waste to obtain a usable aggregate are evaluated in comparison with the processing of a natural aggregate. The results showed that electric arc furnace slags have a suitable chemical composition and excellent physical and mechanical properties for use in bituminous mixtures, even on high traffic roads. At the same time, it was determined that their use produces a considerable reduction in environmental afflictions. Therefore, it could be affirmed that the use of electric arc furnace slags in bituminous mixtures is recommendable as a way to develop more sustainable materials for construction.

Effect of Pre-Wetting Recycled Mortar Aggregate on the Mechanical Properties of Masonry Mortar

In this research we evaluated the use of recycled fine mortar aggregate (RFMA) as a fine aggregate for new masonry mortar creation. The pre-wetting effect on the aggregate before creating the mixture was analyzed as a method to reduce its absorption potential. A control mixture of conventional mortar and two groups of recycled mortars were designed with a partial replacement of natural sand by RFMA (pre-wetted and not pre-wetted) performed in different proportions. The results established that the pre-wetting process allows a reduction in the amount of water required during the creation of new mixtures, regulating the water/cement (W/C) ratio and improving the properties of recycled mortars such as air content, fresh and hardened densities, and compressive and adhesive strength for all substitution levels. Mortar made with a 20% substitution and pre-wetted until it was at 67% of its absorption capacity displayed adhesive values higher than the ones shown by the reference mortar. The pre-wetting process proves to be an easy performance technique; it is inexpensive, environmentally friendly, and the most valuable fact is that specialized equipment is not necessarily needed. This process is the most profitable option for improving RFMA exploitation and reuse.

Characterization of Mechanical and Hygroscopic Properties of Individual Canes of Reed

The search for sustainability has led to the utilization of more ecological materials with at least, a similar structural performance to those used at present. In this regard, reed fits the environmental and structural requirements as it is a sustainable and biodegradable lignin-cellulose material with remarkable mechanical properties. This research confirms the reed’s structural efficiency as it demonstrates that it has excellent strength and stiffness in relation to its density. The reed anisotropy has a large impact on its properties. Indeed, the strength and stiffness parallel to the fibers are clearly higher than in the perpendicular direction. The results confirm that strength and stiffness decrease with the moisture content and nodes act as reinforcement in compression and bending. If compared with steel, timber and concrete, the reed possesses the highest value for strength. Hence, reed constitutes a strong candidate for environmentally friendly engineering.

Evaluation of Eco-Efficient Concretes Produced with Fly Ash and Uncarbonated Recycled Aggregates

The fabrication of conventional concrete, as well as remains from demolition, has a high environmental impact. This paper assessed the eco-efficiency of concrete made with uncarbonated recycled concrete aggregates (RCA) and fly ash (FA). Two concrete series were produced with an effective water/cement ratio of 0.50 (Series 1) and 0.40 (Series 2). In both series, concretes were produced using 0% and 50% of RCA with 0%, 25% and 50% FA. After analysing the compressive strength, and carbonation and chloride resistance of those concretes, their eco-efficiency based on the binder intensity and CO₂-eq intensity was assessed. We found that the use of 50% uncarbonated RCA improved the properties of concretes produced with FA with respect to using natural aggregates. The concrete made of 25% FA plus RCA was considered the most eco-efficient based on the tests of compressive, carbonation and chloride properties with the values of 4.1 kg CO₂ m⁻³ MPa⁻¹, 76.3 kg CO₂ m⁻³ mm⁻¹ year^0.5 and 0.079 kg CO₂ m⁻³ C⁻¹, respectively. The uncarbonated RCA improved carbonation resistance, and FA improved chloride resistance. It can be concluded that the use of 50% un-carbonated RCA combined with FA considerably enhanced the properties of hardened concrete and their eco-efficiency with respect to concretes produced with natural aggregates.

