Water Porosity Research Articles

Endogenous electric field coupling Mxene sponge for diabetic wound management: haemostatic, antibacterial, and healing

Improper management of diabetic wound effusion and disruption of the endogenous electric field can lead to passive healing of damaged tissue, affecting the process of tissue cascade repair. This study developed an extracellular matrix sponge scaffold (K1P6@Mxene) by incorporating Mxene into an acellular dermal stroma-hydroxypropyl chitosan interpenetrating network structure. This scaffold is designed to couple with the endogenous electric field and promote precise tissue remodelling in diabetic wounds. The fibrous structure of the sponge closely resembles that of a natural extracellular matrix, providing a conducive microenvironment for cells to adhere grow, and exchange oxygen. Additionally, the inclusion of Mxene enhances antibacterial activity(98.89%) and electrical conductivity within the scaffold. Simultaneously, K1P6@Mxene exhibits excellent water absorption (39 times) and porosity (91%). It actively interacts with the endogenous electric field to guide cell migration and growth on the wound surface upon absorbing wound exudate. In in vivo experiments, the K1P6@Mxene sponge reduced the inflammatory response in diabetic wounds, increased collagen deposition and arrangement, promoted microvascular regeneration, Facilitate expedited re-epithelialization of wounds, minimize scar formation, and accelerate the healing process of diabetic wounds by 7 days. Therefore, this extracellular matrix sponge scaffold, combined with an endogenous electric field, presents an appealing approach for the comprehensive repair of diabetic wounds.

A new fractal model for flow-solid-chemical multi-field coupling in underground engineering

The permeation diffusion behavior of chloride ions with seawater is one of the key factors causing damage to reinforced concrete structures due to seawater erosion of steel bars. This study establishes a new mathematical model for chloride ion transport in reinforced concrete structures exposed to seawater. The model captures the effect of chloride ions on underwater tunnel structures effectively and provides a valuable theoretical basis for the maintenance and safety of these structures. The proposed model uniquely incorporates the microscopic pore structure characteristics of concrete and the effects of static water pressure and porosity on chloride ion diffusion. The results show that: (1) the diffusion coefficient of chloride ions first increases rapidly, then remains basically unchanged and gradually decreases; (2) there is a non-linear positive correlation between porosity, static water pressure, and maximum corrosion thickness; and (3) the fractal dimension of pore curvature is opposite to the fractal dimension of pore size and crack length.

Experimental study on effective utilization of industrial solid wastes in developing Ultra-High Performance Geopolymer Concrete

<p><a><span style="font-size:12.0pt"><span style="line-height:115%"><span style="font-family:"Times New Roman",serif">This experimental study explores the use of Ground Granulated Blast Furnace Slag(GGBS) and dolomite as alkali activated binders and copper slag as aggregate to achieve a cost-effective and sustainable Ultra-High-Performance Geopolymer Concrete(UHPGC). Several concrete compositions utilizing copper slag as a substitute for natural aggregates were formulated. Tests have shown that the inclusion of 100% copper slag fine aggregate leads to significant improvements in the mechanical properties and density of geopolymer concrete. Specifically, the compressive strength increased by 56.8% and the density increased by 17.5%. To understand the influence of dolomite in GGBS binder, several mixes varying dolomite proportion in GGBS were examined. The compressive strength of the 80% GGBS/20% dolomite geopolymer matrix is 32.8% higher compared to the compressive strength of UHPGC with 100% GGBS. The UHPGC mixture containing 1% crimped steel fibers showed the highest compressive strength, measuring 146.6 MPa. The split tensile and flexural strengths of the 20% dolomite matrix show a significant increase of 30.55% and 30.24% respectively compared to the 100% GGBS matrix. The water absorption and porosity of the 100% GGBS specimen were found to be lower compared to the 20% dolomite UHPGC specimen. The microscopic study reveals the positive impact of dolomite and GGBS on enhancing the bonding of the geopolymer matrix along with decreasing permeability. This study highlights the potential of geopolymer technology in producing ultra-high-performance concrete using GGBS, dolomite, and copper slag.</span></span></span></a></p>

