Addition Of Bentonite Research Articles

Concentrating Cocoa Polyphenols—Clarification of an Aqueous Cocoa Extract by Protein Precipitation and Filtration

The seeds of Theobroma cacao L. are rich in antioxidant flavonoids such as flavan-3-ols, which are valued for their health benefits. In this context, it is of interest to improve flavanol content in cocoa extracts. The present study aimed at improving the clarification process of an aqueous cocoa extract using protein precipitation and filtration. Five pH modifications and two bentonite amounts were tested for their effects on protein precipitation and flavanol content. Micro- and ultrafiltration as a subsequent step was done by testing three different ceramic membranes (30, 80, and 200 nm). Lower pH in pre-treatment reduced protein content and kept flavanols constant, while at higher pH, flavanols were reduced up to 40%. Larger membrane pores enhanced polyphenol permeation, while smaller pores limited protein permeation. Adjusting pH to the isoelectric point increased protein adsorption, improving filtration quality despite decreased permeate flux. However, membrane fouling results in higher permeate quality due to increased selectivity. Furthermore, the addition of bentonite during filtration reduced both protein and flavanol content in the permeate, similar to the effects seen in the pre-treatment of the supernatant. Optimizing pH and membrane pore size enhances the recovery and quality of polyphenols during filtration, balancing protein removal and flavanol retention.

Experimental Investigation of the Lubricant Effect of Thixotropic Slurry on Pipe–Soil Interfacial Friction Characteristics

Based on the technical issues encountered during underground pipe jacking construction in the Jining area, a series of ring shear tests were conducted on silty clay below the groundwater level to investigate the interfacial friction characteristics under the lubrication of thixotropic slurry during construction. Seven different slurry formulations were prepared, and ring shear tests were conducted under varying normal stresses, shear rates, and shear displacements. The friction characteristics during the shearing process were analyzed, and the corresponding friction coefficients were determined. The experimental results indicate that shear stress increases with increasing normal stress, but it is not affected by shear rate and shear displacement. As normal stress increases, the friction coefficient also exhibits a slight rise, which may be due to the uneven distribution of the slurry under pressure. Among the seven formulations, Slurry 1 exhibited the best lubricating effect, which reduced the friction coefficient by 64.5%, while Slurry 0 had the poorest effect with a reduction of 42.6% in friction coefficient. Additionally, the excessive addition of bentonite in the slurry reduces its lubricating effect, and the content of fiber has a significant effect on the friction reduction degree by thixotropic slurry.

DEVELOPMENT OF TECHNOLOGY FOR SALT-LICKER BRIQUETTES WITH BENTONITE FOR THE PREVENTION OF MINERAL DEFICIENCY IN CATTLE

Technologies have been developed for the production of salt briquettes with the addition of crushed bentonite for cattle, which are fed to animals during the winter stall period. Bentonites contain a significant amount of macro and microelements, of which the most important in the physiology of the animal body are oxides of iron, calcium, potassium, phosphorus, etc.), briquettes measuring 15x15 cm and 12 cm thick are obtained, which have a yellowish tint. The greatest attraction for cows to lick is observed with lick briquettes containing 10% bentonite. The use of salt briquettes-licks with the addition of bentonite in the specified amount to cows during the winter stall period has a beneficial effect on the body of cows. The animals had less morbidity after calving and subsequently had higher milk production. Calves born from these cows had greater vitality, were less sick, and had higher weight gain. Keywords: technology, bentonites, salt briquettes, macro and macroelements, cattle, productivity.

