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Polymer modified asphalt binders (PMB) are being commonly used instead of neat binders when superior performance is needed during the road service life. The addition of polymer improves the binder’s properties at high, low and mid-range temperatures. However, the effectiveness of polymer modification in improving road performance depends on a chemical-structural modification in the binder’s composition to be effective and durable. The phase inversion phenomenon between asphalt components and the added polymer leads the binder to assimilate the polymer characteristics. PMBs can have stability problems and separation; in fact, polymers and bitumen components can lose most of the benefits from the modification due to separation during the storage phase. Common testing for storage stability assessment includes the cigar tuben test (EN 13399, 2010) which provides an indication of whether separation has occurred. To evaluate the effects of separation on performance-related properties of the binder, the present study analyzed the storage stability and separation phenomena of five PMBs by performing an advanced-rheological storage stability test, based on frequency sweep tests on samples taken from the top and bottom part of 3, 5 and 7-day stored cigar tuben specimens. Master curves were developed for newly mixed and several storage conditions and were compared to identify possible separation phenomena between top and bottom samples. Indices were also developed to quantify separation of samples. Results showed that storage stability problems commonly start at the third day of storage. Binders which were seriously affected by separation, seemed to incrementally lose their homogeneity (top and bottom part) between 3 and 7 days. Other binders preserved their rheological characteristics during storage, maintaining equal values between the top and bottom samples. All stored binders were affected by an aging factor. [ABSTRACT FROM AUTHOR]

• This study explored different EoL c-Si module waste management scenarios through LCA. • The Chemical delamination of PV modules appeared to offer comparatively higher environmental benefits, but the toxicity of chemicals must be thoroughly assessed. • Main contributors to impacts are: transport, incineration of the polymeric layers and the utilization of chemicals during material recovery. • Economic benefits of PV recycling are discussed. The worldwide adaptation of Photovoltaic (PV) technology as a sustainable alternative to fossil fuels, has experienced exponential growth in recent years. However, the lack of effective waste management policies has hindered efficient PV panel disposal and recycling practices. In the absence of effective policies, the worldwide End-of-Life (EoL) PV module accumulation is predicted to reach a critical stage in the early 2030s. This study examines the environmental impacts of different EoL management practices using Life Cycle Assessment (LCA), based on a comprehensive database generated from both literature and industrial data. Five different EoL scenarios were considered for 1000 kg of Crystalline Silicon (c-Si) PV modules with a focus on Australia as a case study, while considering the energy recovery options and emphasizing the economic benefits. From a comprehensive LCA study, it is found that upcycling options reduce the environmental impacts significantly compared to downcycling, while chemical treatment emerges as a preferred option, demonstrating a reduced environmental burden. Nevertheless, the utilization of toxic chemicals during chemical treatment-based PV recycling needs to be reconsidered. Additionally, the usage of chemicals during the metal recovery process of PV module recycling caused the highest environmental burden, necessitating the importance of moving to greener treatment practices. This research study will enable the identification of optimum EoL c-Si module recycling options, contributing to sustainable waste management. [ABSTRACT FROM AUTHOR]

• Sustainable way of ground treatment was investigated using CSA cement. • CSA cement showed significant and rapid strength improvement for expansive soils. • Key phases of stabilization mechanism of CSA cement for expansive soils are unveiled. • Stabilization follows cationic exchange and flocculation and agglomeration. • Subsequently, cementitious hydration form space filling ettringite needles. Expansive soils are a common problem to overlying geotechnical structures risking for distress and damage caused by moisture induced ground movements. Calcium-based stabilization is readily adopted to improve and enhance the problematic expansive subgrade increasing strength and the volume change behaviour. For ground improvement, the use of lime and Ordinary Portland Cement (OPC) to treat expansive soil has been in common practice; however, Calcium Sulfoaluminate (CSA) cement can be an effective alternative due to the reduced environmental impact. To date, limited literature surrounds the understanding of CSA cement in expansive soil, but largely focussed its applications on concrete infrastructure. This paper investigates the stabilization mechanism of CSA treated expansive soils by identifying the major hydration products and microstructural characteristics with respect to CSA cement dosage and curing rate. The study reveals CSA cement stabilization directly affects mechanical properties and microstructural characteristics due to three key phases of cationic exchange, flocculation and agglomeration between the clay sheets and cementitious hydration. The addition of CSA cement in the ground stabilization serves to shift towards a sustainable approach in reducing the carbon impact of traditional stabilization techniques. [ABSTRACT FROM AUTHOR]

Expansive clays are problematic soils as they contain minerals that swell when wetted and shrink during drying. Highway construction on expansive soils requires some form of chemical stabilisation or other treatments to improve pavement performance. Many commercial and waste by-products, such as cement, lime, fly ash and slag, are used as chemical stabilisers to treat expansive clays. Municipal solid waste incineration (MSWI) fly ash is a product obtained from waste-to-energy plants which have attracted increasing attention to prevent land contamination and to reduce landfill costs. This paper investigates the stabilisation mechanism and hydro-mechanical performance of MSWI fly ash-stabilised high plasticity expansive clays. In this study, compressive strength, California bearing ratio (CBR), dynamic cone penetration, shrinkage and swelling, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray micro-computed tomography (micro-CT) tests were conducted to understand the performance of MSWI fly ash for the treatment of high-plasticity expansive clay. The study found that MSWI fly ash reduces swelling potential and increases the ten-day soaked CBR to about 80%. Microlevel analysis showed that hydration reaction, cationic exchange, flocculation, and agglomeration between clay sheets are the key phases in MSWI fly ash stabilisation. In addition, the porosity of the clay reduced from 3.43% to 0.18% after stabilisation with 20% MSWI fly ash. The outcomes from the study provide guidance on using MSWI ash for improving problematic soils while enabling an efficient way to manage municipal solid wastes. [Display omitted] • Application of municipal solid waste incineration ash (MSWI fly ash) to stabilise high plasticity clay was investigated. • MSWI fly ash stabilised samples exhibit negligible swelling and shrinkage. • Even for extreme rainfall cases, MSWI fly ash stabilised samples perform well. • Cationic exchange and hydration are the main stabilisation mechanisms. • Porosity of clay reduced from 3.43% to 0.18% after stabilisation with 20% MSWI fly ash. [ABSTRACT FROM AUTHOR]

The present study investigates – from an environmental perspective – the processes that lead to the conversion of waste plastics into recycled plastic pellets to be used either as an additive (wet method) or as a replacement of natural aggregate (dry method) in the production of asphalt mixes. Data from recycling facilities in Victoria, Australia, were collected and used as the basis for a comparative life cycle assessment (LCA) study. Analyses were conducted by considering several replacement ratios of virgin material by its recycled counterpart in the so-called wet and dry method. A case study considering the production of recycled-plastic asphalt to be applied in the construction of a typical surface layer of a road in Victoria was evaluated. In general, the results show that recycling plastics as a polymer for bitumen modification and as a synthetic aggregate replacement in asphalt mixes has the potential to be environmentally advantageous compared to their virgin counterpart (i.e. virgin polymers and natural quarry aggregates). Unlabelled Image • Primary data was collected from plastic recycling companies in Australia. • Waste plastic as polymer in bitumen produces considerable environmental benefits. • Recycling plastics to produce synthetic asphalt aggregate is minimally beneficial. • Recycling locally amplifies the environmental benefits of using plastics in roads. [ABSTRACT FROM AUTHOR]