The accumulation of waste glass (WG) from construction and demolition waste is detrimental to the environment due to its imperishable nature; therefore, it is crucial to investigate a sustainable way to recycle and reuse the WG. To address this issue, this study examined the mechanical strength, microstructural characteristics, and environmental durability-specifically under wet- dry (WD) and freeze-thaw (FT) cycles-of WG obtained from construction and demolition waste, with a focus on its suitability as a binding material for soil improvement applications. Firstly, sand and WG were mixed, and an alkali solution was injected into the mixture, considering various parameters, including WG particle size, mixing proportions, sodium hydroxide (NaOH) concentration, and curing time. Subsequently, the effect of WG grain sizes on micro- morphology characteristics and mineralogical phases was evaluated before and after the treatment through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and ultrasonic pulse velocity (UPV). The results revealed that reducing the WG particle size and increasing the WG/S ratio significantly improved the strength of the WG-treated samples. Additionally, decreasing the NaOH concentration and extending the curing time also positively influenced their strength. The UCS test results indicate that the particle size of WG significantly influenced the strength development of the samples, as the maximum compressive strength increased from 1.42 MPa to 7.82 MPa with the decrease in particle size. Although the maximum UCS values of the samples varied with different WG particle sizes, the values exceed the minimum criterion of 0.80 MPa required for use as a road substructure, as specified in the ASTM D4609 standard. Moreover, as WG grain size decreased, more geopolymer gels formed, continuing to fill the voids and making the overall structure denser, and the changes during geopolymerization were confirmed by XRD, SEM, FTIR, and UPV analysis. The optimum WG/S ratio was found to be 20 %, with strength increasing by approximately 3.88 times higher as the WG/S ratio shifted from 5 % to 20 %. In addition, the optimum NaOH concentration was determined to be 10 M, as higher molarities led to a decrease in strength. Moreover, UPV results indicate that WG-treated sand soils exhibited UPV values 9.4-13 times greater than untreated soils. The WD and FT test results indicate that WG-treated samples experienced more rapid disintegration in the WD cycle than in the FT cycle; however, a decrease in WG particle size resulted in reduced disintegration effects in both WD and FT conditions. In both the FT and WD cycles, the declining trend exhibited a stable tendency around the eighth cycle. Nevertheless, the WD cycling damage considerably intensified disintegration, causing a profound deterioration in the structural integrity of the samples. As a result, repeated WD cycles lead to the formation of microcracks, which progressively weaken soil aggregation and reduce the overall strength of the samples. Consequently, this green and simple soil improvement technique can provide more inspiration for reducing waste and building material costs through efficient use of construction and demolition waste.

Recycling paper sludge waste (PSW) into inexpensive sheets for applications in household interiors, construction, and footwear is a sustainable approach to resource utilisation and pollution reduction. A flexible recycled sheet (FRS) in board form was developed using cellulosic-based PSW from the paper industry and a styrene-butadiene rubber (SBR) binder. Various SBR concentrations were tested to determine the optimal amount for superior mechanical properties. The produced FRS was characterised using Fourier transform infrared spectroscopy, thermogravimetric analysis, high-resolution scanning electron microscopy, and energy-dispersive X-ray spectroscopy. FRS made with 1000 g of PSW:300 ml of SBR exhibited enhanced mechanical properties, including tensile strength (62.32 +/- 0.51 MPa), elongation at break (51.99 +/- 0.94%), tearing strength (17.76 +/- 0.45 N/mm), and flexibility (6.98 +/- 0.24%). A biodegradation study, conducted per ASTM D 5988-03, assessed environmental impact by measuring carbon-to-CO2 conversion in soil over 90 days. All FRS samples showed similar degradation within the first 30 days, with FRS 5 degrading significantly faster thereafter due to its higher cellulose and hemicellulose content. This highlights the potential of PSW-based FRS as an environmentally friendly and mechanically robust material for diverse applications.

Industrial wastes cause damage to the environment and pose a threat to public health. The utilization of industrial wastes is inevitable if a circular economy needs to be achieved. Cement kiln dust (CKD) is a potential engineering material that can be used in many civil engineering works. The volume change behavior of a CKD is reported here. One-dimensional swelling and compression tests were carried out on CKD specimens to derive the compressibility parameters and coefficient of permeability. A cyclic wet-freeze-thaw-dry test was carried out to study the volume change of the material upon exposure to various seasonal climatic processes under a low surcharge pressure. The experimental results show that CKD can exhibit swelling under light loads. The correlations between plasticity properties and compressibility parameters that are applicable to fine-grained soils were found to overestimate the parameters of the CKD. The magnitudes of frost heave and thaw settlement were found to be significant, with an uprising type of movement accompanied by strain accumulation when the material was taken through several wet-freeze-thaw-dry cycles.