Dynamics and viscoelasticity of potato and corn starch bio-polymers reinforced with bentonite nanoclay

The influence of bentonite nanoclay on the viscoelasticity and dynamics of potato starch (PS) and corn starch (CS) films was investigated. Free standing films were plasticized with glycerol and displayed elastomeric behavior. The addition of bentonite (up to 4 wt%) increased the glass transition temperature Tg of PS/bentonite nanocomposites, however the Tg of CS/bentonite nanocomposites was reduced. On the other hand, bentonite increased the tensile modulus E’ of both type of nanocomposites. Dynamic mechanical analysis (DMA) showed that CS film displayed two mechanical relaxations, named α and α’, whereas PS film displayed only the α relaxation. The α relaxation was associated with the glass transition whereas the α’ relaxation appears to be associated to starch-rich domains due to lower miscibility of CS with glycerol. Rheology showed that bentonite increased the rubbery modulus Ec of the nanocomposites thus explaining the mechanical reinforcement. The starch nanocomposites exhibited exfoliated and intercalated morphologies (at low and higher bentonite content, respectively). Hence, nanoconfinement and domain separation appear to drive the thermo-mechanical properties and dynamics of the starch-based nanocomposites.

Effects of ionic strength and bentonite ratio on the migration of Cr(VI) in clayey soil-bentonite engineered barrier.

Soil-bentonite (S-B) barriers have been widely used for heavy metal pollution containment. This study conducted batch adsorption tests and diffusion-through tests to evaluate how ionic strength and bentonite ratio influence the migration of Cr(VI) in natural clay-bentonite mixtures. The test results indicated that the adsorption of Cr(VI) exhibited an obvious anion adsorption effect, the pH of the soil mixture increased with the addition of bentonite, resulting in a decrease in the positive surface charge. This change led to a decrease in Cr(VI) adsorption capacity, from 775.19 mg/kg for pure clay to 378 mg/kg for mixture samples with excessive bentonite. Furthermore, as the ionic strength increases from 0 to 0.1 M, the Cr(VI) adsorption capacity increases slightly due to the weakening of electrostatic repulsion on the clay particle surface, but the effective diffusion coefficient (De) increases by 21.97%. The compression of the diffusion double layer (DDL) under high ionic strength conditions enlarges the diffusion path and enhances the migration of Cr(VI) through the pore flow paths. Moreover, hydrated bentonite effectively fills the interaggregate pores of natural clay, thus creating narrower and more tortuous flow paths. However, excessive bentonite increases the pH value and pore volume, resulting in changes to the soil microstructure and disrupting the continuous skeleton of natural clay, which is unfavorable for Cr(VI) containment. Based on the study of the Cr(VI) contaminated site, a bentonite ratio of 2:10 is recommended for optimal natural performance of the natural clay-bentonite barrier.

Catalytic Microwave Pyrolysis of Albizia Branches Using Iraqi Bentonite Clays

Catalytic microwave-assisted pyrolysis of biomass is gaining popularity as an alternative to fossil fuels due to health, environmental, climate, and economic issues. This study conducted a catalytic pyrolysis process of the Albizia plant's branches using an Iraqi clay catalyst (bentonite) focusing on the variables including the biomass-particle size, experimental time, microwave power level, and the catalyst-to-biomass ratio. The physical and chemical properties of the resulting biofuel were analyzed presented by HHV, acidity, density, viscosity, GC-MS, FTIR for bio-oil and SEM, EDX, BET, HHV, FTIR for biochar. The study revealed that addition of bentonite as a catalyst led to enhanced production of biogas produced from 5% to 45% and decreased the power level used from 700 W to 450 W. Also, it raised the production of bio-oil generated with less power level and duration time. The addition of catalyst also affected the characteristics of bio-oil produced such as reducing the acidity by increasing its pH from 5 to 5.7, lowering the viscosity from 4.8 to 3.3 cSt, and the density from 1045 to 1039.2 kg/m3. Adding catalyst increased the percentage of aromatic and alcoholic substances in the bio-oil which led to improve the calorific value from 19.5 to 23 MJ/kg. Additionally, the biochar properties also improved, where the surface area and pore volume increased from 0.5512 to 40.384 m2/g and 0.00011 to 0.0361cm3/g respectively. The higher heating value was raised from 23.5 to 25 MJ/kg also. CH4 is also increased from 3.6 to 8.6% which is one of the essential fuel gasses.

