•The waste incorporation up to 25 vol.% allows structural application of concrete.•Considerable lightening and high thermal performance of composites were observed.•Designed concretes may find usage ...for special filling and flooring applications.•The waste application mitigates negative environmental impacts.
Intensive quarrying of natural non-renewable resources belongs to the actual topics related to the dynamically developing construction industry worldwide. However, at the same moment, an appreciable quantity of construction and demolition waste (CDW) is generated, from which the primacy to concrete, ceramic and masonry derived materials is attributed. These are already traditionally applied in concrete manufacturing as supplementing and filing materials due to their good recycling ability. Nevertheless, a number of material blends which separation is complicated or highly financial demanding still remain and thus burden our environment. This work has been aimed at the effective application of lightweight blended building waste (LBW) in the manufacturing of eco-friendly concretes. Concrete mixtures with the volumetric content 0–100% of the waste blend have been prepared. The influence of LBW on 28 days’ water cured samples has been investigated with the application of a wide range of experimental procedures and various instrumental techniques. Performed tests revealed a substantial lightening effect of LBW – leading to hardened concretes with a unit weight of about 760 kg·m−3. On the other hand, a high rate of lightening caused considerable decrease in strength properties of produced composites. However, application of LBW up to 25% can be used to preserve usage of these blended concretes for construction applications. Other performed tests showed excellent thermal performance of waste aggregate enriched concretes, and thus these materials may find usage for special filling and flooring applications with minimum loading of bearing structures.
A large quantity of building waste concrete is produced annually in China, which pollutes our ecological environment with its strong alkalinity. To recycle the building waste concrete, capture carbon ...dioxide at a low price, produce low-carbon, low-cost energy storage materials to provide clean energy for buildings. This work showcases a clever and forward-thinking approach by harnessing the carbon sequestration potential of building waste concrete. In a groundbreaking move, the researchers ingeniously exploited concrete from building waste to not only capture carbon dioxide, but also convert it into form-stable phase change composites, which were later carried out in detailed comparative analysis. Results show that the carbon capture efficiency of the building waste concrete reaches 24.7 % under the specific experimental conditions. The latent heat of the form-stable phase change composite prepared by carbon capture is higher (C-SS3, 50.31 J/g) than that without carbon capture (SS3, 39.84 J/g) by adding the same mass fraction of phase change material. In the range of 100–400 °C, the highest TES densities of sample SS4 and sample C-SS3 reached 339.78 J/g and 303.30 J/g, respectively. The compressive strength of SS2 is the highest, which is 121.54 MPa, and the compressive strength of both the building waste concrete and the form-stable phase change composite increased after carbon capture process. The thermal conductivity of the samples after carbonization (0.648 W/(m∙K)) was lower than that of before carbonization (0.884 W/(m∙K)). The form-stable phase change composites before and after carbon capture have good chemical compatibility among the components, and the form-stable phase change materials are densely bonded with the skeleton materials. Experimental verified the feasibility of preparing form-stable phase change composites using building waste concrete before and after carbon capture as a skeleton material.
•Waste concrete carbon capture is up to 24.7 % efficient.•Sample SS4 with optimal mass ratio reaches the maximal TES density of 339.78 J/g.•Increase in latent heat of samples of the same mass ratio after carbon capture.•The compressive strength of the waste concrete increased 74.65 % after carbon capture.•Best ratio samples have significant carbon reduction capacity.
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.
•This paper develops the prefabricated building waste generation and disposal systems.•The model predicts the construction waste and associated carbon emissions by 2030.•Raising landfill fee is an effective policy for decarbonizing construction waste by 31.06%.•Prefabrication rate reaching 100% can reduce 18.04% of carbon emissions from waste.•Applying all policies is most effective, achieving a 44.34% carbon emissions reduction.
•4D GIS-MFA-LCA model was used to analyze the characteristic of BMS, BW and ECEs.•The consumption of metallic building materials in construction sector is increasing.•Tourism and entertainment area ...appears to have the fastest increasing rate of BMS.•Cement can capture about 517 kt CO2 eq of ECEs, as a carbon sink source.•Economy and population are the driving force for urban BMS in Macao.
Enhancing the understanding on the temporal and spatial distribution of urban building material metabolism is crucial for informing urban resource, waste, and environmental management. However, this endeavor is often impeded by inaccuracies and inconsistencies in the typology and material composition data of buildings. Taking Macao as a case, this study established a 4D GIS-MFA-LCA model and compiled a local material composition database to address these gaps, for a detailed characterization of the quantity, quality, and temporal-spatial distribution of the urban building stocks and flows in Macao. The results show that between 1980 and 2020, the building materials stock (BMS) in Macao increased from 6.3 to 55.1 Mt (equaling 1.1 to 14.7 Mt CO2 eq of embodied carbon emission), accompanied by corresponding increases of 0.03 Mt to 0.7 Mt of building waste (BW). The tourism and entertainment area exhibited the fastest increasing rate of BMS in Macao. IPAT analysis shows that the economy, population growth and demographic changes have been the driving forces for BMS in Macao. The results of this study can help cities take effective measures toward achieving a circular economy and highlight the role of such information and urban planning in urban building resource, waste, and management strategies.
