Bentonite is a multipurpose material, served in diverse industries for various applications. The grade of this substance utilized in civil engineering is called construction bentonite. It is one of the subgrades of sodium bentonite that holds multiple physicochemical properties. It includes remarkable plasticity and lubricity, excellent dry-bonding properties, high compressive and shear strength, and resistance to permeability. These properties make construction bentonite a suitable applicant for industries such as tunneling, construction of facilities, and waterproofing. Construction bentonite also serves as Lubricant and Thixotropic Agent.
Iran bentonite Co. is a trustworthy company that relies on its equipped factories and experts to provide the customers with high-quality material. Every company can count on Iran bentonite Co’s products for different construction purposes. This company enjoys raw materials needed for bentonite manufacture that lead to an outcome with high physicochemical properties. You can rely on this company as a powerful bentonite manufacturer and supplier from every corner of the world. Please remember that you can also choose Iran bentonite Co. for other grades of material besides construction bentonite.
What Is Bentonite?
Bentonite is a naturally occurring substance mostly made of smectite clay. This material can be found as layers between other rocks and is created in marine environments by converting volcanic ash to clay particles. It is a clay that can swell and gelatinize when combined with water. Bentonite, commonly referred to as bleaching clay, has significant commercial significance and naturally bleaches materials like fuller’s earth. It is considered high plastic clay since it contains more than 85% of the clay mineral montmorillonite. The smectite group of crystal minerals, which contains hydrated aluminum silicates including iron, magnesium, sodium, or calcium, make up most of its composition.
Known varieties of bentonite include sodium, calcium, and potassium bentonite, and depending on their unique physical characteristics, each is used for a different purpose. It is helpful to know that bentonite is a common name for “calcium bentonite,” whereas “sodium bentonite” is known as “Fuller’s earth.” This substance’s commercial significance is primarily influenced by its physical properties rather than its chemical details. Bentonite is commercially viable due to its superior plasticity and lubricity, high dry-bonding strength, high shear and compressive strength, low permeability, and low compressibility. Bentonite is valuable for binding foundry sand, drilling mud, pelletizing iron ore, and as a waterproofing and sealing agent in construction projects; it also finds other applications in the industry.
It is helpful to remember that bentonite has a wide variety of industrial uses due to its ability to swell in water and create viscous suspensions. Bentonite is clay that may be dissolved in water to develop colloidal particles with a higher surface area than their weight. These colloidal particles can be an efficient emulsion stabilizer or carrier for other chemical compounds.
What Is Construction Bentonite?
As mentioned above, various grades of bentonite are employed in many industries based on their physical properties. Each grade holds its unique characteristics. One of the bentonite grades that is famous in construction projects is called ‘civil engineering bentonite” or “construction bentonite.” It is essential to know that the excellent properties of this substance lead to such applications. Its properties include:
- Constructing excellent ponds;
- Keeping the excavation stable;
- Achieving effective suspension at low doses;
- Clogs pore by deeply penetrating cleavages and fissures;
- Supporting the suspension for cutting of shield tunneling and wall construction;
- Serving as Subsoil friction and sealing agent;
- When wet, swelling 15–18 times its original size;
- When used appropriately, being environmentally safe and does not cause harm to the water, livestock, or wild animals.
Traditional uses of bentonite in civil engineering include pipe jacking, horizontal directional drilling, and diaphragm walls and foundations. This chemical compound serves as a thixotropic support and lubricant agent, too. Bentonite is also utilized in Portland cement and mortars because of its viscosity and plasticity. To ensure groundwater protection from pollutants, bentonite is operated as a sealing material in the building and rehabilitation of landfills, per European Union directives.
Different Grades Of Construction Bentonite
Chemicals are the foundation of any business since they are employed in producing or testing nearly every industrial product. However, many people working in the industry lack the necessary skills. As a result, most chemical compounds are marked with a grade. In this situation, producers employ several classes to communicate complex aspects of their products. Chemical grading is the process of counting the impurities in a sample of chemicals. Although numerous standards are used in grading, you will most likely come across the ACS, Reagent Grade, and Laboratory Grades.
Bentonites, like other multipurpose substances, are presented in many grades and qualities, indicating their physical and chemical properties. For instance, Iran Bentonite manufacturers usually divide their products into two general categories: sodium and calcium bentonites that contain specific characteristics.