The investigation the influence of the fiber son the evolution of mechanical properties of the concrete affected by high temperature by destructive and non-destructive test method

This paper presents an experimental examination of the effect of high temperatures on concrete prepared with different fibers types. For this study the concrete were prepared with four types of fibers (Steel, polypropylene, carbon and the combination of several types of fibers) and water/cement ratio fixed (w/c of 0.35). Specimens were heated under five different temperatures: 20 °C (ambient temperature), of 200 ºC, 300, 400 ºC and 600 ºC respectively. The following settings: compressive strength, ultrasonic pulse velocity, rebound hammer, concrete mass loss, and water porosity were examined in this Research experimental. Also A scanning electron microscopy study was used to comprehend the change in texture. The cracks were also examined using a microscope and other methods. This article is a contribution to the general understanding of the impact of fibers in high temperature concrete and highlights the significant impact of different types of fibers on the physical and mechanical properties of concrete who they were explore using destructive and nondestructive methods.

Humidity-Controlling Ceramic Bricks: Enhancing Evaporative Cooling Efficiency to Mitigate Urban Heat Island Effect

Passive evaporative cooling technology using the building envelope is a crucial measure to mitigate the urban heat island effect. This study aims to enhance the cooling efficiency of the surface of enclosure structures by utilizing volcanic ash, potassium–sodium stone powder, and silica-based mesoporous oxide (SMO) as primary materials. These components are incorporated into the ceramic brick production process to create innovative humidity-controlling ceramic bricks (HCCTs). This study extensively investigates the impact of SMO and the amount of applied glaze on the physical and mechanical characteristics of these HCCTs. Additionally, it examines the water absorption and evaporative cooling properties of the studied materials under optimal substitution conditions. Numerical calculations are used to determine the heat and moisture transfer properties of HCCTs. The results indicate that incorporating 2% SMO and applying 70 g/m2 of glaze results in a moisture absorption capacity of 385 g/m2 and a moisture discharge capacity of 370 g/m2. These conditions also yield a notable flexural strength of 15.2 MPa. Importantly, the HCCTs exhibit significantly enhanced capillary water absorption and water retention capabilities. Increased water absorption reduces surface temperature by 2–3 °C, maintaining the evaporative cooling effect for 20 to 30 h. It is also found that the temperature of HCCTs decreases linearly with increasing water content and porosity, while the temperature difference gradually decreases with thickness. Water migration in HCCTs with greater thickness is notably influenced by gravity, with water moving from top to bottom. Therefore, it is recommended that brick thickness does not exceed 15 mm.

Mineralogical and Engineering Properties of Soils Derived from In Situ Weathering of Tuff in Central Java, Indonesia

This paper presents the results of borehole investigations and laboratory tests carried out to characterize the soils derived from in situ weathering of tuff in Central Java, Indonesia. The 70 m thick weathering profile of the Quaternary tuff consisted of residual soil and completely to highly decomposed rocks. The relatively low dry unit weight and cohesion but high water content, porosity, plastic and liquid limits, and angle of internal friction of the soils in the present study were related to the dominance of halloysite clay minerals. The established relationships to predict soil shear strength parameters from the soil plasticity index and standard penetration test (SPT) N-values were examined, and linear and non-linear relationships for soils derived from in situ weathering of tuff were proposed.

Study on characteristics of the resistivity parameter and its coupling model of Chazangcuo copper-lead-zinc deposits based on microscopic analysis