A New Methodology to Design Sustainable Archimedean Screw Turbines as Green Energy Generators

Current energy demand and climate target plans are leading to green energy facilities which are efficient and sustainable. Archimedean screw turbines (ASTs) are used to generate hydroelectricity in low heads. They have been manufactured and installed worldwide. However, there is a lack of knowledge about how to design them efficiently. In this study, the performance of ASTs is analyzed using an analogy between ASTs and bucket elevators. Based on this analogy, a theoretical hypothesis on how to produce efficient ASTs is proposed. The new methodology for the design of ASTs is based on two considerations: the filling level of the AST buckets must be 85% and the increase of leakage losses must be minimized. This hypothesis is numerically and experimentally studied. Two experimental prototypes were developed and installed in the north of Spain. The numerical and experimental results are provided. A discussion comparing the results of this work and other results from the literature is presented. Finally, conclusions are drawn from this work that contribute to the improvement of AST technology as a sustainable facility to generate green energy.

Manufacture and Characterization of Polypropylene (PP) and High-Density Polyethylene (HDPE) Blocks for Potential Use as Masonry Component in Civil Construction

The lack of suitable destinations for plastics materials can be a global environmental problem. The alternative use of materials for sustainable construction encourages the standardization of waste and promotes effective social, environmental and economic gains at the local level and ensures savings and income for communities. The aim of this paper is the development, manufacture, and characterization of PP and HDPE recycled polyolefin blocks as masonry components in civil construction. These blocks were manufactured by the rotational molding process. Besides this, the mechanical, physical, impact and flammability properties of the blocks were studied. In conclusion, HDPE showed better behavior than PP in tests realized.

The Reuse of Biomass and Industrial Waste in Biocomposite Construction Materials for Decreasing Natural Resource Use and Mitigating the Environmental Impact of the Construction Industry: A Review

The construction industry is the world's largest emitter of greenhouse gases. The CO₂ emission levels in the atmosphere are already reaching a tipping point and could cause severe climate change. An important element is the introduction of a technology that allows for the capture and sequencing of carbon dioxide levels, reducing both emissions and the carbon footprint from the production of Portland cement and cement-based building materials. The European Union has started work on the European Climate Law, establishing the European Green Deal program, which introduces the achievement of climate neutrality in the European Union countries. This includes a new policy of sustainable construction, the aim of which is to develop products with a closed life cycle through proper waste management. All efforts are being made to create generated waste and thus to support their production and/or use as substitutes for raw materials to produce biocomposites. This article reviews environmental issues and characterizes selected waste materials from the agri-food, mineral, and industrial sectors with specific properties that can be used as valuable secondary raw materials to produce traditional cements and biocomposite materials, while maintaining or improving their mechanical properties and applications.

Effectiveness of Concrete Reinforcement with Recycled Tyre Steel Fibres

The role of searching for industrial waste management solutions in construction is key for environmental protection. Research in recent years has focused on solutions aimed at reducing the carbon footprint. This paper presents the results of tests conducted on concrete reinforced with treated recycled tyre steel fibres (RTSFs) compared to the same amount of manufactured steel fibres (MSFs). The effectiveness of concrete reinforcement with RTSFs was analysed using the fracture mechanics parameters of cementitious composites. Rheological tests, residual flexural tensile strength tests, work of fracture measurements, toughness indices, examinations of the fibre distribution in the concrete, and SEM observations of the concrete fractures with fibres were performed. Determining the work of fracture and toughness indices was an innovative aspect of this paper. As the amount of RTSFs increased, a decrease in the consistency was observed, although the distribution of fibres in the concrete was uniform, as proven by the results of computer tomography tests. Concrete reinforced with RTSFs that is purified and refined during the recycling process might have better properties than concrete reinforced with the same amount of MSFs. The application of RTSFs in construction has environmental and economic benefits in addition to the strengthening of cementitious composites.

Cultural shift towards sustainability in the construction industry of Hong Kong

Sustainable development is forward-looking; it is a continuous mission for future developments of human society. A genuinely sustainable society is one that initiates developments in sustainable ways. The development of a genuinely sustainable society is supported by its citizens who think and act according to a recognized code of conduct - the sustainable culture. Similar to other forms of culture, sustainable culture of a society is not static, but changes over time. The changes found in a sustainable culture are reflections of the status of sustainability in a society and these changes should be measured from time to time. The resulting measurement gives very important information for decision-makers, in the government and in the private sector, to examine the magnitude of changes that have taken place in a given period of time. The results will also enable them to review and adjust policies in order to better accommodate changes according to the trends of society. This paper provides a method - the T-model, to investigate and measure the extent of change of sustainable culture through two extensive surveys among participants of the construction industry of Hong Kong. The change in sustainable culture is reflected by the change in attitude and practice among construction participants, this can be found in their performance in project development, design and construction operations. The data of these changes are collected and converted to numerical scores. The T-model synthesized these scores and revealed the change of sustainable culture within the specific study time frame.