Mechanism of geopolymeric solidification in shield-tunnelling slurry from diverse sources: The role of bentonite adsorption in influencing the reaction process

Geopolymeric solidification is an effective process for treating engineering waste slurry, yet its efficacy varies with source of slurry. This study examined four shield tunneling spoil types for geopolymeric solidification. The unconfined compressive strength of the best sample was 17–126% higher than the least effective one. A significant negative correlation between strength and bentonite indices was found. Subsequently, the addition of bentonite to the shield tunneling spoil for experiments, followed by various analyses, comfirmed bentonite's negative impact on strength. Bentonite forms agglomerates during geopolymerization, adsorbing hydration gel, weakening the direct linkage of the hydration gel; they also adsorb elements such as Al, Ca, and Na, hindering the formation of geopolymer products. However, the final adsorption ratio was not within the optimal range for geopolymer reactions, impeding the improvement in curing strength. This study offers the theoretical guidance for improving engineering waste slurry treatment processes.

Effect of Bentonite on the Electrical Properties of a Polylactide-Based Nanocomposite.

In this paper, a novel polylactide-based nanocomposite with the addition of bentonite as a filler, Fusabond, and glycerine as a compatibilizer and plasticizer, were prepared and investigated. Four samples with different contents of bentonite (1, 5, 10, and 15 wt.%), as well as three samples without fillers, were prepared with an easily scalable method: melt blending. The electrical properties of all prepared samples were investigated with broadband dielectric spectroscopy in the frequency range between 0.1 Hz and 1 MHz. Measurements were conducted at nine temperatures between 293.15 and 333.15 K (20 to 60 °C) with steps of 5 K. It was found that the increase in the content of bentonite in polylactide has a significant effect on the electrical properties of the prepared nanocomposites.

Effects of Clay Contamination on the Stability of Aqueous Foams at High Pressure

Summary Because of its low density, high viscosity, and good hole-cleaning performance, foam is used in the industry as a drilling and completion fluid. Due to these unique properties, foam can be applied in underbalanced drilling. After an extended period, however, the degradation of its thermodynamically unstable structure leads to the gradual loss of these valuable properties. While a number of research studies have been performed to investigate foam flow behavior, more is needed to know about their drainage characteristics and stability at high pressure. The primary goal of this investigation is to examine the effects of clay contaminants on the drainage of foam at high pressure. Moreover, the results and findings of this study not only show the effect of clay contaminants on foam stability but also help develop clay-based stable foam formulations without using chemicals that have the potential to contaminate groundwater or seawater. This paper shows the findings of an investigation on the aqueous foam stability in the presence of clay (bentonite and kaolinite) contaminants. Experiments were conducted at ambient temperature while varying foam quality and clay concentration at a constant pressure of 6.8 MPa. During the study, the foam was created in a flow loop. After generation, its rheology and stability were measured using a pipe viscometer and a vertical test tube (column). The hydrostatic pressure profile in the column was measured with time to assess foam drainage. The results show that clay type and concentration affect aqueous foam drainage and flow behavior. The impact of clay on these foam properties is controlled by foam quality. Adding more than 2.5% bentonite considerably enhanced foam stability and viscosity. In contrast, the impacts of kaolinite on these foam properties were minimal at the same concentration. The drainage became negligible when 5% bentonite was added to the foam. However, at a reduced concentration (2.5%), bentonite addition was only an effective stabilizer for low-quality foam (40%). Microscopic examination of the foams prepared under ambient conditions demonstrated the accumulation of colloidal particles at the plateau borders and nodes that block the drained liquid flow and reduce drainage.

Mock-up performance evaluation study for crack reduction of blast furnace slag powder concrete mixed with expansive and swelling admixtures

In this study, the drying shrinkage and crack reduction characteristics of blast furnace slag concrete mixed with expansive and swelling admixtures were investigated. Basic performance experiments were conducted using different mixtures of ground granulated blast-furnace slag (GGBS), with calcium sulfoaluminate as the expansive admixture and bentonite and hydroxypropyl methyl cellulose (HPMC) as swelling admixtures. Bentonite outperformed HPMC as a swelling admixture. Specimens were then prepared for mock-up tests to evaluate the drying shrinkage of blast furnace slag concrete with different combinations of bentonite, a hardening accelerator, and a self-healing agent. The addition of bentonite and calcium phosphate as a self-healing agent in small quantities reduced the drying shrinkage of the specimens, thereby reducing cracks. The cement mixture composed of 30% GGBS, 1% bentonite, and 1% calcium phosphate (30-E1-I1) showed the optimal performance among the specimens. Further, crack monitoring was performed in concrete made with ordinary Portland cement and optimal mixture 30-E1-I1. No cracks were observed for the optimal mixture. This shows that GGBS concrete can be used in practical and field applications, subject to mid- and long-term tests for cracking.