Abstract The resistivity exploration has made a great contribution to prospecting at the macro level, but the resistivity exploration at the micro level is relatively weak. In this paper, the corresponding resistivity is analyzed through a geochemical element test, temperature and pressure test, water content and porosity test, and the resistivity parameter model of the rock and ore is established based on the response surface. The main conclusions and understandings obtained are as follows: with the increase of Cu-Pb-Zn content, the rock-ore resistivity shows an obvious decreasing trend, with sphalerite resistivity (72.8×10−2 Ω·m) > pyrite resistivity (32.5×10−2 Ω·m) > galena resistivity (76.5×10−3 Ω·m) > chalcopyrite (11.3×10−3 Ω·m). The resistivity increases with the temperature, showing a quadratic term function trend increases. The resistivity decreases with the increase of pressure, decreasing rapidly at the beginning of loading and gradually slowing down. The resistivity decreases rapidly with the increase of water content and porosity in an exponential function trend. The degree of influence of four factors, temperature, pressure, porosity, and water content, on the resistivity of the ore samples, is the order of water content, porosity, pressure, and temperature. The coupled model of resistivity of Cu-Pb-Zn ores established by multivariate quadratic regression analysis is more reliable, and the predicted value of rock and ore resistivity is more consistent with the test data.

Preparation of an adsorptive membrane of polyvinylidene fluoride incorporated functionalized boron nitride nanosheets for arsenic removal

Incorporating nanomaterials into membranes will enhance wastewater treatment efficiency with their unique characteristics, such as higher permeability, thermal stability, surface roughness, hydrophilicity, and fouling control. In this study, the surface modified boron nitride with phosphoric acid 2-hydroxyethyl methacrylate ester (PA/BN) was grafted with polyethylene glycol (PEG) via conventional grafting. The PEG grafted PA/BN (PEG-g-PA/BN) melt blended with polyvinylidene fluoride (PVDF) resin by using an internal mixer at different mass percentages (100% PVDF (PVDF), 3% PEG-g-PA/BN + 97% PVDF (97:3 BN), 5% PEG-g-PA/BN + 95% PVDF (95:5 BN), 7% PEG-g-PA/BN + 93% PVDF (93:7 BN), and 7% PEG-g-PA/BNNS + 93% PVDF (93:7 BNNS). Phase inversion technique was used to cast the blended mixture into a thin membrane. The prepared membranes were analyzed with different characterization techniques to determine chemical composition, crystallinity, morphology, and thermal properties. The prepared composite membrane was evaluated in terms of water permeability, anti-fouling resistance, and solute rejection efficiency with deionized water, bovine serum albumin, and arsenic solution as well. PVDF membranes show high water flux and porosity. The water flux and porosity of the blends decrease as the percentage of PEG-g-PA/BN increases. However, the highest removal capacity for arsenic was observed at 93:7 BN. The adsorption of arsenic ions takes place via complexation with PA/BN in the PVDF matrix. This was confirmed with field emission scanning electron microscopy–energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy analyses.

Bacterial cellulose biosynthesis: Optimization strategy using iranian nabat industry waste

Bacterial cellulose (BC) is a biopolymer has found extensive applications across different fields due to its nanostructure and biomaterial performance. This study focused on optimizing yield of BC produced by Komagataeibacter xylinus CH1, isolated from kombucha SCOBY. The study aimed to use Nabat industry waste (NIW) as a cost-effective alternative carbon source for submerged fermentation. To optimize the fermentation criteria, the central composite design was used with the inoculation amount (1.5–4.5 % VV−1), NIW (0–1%), and fermentation time (3–7 days) as independent variables. The impressive results indicated the yield was enhanced up to 45.543 gL-1 at 3.013 % VV−1 of inoculation, 0.516 % NIW, and 7 days of stirred fermentation. SEM, XRD, FTIR, and TGA were applied to evaluate the characteristics of freeze-dried BC, such as the three-dimensional, porous structure, crystalline peaks, amorphous haloes, and thermal stability. The physicochemical properties of BC including high moisture content (93.022 ± 0.472 %), water absorption rate (569.473 ± 3.739 %), water-holding capacity (1333.016 ± 3.680 %), porosity (166.247 ± 2.055 %), and low water activity (0.296 ± 0.030 %) were achieved. Rheological properties of BC suspensions showed that G′ dominated over G″, with tan δ values lower than 1. These characteristics indicate NIW and stirred fermentation conditions are a promising method for producing BC in high yield.

