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The volumetric instability of steel slag hinders its use in pavement layers and embankments. Accordingly, evaluating the swelling potential of steel slag and designing volumetrically stable steel slag mixtures is required to promote its sustainable utilization. This paper focuses on the comparison of the swelling response of basic-oxygen-furnace steel slag (BOFS), electric-arc-furnace steel slag (EAFS), BOFS-fly ash and BOFS-glass powder mixtures based on the results of three different types of tests: (i) long-term California bearing ratio (CBR) swelling, (ii) heated water bath swelling and (iii) autoclave tests. BOFS mixtures were prepared using glass powder or class F fly ash with 5%, 10%, and 20% replacement ratios. The compaction characteristics, permeability, and California bearing ratio (CBR) of steel slag and steel slag mixtures were also assessed within the framework of a detailed discussion of their swelling response. At the end of swelling tests, the measured maximum 1D strains of EAFS were all at negligible levels. Based on the test results, BOFS and BOFS-glass powder mixtures had ∼5.0–5.5% swelling strains after 20.5 months without signs of stabilization. 20% class F fly ash replacement stabilized the swelling strains of the mixture at about 0.75% after ∼3 months of monitoring in long-term tests. 1D swelling rates measured for all BOFS-class F fly ash mixtures decreased with increasing fly ash content. CBR and swelling response of BOFS-class F fly ash mixtures were more favorable compared to those of BOFS. The heated water bath tests provided higher estimates of the swelling strains compared to those obtained from autoclave tests for the steel slag mixtures that contain 15% or more fines. The results of this study showed that glass powder replacement is not effective in alleviating the swelling of BOFS. The volumetrically stable BOFS-class F fly ash mixtures indicated favorable mechanical properties for their use in pavement layers. [Display omitted] • Glass powder replacement is not effective in alleviating the swelling of BOF slag. • 20% class F fly ash replacement can suppress the 1D strains of BOF slag. • Autoclave may provide relatively low estimates of strain for steel slag with 15% or more fines. • Separate handling of EAF and ladle steel slag in the plants can help their utilization. • BOF steel slag-class F fly ash mixtures show potential to be used in bound pavement layers. [ABSTRACT FROM AUTHOR]

Globally, decentralized energy systems are gaining popularity due to their potential for energy accessibility, energy resilience, and sustainability benefits. Existing research on an energy system decentralization approach, community choice aggregation (CCA), shows its ability to lower energy costs and increase renewable electricity consumption for U.S. communities. Nevertheless, research on the relationship between CCA and distributed electricity generation development is lacking. This paper fills this gap by investigating if the CCA approach associates with distributed generation capacity interconnection in California municipalities. The finding shows that although the average capacity has increased for all municipalities throughout the study period, contrary to proponents' arguments, the CCA approach has insignificantly decreased the capacity interconnected for municipalities. It is unclear if the result is due to a lack of higher-level support for the full CCA implementation or substitution by community-owned distributed generation. Future research is necessary to determine the CCA effect comprehensively in California. With this understanding, the research could be expanded to explore how community energy approaches work towards distributed generation across the U.S. and the globe. • Statistical evaluation of the CCA-distributed generation relationship. • The finding is contrary to CCA proponents' expectations. • Results show that CCA does not increase residential distributed generation capacity. • Global, national, and state legislative and financial supports are necessary. • Need community- and household-level distributed generation tradeoff research. [ABSTRACT FROM AUTHOR]

Microbially induced calcium carbonate precipitation (MICP) technology has a great potential for improving the engineering properties of recycled aggregates, but the major limitation is the inhomogeneous distribution of calcium carbonate precipitation resulting in the nonuniform modification of recycled aggregates. This paper proposed a spraying method to equally distribute the calcium carbonate, and discussed the influence of the new treatment on the physical and mechanical properties of the MICP modified recycled aggregates. The results showed that the water absorption of the coarse, medium and fine aggregates after seven cycles of treatment was greatly reduced by 58%, 26% and 46%, respectively. The shear strength, crushing value and California bearing ratio (CBR) were increased by the treatments, while the improvement was limited by the strength of the generated calcium carbonate precipitation. A significant decrease in the porosity and total pore volume was found after treatments, and the cubic and spherical calcium carbonate crystals were generated on the surface of the recycled aggregates. This indicated that the improvement of the physical and mechanical properties of the recycled aggregates was mainly attributed to the generated calcium carbonate filling the pores and reinforcing the surface. The MICP technology facilitates the high-value utilization of the recycled aggregates in pavement engineering. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic not only poses an unprecedented threat to global health but also severely disrupts the natural environment and ecosystems. Mitigating the adverse impacts of plastic-based personal protective equipment (PPE) waste requires the cooperation of professionals from various fields. This paper discusses a novel, cleaner approach to soil stabilisation by repurposing the nitrile gloves into a sustainable road material to improve the mechanical properties of expansive clay soil as pavement subgrade. For the first time, extensive geotechnical testings, including standard compaction, unconfined compressive strength (UCS), unsoaked California bearing ratio (CBR), repeated load triaxial (RLT), and swelling-shrinkage tests, were carried out to investigate the engineering performance of different proportions of the shredded nitrile gloves (SNG) (e.g., 1%, 1.5%, 2%) were blended with expansive clay (EC). In addition, surface roughness, scanning electron microscopy (SEM), and X-ray micro-CT analyses were conducted, and images were obtained to study the microstructural modification of the EC-SNG mixtures. The experimental results indicated that the blend of expansive clay with SNG helped in increasing the compressive strength, resilient modulus, and CBR and assisted in reducing the swelling and shrinkage of the soil. SEM and surface roughness analyses indicated the interaction between the soil matrix interface and the rough surface of the SNG. The main reasons for increasing the strength and stability of clay soil could be attributed to the high tensile strength of the SNG and the formation of the three-dimensional grid, and friction between the soil particles and SNG. According to the X-ray micro-CT test results, the incorporation of SNG led to an increase in closed porosity. [Display omitted] • An innovative approach to mitigate the problem of medical waste generation associated with COVID-19 is presented. • A cleaner and sustainable subgrade was developed by using discarded nitrile gloves. • The addition of 1.5% SNG to the soil provided the highest strength properties. • SNG reduced the swelling and shrinkage of the expansive clay subgrade. [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]

