In this study, a flexible vertical graphene (VG) strain sensor was developed for monitoring geogrids deformation. The VG material was fabricated using radio frequency plasma-enhanced chemical vapor deposition, followed by spin-coating a polydimethylsiloxane (PDMS) solution for film curing, resulting in a flexible sensor within a PDMS substrate. The VG sensor was integrated with a wireless Bluetooth data acquisition system for automated and remote strain measurement. The stability performance of VG sensors was examined and effectively improved through cyclic loading tests in the laboratory. The drift ratio of electrical resistance before cyclic loading tests is 37.01%, which is reduced to only 0.5% after cyclic loading tests. Calibration tests show that the maximum measurement resolution and maximum measurement range of VG sensors is 0.7 micro-strain and 40000 micro-strain, respectively, indicating that VG sensors are highly effective for both high-strain resolution identification and large-strain measurement. Pullout tests demonstrate an average error of 5.67% between VG sensors and fiber Bragg grating sensors, suggesting that VG sensors are a promising alternative for large strain, wireless, and long-term geogrid monitoring.

Poly(butylene adipate-co-terephthalate) (PBAT) and graphene oxide (GO) nanocomposite films were prepared by extrusion to evaluate their potential as films for food packaging. The films were prepared with contents of 0.05, 0.1, and 0.25% in mass of GO by solid-solid deposition methodology. It was verified that GO did not modify the hydrophobicity and crystallinity degree of PBAT. The reduction of molecular weight due to GO incorporation was verified, and it could be the main reason for the observed decrease in tensile strength and increase in elongation. The nanofiller permitted ultraviolet blocking, thermal stability, and oxygen barrier improvements without compromising film visibility. Compared to the neat PBAT film, the oxygen permeability coefficient was reduced by 13.6% for PBAT/GO0.25. The elongation and tenacity were also improved by 90% and 33%, respectively, for the highest concentration of GO (0.25%). Besides, GO at 0.25% accelerated the mineralization rate of PBAT in soil, probably due to the lower molecular weight of nanocomposites in relation to the neat polymer. The preliminary information obtained in this work indicates that the level of PBAT hydrolytic degradation during the extrusion process was not high enough to avoid its application in food packaging because the obtained thermal, mechanical, and ultraviolet (UV) barriers still indicate an exciting balance of properties for this purpose, which can even be improved with future research.

This study investigates the potential of graphene-based additives to improve the mechanical properties of compacted soil mixtures in rammed-earth construction, contributing to the development of environmentally friendly building materials. Two distinct soils were selected, combined with sand at optimized ratios, and treated with varying concentrations of a graphene liquid solution and a graphene-based paste (0.001, 0.005, 0.01, 0.05, and 0.1 wt.% relative to the soil-sand proportion). The effects of these additives were analyzed using the modified Proctor compaction and unconfined compressive strength (UCS) tests, focusing on parameters such as optimum water content (OWC), maximum dry density (MDD), maximum strength (qu), and stiffness modulus (E). The results demonstrated that graphene's influence on compaction behavior and mechanical performance depends strongly on the soil composition, with minimal variation between additive types. In finer soil mixtures, graphene disrupted particle packing, increased water demand, and reduced strength. In silt-sandy mixtures, graphene's hydrophobicity and limited interaction with fines decreased water absorption and preserved density but likewise led to diminished strength. Conclusions from the experiments suggest a possible interaction between graphene, soil's finer fraction, and potentially the swelling and non-swelling clay minerals, providing insights into the complex interplay between soil properties.

Edge-oxidized graphene oxide (EOGO) is a nano-sized material that is chemically stable and easily mixed with water due to its hydrophilic properties; thus, it has been used in various engineering fields, particularly for the reinforcement of building and construction materials. In this study, the effect of EOGO in soil reinforcement was investigated. When mixed with soil, it affects the mechanical properties of the soil-GO mixture. Various amounts of the GO (0%, 0.02%, 0.06%, 0.1%) were added into the sand-clay mixture, and their geotechnical properties were evaluated via multiple laboratories testing methods, including a standard Proctor test, direct shear test, compressibility test, and contact angle measurement. The experimental results show that with the addition of EOGO in soil of up to 0.06% EOGO, the compressibility decreases, the shear strength increases, and the maximum dry density (after compaction) increases.

Adding graphene microflakes with excellent mechanical properties to asphalt materials can promote the development of sustainable transportation infrastructure. Recently, graphene oxide-modified asphalt has gained popularity due to its enhanced storage stability, ease of construction, and high-temperature stability. However, the modification mechanism of graphene oxide and polymer modifiers within asphalt remains unclear. This study aims to investigate the mechanism of action of aminated graphene oxide and styrene-butadiene-styrene (SBS) within asphalt and elucidate their influence on the properties of composite-modified asphalt. This research utilized X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and thermogravimetry analysis (TGA) to explore the performance of composite-modified asphalt and the modification mechanism of modifiers. X-ray diffraction and Fourier transform infrared spectroscopy showed that the modification effect was better, the surface wrinkles of modified graphene oxide increased, and the interlayer spacing expanded, which was favorable to its compatibility with asphalt. Conventional test and Brookfield viscosity revealed that composite-modified asphalt possessed favorable high-temperature resistance and plasticity compared to the original asphalt. Additionally, dynamic shear rheological and storage stability tests indicated that the addition of aminated graphene oxide not only improved the viscoelastic properties of asphalt but also enhanced the compatibility between various substances. Multiple stress creep recovery and bending beam rheometer tests measurements confirm that the composite-modified asphalt exhibits superior high-temperature rutting resistance and low-temperature crack resistance. Fluorescence microscopy analysis demonstrated the uniform distribution of the modifier and SBS within the asphalt, while thermogravimetry analysis revealed that composite-modified asphalt exhibited higher thermal stability compared to SBS-modified asphalt. This study holds significant importance in advancing the development and practical application of road modification materials.