Novel bentonite modified PVDF membrane for desalination of synthetic-produced water by vacuum membrane distillation

ABSTRACT Membrane distillation (MD) has emerged as a highly promising method for the treatment of intricate and heavily contaminated water sources, such as those containing oily wastewater. The present study endeavors to advance the field by designing and evaluating a novel nanocomposite membrane comprised polyvinylidene fluoride (PVDF) and Bentonite (BNT) for application in vacuum membrane distillation (VMD) processes targeted at treating oily wastewater. A series of five nanocomposite flat sheet membranes were meticulously fabricated, incorporating varying quantities of bentonite (ranging from 0 to 0.8 g). Systematic characterizations were meticulously undertaken to comprehensively elucidate the influence of BNT incorporation on the structural and functional attributes of the developed membranes. These encompassed an array of analytical techniques, including Fourier Transform Infrared Spectroscopy (FTIR), atomic Force Microscopy (AFM), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), contact angle measurements (CA), as well as assessments of membrane thickness, porosity, pore size, and pore size distribution. The findings distinctly showcased the successful integration of BNT within the PVDF matrix, which correspondingly led to discernable augmentations in membrane surface roughness, hydrophobicity, and porosity. Employing consistent operational conditions involving a feed temperature of 50°C, a vacuum pressure of 30 kPa, and a NaCl solution with a concentration of 14.75 g/L, VMD experiments were systematically conducted. The empirical outcomes revealed that the incorporation of BNT notably conferred substantial enhancements upon the nanocomposite membrane’s performance. The pinnacle achievement was evidenced in a flux rate of 34 L/m2.h and a remarkable NaCl rejection rate of 99.92%, a result achieved by the nanocomposite membrane incorporating the highest content of BNT additives.

The Additives Impact the Gel Strength of the Water Based Drilling Mud

One of the most important functions of drilling mud is its ability to suspend the rock cuttings during drilling cease, this ability is related mainly to gel strength. Gel strength is caused by the attractive forces between the active particles of bentonite (clay) during the static period. Sodium-based bentonite concentration has a direct effect on the gel strength. In addition, cement contaminants may encounter drilling mud as a result of casing string cementation which in turn also leads to a noticeable impact on gel strength. As consequence, it is vital to observe drilling mud gel strength continuously to identify efficient drilling mud functions. In this paper, an experimental study was performed via a shearometer, the aim of this study is to investigate the effect of the variety of the weights of sodium-based bentonite and cement slurries on the gel strength of water based mud. To analyze the influence of bentonite additives, four drilling mud samples were prepared with bentonite weights; 40, 60, 70, and 80 gm respectively, and gel strength was measured at each weight. While cement contamination had been examined by preparing three drilling mud samples contaminated with 2 gm, 3 gm, and 5 gm of class G cement. The results showed that an increase in bentonite quantities leads to rising in gel strength directly. The findings also showed that gel strength increased as the level of cement slurries raised. Furtherer increase appeared from 20.2 to 42 lb/100 ft2 when cement weight increased from 2 to 5 gm respectively.