Influences of Geological and Petrophysical Attributes on Electrical Resistivity–Based Reserve Evaluation: Enhancing Carbonate Reservoir Classification, Permian-Triassic Reservoirs of Southern Iran

Summary The strong heterogeneity of carbonate reservoirs makes it challenging to assess the spatial distribution of fluid behavior, geological attributes, petrophysical properties, and estimate oil reserves. The diversity in facies and diagenetic processes contributes significantly to the heterogeneity in these reservoirs. The ability to accurately characterize and manage hydrocarbon reservoirs heterogeneity hinges on a comprehensive understanding of geological and petrophysical attributes such as water saturation, porosity, permeability, and electrical conductivity. In the quest for optimizing hydrocarbon reservoir identification and management, understanding the intricate relationship between the geological, petrophysical characteristics, and electrical conductivity of reservoir rocks is paramount. Electrical conductivity serves as an indicator of the structural attributes of pore networks, reflecting sedimentary and diagenetic influences on reservoir quality. Despite the extensive use of electrical resistivity in hydrocarbon reservoir assessments, accurate interpretation of its variations remains a significant challenge, which is due to complex geological factors. Thus, acquiring a thorough insight into the impact of geological and petrophysical attributes on electrical resistivity is crucial for a dependable assessment of hydrocarbon reservoirs. In this article, we explore the complex interplay between various geological and petrophysical factors and their impact on the electrical conductivity of rocks, which serves as a vital parameter in the assessment of hydrocarbon reservoirs. The focus is on how sediment texture, pore types, depositional environments, diagenetic processes, and characteristics of pore throat radius influence the electrical properties of rocks. The objective of this comprehensive approach is to decipher the geological and petrophysical modifications using electrical data, thereby improving the analysis of electrical discrepancies. Moreover, the accuracy of categorizing rocks based on their electrical characteristics is evaluated to effectively manage reservoir heterogeneity. Different data were gathered from an exploratory well situated in the western Persian Gulf. This data set comprised evaluations of 1,370 thin sections, 1,110 porosity and permeability data, 32 scanning electron microscopy (SEM) analyses, wireline logs, 29 mercury injection capillary pressure (MICP) data, 58 formation resistivity factors (FRFs), 20 formation resistivity indexes (FRIs), and 157 Dean-Stark measurements. Rocks were classified into different groups with similar electrical behavior utilizing the electrical quality index (EQI) approach. The efficiency of this method in managing reservoir heterogeneity, as one of the techniques for determining electrical rock type, was assessed, particularly by comparing the precision of predicted water saturation with Dean-Stark saturation data. The findings of this study demonstrated that diagenetic processes, especially dolomitization and dissolution, have the most significant impact on variations in the electrical conductivity of rocks. These processes govern pore size, distribution, pore types, and the radii of pore throats. According to the findings of this research, categorizing rocks based on their electrical characteristics improves the precision of water saturation predictions. In additionally, the use of constant Archie coefficients in water saturation calculations results in an overestimation of water saturation, leading to an underestimation of hydrocarbon reserves in the reservoir. The results of this research allow for more knowledgeable decision-making concerning reservoir efficiency, hydrocarbon reserves, production techniques, and increased oil recovery.

Reactive transport modeling of the Aquifer Thermal Energy Storage (ATES) system at Stockton University, New Jersey during seasonal operations