Graphene Oxide (GO) is widely used, but its hydrophilic properties make it difficult to remove once it enters water and soil environments. In this paper, the adsorption effect of calcium carbide residue (CCR) as adsorbent on GO was investigated through a series of adsorption tests. Adsorption thermodynamics, kinetics, isotherm models, and various characterization techniques were employed to explore the adsorption mechanism. Additionally, the study assessed CCR's ability to stabilize GO-contaminated soils through unconfined compressive strength tests. The results showed that (1) at T = 303 K, with a pH of 11 and an initial GO concentration of 80 mg/L, CCR demonstrated excellent adsorption performance. (2) The adsorption process followed the Langmuir isotherm and a quasi-second-order kinetic model, indicating chemical adsorption with spontaneous heat adsorption. (3) CCR not only acts as an effective adsorbent for removing GO from wastewater but also has the potential to strengthen GO-contaminated soils. In addition, due to its favorable environmental benefits, this study has a wide range of potential applications in industrial fields such as wastewater treatment, air purification, and energy storage and conversion. This study not only proposes an effective method for removing graphene oxide from aqueous environments, but also provides a new idea for waste resource utilization, which helps to achieve the dual goals of environmental protection and resource reuse.

In recent years, graphene oxide (GO) has been widely used in various fields owing to its high specific surface area and rich oxygen-containing functional groups. Adding an appropriate amount of GO (about 0.01-0.1 wt%) is beneficial to strengthen the soft soil foundation, which can improve the mechanical properties of the geopolymers, promote the hydration reaction, and improve the pore structure. The main mechanisms include the distortion effect, intercalation effect, template effect, bridge effect, active catalytic effect, adsorption cementation effect, and nucleation effect. Currently, GO research on cement materials mainly focuses on mortar and concrete and pays less attention to geotechnical engineering fields, such as cement soil. Therefore, to fully understand the unique advantages of GO, to clarify the method and mechanism of GO strengthening soft soil foundations, and to expand its application in geotechnical engineering, we briefly summarise the characterisation methods, dispersion of GO, analyse the influence of the single incorporation of GO on the mechanical properties of geopolymers, and discuss its microscopic mechanism. The environmental and safety effects are also discussed. Finally, the problems existing in the current research are analysed and future research directions are discussed.

Graphene oxide (GO) has been shown to improve the static mechanical properties of cement soils. However, the dynamic mechanical properties of GO-modified cement soils are rarely investigated. Therefore, in this study, the effects of different confining pressures, GO contents, and curing ages on the small-strain dynamic shear modulus (G) and damping ratio (D) of GO-modified coastal cement soil (GOCS) are investigated via resonant column tests. The results show that the G of GOCS increases with the confining pressure, GO content, and curing age, whereas D decreases. Moreover, the GOCS indicate the highest stiffness improvement when 0.05 % GO is used as a modifier. The variation patterns of the maximum dynamic shear modulus and maximum damping ratio with the increase in the confining pressure, GO content, and curing age of the GOCS are consistent with the measured results. Microstructural analysis shows that the incorporation of GO can promote the early cement hydration of GOCS and increase its internal calcium-silicate-hydrate gel as well as its crystal types and numbers. The filling and bridging effects of GO not only enhance the stiffness of GOCS, thus increasing its G value, but also effectively reduce the energy consumption of the vibration wave in the sample, thus reducing its D value. The results of this study can provide important references and guidance for the design and construction of coastal soft-soil roadbed projects.

Mercury ion (Hg2+) is one of the most toxic pollutants that can exist throughout the environment and be diffused into water, soil, air, and eventually the food chain. Even a very low level of Hg2+ diffused in living organisms can hurt their DNA and cause the permanent damage of the central nervous system and a variety of consequential disorders. Hence, the development of a sensitive and specific method for the detection of Hg2+ at trace ranges is extremely important as well as challenging. Fluorometric detection assays based on graphene quantum dots (GQDs) and carbon quantum dots (CQDs) offer considerable potential for the determination and monitoring of heavy metals due to their fascinating properties. Although the quantum yield of GQDs and CQDs is sufficient for their use as fluorescent probes, doping with heteroatoms can significantly improve their optical properties and selectivity toward specific analytes. This review explores the primary advances of CQDs and GQDs in their great electronic, optical, and physical properties, their synthetic methods, and their use in Hg2+ fluorimetry detection.

Graphene is regarded as a promising additive to enhance the thermal conductivity of bentonite in the geological repository, yet the hydro-mechanical properties of its mixture with bentonite under chemical conditions remain unclear. This work examined the one-dimensional swelling deformation of high-density graphene-modified bentonite (GMB) in NaCl solutions, considering the influences of graphene content and NaCl concentration. Results indicate that both graphene and NaCl reduced the maximum swelling strain and the primary and secondary swelling coefficients of GMB. Additionally, graphene enhanced the stability of swelling deformation in bentonite across various NaCl concentrations and decreased the GMB's test duration. The relationship between test duration and NaCl concentration was nonmonotonic. The ratio of swelling strain at each stage to total swelling strain was rarely affected by graphene content or NaCl solution. Scanning electron microscope examinations on selected samples post-swelling tests unveiled a unique soil structure in GMB. Furthermore, a model was put forward to predict the maximum swelling strain of GMB inundated in NaCl solutions, and its feasibility was verified.