A Full-Scale Experimental Investigation of Utility Poles Made of Glass Fibre Reinforced Polymer

Utility poles made of glass fibre-reinforced polymer (GFRP) are becoming increasingly common in European countries. Therefore, it is necessary to accurately examine their structural properties to ensure the integrity and safety of the poles. The purpose of this article is to compare the bending resistance of GFRP composite lighting columns obtained using European standard procedures with full-scale experimental tests. Several composite lighting columns were tested as part of the research study, and coupon tests were performed to assess the material properties required to calculate their bending resistance according to European Standard (EN) 40-3-3. The results obtained differed significantly. Furthermore, it was observed that the current standard rules for obtaining the resistance of GFRP poles based on the limit state method show a higher load capacity of the column in comparison to the capacity obtained from the tests.

A Pedagogy of Digital Materiality: Integrated Design and Robotic Fabrication Projects of the Master of Advanced Studies in Architecture and Digital Fabrication

This paper illustrates the pedagogical approach to teaching computational design and digital fabrication in the Master of Advanced Studies in Architecture and Digital Fabrication. It demonstrates how the introduction of computational design and digital fabrication methods foster a holistic approach to integrate novel material and constructive systems into the design process. Such an integration allows the students to combine digital fabrication techniques with sustainable material processes, taking into account the questions of reversibility, recycling and reuse, and thus designing for a more sustainable construction. In the presented paper, the structure and the curriculum of the MAS programme is introduced and the pedagogical approach of the Integrated Design and Robotic Fabrication Project is demonstrated through four case studies, highlighting their respective teaching strategies in combination with the learning experiences of the students.

Effects of the Curing Regime, Acid Exposure, Alkaline Activator Dosage, and Precursor Content on the Strength Development of Mortar with Alkali-Activated Slag and Fly Ash Binder: A Critical Review

Reductions of green gas emissions and the reuse/recycling of industrial byproducts are important for the mitigation of the environmental impact of the construction industry. The replacement of ordinary Portland cement (OPC) is a concrete binder with industrial byproducts that possess sufficient cementitious and pozzolanic properties, such as ground granulated blast furnace slag (GBS) and fly ash. This critical review analyzes the effect of some of the most critical parameters on the development of the compressive strength of concrete or mortar that consists of combinations of alkali-activated GBS and fly ash as binders. The review includes the effects of the curing environment, the proportions of GBS and fly ash in the binder, and the concentration of the alkaline activator on strength development. The article also reviews the effect of exposure as well as the age of samples at the time of exposure to acidic media on the development of concrete strength. The effect of acidic media on mechanical properties was found to depend not only on the type of acid but also on the alkaline activator solution, proportions of GBS and fly ash in the binder, and the age of the sample at the time of exposure, among other factors. As a focused review, the article pinpoints important findings such as the change in compressive strength over time when mortar/concrete is cured in an environment that permits the loss of moisture versus curing in a system that retains the alkaline solution and keeps reactants available for hydration and the development of geopolymerization products. The relative contents of slag and fly ash in blended activators have a significant impact on strength development. Research methods used include a critical review of the literature, a comparison of reported research findings, and identifying reasons for agreement or disagreement of findings.

