Classification and characteristics of river sand

River sand is a widely used and readily available material in the construction industry. It is mostly made up of tiny fragments that weather and erode from rocks naturally. River sand, which is found on banks and in riverbeds, is widely used to make plaster, concrete, and other building materials.

For river sand to be used effectively in construction projects, it is essential to understand how it is classified. Based on their origin, color, and grain size, different types of river sand are categorized. These divisions aid in identifying the most advantageous application for every kind, guaranteeing top-notch outcomes in a range of building contexts.

River sand’s texture, purity, and composition are some of its key attributes that determine how well-suited it is for various building projects. For instance, coarser sand works better in concrete mixtures, but the smooth texture of fine river sand is perfect for plastering walls. By choosing the ideal sand for their particular requirements based on these qualities, contractors and builders can improve the strength and longevity of their work.

Apart from its pragmatic uses, river sand procurement has an environmental cost that must be taken into account. In addition to ensuring the long-term availability of this priceless resource, sustainable sand extraction methods can contribute to the preservation of river ecosystems. We can support more environmentally friendly building techniques by selecting river sand that has been responsibly sourced.

Classification of river sand by origin and fineness modulus

River sand is classified into two categories based on where it came from: coarse-grained from dried-up reservoirs and washed (with an average fraction size, yellowish or grayish tint), mined from river bottoms. Because coarse-grained sand is more uncommon, washed river sand is less expensive.

While deciding where to use bulk material, the fineness modulus—the permissible sizes of individual particles in raw materials—is a crucial indicator. Every sand is separated into multiple groups:

• Flowerful (that is, very thin, thin and very small). Differs in a structure similar to dust. The size of the fractions varies from 0.5 mm to 1.5 mm.
• Small. Granular size – 1.5 ÷ 2.0 mm.
• Average. Fractions in size from 2 mm to 2.5 mm.
• Large – 2.5 ÷ 3 mm.
• Increased size – 3 ÷ 3.5 mm.
• Superciper – from 3.5 mm and more.

One easy method of sorting by size module is to run the material through a sieve with holes that have been calibrated.

Other technical characteristics of sand

The specific gravity (density) of the sand mass directly depends on the size of the grains. Specific density is divided into bulk and true. The true density on average is 2.5 tons/mᶟ. In practice, basically in the calculations, a bulk specific density is used (that is, the amount of raw materials in a bulk, a unclean state contained in one meter of cubic). When determining this value, in addition to the volume of particles, the voids between them are also taken into account: as a result, it turns out that the bulk density value is slightly less than the true value. Bulk specific gravity of river sand is 1.3÷1.5 tons/mᶟ.

The primary benefit of river sand is its lack of impurities such as silt, clay, and dust, which only account for 0.7% of its weight. This feature improves the characteristics of ready-made dry mixes that incorporate this bulk material.

Regarding radiation safety, practically all natural raw materials fall into the first category, meaning they are appropriate for use in any kind of work and safe from radiation.

When carrying out construction work, not only such characteristics of sand as particle size, the presence of clay components, specific gravity are important, but also the filtration coefficient (expressed in the distance that the liquid overcomes in the thickness of the material during the day), characterizing the ability of the sand mass to pass water. The value of this indicator largely depends on the structure of the material, as well as on the amount of certain impurities contained in it: the cleaner and larger the sand, the higher its water permeability. Raw materials with clay have low water permeability, since clay practically does not allow liquid to pass through. Therefore, the scope of application of such material is significantly narrowed. The filtration coefficient of sand (particle size – 2 ÷ 2.5 mm) is 5 ÷ 20 m / day; and material with a granule size of 1 ÷ 2 mm – varies from 1 to 10 m / day (for comparison: quarry sand has a filtration coefficient of 0.5 ÷ 7 m / day).

Counseling! To improve the filtration coefficient, remove any clay impurities from the material.

River sand is an essential building material that comes in a variety of forms, each with special qualities that affect which projects they work well with. The classification of river sand according to its composition, size, and texture will be discussed in this article, along with how these characteristics impact its use in masonry, concrete, and other construction applications. Comprehending these variations aids constructors in choosing the appropriate sand type to guarantee longevity and structural soundness.