Hydrogeochemical processes associated with Aquifer Thermal Energy Storage (ATES) operations can often impact the system performance owing to mineral precipitation either at the wellbore or in the aquifer owing to changes in temperature and fluid disequilibria. Although failure of ATES systems due to mineral precipitation ("fouling") is common, predictive reactive-transport models have rarely been applied to plan their design and operation. The objective of this study is to develop a reactive-transport model by coupling thermal, hydrological, and chemical (THC) processes to evaluate effects of introduced atmospheric oxygen on water chemistry, mineral precipitation/dissolution, porosity, and permeability changes associated with an ATES system at Stockton University (New Jersey, USA). The THC model builds on a Thermal-Hydrological-Mechanical (THM) model of the site (Smith et al., 2021) that evaluated system failure owing to possible fracturing in the caprock or around the wellbore. The causes of the system failure are not known – potential causes include hydraulic fracturing owing to elevated pump pressures that took place, a flow pathway created by one of the boreholes, or a pre-existing natural hydrologic connection between the upper unconfined aquifer and the ATES aquifer, any of which could have led to oxygenated water entering the reservoir and causing the observed Fe-oxide fouling on well screens. The THC model is used to evaluate some of the hypotheses and observations regarding system failure owing to geochemical processes.The reactive-transport code TOUGHREACT V4 (Sonnenthal et al., 2021) was used to model the THC processes during seasonal heating and cooling operations at the Stockton ATES site over 6 years of operation. In the THC simulations, the primary effects on geochemistry were observed when the injection water is saturated with atmospheric oxygen. Simulations show greater precipitation of goethite near the cold wells as compared to the warm wells. Although volume fractions of Fe-hydroxides were relatively small, the model was aimed at processes in the aquifer at the scale of meters and larger rather than at the scale of mm or cm (i.e., a well screen). Kaolinite is the dominant precipitating phase, also around the cold wells. Illite dissolves near the cold wells and precipitates near the warm wells. There is a net decrease in the porosity near the cold wells and increase near the warm wells, although a slight amount of thermal contraction near the cold wells and expansion near the warm wells is responsible for a significant proportion of the porosity change. Owing to the coarse discretization of the numerical grid near the wells (compared to the screen thickness) the magnitude of permeability changes at the wellbore are likely underestimated. The reactive transport model in this study can be used for characterization of aquifers, optimizing the operational parameters (temperature, pressure, pH etc.), and planning of mitigation strategies for ATES systems.

Flow unit classification and characterization with emphasis on the clustering methods: a case study in a highly heterogeneous carbonate reservoir, eastern margin of Dezful Embayment, SW Iran

Previous attempts to classify flow units in Iranian carbonate reservoirs, based on porosity and permeability, have faced challenges in correlating the rock's pore size distribution with the capillary pressure profile. The innovation of this study highlights the role of clustering techniques, such as Discrete Rock Type, Probability, Global Hydraulic Element, and Winland's Standard Chart in enhancing the reservoir's rock categorization. These techniques are integrated with established flow unit classification methods. They include Lucia, FZI, FZI*, Winland R35, and the improved stratigraphic modified Lorenz plot. The research accurately links diverse pore geometries to characteristic capillary pressure profiles, addressing heterogeneity in intricate reservoirs. The findings indicate that clustering methods can identify specific flow units, but do not significantly improve their classification. The effectiveness of these techniques varies depending on the flow unit classification method employed. For instance, probability-based methods yield surpassing results for low-porosity rocks when utilizing the FZI* approach. The discrete technique generates the highest number of flow unit classes but provides the worst result. Not all clustering techniques reveal discernible advantages when integrated with the FZI method. In the second part, the study creatively suggests that rock classification can be achieved by concurrently clustering irreducible water saturation (SWIR) and porosity in unsuccessful flow unit delineation cases. The SWIR log was estimated by establishing a smart correlation between porosity and SWIR in the pay zone, where water saturation and SWIR match. Then, the estimated saturation was dispersed throughout the reservoir. Subsequently, the neural network technique was employed to cluster and propagate the three finalized flow units. This methodology is an effective recommendation when conventional flow unit methods fail. The study also investigates influential factors causing the failure of flow unit classification methods, including pore geometry, oil wettability, and saturation in heterogeneous reservoirs.

Experimental Study on the Relationship Among Complex Resistivity, Water Saturation, and Salinity in the Jiaozuo Anthracite Reservoir.