Marine soft soils, characterized by high water content and low strength, present significant challenges to foundation stability. These soils often lead to settlement and uneven deformation, posing risks to infrastructure safety. This study tackles these challenges and promotes industrial waste utilization by developing a novel curing material for marine soft soils. The material consists of ground granulated blast furnace slag (GGBS), phosphogypsum (PG), and calcium carbide slag (CCS), and is compared to ordinary Portland cement (OPC). A D-optimal design was employed to establish regression equations for unconfined compressive strength (UCS) at 7 and 28 days. The interactions between factors were analyzed to optimize the mix ratio. The effects of different curing ages on the unconfined compressive strength, modulus of elasticity, moisture content, and pH of GPCOR solidified soft soil and cement solidified soil were investigated. The microstructure of the solidified soils was analyzed using SEM, XRD, FTIR, and BET techniques. The results indicated that the optimal GPC ratio was GGBS: PG: CCS = 64.81: 20.00: 15.19. After 28 days, GPCOR solidified soil exhibited superior UCS (4.48 MPa), 1.47 times greater than that of OPC solidified soil, and a deformation modulus 2.04 times higher. Furthermore, GPCOR exhibited a denser microstructure with smaller average pore sizes, improved durability, and better water retention than OPC. These findings underscore the potential of GPC as a sustainable alternative to conventional cement for reinforcing marine soft soils, promoting both soil stabilization and industrial waste resource utilization.

Background: The problem of toxic industrial waste impacting soil and water quality remains a significant environmental threat, yet comprehensive solutions are lacking. This review addresses this gap by exploring the effects of industrial waste on ecosystems and proposing strategies for remediation. Its aim is to provide a thorough understanding of the issue and suggest actionable solutions to minimize environmental damage.Methods: A comprehensive scoping review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data were sourced from major academic databases, including Science Direct, Scopus, PubMed, Academic Search Premier, Springer Link, Google Scholar, and Web of Science. A total of 105 relevant articles were included based on strict eligibility criteria. The review process encompassed identification, screening, and eligibility checks, followed by data abstraction and analysis.Results: The scoping review highlights the severe impact of toxic industrial waste on soil and water quality, emphasizing pollutants such as heavy metals (cadmium, lead, chromium), organic contaminants, and excess nutrients (nitrogen and phosphorus). These pollutants degrade aquatic ecosystems, causing acidification, eutrophication, and oxygen depletion, leading to biodiversity loss and the mobilization of toxic metals. Soil health is similarly compromised, with heavy metal contamination reducing fertility and disrupting microbial communities essential for nutrient cycling. Mitigation strategies, including cleaner production technologies, effluent treatment, bioremediation, and phytoremediation, offer promising solutions. These eco-friendly approaches effectively reduce pollutants, restore ecosystems, and enhance environmental sustainability, thus mitigating the long-term risks posed by industrial waste on soil and water quality.Conclusions and recommendations: The findings confirm that toxic industrial waste is a critical environmental threat that impacts both aquatic ecosystems and terrestrial soils. Immediate action is necessary to address ecological degradation. Recommended strategies include banning harmful raw materials, pre-treatment of waste, riparian buffering, bioremediation, and stricter regulations to control pollution and safeguard ecosystems.

Various industrial waste binders (IWBs) are being recycled in soil stabilization to save cement consumption. However, the coupled effects brought out by combined IWBs on stabilized soils are still unclear. IWBs are categorized into two typical categories (IWB-A and IWB-B) referring to their chemical role in this study. The alkali-source effect, pore-filling effect and cementation damage effect by IWBs in soil stabilization are explored. A series of mechanical and microscopic tests is performed on stabilized clay with different proportions of IWB-A and IWB-B. Moreover, initial water contents and cement contents of cement-stabilized clay are varied to examine the evolution of coupled effect with void ratio and cementation level. The results indicate that the alkali-source effect strengthens the cementation bonds and increases the early strength by 0.5-1.3 times, whereas the pore-filling effect improves the microfabric especially for the specimen with a large void ratio. The alkali-source effect increases soil cohesion cuat the pre-yield stage, and the pore-filling effect increases frictional angle 4uat the post-yield stage. The cementation damage effect is remarkable at a low void ratio, which may result in many extruded pores among soil aggregates. The strength evolution with IWB proportions can be well stimulated by considering the coupled alkali-source effect, pore-filling effect and cementation damage effect. The optimal proportion of IWBs corresponds to an optimal combination of coupled effect. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

This study endeavors to realize the concurrent utilization of marine soft clay (MSC) and industrial waste, specifically calcium carbide residue (CCR) and fly ash (FA), through a series of experimental investigations. The optimal ratio between CCR and FA, as well as the efficacy of the composite agent (CF-1), were examined, and an empirical equation associating the unconfined compressive strength (q(u)) of stabilized MSC was developed through unconfined compressive strength (UCS) tests. Microscopic analyses, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS), were employed to unveil the intrinsic mechanisms underlying CF-1 stabilized MSC. Subsequently, the suitability of CF-1 solidified MSC as a roadbed filler was ascertained through laboratory tests. Results revealed the optimum CCR:FA ratio for CF-1 to be 4:1, demonstrating superior curing effects compared to individual components such as Portland cement (PC), CCR, and FA, with commendable environmental and economic benefits. The developed empirical equation exhibited effectiveness in predicting the q(u) of CF-1 solidified MSC under varying curing dates (T) and dosages (W-g) conditions. Characterization through XRD, SEM, and EDS identified the primary products formed within the stabilized MSC matrix with CF-1 as comprising calcium-silicate-hydrate (C-S-H) gel, calcium-aluminate-hydrate (C-A-H) gel, and a minor amount of calcite. As T and W-g increased, the reduction in pores between soil particles enhanced the structural integrity and macro-strength of the cured MSC. The failure pattern of CF-1-solidified MSC elementary samples depended on the CF-1 dosage and curing duration. The solidification mechanism of CF-1 on MSC involved pozzolanic, ion exchange, and carbonation reactions. CF-1 solidified MSC satisfied all the specified requirements for roadbed filler in the relevant code, demonstrating substantial potential for in-situ solidification projects involving MSC.