An Analytical Review on Comparative Analysis of Ground Improvement Using Various Admixtures

Soil improvement in the most sustainable way is the need of the hour and prime importance for the modern construction industry. Most of the time, it has been observed that the soil below the foundation is not mechanically capable of withstanding the load from the structure, and it might cause the failure/collapse of the structure. To prevent it, various significant soil improvement techniques have been introduced, such as mechanical stabilisation, thermal methods, use of admixtures etc. Ground improvement using admixtures involves the addition of various chemical alternatives to the subsoil to enhance its loadbearing capacity. These procedures also give long-term sustainability regarding the soil's bearing capacity. Various potential scholarly works on ground improvement have been done, i.e., the addition of bentonite, kaolinite, bitumen, rice husk ash, pond ash, lime, and cement into the soil, which has been intensely reviewed. From the combined observed experimental results of several researchers presented in this paper, it can be identified how much improvement of a particular soil property can be made by adding several types of admixtures. A clear idea can be generated as to which type of admixture is most suitable for the improvement of a particular type of soil and which soil properties can be improved by the addition of that admixture.

Combined Effects of pH Adjustment and Bentonite Addition Timing on Protein Stability of Sauvignon Blanc Wine

Background and Aims. Bentonite fining is commonly used in white wine production, which can lead to the loss of wine volume and aroma compounds. Many factors influence the efficacy of bentonite fining. The effect of pH adjustment and timing of bentonite addition were studied for their combined effects on Sauvignon Blanc wine protein haze formation and bentonite requirement at microscale and commercial scale. Methods and Results. Three bentonite addition timings were conducted on a juice pH adjustment trial: before fermentation, during fermentation, and after fermentation. The hot and cold test was utilized to determine the bentonite requirement for protein stabilization. Wine proteins were analyzed using a modified Coomassie brilliant blue (CBB) assay, lithium dodecyl sulphate polyacrylamide gel electrophoresis (LDS‐PAGE), and sodium dodecyl sulphate capillary gel electrophoresis (SDS‐CGE). Lower juice pH (2.80 and 3.00) resulted in sluggish fermentation, whereas the presence or absence of bentonite during fermentation showed similar fermentation kinetics at each pH. The presence of bentonite remaining in contact with ferment improved the completion of fermentation for the most sluggish ferment (pH 2.80). Commercial wine made from same batch of juice was adjusted to different pH values, and low‐pH wines had a lower wine protein content and an increasing protein adsorption efficiency of bentonite fining, leading to lower bentonite requirement. Conclusions. Bentonite addition during fermentation was the most efficient in protein removal but fining after fermentation required the least overall bentonite dosage. The different fermentation scales (i.e., microscale versus commercial scale) slightly affected wine protein contents but not molecular weight (MW) profiles. Protein contents and MW profiles in stabilized wines were affected by the original juice pH with more complex patterns from high‐pH juice. Significance of the Study. The findings of this study provide valuable information on optimization of bentonite fining to minimize the dosage so as to reduce the loss of wine volume and quality.

APPLICATION OF BENTONITE IN OBTAINING SULFUR-CONTAINING UREA BASED ON A FLUSH OF UREA AND SULFUR

This paper presents the results of a study of the processes for obtaining granular sulfur-containing carbamide from sulfur and a liquid carbamide melt using bentonite to influence the surface tension between two phases of sulfur and urea to obtain a mixed homogeneous phase. It was revealed that the addition of bentonite to sulfur before adding the latter to the melt of urea, which has a temperature of 135-145 °С at mass ratios (NH2)2CO : bentonite : sulfur = 100 : (1-7) : (1-15) prevents the stratification of melts sulfur and urea. The optimal conditions for obtaining, the composition and properties of granular sulfur-containing urea with a balanced content of nitrogen and sulfur are determined by adding a mixture of sulfur with bentonite to the urea melt before granulation. In fertilizers obtained with the addition of a mixture of sulfur with bentonite to the melt of carbamide at the studied ratios, the strength of the granules increases from the initial 2.65 to 4.76 MPa, the gyroscopic point increases from 58.4% to 62.3%, pH and porosity decrease from 8 02 to 5.32 and from 5.60 to 4.55, respectively, and the dissolution rate of the granules decreases 3.36 times. It was also found that when adding a mixture of sulfur with bentonite to the melt of carbamide, the density and viscosity of the melt increase with an increase in the amount of added mixture of sulfur with bentonite. An increase in the amount of addition of a mixture of sulfur and bentonite from 1 to 15 and from 1 to 7 g per 100 г melt of urea at a temperature of 135 °C leads to an increase in the density and viscosity of the melts from 1.16 to 1.33 g/cm3 and from 2.56 to 3.06 cPz. Microscopic examination showed that adding a mixture of sulfur with bentonite to the carbamide melt leads to a decrease in the size of micropores and microcracks up to 0.93 microns wide. On the basis of the results obtained, optimal technological parameters and a process flow diagram for the production of sulfur-containing granulated carbamide are proposed.

