Papers by Keyword: Bentonite

Abstract: This study evaluates the effect of acid attack on the behavior of concrete containing bentonite and fly ash. The concrete mixes contain varying dosages of bentonite mixed with a constant ratio of 10% fly ash. The concrete mixes include A0, A1, A2, A3, A4, and A5, which contain 0%, 10%, 20%, 30%, 40%, and 50% bentonite, respectively. Experimental results reveal that the addition of 10% fly ash along with 10% bentonite can show significant resistance toward acid attack. The concrete mix A1, containing 10% fly ash and 10% bentonite, loses only 1.1% of its mass as compared to the controlled mix of concrete, which shows a significant loss of its mass up to 8.4%. Microstructural analysis of concrete specimens reveals significant changes in hydration products using scanning electron microscopy (SEM). The addition of 10% bentonite along with fly ash creates a denser microstructure due to the formation of calcium silicate hydrate gel and refines the internal pores of the concrete, which provides a significant resistance towards acid attack. In addition, higher dosages of bentonite lead to a porous and loose microstructure, which becomes susceptible to microcracking and spalling.

Abstract: Use of Waste materials and pozzolanic materials in concrete offer a solution to solve environmental problems arising due to the production of cement and discarded rubber tyres worldwide. The use of crumb rubber in concrete decreases the formation of cracks which helps to withstand greater tensile loads. Several Studies have been conducted to use pozzolanic materials in concrete, like Fly ash, Silica Fumes and GGBS. Very limited research has been done on the use of naturally occurring clay, which is rich in silicain, which provide pozzolanic properties in bentonite. The present study is conducted to evaluate the properties of concrete by partially replacing sand by 5%, 10% and 15% crumb rubber, and bentonite is used to replace cement by 10%, 20% and 30%. Several tests, slump test, compressive tests, were performed at 28 days to evaluate the properties of concrete. The test results showed that the strength decreases with the increase in crumb rubber percentage. This effect was minimized by the use of bentonite which filled the voids generated by rubber particles up to 10% use of bentonite replacement level, and beyond that the strength decreases due to poor bond formation between particles due to increased replacement of cement.

Abstract: This study investigates the mechanical and durability properties of Self-Compacting Concrete (SCC) incorporating bentonite clay and marble dust as partial cement replacements. Bentonite clay, a natural pozzolanic material sourced from Jehengirah (Swabi district), was evaluated for its physical properties, including specific gravity, setting time, and soundness. Results indicate that bentonite has a lower specific gravity and shorter initial setting time compared to Ordinary Portland Cement (OPC), though the final setting time remains similar. A total of nine SCC mix designs were prepared, replacing cement with up to 20% marble dust and 20% bentonite clay by weight. The study focuses on assessing compressive strength, split tensile strength, and durability characteristics compared to conventional SCC. Findings reveal that exceeding 20% cement replacement with pozzolanic materials leads to a notable reduction in compressive strength. However, while the modulus of rupture at 28 days is lower than conventional concrete, the flexural strength relative to compressive strength shows improvement.

Abstract: Solid acid catalysts offer several advantages over liquid acids, primarily in terms of environmental friendliness, ease of separation, and reusability. They have enhanced selectivity and catalytic activity. They are particularly useful in industrial processes where corrosive liquid acids pose handling and waste disposal challenges. Potential solid acid catalysts can be prepared by the modification of naturally occurring clay samples like kaolinite, bentonite, etc. A new, economically and environmentally benign solid acid catalyst for the esterification of cyclohexanol with glacial acetic acid has been prepared from bentonite by mixing with carbon nanodots (CND) prepared from different sources. The carbon sources used for the preparation of CND are glucose, watermelon peel, lemon peel and sucrose. The samples were characterized by acidity measurements and X-ray diffraction (XRD). The XRD pattern of the sample showed that both the components (carbon nanodots and bentonite) are present in the Clay-CND composite. Clay-CND composites showed greater acidity and activity than the pure clay sample. The results showed that the greater the amount of carbon nanodots in the clay-CND composite greater the activity and acidity. Acidity and catalytic activity are correlated. The sample B-SCND, in which CND was prepared from sucrose, showed maximum percentage conversion and acidity.

Abstract: The research consists of incorporating CTAB into the layers of the the bentonite structure, integrating acid-treated bentonite with cetyltrimethylammonium bromide (CTAB), and obtaining an organic material adsorbent. The physical and chemical properties of the sample modifications are identified by employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric/thermal analysis (TGA/DTA). The bentonite used in this study was recovered from the Trebia deposit, located on the north-western flank of the Tidiennit massif in the Nador region (northeast Morocco). The composite developed in the present study is a practical adsorbent for the treatment of industrial wastewater. CTAB was successfully inserted into acid-activated bentonite, demonstrating intercalation processes through X-ray diffraction, FTIR, SEM, and TGA/DTA. The modified Bentonite structure showed increased interlayer space due to the introduction of molecules or ions. The TGA/DTA graphs confirmed the hydrophobic alteration of Bentonite, with reduced clay dehydration and a surfactant decomposing on the surface and interlayer spaces. Morphologically, CTAB formed large particles and cavities.

