The use of urban biowaste and excavated soil in the construction sector: A literature review

Management of excavated soil and dredging spoil waste from construction and demolition within the EU: Practices, impacts and perspectives

Excavated soil and rock (ESR) and dredging spoils (DDS) account for 23 % of the total EU waste generation in 2020. This study performs a life cycle assessment and life cycle costing to quantify the potential environmental and cost savings resulting from increasing the level of ESR and DDS prepared for reuse and recycled in comparison to the business-as-usual practice. Scenarios for the waste management pathways based on the status quo, technical feasibility or normative impositions are assessed, including the potential contribution to achieving the European Green Deal goals. Results show that promoting preparing for reuse and recycling could lead to non-negligible GHG reductions (up to 3.6 Mt. CO2 eq.) and economic savings (EUR 12.3 billion) annually. Depending upon the scenario, 0.2 % to 1 % of the net annual GHG emissions reductions sought by the European Green Deal could be facilitated by scaling up improved circular management of ESR and DDS at the EU level. Finally, the study highlights the main barriers to scaling up to more circular (i.e., preparing for reuse and recycling) and better performing management options in Europe. The results provide new insights for the European Green Deal and circular economy policymaking for CDW.

Performance of cementitious systems containing calcined clay in a chloride-rich environment: a review by TC-282 CCL

In this review by TC- 282 CCL, a comprehensive examination of various facets of chloride ingress in calcined clay-based concrete in aggressive chloride-rich environments is presented due to its significance in making reinforced concrete structures susceptible to chloride-induced corrosion damages. The review presents a summary of available literature focusing on materials characteristics influencing the chloride resistance of calcined clay-based concrete, such as different clay purity, kaolinite content and other clay minerals, underscoring the significance of pore refinement, pore solution composition, and chloride binding mechanisms. Further, the studies dealing with the performance at the concrete scale, with a particular emphasis on transport properties, curing methods, and mix design, are highlighted. Benchmarking calcined clay mixes with fly ash or slag-based concrete mixes that are widely used in aggressive chloride conditions instead of OPC is recommended. Such comparison could extend the usage of calcined clay as a performance-enhancing mineral admixture in the form of calcined clay or LC2 (limestone-calcined clay). The chloride diffusion coefficient in calcined clay concrete is reported to be significantly lower (about 5-10 times in most literature available so far) compared to OPC, and even lower compared to fly ash and slag-based concrete at early curing ages reported across recent literature made with different types of cements and concrete mixes. Limited studies dealing with reinforcement corrosion point out that calcined clay delays corrosion initiation and reduces corrosion rates despite the reduction in critical chloride threshold. Most of these results on corrosion performance are mainly from laboratory studies and warrant field evaluation in future. Finally, two case studies demonstrating the application of calcined clay-based concrete in real-world marine exposure conditions are discussed to showcase the promising potential of employing low-purity calcined clay-based concrete for reducing carbon footprint and improving durability performance in chloride exposure.

Organic waste-to-bioplastics: Conversion with eco-friendly technologies and approaches for sustainable environment

Petrochemical-based synthetic plastics poses a threat to humans, wildlife, marine life and the environment. Given the magnitude of eventual depletion of petrochemical sources and global environmental pollution caused by the manufacturing of synthetic plastics such as polyethylene (PET) and polypropylene (PP), it is essential to develop and adopt biopolymers as an environment friendly and cost-effective alternative to synthetic plastics. Research into bioplastics has been gaining traction as a way to create a more sustainable and eco-friendlier environment with a reduced environmental impact. Biodegradable bioplastics can have the same characteristics as traditional plastics while also offering additional benefits due to their low carbon footprint. Therefore, using organic waste from biological origin for bioplastic production not only reduces our reliance on edible feedstock but can also effectively assist with solid waste management. This review aims at providing an in-depth overview on recent developments in bioplastic-producing microorganisms, production procedures from various organic wastes using either pure or mixed microbial cultures (MMCs), microalgae, and chemical extraction methods. Low production yield and production costs are still the major bottlenecks to their deployment at industrial and commercial scale. However, their production and commercialization pose a significant challenge despite such potential. The major constraints are their production in small quantity, poor mechanical strength, lack of facilities and costly feed for industrial-scale production. This review further explores several methods for producing bioplastics with the aim of encouraging researchers and investors to explore ways to utilize these renewable resources in order to commercialize degradable bioplastics. Challenges, future prospects and Life cycle assessment of bioplastics are also highlighted. Utilizing a variety of bioplastics obtained from renewable and cost-effective sources (e.g., organic waste, agro-industrial waste, or microalgae) and determining the pertinent end-of-life option (e.g., composting or anaerobic digestion) may lead towards the right direction that assures the sustainable production of bioplastics.

Bioplastic production in terms of life cycle assessment: A state-of-the-art review

The current transition to sustainability and the circular economy can be viewed as a socio-technical response to environmental impacts and the need to enhance the overall performance of the linear production and consumption paradigm. The concept of biowaste refineries as a feasible alternative to petroleum refineries has gained popularity. Biowaste has become an important raw material source for developing bioproducts and biofuels. Therefore, effective environmental biowaste management systems for the production of bioproducts and biofuels are crucial and can be employed as pillars of a circular economy. Bioplastics, typically plastics manufactured from bio-based polymers, stand to contribute to more sustainable commercial plastic life cycles as part of a circular economy in which virgin polymers are made from renewable or recycled raw materials. Various frameworks and strategies are utilized to model and illustrate additional patterns in fossil fuel and bioplastic feedstock prices for various governments' long-term policies. This review paper highlights the harmful impacts of fossil-based plastic on the environment and human health, as well as the mass need for eco-friendly alternatives such as biodegradable bioplastics. Utilizing new types of bioplastics derived from renewable resources (e.g., biowastes, agricultural wastes, or microalgae) and choosing the appropriate end-of-life option (e.g., anaerobic digestion) may be the right direction to ensure the sustainability of bioplastic production. Clear regulation and financial incentives are still required to scale from niche polymers to large-scale bioplastic market applications with a truly sustainable impact.