Bentonite specific weight: weight of 1 m³ and density

Humans have long learned to use the useful minerals of our planet for their needs. Oil, coal and metal ores have long been widely used in industry, but some natural substances entered our lives comparatively recently. Bentonite, or bentonite clay, belongs to such useful minerals.

Physical Properties of Bentonite

Bentonite clays are fine-dispersed rocks of a waxy nature. Clay color can vary from pale yellow and grayish to green, bluish and even brown depending on the amount and variety of mineral impurities.

Bentonite formed during periods of increased volcanic activity on our planet. Ash, tuffs and lava underwent chemical changes when entering seawater or during surface weathering. As a result, clay rocks with unique water-absorbing and sorption characteristics were formed.

• The main property of hydrous aluminosilicate is swelling during hydration and retaining moisture inside the formed mass. When wetted, bentonite can increase in volume by 16-20 times. If clay is placed in a confined space and water is added, it turns into a gel-like substance and passes moisture much less readily. Therefore, bentonite is used as an effective water-barrier material, but waterproofing reliability depends on design, layer thickness, raw material quality and installation. This feature is used in construction for:

• foundation laying;

• swimming pool construction;

• production of waterproofing bentonite mats.

• In its natural state, with moisture content not exceeding 15%, the specific weight of bentonite is 2.5-2.76 g/cm³, and volumetric weight is 0.93-1.96 g/cm³.

For convenient conversion, specific and volumetric weight data for bentonite are shown in the table.

• Bentonite sinters at 900-950 °C, with a maximum temperature of 1430 °C.

Two types of bentonite are distinguished:

• calcium bentonite, which usually swells less and has lower water-absorption capacity;

• sodium bentonite, which has a higher ability to swell and retain water.

Numerical swelling indicators depend on the test method, fraction, moisture and chemical activation of the bentonite, so they should not be mixed with material density.

Such bentonites are called activated, but in natural form the indicators can differ significantly.

Areas of Use

Bentonite is used not only in construction. Due to its sorption properties and swelling ability, it is used as a component in medicine, the food industry, fabric production, cosmetics and perfumery, but such uses require raw material of the appropriate purity and approval.

Bentonite has a special place in winemaking. It is used to clarify wines and fruit juices, and its sorption properties are used to remove protein and microorganisms from must and to adsorb oxidative enzymes.

Bentonite of different forms is placed in aquariums and terrariums as decorative elements.

In agriculture, bentonite may be used as a mineral additive, sorbent or component for improving soil and feed properties. The effect depends on clay composition, dosage, crop, animal species and safety requirements, so these uses require compliance with standards and raw material quality control.

Bentonites are used as adsorbing coloring pigments in some construction paints, as a binder or directly adhesive agent, and in the production of wallpaper and asbestos cardboard.

In mining and processing industries, bentonite clays are used as a component of drilling fluids, as additives in concretes to increase strength and water resistance, for producing expanded clay and agloporite, and as an element in the production of ferrous metallurgy alloys.