In order to investigate the electrical response characteristics of anthracite coal reservoirs and their correlation with water saturation, salinity, and porosity, the complex resistivity of Zhaogu No. 2 mine anthracite coal was measured across a frequency range of 1 Hz to 100 kHz. The experimental findings indicate that as water saturation, salinity, and porosity increase, the amplitude of both the real and imaginary components of the complex resistance of the coal sample gradually decreases, leading to a decrease in the dispersion degree and an increase in the interface polarization frequency. By analyzing the experimental data and studying the polarization mechanism of coal in a sodium chloride solution, this study proposed an enhanced model that integrates the aspects of the Cole-Cole model and the Warburg model to overcome the limitations of the traditional first-order model, which can fit only single-peak curves. The second-order series Cole-Cole model not only delves into microscopic mechanisms underlying the low-frequency polarization effect of coal samples but also provides a highly accurate fit for complex resistivity dispersion curves under varying conditions. This research offers both an experimental foundation and a theoretical framework for leveraging the electrical properties of anthracite coal reservoirs in assessing the pore structure and permeability of coal seams.

Graphene oxide decorated copper nanoparticles embedded polysulfone nanocomposite membrane: Anti-bacterial, organo-bio fouling evaluation in pharmaceutical wastewater treatment via MBR

This study investigates the impact of incorporating graphene oxide (GO) nanosheets and copper nanoparticles decorated reduced graphene oxide (Cu/rGO) on the performance of polysulfone (PSf) membranes in a membrane bioreactor (MBR) system. The characterization of the synthesized nanomaterials confirmed superior antibacterial activity of Cu/rGO compared to GO. Compared to the neat PSf membrane, the prepared nanocomposite membranes exhibited enhanced antibacterial, hydrophilic properties, pure water flux and porosity. Furthermore, the morphological analysis suggested that the GO and Cu/rGO nanohybrids exhibited outstanding interface compatibility and less release (<7%) during 20 days of immersion. During the treatment of the pharmaceutical wastewater in bench scale MBR system, total fouling ratio (TFR) was decreased from 80.24 % for neat PSf membrane to 74.37 % and 67.85 % for PSf-GO and PSf-Cu/rGO membranes, respectively. Notably, the flux recovery ratio (FRR) of the optimized PSf-Cu/rGO and PSf-GO nanocomposite membranes significantly increased 1.44 and 1.25 folds compared to the neat PSf membrane, respectively. The analysis of extracellular polymeric substances indicated an outstanding reduction in protein and carbohydrate concentrations in the cake layer in the presence of nanohybrids, confirming the membranes’ ability to mitigate organic and bio-fouling. These findings suggest GO and Cu/rGO nanohybrids enhance PSf membranes performance in MBR applications.

A cost-effective way to utilize low-grade Ti-rich clay: Preparing cordierite-mullite composite ceramics for thermal storage

Cordierite-mullite composite ceramics were prepared by solid-state method using Panzhihua low-grade Ti-rich clay, talc, and alumina. Influences of cordierite/mullite ratio, sintering temperature, and the chemical composition of clay on the phase composition, microstructure, physical properties, and thermal properties were investigated in detail. The results showed that the impurity oxides inside the Ti-rich clay had a great ability of forming liquid. Above 1300 °C, the reaction between TiO2 of the clay and Al2O3 produced stable Al2TiO5, which was conducive to decreasing the coefficient of thermal expansion (CTE). At 1300–1350 °C, the secondary mullitization caused the volumetric expansion, decreasing the bending strength and increasing the CTE. The optimum ratio of cordierite to mullite ranged from 90:10 to 80:20, and the sample fired at 1400 °C exhibited the lowest water absorption and porosity (0.64 % and 1.56 %, respectively), optimal bulk density, and bending strength (2.59 g cm−3 and 87.79 MPa), as well as better CTE, thermal conductivity, and thermal storage density (2.91 × 10−6 °C−1, 4.11 W/(m⋅K) (30 °C), and 1181 kJ kg−1, respectively). Compared with the reported values of cordierite-based thermal storage ceramics prepared by using the high-grade clay or minerals, the obtained samples showed the advantages such as lower costs for raw materials, higher bending strength, higher thermal conductivity (1.63–2 times higher), low CTE, and high thermal storage density. This study demonstrated that the low-grade Ti/Fe-rich clay has excellent cost-effective potential for the preparation of thermal storage ceramics.