Residual mechanical properties of concrete incorporated with nano supplementary cementitious materials exposed to elevated temperature

Abstract The construction industry commonly employs concrete as a construction material, which sometimes may be subjected to fire exposure. It is important to adopt fire safety measures while planning and constructing such structures to ensure the safety of the occupants and the structural integrity of the concrete. So, determining its performance at elevated temperatures is of utmost importance. The main objective of this study was to investigate the impact of mineral incorporations, namely, nano bentonite clay (NBC) and nano fly ash (NFA), on the retained properties of concrete at normal (27°C) and at elevated temperatures. The feasibility of partly substituting ordinary Portland cement utilizing a mixture of NBC (0–5%) and NFA (0–50%) in concrete was assessed under the exposure to an elevated temperature ranging from 200 to 600°C. Several parameters were examined, including compressive strength, flexural strength, split tensile capacity, water penetration, loss of mass, ultrasound pulse velocity, and microstructure properties. After the experimental analysis, it was observed that the fire endurance was shown to be improved with the inclusion of nanoparticles (BC and FA). A reduction in the loss of mass by samples subjected to elevated heat was observed with the addition of nano bentonite and NFA. The mechanical strength results were obtained as maximum for the concrete specimens with 2% NBC and 20% NFA and further, the specimens performed better when exposed to elevated temperature as compared with normal concrete specimens. The microstructure of the concrete also upgraded with better impermeability owing to the use of NBC and NFA.

Effects of a Bentonite Clay Product and a Preservative Blend on Ileal and Fecal Nutrient Digestibility in Pigs Fed Wheat Naturally Contaminated with Deoxynivalenol.

The objectives were to determine the effects of dietary deoxynivalenol (DON) on apparent ileal digestibility (AID) of nutrients and to evaluate the efficacy of a bentonite (BEN) and a preservative blend (PB) product for alleviating DON effects on the nutrient digestibility of pigs. Twelve crossbred barrows with an initial body weight of 69.4 kg (standard deviation = 3.5) equipped with a T-cannula in the distal ileum were allotted a triplicated 4 × 2 incomplete Latin square design with four dietary treatments and two periods. Dietary treatments were (1) an uncontaminated diet, (2) a contaminated diet (CD) mainly based on contaminated wheat with 1.6 mg/kg DON, (3) CD + 0.25% PB consisting of preservation components as major sources, antioxidants, microorganisms, and amino acids (AA), and (4) CD + 0.25% BEN. The AID and ATTD of dry matter, organic matter, crude protein, most minerals, and most AA were not affected by DON contamination. Dietary DON decreased the AID and ATTD of sodium (p < 0.05) but were restored by supplementing the PB product (p < 0.05). The AID of zinc was increased (p < 0.05) by dietary DON, but supplementing BEN decreased zinc digestibility (p < 0.05). The AID of Arg, Ile, Thr, and Asp was decreased (p < 0.05) by BEN addition. In conclusion, dietary DON affected the digestibility of some minerals but not AA in pigs. Supplemental BEN can negatively affect the nutrient digestibility of some minerals and AA in pigs. The addition of a PB product in pig diets can restore digestibility of sodium but not of other nutrients. Based on these observations, feed additives for alleviating DON effects on nutrient digestibility of pigs can be carefully selected by swine diet formulators.