An Inspection of the Life Cycle of Sustainable Construction Projects: Towards a Biomimicry-Based Road Map Integrating Circular Economy

According to the National Energy Plan in Panama, the construction sector is one of the most prosperous and impactful sectors in the economy and it is expected to expand due to population growth by almost 300% by 2050. However, this sector must work on the transition towards sustainability and resilience in the face of climate change, since its growth implies a high consumption of resources and the contribution of greenhouse gases. The need to establish practices and strategies that embrace the dimension of sustainability and a circular economy is imminent. Currently, there is little guidance in the reference framework beyond certifications in planning, management and evaluation tools for its implementation. Different studies vary in the number of phases and considerations for projects. Therefore, the present work proposes the development of a unified road map, with defined phases, practices and indicators based on principles inspired by nature, such as biomimicry (Greek words: “bio” means life and “mimesis”, imitation), and focuses on a circular economy, validated by construction professionals, where strengths, opportunities, skills and threats are identified with a high level of acceptance. This contributes to strengthening the field of sustainable construction project management and a precedent for Panama.

What Inspires Biomimicry in Construction? Patterns, Trends, and Applications

Biomimicry is redefining the design, architecture, and construction industries by transforming biological principles into innovative solutions that optimize structural, energy, and environmental performance. This study identifies the organisms and natural systems that inspire the industry, establishing patterns, trends, and key applications. Through a systematic literature review, 70 studies documenting bio-inspired applications in materials, structures, and construction systems were analyzed. The findings are organized into a categorization of organisms based on their biological group and a detailed classification according to imitation criteria-form, function, structure, and process-highlighting their applications in the built environment. The results demonstrate the convergence between technology and nature, underscoring the potential of biomimicry for the development of a more sustainable and resilient industry. Furthermore, this study identifies the most recurring sources of inspiration and the main lines of interest in the implementation of biomimetic strategies in construction, consolidating its role as a key tool for the architecture of the future. Based on these findings, the research proposes a biomimetic design framework that aligns architectural needs with suitable imitation strategies and biological analogs, offering a practical tool to guide decision making in the early design phases.

The Use of Recycled Cement-Bonded Particle Board Waste in the Development of Lightweight Biocomposites

Cement-bonded particle boards are gaining popularity globally due to their durability, strength, and, more importantly, environmental sustainability. The increasing demand for these materials has also created the necessity for the sustainable recycling of these materials. In this study, the potential to recycle wood-wool cement board (WWCB) waste into new lightweight insulation biocomposite material was examined. The waste WWCBs were crushed and separated into a fine aggregate fraction, and WWCB production line residues were also collected and compared. The crushed WWCBs were used to produce biocomposites with various compaction ratios and different binder-to-aggregate ratios. To improve their thermal properties and reduce their density, hemp shives were used to partially replace the recycled WWCB aggregate. Their physical, mechanical (compressive and flexural strength), and thermal properties were evaluated, and the drying process of the biocomposites was characterized. The results showed that the density of the produced biocomposites ranged from 390 to 510 kg/m3. The reduction in density was limited due to the presence of cement particles in the aggregate. The incorporation of hemp shives allowed us to reduce the density below 200 kg/m3. The thermal conductivity of the biocomposites ranged from 0.054 to 0.084 W/(mK), placing the material within the effective range of natural biocomposites. This research has demonstrated that industrially produced WWCBs can be successfully recycled to produce sustainable lightweight cement-bonded insulation materials.

Sustainable Infrastructure: Recycled Concrete Aggregates for Cycle Paths

The application of recycled concrete aggregates (RCAs) has become increasingly popular for different types of structures, as presented in several studies. However, depending on the type of structure and the region, RCAs might have different properties. This study aims to investigate the application of RCAs of different origins for substructure layers of the cycle paths located in Central Europe, which was not analysed previously. Recycled aggregates from an airport, road overpass, and building demolition were tested according to European standards and used to produce concretes, in which compressive strength, density, water absorption, and frost resistance were tested. After 28 days, RCA concrete had compressive strengths from 5.9 to 17.3 MPa and frost resistance ratios close to 1.0. The concrete parameters indicate that RCAs might be used for the construction of cycle path substructural layers with the appropriate class of cement and W/C ratio. To meet the requirements of EN 12390-3 to achieve class C8/10, RCA concrete with CEM II B/V 32.5 should be used with a W/C ratio of 1. To meet the requirements of D-04.05.01v02, RCA concrete with CEM II B/V 32.5 and a W/C ratio smaller than 1.50 should be used. Applying recycled RCAs in various structures helps protect natural resources by reusing materials. However, the variability in RCA properties requires testing to guarantee quality.