Sand compaction coefficient

It is essential to accurately calculate the volumes of the materials used before beginning any construction project. The sand compaction coefficient (Kupl), which is found by comparing the density of the material in a particular area with the value specified in regulatory documents, must be used in calculations to determine how much bulk material is needed. This coefficient shows the degree to which the construction site work was completed in compliance with GOST 8736-93 and 25100-95 requirements. In general, Kupl varies between 0.95 and 0.98, depending on the kind of construction (though it shouldn’t go above 1.15).

The calculation is made as follows: multiply the compaction coefficient by the required volume. But it is necessary to remember that during the process of loading and transporting bulk material, it is rammed, in addition, moisture can get into it. Therefore, in order to determine how much sand mass is required, the volume of material delivered to the construction site must be multiplied by the coefficient of relative compaction. The method for determining the coefficient of relative compaction of sands consists in determining the ratio of the density of dry sand ("skeleton") to the density of dry material at the point of its receipt. The relative compaction coefficient is determined by calculation and indicated in the design documentation for the construction site.

Distinctive properties of river sand and its application

River sand has two primary characteristics: fractional homogeneity and natural purity. This material’s high flowability and moisture capacity are attributed to the rounded and smooth shapes of its particles.

Counseling! Consider that the weight of bulk material varies with humidity; that is, one cube of dry sand contains more than one mᶟ of wet material. If not, you run the risk of purchasing a lot by weight but insufficient by volume. Keep in mind that reference books indicate the specific gravity value for dry material when calculating the required amount.

In addition to being used to arrange floor screeds and purify water (from mechanical impurities) for drainage, river sand is also a component of ready-made building mixtures. Gardeners combine this bulk material with soil to make it crumblier and lighter.

Washed quarry is the term for the relatively clean material that is produced by washing the sand mass that is taken out of the quarry and contains stones, clay, and other impurities with water.

Screened quarry refers to quarry sand that has been sifted to remove large fractions and stones. These materials are highly sought after in the construction industry: plastering, foundation building, and masonry mortar.

It is impossible to give a clear answer to the question of which material is better: river or quarry, since everything depends on the type of construction work. But it is possible to say for sure that washed quarry sand is most often used for concrete. The fact is that the grains of river material, due to their roundness and the absence of sharp edges, do not adhere well to cement: this can negatively affect the quality of the final product. However, river sand does not contain any inclusions, but quarry sand contains some organic impurities that can behave unpredictably when reacting with the chemical components of the mixture. Therefore, make your own decision: to use washed quarry or river sand.

How river sand is mined

A dredger, which has hydromechanical components like a hydraulic pump, a storage tank, and a sieve, is used to mine river sand (see photo below). Depending on the technological process, the sand mass is first lifted from the riverbed using a strong pump and stored on a barge. Next, it is loaded onto the shore into dump trucks or transported to a temporary storage location using a conveyor.

An excavator is used to mine coarse-grained sand material from the bed of a dried-up reservoir. Dump trucks then load the material and deliver it to a warehouse or construction site. The entire technological process bears a striking resemblance to the quarry extraction process.

Crucial! GOST says that the sand needs to be cleaned. If not, it is regarded as inadequate and inappropriate for use in building projects. The amount of sludge in the raw materials will determine how many times they need to be washed during the extraction process.

The sand mass cannot be moved to a permanent storage location or sold until it dries to the level of "normal humidity," which is controlled by GOST.

For river sand to be used effectively in construction, it is essential to comprehend its classification and properties. River sand is a naturally occurring substance with special qualities that make it ideal for a wide range of building uses. When combined with cement and other aggregates, its fine texture and reliable quality guarantee a solid and long-lasting foundation.

The cleanliness of river sand is one of its main benefits. It has less organic material and contaminants than some other types of sand. Because of its purity, river sand-based concrete is more durable and dependable. Furthermore, the naturally rounded river sand particles make concrete easier to mix and pour by increasing its workability.

The use of river sand has advantages, but it needs to be handled carefully. Environmental problems like habitat destruction and riverbank erosion can result from overextraction. To reduce the negative effects on the environment, it is crucial to source river sand responsibly and to take into account alternatives whenever feasible.

In conclusion, river sand’s superior qualities make it an invaluable resource for the building sector. Building professionals can produce long-lasting, high-quality concrete structures while simultaneously preserving the environment by being aware of its properties and employing it responsibly. Selecting the right materials with knowledge guarantees the success of building projects and the protection of our natural resources.

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