Prediction of reservoir properties and fluids using rock physics techniques in the Rio Del Rey Basin, Cameroon

The application of rock physics modeling has been a breakthrough in oil and gas industry and has greatly managed exploration and interpretation risk. In the Rio del Rey Basin, the rock physics method was used to ascertain the reservoir's characteristics and relate them to the elastic characteristics. Using conventional techniques to connect to the elastic properties and assess various rock physics diagnostics, the estimated petrophysical parameters were water saturations, porosity, and shale volume. By connecting the saturated bulk modulus to its porosity, the bulk modulus of the porous frame, the bulk modulus of the mineral matrix, and the bulk modulus of the pore filling fluids, the Gassmann fluid replacement modeling was used to simulate various fluid scenarios. Finally, an evaluation was conducted on rock physics boundaries and cement models. The reservoirs are rated as extremely good based on the results. The rock physics model generated showed the friable sand model is a suitable model for the said basin and the rock physics bounds that were evaluated indicated that the sediments are deposited below the critical porosity and less compacted thereby depicting a soft sand model. Conventional petrophysical study would not be able to reveal the clustering of the gas sands from the brine sand and the shale zone in connection to the geologic trend as demonstrated by the rock physics template. The anticipated model will be useful to extrapolate the study to other sedimentary basins in Cameroon and estimate porosity from the impedance acquired from seismic data throughout the basin.

Predicting anion diffusion in bentonite using hybrid machine learning model and correlation of physical quantities

Radionuclide diffusion will be influenced by numerous factors. Establishing a model that can elucidate the internal correlation between mesoscopic diffusion and the microscopic structure of bentonite can enhance the comprehension of radionuclide diffusion mechanisms. In this study, a light gradient boosting machine (LightGBM) was employed to predict the effective diffusion coefficients of HCrO4−, I−, and CoEDTA2− in bentonite. The model's hyperparameters were optimized using the particle swarm optimization (PSO) algorithm. Several correlated physical quantities, such as mesoscopic parameters (total porosity, rock capacity factor, and ion molar conductivity) and microscopic parameters (ionic radius and montmorillonite stacking number) were incorporated to develop a machine learning model that incorporated micro- and meso-scale features. The predictive performance of PSO-LightGBM was verified using diffusion experiments, which investigated the diffusion of HCrO4−, I−, and CoEDTA2− at compacted dry densities of 1200–1800 kg/m3 using a through-diffusion method. Spearman correlation and Shapley additive explanation analyses revealed that the compacted dry density, ionic diffusion coefficient in water, ionic radius, and total porosity were the top-four influencing factors among the 16 input features. Partial dependence plot analysis elucidated the relationship between the effective diffusion coefficient and each input feature. The analysis results were consistent with the experimental findings, demonstrating the reliability of machine learning. Due to the incorporation of multi-scale features, the PSO-LightGBM model demonstrated enhanced predictive accuracy, linking the microstructure of bentonite to radionuclide diffusion, and providing a comprehensive interpretation of the diffusion mechanism.

Mechanism study and formula development by numerical simulation and visualization experiment in a microfluidic system for enhanced oil recovery

In this study, microfluidic system was adopted to investigate the effects of hydrodynamic factors on chemical flooding. The combination of visualization experiments and computational fluid dynamics (CFD) simulations was used to evaluate the effects of flow rate, interfacial tension (IFT), viscosity, density, contact angle and porosity on EOR (enhanced oil recovery). The chemical flooding regulation model was built through dimensional analysis of hydrodynamic factors, affording oil displacement empirical formula for oil displacement by fitting EOR data. The empirical formula displayed high applicability within a certain range of capillary number (Ca), oil–water density ratio and porosity. In addition, the empirical formula was expected to guide the development of a cardanol-based surfactant, whose preparation process was optimized in the microreactor. These findings would provide useful references for understanding the EOR mechanism of chemical flooding at micro-scale.