Effect of Different Levels of Aflatoxin B1 in Concentrated Livestock Diets on Some Characteristics of Rumen Fluid in Laboratory with Sodium Bentonite

This study was conducted in the nutrition laboratory of the Department of Animal Production in the College of Agricultural Engineering Sciences at the University of Baghdad, Al-Jadriya. The experiment lasted for 90 days to investigate the effects of adding sodium bentonite (SB) to a concentrated diet contaminated with aflatoxin B1 on some characteristics of rumen fluid in a laboratory setting. Four diets were prepared, each contaminated with different concentrations of aflatoxin B1 (0, 20, 40, 60 ppb), and four different percentages of sodium bentonite (0, 3, 5, 7%) were added to each ration. The results showed a significant increase in pH values among the different treatments, with the diet contaminated with 40 ppb aflatoxin B1 (T3) recording the highest acidity compared to the control treatment at 0% concentration. However, there were no significant differences in pH rates between the treatments. The pH rates of 7% sodium bentonite addition did not differ significantly from 5% and 0%, while 3% had the lowest pH rate. Regarding volatile fatty acids (VFA), there was a significant increase in their percentage with the increase in sodium bentonite concentrations. The second treatment contaminated with 20 ppb aflatoxin B1 recorded the highest VFA percentage among the treatments, while the fourth treatment (T4) at 0% concentration recorded the lowest VFA percentage. Significant differences in VFA percentages were observed among all the treatments, with the highest VFA percentage in T2, followed by T3 and T1, while T4 recorded the lowest percentage. The analysis of ammonia nitrogen values showed a significant increase among the different treatments, with T2 recording the highest value among the treatments, and T4 at 0% concentration recording the lowest ammonia nitrogen value. Significant differences in the average percentage of ammonia nitrogen were observed among all the experimental treatments, with the highest value in T2, followed by T1 and T3, while T4 recorded the lowest percentage. The total number of microorganisms showed a significant increase with the increase in sodium bentonite concentrations, with T2 at 7% concentration having the highest number of microorganisms, while T4 at 0% concentration recorded the lowest number. Significant differences in the average total number of microorganisms were observed among all the experimental treatments, with T2 having the highest number, followed by T1 and T3, while T4 had the lowest number.

Experimental Investigation of Mechanical and Microstructural Properties of Concrete Containing Bentonite and Dolomite as a Partial Replacement of Cement

In this study, the effect of bentonite (BT) and dolomite (DT) on the mechanical and microstructural properties of concrete was evaluated on nine mixes. Cement was replaced with bentonite and dolomite by weight with varying mix ratios. The mixes are divided as M1 (Control mix), M2 (2.5% BT), M3 (2.5% DT), M4 (5% BT), M5 (5% DT), M6 (10% BT), M7 (10% DT), M8 (2.5% BT and 2.5% DT), and M9 (5% BT and 5% DT). Concrete specimens were subjected to mechanical and microstructural analysis tests. Mechanical test results show that the addition of bentonite (2.5%, 5%, and 10% ) leads to an increase in compressive strength (6.31%, 8.94%, and 13.15%) respectively. Similarly, the addition of 2.5% and 5% dolomite enhanced compressive strength by 10.52%, and 8.94% respectively, however, the addition of 10% dolomite reduced compressive strength by 6.8%. Replacement of cement with dolomite and bentonite individually also showed a small contribution to flexural and split tensile strength. Microstructural analysis shows that the addition of bentonite and dolomite filled the microstructure and refined the internal pores contributing to compressive strength. In addition, the replacement of cement with bentonite and dolomite enhanced the formation of CSH gel.

An extended hypoplastic model for sands with additions of highly plastic fines formulated under the ISA framework

In the present work, the hypoplastic model for sands by Wolffersdorff, (1996) coupled with Intergranular Strain Anisotropy (ISA) by Fuentes et al., (2020) is extended to account for the influence of fines content on the undrained cyclic response and liquefaction resistance of the material. A set of undrained cyclic triaxial tests on clean Ottawa C778 sand and on the same sand with additions of bentonite or laponite were simulated to evaluate the model’s capabilities. The comparison between experiments and element test simulation results suggest that the proposed extended model is able to accurately describe the behavior of clean Ottawa C778 sand and the significant influence of plastic fines in the response of the mixtures, such as the reduction in the accumulation rates of strains and pore water pressure under cyclic loading, and therefore, the improvement in the liquefaction resistance with increasing fines content.