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The replacement of cement with sugarcane bagasse ash in concrete is considered due to its rich properties of projecting pozzolanic activity. The availability of aggregates is becoming scarce as a ...result of the non-renewable characteristic of fine and coarse aggregates. The construction waste end products like demolishing waste also cause the problem of improper disposal. Hence a majority of the construction industries have preferred the usage of construction and demolition (C&D) waste as a replacement for coarse aggregate. Substitution of coarse aggregates by construction and demolition waste and fine aggregates by iron slag ash is considered. The Taguchi method is adopted for the determination of mix combinations. This paper focuses on determining the properties of concrete having pozzolanic properties by replacing the cement with sugarcane bagasse ash (SBA), coarse aggregate with demolished building waste (DBW), and Fine aggregate with iron slag ash (ISA). The experimental investigation proved that SBA, DBW and ISA have a potential sign to be used as an alternative sustainable building material. From the comparative analysis of experimental results with ANN, it is revealed that the concrete show an acceptable prediction of physical and strength properties.
The increasing urban development, led by concrete, requires a higher availability of materials and energy, and it will be responsible for a high waste generation. To face the exploitation of natural ...resources, the use of fossil fuels and the reduction of waste disposal, new environmental-friendly strategies emerge accomplishing the circular economy principles. In this research, the use of poor reactive agro-industrial ashes as sand replacement in cement-based materials is investigated. Poor reactive sugar cane bagasse ashes (fly and bottom ash -SCB FA and SCB BA, respectively) from a power plant in Dominican Republic have been used in substitution rates of 10%, 20% and 30% of weight of sand. Physico-chemical characteristics of ashes are investigated and correlated to the performance of the bio-concretes. SCB FA showed being an enhancer of durability-related properties of the concrete even with high content of silica in form of quartz, due to the capability of modifying the microstructure of the concrete and an additional binding capacity of chlorides ions. Durability-related tests (open porosity test, electrical resistivity test, capillary absorption test and chloride migration test) have been conducted at 28, 60, 90 and 240days. Direct correlations exist when compared chloride migration resistance against porosity and electrical resistivity in concretes with SCB FA, not so for capillary absorption. This demonstrates the inadequacy of establishing conclusions about durability performance of bio-concretes based on durability tests when run independently. The use of agro-industrial ashes as substitutes of natural aggregates not only reduces the consumption of natural sand but can deliver bio-concretes with potential benefits in terms of compressive strength and durability.
•Concretes containing SCBA (SCB FA and SCB BA) as sand replacement were characterised.•Low-treated industrial SCBA showed potential uses in concrete production as sand replacement.•SCB FA provided enhanced durability-related properties in proportion to the substitution rate.•SCB BA have potential uses when non durability properties are required, and w/c applied.•Concrete properties correlations were found.
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•A novel tablet material was developed for phosphorus removal and recovery.•The tablet material was developed from building wastes.•Phosphate was recovered through an adsorption ...assisted precipitation process.•The phosphate was recovered as hydroxyapatite and brushite.
Phosphate is very important basic material in agricultural and other industrial applications. In present study, phosphate was precipitated and recovered through a tablet precipitation material (TPM) which was developed from solid building waste. The development of TPM provided an alternative for the management of building waste. The results showed that TPM could effectively recover phosphate from aqueous solution; the final precipitates were consisted of hydroxyapatite and brushite. The precipitation recovery process was assisted and drove by adsorption mechanism. The adsorption process concentrated and attracted phosphate that supplied partial phosphate supersaturation surround the surface of TPM and assisted the precipitation process. The equilibrium of removal and recover process could be attained in 60min. The maximum recovery capacity achieved 3.81±0.24mgg−1. In addition, the release of Ca2+ from TPM fitted a pseudo-2nd order model, and the release process was divided into two stages according to the Fick’s law. Totally, TPM developed from building waste exhibited sufficient potential in phosphate recovery.
•A characterisation method for residential grey water streams is presented.•Urban energy saving and cost calculation methods are proposed.•In-building shower and grey water heat recovery systems are ...assessed.•Integrated energy savings of 28–41% can be achieved in high efficiency buildings.•Urban energy assessments considering grey water heat recovery are improved.