Geopolymer based soil stabilization is an emerging research field as shown by recent research studies which indicate strong potential of their wide use for sustainable ground treatment. This paper comprehensively reviews the literature on expansive soil stabilization using alkali activated binders, focusing on the stabilization mechanism and geotechnical characteristics of treated soil inclusive of mechanical strength and durability characteristics. The stabilization mechanism is governed by the cation exchange process and the geopolymer/hydration products formation. The reported highest unconfined compressive strength (UCS) and California bearing ratio (CBR) of the geopolymer treated expansive soil cured at room temperature are 15 MPa and 81%, respectively and these values satisfy the strength criteria of most of the standards used for road base materials. The findings of the review revealed that incorporation of precursors in the range of 15–20%, alkaline molarities between 5 and 10 M, along with strong alkalis (NaOH or KOH), Ca rich additives, and discrete fibers could enhance the stabilization performance with respect to strength, swell, and durability. Alkaline activation treatment is expensive compared to the conventional Portland cement based stabilization methods, and yet the cost can be significantly reduced by employing cost effective silicates for alkaline activation. Overall, alkali activated binders (AAB) can be sustainable stabilizers to treat expansive soils for satisfactory geotechnical performance (compaction, strength and durability), however, as recommended in this review, further research should be advanced to realize the utmost viability of this promising approach in successful field application. • Precursor contents between 15 and 20% and alkaline molarities between 5 and 10 M are endorsed for better strength gains in treated soil. • Activator/Precursor ratios between 0.7 and 0.85 reduce the swelling and permeability characteristics of treated soil. • Fiber reinforced AAB-soil mixed with slag, effectively enhances soil stiffness, and tensile and flexural resistance. • AAB treatment is endorsed for tropical climates, but not for freezing weathers. • Liquid alkaline activator contributes to a major portion of the greenhouse gas emissions and costs of AAB-expansive soil treatment. [ABSTRACT FROM AUTHOR]

Californian strawberry growers have been relying on methyl bromide for several decades. Notwithstanding the substantial dependence on this broad-spectrum biocide, a phase out was planned due to its ozone layer depleting character. With the aim to meet sustainability issues facing the emerging organic strawberry producers and reinforce the interaction among local actors, a research network was developed through 2004–2020. In this paper we investigated the factors affecting the creation and dissemination of knowledge within the above-mentioned multi-year network. Embeddedness in agro-food networks is the framework that we chose, while from an empirical point of view we analyzed a case study with many available datasets. We observed a progressive build-up of trust among people throughout the sixteen years. The shared activities and the already established relationship provided the base of this strong networking. Furthermore, innovative methods emerging from network activities provided critical information and management approaches for expanding organic production in the region. Relational embeddedness explains the observed performance, whereas a complementary role seems to be played by the structural aspect of the same framework at the regional level. The facilitation function by a university within a participatory method, the unique role of advisors along with the connection to the industry contributed to the reinforcement of the network allowing new ways of stable multi-year co-operation. [ABSTRACT FROM AUTHOR]

Last-mile deliveries usually occur within urban areas where logistics operations increase congestion and emissions, as well as associated roadway-related health impacts. This paper evaluates the role of incentives for zero and near-zero emission vehicle (ZEV) technologies in last-mile delivery operations. Specifically, the study investigates the total cost of ownership and life cycle environmental impacts associated with last-mile deliveries, and compares the private and public costs of different vehicle powertrain and fuel pathways, under existing incentives in the State of California. The study analyzes driving patterns for several last-mile delivery vocations, including beverage, warehouse, parcel, grocery, food and local deliveries based on real-world truck travel data. Statistical analyses are conducted to compare driving patterns across vocations, vehicle classes, and powertrains, as well as across parcel carrier fleets. To better assess the role of the incentives, the study also provides a comparative estimate of the marginal health damages from life cycle emissions of criteria pollutants (e.g. $/ton). Our results suggest that parcel deliveries are characterized by short trips (95% less than 100 miles), a high number of stops, and lower average driving speeds compared to other delivery vocations. Total cost of ownership for conventional diesel Class 3 to 6 vehicles used in last mile applications were estimated to be approximately between $282 and $305 thousand dollars, with the cost of negative health impacts ranging from $38 to $64 thousand dollars over the vehicle lifetime. The results show that battery electric freight vehicles are cost competitive with conventional diesel vehicles, particularly for smaller (Class 3) light commercial vehicles. Available financial incentives were sufficient to offset additional purchase and fuel expenses, leading to lower total costs of ownership. • The study evaluates the use of electric zero-emission vehicles for parcel deliveries. • Evaluates total cost of ownership (TCO) for various powertrains and fuels. • Estimates environmental (health-damages) impacts of last-mile deliveries. • Conducts sensitivity analyses for factors affecting the TCO. • Evaluates the role of financial incentives with respect to pollution abatement. [ABSTRACT FROM AUTHOR]