Abstract: Sustainable concrete has become more popular due to supplementary cementitious materials (SCMs) that help achieve sustainability. Despite the well-established benefits of these SCMs, the search for substitute materials continues as they become harder to find and adapt to changes with the industry. Concrete performance may be enhanced using bentonite, a commercially available clay mineral that shows promise as an SCM. In the present work, an Artificial Neural Network (ANN) model was developed to predict the compressive strength of cement-based mortar incorporating bentonite as a SCM, by training it on existing data, allowing for better performance and mix design improvement. A comprehensive experimental database comprising test specimens was established. A critical assessment of the collected experimental data suggested that there are several key parameters governing compressive strength gains. The proposed model's parameters, such as weights, biases, and transfer functions, were effectively transformed into a mathematical model that correlates the compressive strength with the key input parameters. An experimental investigation measuring the impact of treating bentonite at various temperatures on compressive strength was also included in the study.The statistical evaluation results indicated that a three-layered Artificial Neural Network model with different hidden neurons could precisely estimate the compressive strength of mortar mixtures modified with bentonite, showing strong agreement with the experimental results. The mortar's compressive strength may be increased by partially replacing cement with calcined bentonite, especially in the initial stages. The type of bentonite and the intended performance determine the appropriate replacement rate and calcination temperature.

Abstract: Expansive soil is strongly influenced by the water content inside the soil particle , the significant changes of moisture content cause volume changes. The swelling and shrinkage potential of the soil can be indirectly identified by running the consistency limits test which are by controlling the plasticity index (IP) value and shrinkage limit (SL) value. This research aims to determine the value of liquid limit (LL), plastic limit (PL), plasticity index (IP), and shrinkage limit (SL) of soil-bentonite mixtures as expansive soil materials and analyzing the expansion potential of the modificated materials by its value. There were 5 variations of mixtures which are original soil (S), bentonite (B), 25%S+75%B, 50%S+50%B and 75%S+25%B. The results show the properties of soil-bentonite mixtures. The specific gravity and the grain size distributions were not significantly affected by the increase of the amount of bentonite. LL,PL and PI value significantly increase while SL value were decreased. Along with the increase of bentonite percentage, the activity value also increased by 1.5 to 4. It summarizes that by adding bentonite on the original soil, the expansion potential of the soil mixtures also increased.

Abstract: One kind of heavy metal that comes from industrial waste is Cr (VI), which is obtained from steel, textile, tanning, photography, dyes, explosives, matches, and fuel mobilization waste. Cr (VI) is a carcinogen and extremely hazardous to both people and animals. In Indonesia, bentonite is a raw material that is abundantly available. This study aims to investigate the effects of varying adsorbent doses on the properties, % removal, isotherms, and kinetics of adsorption of Cr (VI) from aqueous solution. Adsorbent doses ranged from 10 g/L to 30 g/L for 0–80-minute contact periods. morphological analysis of bentonite using a scanning electron microscope (SEM). Features of bentonite were tiny lumps of varying sizes and the absence of pores. 96.5% is the optimal elimination of Cr (VI). The morphological analysis of bentonite using a scanning electron microscope (SEM). Features of bentonite were tiny lumps of varying sizes and the absence of pores. When using a dose of 20 g/L and a 60-minute duration, the maximum elimination of Cr (VI) is 96.5%. Isotherms follow Langmuir and kinetics fit to first order. These findings demonstrate that bentonite is a valuable material for future development and is effective at removing Cr (VI) from aqueous solutions.

Abstract: The construction industry significantly contributes to global CO₂ emissions and environmental impact, mainly due to concrete usage, which consumes vast resources and energy while emitting CO₂. Researchers are exploring alternatives such as geopolymer concrete (GPC), formed without traditional cement but through alkaline activation of industrial by-products like fly ash, ground granulated blast furnace slag, bentonite, and metakaolin clay. This study evaluates the effects of incorporating bentonite and polypropylene (PP) fibers on the workability and strength properties of GPC based on slag. Bentonite substituted 10% of slag, and PP fibers were added at varying ratios (0.5%, 0.75%, and 1%). Both untreated and heat-treated bentonite, heated up to 200°C, were used. Workability was assessed using a slump cone, while mechanical properties, including compressive, split-tensile, and flexural strength, were analyzed. Notably, heat-treated bentonite and PP fibers exhibited significant enhancement in the mechanical properties of the GPC mixes.

Abstract: Clay minerals possess substantial potential for developing innovative functional materials, particularly in the context of environmental protection. This study focuses on the adsorbent zeolite-clay and bentonite-clay, shaped into honeycomb monoliths to efficiently remove Fe²⁺ ions from water. The process involved physically activating powdered zeolite-clay and bentonite-clay through calcination at 600°C. The activated materials were then mixed with distilled water and molded into monolithic shapes through extrusion with stainless steel molds, resulting in cylindrical structures measuring 1.8 cm in diameter and 2 cm in height, featuring 40 perforations. Mechanical characterization aimed to evaluate structural strength and assess pressure drop during operation, revealing superior mechanical strength in bentonite-clay compared to zeolite-clay. The monolithic form exhibited lower pressure drop during operation compared to pellet adsorbents. In terms of adsorption performance, a batch reactor assessed efficiency, isotherm, and kinetics with 2 and 4 ppm Fe2+ ion solutions over a 240-minute period. The zeolite-clay monolith demonstrated the highest capacity, achieving a removal efficiency of up to 65%. Maximal adsorption capacities for bentonite-clay and zeolite-clay were 0.209 and 0.289 mg/g, respectively, with corresponding Langmuir adsorption equilibrium constants (KL) of 0.187 and 0.181 L/g by the Langmuir isotherm model. Kinetic analysis favored the pseudo-first-order non-linear model, indicating rates for zeolite-clay and bentonite-clay adsorbents at 2 and 4 ppm Fe²⁺ ion concentrations of 0.0043, 0.0030, 0.0039, and 0.0038 min^-1. This study signifies a significant advancement in solid adsorbents, optimizing the adsorption process for broader applications.