Residential domestic hot water energy consumption represented 16% of the EU household heating demand in 2013. With the improvement of the building insulation envelope, domestic hot water contribution to energy consumption is expected to increase significantly, with values between 20% and 32% in single family buildings, and between 35% to almost 50% in multifamily buildings. This energy, currently lost to the environment, can be recovered by waste water heat recovery systems inside buildings (in-building solutions). While most publications in this field focus on shower heat recovery and on waste water as heat source for heat pumps, the detailed impact of waste water heat recovery at a city scale by aggregating building data has not been addressed yet. Furthermore, waste water heat recovery potential and relevance was not yet quantified as a function of the specific inhabitant and household numbers, end-use occurrence, and building type and age.
A method to quantify the building-specific energy cost and energy saving potentials, based on pinch analysis, at the urban scale of in-building waste water heat recovery systems is therefore proposed. A complementary method to spatially allocate and characterise grey water streams as to thermal load and temperature levels in function of the building specificities is also developed.
These methods are applied in two case studies, first as retrofitting solution in a city in Luxembourg and, second, as optimisation measure for high efficiency residential buildings. Grey water heat recovery would reduce the residential fuel consumption of the city by 6.3%. An integrated approach combining grey water heat recovery for hot water preheating and a heat pump yields up to 28% and 41% electricity savings for passive single family houses and multifamily buildings, respectively.
With the detailed characterisation of various grey water streams as a function of inhabitant number and end-use occurrence, the quantification of the energy savings and costs through heat recovery is improved. The outcomes of urban energy and cost assessments concerning grey water heat recovery are more specific, as the results at building level are aggregated to the considered geographical scope. The proposed method therefore complements current urban energy and cost assessments with the detailed integration of in-building grey water heat recovery systems.
Building waste heat is the dominant contributor to anthropogenic heat that causes the urban heat island effect. Numerous studies have estimated the impact of anthropogenic heat emissions on the urban ...environment using the inventory (IVT) approach, but the assumptions of this method - equating building energy consumption to anthropogenic sensible heat emissions, can lead to over/underestimation of air and surface temperatures in the urban canyon. The building energy modelling (BEM) approach, considering the dynamic interaction between the outdoor microclimate and indoor environment, provides a reliable way to quantify the impact of building waste heat on urban climate. However, the temperature bias caused by the inventory approach has not been systematically investigated in the literature. In this study, we conduct simulations in Beijing for three building types (residential, office, and hotel) in four months (January, April, July, and October) to reveal the temperature biases by the IVT approach using the results from the BEM approach as the ground truth. Results show that the IVT approach overestimates the canyon air temperature (Tcan) in heating and ventilation months. The positive bias of daily maximum Tcan is >1°С in January and 2°С in October. In the summertime, the temperature bias by the IVT approach varies with the type and location of air conditioning (A/C). Daily mean Tcan is underestimated by up to 1.2°С when using window-type A/C, and is overestimated by up to 2.1°С when using water-cooled A/C at rooftop. The temperature bias is more evident in compact neighbourhoods with higher building surface fractions. Furthermore, it is found that the IVT approach causes overestimation of sensible heat flux and underestimation of latent heat flux in most of the studied scenarios, indicating a possible overestimation of urban heat/dry island in previous studies using the IVT approach. This study offers important insights into the building-microclimate feedback in the urban environment.
•Temperature biases caused by the IVT approach in four months are quantified.•The IVT approach may cause a possible overestimation of urban heat/dry islands.•The IVT approach overestimates Tcan by up to 1.4°С in January and 2.3°С in April.•Mean Tcan is overestimated by up to 2.1°С when A/C waste heat releases to rooftop.•The IVT approach wrongly estimates the redistribution of the building energy use.
In pavement engineering, concrete is the most widely used building material, but it has its own shortcomings such as low tensile and flexural strength, brittleness and poor durability, which easily ...lead to pavement damage. Common cement concrete repair materials have a long construction period, which affects traffic. Therefore, it is necessary to adopt fast repair materials to meet the requirements of traffic in a short time. The addition of fibers in pavement cement concrete can significantly improve the tensile and flexural strength and durability of concrete, and play a role in strengthening toughness. Compared with the single fiber concrete, which is relatively mature at present, this paper aims at strengthening and repairing the defects of waste concrete subgrade and base cracks, void at the bottom of pavement slab, etc. The fluidity and mechanical properties of recycled aggregate grouting material are studied through experiments, and on this basis, the mechanical properties of recycled concrete grouting are further analyzed. The results reveal the relationship between the amount of recycled fine aggregate, ambient temperature and the fluidity of recycled aggregate grouting, and the influence of the amount of recycled fine aggregate and the water-cement ratio on the mechanical properties of recycled aggregate grouting and grouting recycled concrete.
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