Sodium bentonite:
When saturated with liquid, sodium bentonite swells and can absorb up to several times its dry mass. Due to its exceptional colloidal characteristics, it frequently appears in drilling mud for oil and gas wells and boreholes utilized for geotechnical and environmental research. Because it creates a self-sealing, low permeability barrier due to its swelling ability, sodium bentonite is also effective as a sealant. For instance, it is used to line the bottom of landfills. Bentonite is also a component of the backfill utilized at the Waste Isolation Pilot Project.
Calcium bentonite:
Both ions in solution and fats and oils can be effectively adsorbed with calcium bentonite. It is the primary component of fuller’s earth, which is likely among the oldest industrial cleaning products. Compared to sodium bentonite, it has a substantially lower capacity for swelling.
Bentonite manufacturers also provide these materials in commercial grades. It means that they present each outcome specific to an application. Casting bentonite, OCMA bentonite, and water treatment bentonite are examples of such a classification.
Construction bentonite is a commercial grade of this substance suitable for several applications. It is widely used in various construction projects, such as tunneling, metro construction, and building facilities using the “Slurry wall” technique, sealing cracks and voids when building hydropower plants, waterproofing for foundation construction, and building (installing) waterproofing screens. Furthermore, we must note that even bentonite’s construction grade can be divided into several qualities. The point is that every manufacturer will produce this substance in a specific way that leads to a particular outcome with different physical and chemical grades and perhaps varied amounts of purity.
Construction Bentonite Production Process
Bentonite is a raw material that is mined in open pit quarries and is found in many countries. Most commonly, lenticular layers in bentonite deposits are quite large and only a few meters deep. Speaking briefly, mining the ore, drying, grinding, and sodium activation are all steps in manufacturing this material. Calcium ions are exchanged for sodium carbonate during sodium activation, transforming calcium bentonite into sodium bentonite. The bentonite’s 25–35% natural moisture content is decreased through drying. This is a challenging operation that must be carried out at a controlled temperature to avoid damaging the molecular structure of bentonite because it is hygroscopic. Bentonite loses all its characteristics and becomes a grog at temperatures higher than 500 °C, where crystallization water is irrevocably eliminated from the material (aggregates).
Moreover, manufacturers, such as Iran Construction Bentonite producers, try using different equipment and advanced procedures to invent new ways of activating bentonite that works more productively. As a result, several forms of activating bentonite are varied by their steps and the final results. Below, you can discover three methods dedicated to this purpose.
1st Method
In this process, sodium carbonate is sprinkled dry or dissolved (dissolved in water) over the previously torn bentonite layer and pushed into the clay using a disc or roto-tiller. After that, the bed is periodically revised over several months to increase homogeneity. Due to the bentonite’s natural moisture content, rain, water, and snow, sodium carbonate that is poured over the bed in the dry form will dissolve. A coating of 15 to 20 cm thick bentonite is laid down when the stockpile is activated. Then, after spreading or sprinkling sodium carbonate on top of this layer, discing is applied. Once the required stockpile size is reached, these stages are repeated.
2nd Method
In this method, sodium carbonate may be added to wet crude bentonite before it enters an extruder or several extrusion stages, followed by drying in cases when bentonites are not field-dried. Water is frequently added in addition to sodium carbonate to aid with extrusion. The shearing action causes the particles to become disoriented and speeds up ion exchange. Here, the bentonite is not dried, and after extrusion, the moisture content is decreased to around 20%.
3rd Method
During this activation method, before steam is applied to the clay, the bentonite is first run through a mechanical kneader to incorporate the sodium carbonate. The ste-a will split the clay aggregates, allowing for penetration and ion exchange thanks to its low viscosity, which enables it to do so. Additionally, the action of the steam increases the mobility of sodium ions, boosting the exchange rate.
Construction Bentonite Applications
The reactivity of bentonite with various substances, such as water, organic materials, amines, etc., determines how this substance is used in the industrial sector. It includes the use of bentonite in paint, the refinement of industrial and edible oils and chemicals, the drilling of oil and gas wells, industrial adhesives, and a variety of other products. Another critical feature of bentonite is the environment in which the mineral was formed. Based on this environment, the mineral can be classified as sodium bentonite or calcium bentonite. Compared to calcium bentonite, sodium bentonite is more capable of swelling. Another physical characteristic, the ion exchange, in various industries is suggested by contrasting the swelling rates of calcium and sodium bentonite.
