The strength and durability of concrete may be the first things that spring to mind. However, did you know that the kind of sand used in concrete can significantly alter its quality? Sand is an essential component that influences the strength, texture, and durability of concrete; it is not just a filler. Making better decisions when managing a construction site or taking on a do-it-yourself project can be aided by knowing the function of sand.
There are various types of sand for concrete, and each type has unique characteristics. For example, coarser sand may be better for structural strength, but finer sand can help achieve a smoother finish. The overall mix can be impacted by the quality of the sand, so it’s critical to select the appropriate kind for your project’s requirements. Your concrete project’s final result can be greatly impacted by your ability to choose and use sand correctly.
This post will discuss the various sand types used in concrete, their characteristics, and how to select the best one for your particular requirements. Knowing the function of sand in concrete will provide you with a strong base for getting the best results, whether you’re mixing concrete for a driveway, new patio, or a large construction project.
General requirements for selection
Sand for concrete, which is used to make concrete mortar, must comply with GOST standards. The material is suitable if it contains less than ten percent of particles with a fraction of up to 0.14 mm and no more than three percent of impurities represented by dust, silt and clay. It is the presence of the latter in the mixture that can negatively affect the frost resistance and strength of concrete, since it covers the grains of sand, preventing them from properly connecting with the other components. Also, according to the standards, the content of large-sized particles over 10 mm is not allowed, and the proportion of particles 5-10 mm in size should be within five percent of the total mass of the bulk component. Organic inclusions in the material, represented by humus or plant elements, should be absent.
Particle size
Determine the fineness modulus (fraction), the most crucial factor to consider when selecting a bulk building material, before deciding on the type of sand required for concrete. There is a differentiation made between:
- very large (over 3.5 mm in size);
- high fraction (within 3-3.5 mm);
- large (2.5-3 mm);
- medium-sized (2-2.5 mm);
- small (1.5-2 mm);
- very small (1-1.5 mm);
- fine (0.7-1 mm);
- very fine (up to 0.7 mm).
Manufacturers pass the sand through successive sieves with fractions of 10 mm, 5 mm, 2.5 mm, 1.25 mm, 0.63 mm, 0.315 mm, and 0.14 mm to ascertain the fineness modulus.
The following is a simplified classification that can be given:
In order to prevent the concrete mixture from having a lot of voids, coarse-grained sand that has a sufficient amount of smaller grains must be used in the production process. Cement will be used to fill in the resulting voids, raising the final product’s cost. It has been observed that there is more free space when sand grains of the same fraction do not interact with one another as well. Therefore, to achieve the highest density between the elements, a mixture of various particle sizes is frequently used.
Bulk materials are divided into two classes according to particle size. The absence of microparticles with a diameter of less than 1.5 millimeters sets apart the first class. Since the presence of very fine aggregate negatively affects the sedimentation density of larger fractions, this type of sand material is thought to be superior. Small components are therefore included in the second class. For this reason, premium bulk concrete is used to prepare superior concrete.
Types
Sand is a sedimentary rock with fine grains that can be crushed to create it or found in its finished state. Apart from grain size, another crucial determinant of the grain’s characteristics is the extraction site. Emphasize:
- river;
- nautical;
- career;
- quartz.
Because river sand has very little stone and no clay, it is preferred. Although a little more costly than other forms of bulk, the quality is superior. The uniform and smooth oval-shaped sand grains have a significantly higher sedimentation density compared to quarry sand, which has uneven surfaces and an asymmetrical shape. Dredgers are used in the mining process to extract the sand and water mixture, which is then transported to a storage facility. The water is outflowing into the reservoir at the same time.
Sea sand and river sand have comparable qualities. The inclusion of tiny sea stone and shell fragments gives it a unique quality. That means more cleaning is needed. Sea salt produces uniformly sized and shaped grains. Due to the fact that it must be extracted from the seabed using costly technologies, it is the most expensive bulk material.
Quarry bulk must be cleaned of foreign particles after extraction because it frequently contains stones and clay impurities. It is the least expensive. In sand quarries, rock extraction is the most common practice.
Using specialized grinding units, quartz rocks are artificially crushed to extract quartz sand material. It is produced without the presence of any impurities and is distinguished by its chemical neutrality. The material can be cleaned using any of the following techniques, depending on the processing options:
- washing (a method of cleaning by water washing);
- sifted (according to this method, sieves are used for sifting).
Sand is washed on the mining site itself. The substance is submerged in water and repeatedly stirred to achieve this. The sand grains are thus cleaned of various impurities and dust. Extraneous particles separate from the bulk mass as they float to the top. This process is repeated multiple times. It is true that buying in bulk has a higher price tag. Although sifting is a less expensive process, dust microparticles are not removed.
As the main aggregate that keeps the mixture cohesive, sand is essential to the strength and longevity of concrete. The quality of the finished product can be greatly affected by selecting the appropriate kind of sand and making sure it is clean and appropriately graded. This post will discuss the importance of sand in concrete, what constitutes quality sand, and how to choose the right choice for your project in order to get a durable, long-lasting finish.
Characteristics of the material
Depending on their composition, different types of sand can have varying physical and chemical properties, such as:
- chemical;
- mineral;
- granulometric (display of the composition of particles in percent depending on the fraction).
The actual weight of one meter of cubic sand is a significant indicator. It varies from 1.5 to 1.8 tons. Because there are fewer impurities in the weight, it is better.
Humidity is a significant factor. It should normally be 5%. This indicator determines how much water should be added to the concrete solution. When building a house, you can "by eye" test the material’s moisture content. If the sand does not scatter after compacting in your fist, the typical humidity level has been exceeded, meaning less water will be needed in the mixture.
| Type of Sand | Description |
| Coarse Sand | Has larger grains and is often used for making concrete that needs to be strong and durable. It"s good for structural applications. |
| Fine Sand | Has smaller grains and is used to give concrete a smooth finish. It can be good for decorative work or where a fine texture is needed. |
| Manufactured Sand | Made by crushing rocks into sand-sized particles. It"s a good alternative to natural sand and can be used in most concrete applications. |
| Natural Sand | Obtained from riverbeds or beaches. It"s generally clean and well-rounded, making it a traditional choice for concrete mix. |
| Gravel Sand | Contains a mix of sand and small gravel. It’s used to improve the strength and texture of the concrete. |
In conclusion, sand is an essential component of the concrete mix because it serves as the aggregate that holds the other components together. The strength and longevity of the finished product can be greatly impacted by its type and quality. Whether it’s fine, coarse, or a combination of the two, selecting the appropriate sand will help guarantee that your concrete mixture will have the qualities you want for your project.
Making better decisions regarding your concrete needs can also be aided by having a thorough understanding of the origins and characteristics of sand. Understanding how various sands react with cement and water will help you get better results whether you’re working on a big construction project or a small do-it-yourself project. When sourcing your materials, it’s always important to keep in mind that environmental factors and local availability may have an impact on your decision.
In the end, choosing the appropriate sand carefully can have a significant impact on the caliber of your concrete. You can extend the life and performance of your concrete projects with a little preparation and understanding. The next time you’re getting ready to mix concrete, keep in mind that the sand you select is essential to a good build and not just a small component.