This paper utilizes industrial wastes, including slag powder, desulfurized gypsum, fly ash, and construction waste, to solidify municipal sludge and develop a new type of landfill cover material. To investigate the durability of solidified sludge under wet-dry cycles, this study systematically analyzes its mechanical properties-such as volume shrinkage rate, unconfined compressive strength, and permeability coefficient-along with microstructural characteristics like pore structure, micro-morphology, and hydration products. In addition, the impermeability of the solidified sludge cover under varying rainfall conditions was assessed using rainfall simulation tests. After 20 wet-dry cycles, the solidified sludge samples exhibited volume shrinkage between 0.56% and 0.85%, unconfined compressive strength from 1.31 to 4.55 MPa, and permeability coefficients ranging from 9.51 x 10- 8 to 5.68 x 10- 7 cm/s. Portions of the gelatinous hydration products in the solidified sludge experienced discrete damage, leading to an increase in microporous volume. However, the overall structural integrity of the solidified sludge was maintained. The 3-layer landfill cover system was constructed using engineering soil, coarse construction waste aggregate, and solidified sludge and resisted strong precipitation. The 40 cm thick solidified sludge acted as an impermeable layer and yielded a good water-blocking effect. This study provides data support the application and technical advancement of solidified sludge as a landfill cover material.

Engineering sludge, industrial waste, and construction waste are marked by high production volumes, substantial accumulation, and significant pollution. The resource utilization of these solid wastes is low, and the co-disposal of multiple solid wastes remains unfeasible. This study aimed to develop an effective impermeable liner material for landfills, utilizing industrial slag (e.g., granulated blast furnace slag, desulfurized gypsum, fly ash) and construction waste to consolidate lake sediment. To assess the engineering performance of the liner material based on solidified lake sediment presented in landfill leachate, macro-engineering characteristic parameters (unconfined compressive strength, hydraulic conductivity) were measured using unconfined compression and flexible wall penetration tests. Simultaneously, the mineral composition, functional groups, and microscopic morphology of the solidified lake sediment were analyzed using microscopic techniques (X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy + energy dispersive spectroscopy). The corrosion mechanism of landfill leachate on the solidified sediment liner material was investigated. Additionally, the breakdown behavior of heavy metal Cr(VI) within the solidified sediment liner barrier was investigated via soil column model experiments. The dispersion coefficient was computed based on the migration data of Cr(VI). Simultaneously, the detection of Cr(VI) concentration in pore water indicated that the solidified sediment liner could effectively impede the breakdown process of Cr(VI). The dispersion coefficient of Cr(VI) in solidified sediments is 5.5 x 10-6 cm2/s-9.5 x 10-6 cm2/s, which is comparable to the dispersion coefficient of heavy metal ions in compacted clay. The unconfined compressive strength and hydraulic conductivity of the solidified sediment ranged from 4.90 to 5.93 MPa and 9.41 x 10-8 to 4.13 x 10-7 cm/s, respectively. This study proposes a novel approach for the co-disposal and resource utilization of various solid wastes, potentially providing an alternative to clay liner materials for landfills.

This study proposes a waste-to-value approach; specifically focusing on the utilization of industrial wastewater sludge (IWS) derived pyrolytic biochar (PBC) as an alternative to conventional carbon positive soil stabilizing materials. The IWS was subjected to thermogravimetric analysis (TGA) in N2 environment which suggested the pyrolysis temperature of 450 degrees C for the synthesis of PBC. Five different dosages of PBC by weight were mixed with the soft soil (SS) and unconfined compressive strength (UCS) values were examined across the various curing periods. Test results confirmed that UCS and stiffness values of soil-PBC matrix increased 4-5 and 5-6 times to that of virgin soil respectively. The PBC increased the cation exchange capacity (CEC), point of zero charge (pH(pzc)), alkalinity, and water holding capacity of the soil thereby assisted to initiate pozzolanic reactions. Various spectroscopic techniques were performed to investigate the strength development mechanism. Free oxide of calcium (CaO) in PBC disturbed the laminated structure of soil, reacted with oxides of silica (SiO2) and other silicates of aluminum thereby densifying the soil-PBC structure. Further, leaching test was performed on soil-PBC matrices to evaluate the environmental viability of the PBC. The statistical significance of the test results was confirmed using the Analysis of Variance (ANOVA) technique. Overall, this study concludes that PBC has the potential to serve as an environmentally friendly alternative to conventional soil stabilizing materials.