A significant portion of foundations and other civil engineering activities are still carried out without using bentonite and are incurring significantly higher costs through cast iron or steel liners. It causes the recognition of bentonite as a crucial construction element in its latent stage. There is still a long way to go in raising public knowledge of using bentonite in civil engineering. Due to its rheological properties, bentonite is used primarily in construction in a fluid state, often known as bentonite slurry. Construction bentonite has many uses, including:
- Tunneling industry;
- Facilities construction;
- Filling voids and sealing cracks;
- Foundation waterproofing;
- The installation of waterproofing screens.
Construction Bentonite In The Tunneling Industry
Slurry-type tunneling machines are employed while building tunnels in challenging geotechnical conditions (unstable soils, high groundwater pressure, etc.). Using machinery, a bentonite suspension with precisely determined qualities is injected into the borehole region during tunneling operations. This suspension penetrates the soil under pressure and compacts the tunnel face, preventing subsidence and rock collapse. The bentonite suspension also serves the additional purposes of lubricating, chilling, and clearing away face cuts. It is also worth mentioning that bentonite is a common ingredient in drilling mud used in trenchless engineering techniques as a lubricant and supporting substance in subsurface tunneling activities, including horizontal drilling and pipe jacking. Slurry, drilling mud, and mud mix are other names for drilling mud.
Construction Bentonite In The Structures
Bentonite suspensions are employed as a component of the “slurry wall” method when building densely packed structures. The core of the “slurry wall” technology used to construct underground constructions is that as the soil is removed, a trench is filled with clay mud to prevent the walls from collapsing. To fill the trench walls and prevent them from collapsing before the reinforcing cage is lowered and the trench is filled with concrete, the clay mud’s low viscosity and high mudding ability penetrate the soil and fill the walls of the trench. This crust is relatively thin (0.5-3 mm), reasonably dense, and strong. After the concrete has hardened, the completed structure can act differently. It can be served as a groundwater cutoff that prevents groundwater from entering the underground structure, a supporting element for the foundation, and an enclosure for the walls of the underground construction.
Construction Bentonite As A Thixotropic Agent
Construction bentonite can also be used as a thixotropic agent. Thixotropy is a time-dependent characteristic of shear thinning. When shaken, agitated, shear-stressed, or otherwise disturbed, certain gels or fluids thick or viscous under static conditions will flow over time (become thinner, less dense) (time-dependent viscosity). They then take a predetermined amount of time to become viscous again. Numerous paint and ink types, such as the plastisols used in silkscreen textile printing, exhibit thixotropic properties. In many situations, the fluid should flow just enough to establish a uniform layer before resisting additional flow to avoid sagging on a vertical surface. To safeguard the dot structure for precise color reproduction, some other inks, such as those used in CMYK-type process printing, are made to regain viscosity even faster after application.
Construction Bentonite In Waterproofing Of Foundations
When bentonite is used as a waterproofing membrane below grade, the soil’s natural moisture causes it to hydrate and form an impenetrable barrier that absorbs and expels water and most chemicals, including acids and salts (sodium bentonite). Bentonite can absorb seven to ten times its weight in water and expands up to 18 times its dry volume. It can expand and compress an unlimited number of times. However, this barrier must maintain a continuous minimum pressure of 30 to 60 pounds per square foot for bentonite to work well as a waterproofing barrier (PSF).
About Iran Bentonite Co’s Product
Customers around the world can rely on Iran bentonite Co. as a prominent producer of bentonite. This company tends to utilize high-quality raw materials in Iran and other possible sources to present one of the purest outcomes in the market. Construction bentonite produced by this company holds high properties that make them a perfect choice for usage related to civil engineering. It is also worth mentioning that you can go for different logistics options when dealing with this company. The packing system is based on international standards to ensure safety during shipping. Still, customers select their intended way of packing the material. They can also purchase various grades of bentonite from Iran Bentonite Co; in this case, please contact our experts.
Conclusion
Bentonite, also known as montmorillonite or smectite, is an absorbent swelling clay mainly composed of either Na-montmorillonite or Ca-montmorillonite. There are different grades of this substance, each for a specific purpose. Construction bentonite is a grade of sodium bentonite suitable for purposes related to civil engineering, such as waterproofing of foundations, construction of structures, and the tunneling industry. Manufacturers of bentonite enjoy various methods for producing and activating this substance. In this article, we’ve mentioned some famous activation methods that lead to the manufacture of a superior product.