Influence of combined substitution of slag and fly ash in improving the pore structure and corrosion resistance of foam concrete mixtures used for reinforced concrete applications

Foam concretes (FCs) have been used for several light-weight applications demanding low strength; however, their use for reinforced concrete (RC) applications is limited since high macrovoid amounts result in weaker matrices. The high w/c and overlapping of macrovoids have been identified as critical factors constituting a permeable microstructure in FC systems. Since corrosion performance is a critical aspect in the design of RC members and that the durability parameters of concrete, such as its porosity, pore size distribution, and permeability, also play a vital role in restricting the diffusion of chloride ions, particularly in the cover region of members, it is imperative to determine these properties and thoroughly understand the material behaviour or characteristics. In the current study, five FC mixtures (GF0 to GF4) were produced using ground granulated blast furnace slag (GGBS) and fly ash (FA) as a replacements for cement and sand, respectively, at different dosages, considering both economic and environmental aspects. The principal objective of the study is to determine the pore and permeability related properties of produced FCs, assess their corrosion performance, and ascertain their suitability for RC applications by comparing their performance with that of conventional M25-grade concrete. Also, the influence of the combined effect of GGBS and FA addition and the individual effect of FA addition were assessed. The research findings showed that FCs had a higher water absorption capacity and porosity compared to M25 concrete. In addition, the inclusion of GGBS and FA resulted in a decrease in water absorption by 8%–19% and a decrease in porosity by 23%–36% compared to the control FC mixture. The Mercury Intrusion Porosimetry (MIP) results indicated a substantial enhancement in gel pores, threshold, and critical pore diameter, while the size of the larger capillary pore decreased by 90%–95% when GGBS and FA were added compared to the control FC mixture. The scanning electron microscopy (SEM) analysis and binary images from the image analysis revealed the presence of uniformly distributed and distinct macrovoids formed by foam. These macrovoids were predominantly found within the size range of 7.1μm – 100 µm. The addition of GGBS and FA particles to FC mixes resulted in a significant improvement in the chloride ion permeation (CIP) class, reducing it from 'High' to 'Very Low' compared to M25 concrete. The Accelerated Corrosion Test (ACT) results obtained from FCs demonstrated a significant increase in cracking time ranging from 30% to 323%, as well as a notable decrease in mass loss ranging from 56% to 85% when compared to M25 concrete. The Fourier transform infrared (FTIR) and energy dispersive spectroscopy (EDS) analysis results revealed the presence of corrosion products, including feroxyhyte, akageneite, and Friedel's salt crystal, in both FCs and M25 concrete, indicating the occurrence of corrosion by the chloride ions present in the NaCl solution outside the specimen. Overall, the porosity, CIP, and corrosion resistance of FC with GGBS and FA are superior to those of the M25 concrete, making it suitable for use in RC applications.

Influence of ground granulated blast furnace slag on recycled concrete powder-based geopolymer cured at ambient temperature: Rheology, mechanical properties, reaction kinetics and air-void characteristics

In this paper, ground granulated blast-furnace slag was used to enhance the properties of recycled concrete powder based geopolymer cured at ambient conditions. The rheology, workability, strength, hydration reaction kinetics, microstructure, and air-void characteristics of the geopolymer were investigated. The results showed that adding the slag accelerated the setting process and reduced the water absorption and porosity of the geopolymer mixtures. Excellent mechanical properties were achieved when the slag content exceeds 30 %. The 28-d compressive and flexural strength of the geopolymer with 50 % slag addition reached 61.2 and 5.17 MPa, respectively. The yield stress and plastic viscosity of the geopolymer increased as the slag content increased. A quantitative model between the slag content, resting time, and rheological parameters was established, with high accuracy, realistically reflecting the rheological properties of the geopolymer. The addition of the slag provided nucleation sites for the C-S-H gel, which promoted the hydration reaction, increased the hydration products and the total heat release, and formed a denser and more uniform microstructure, thereby increasing the strength of the geopolymer. The slag addition was also found to reduce the air content, spacing factor, and average chord length of the geopolymer matrix. As the slag content increased, the air bubbles became smaller and more stable, and exhibited a more uniform distribution.