Selecting the proper kind and size of crushed stone, or gravel, is essential to producing concrete that has the required strength and durability. The selection of crushed stone becomes especially crucial for concrete rated at M300, which denotes a mix that can withstand 300 kilograms per square centimeter. The stone particle sizes that are used in the concrete mix are referred to as the fraction of crushed stone. Together with cement, water, and sand, these stones are essential to the creation of a sturdy and long-lasting concrete structure.
For M300 concrete, a crushed stone fraction of between 5 and 20 mm is usually ideal. This range makes sure the stones fit together tightly, giving the concrete mixture strength and stability. For structural concrete, larger stones (20 mm) are better because they require less cement paste and improve the concrete’s resistance to shrinking and cracking. The workability is enhanced by smaller stones (5mm) which bridge the spaces between larger stones.
The quality of the stone is crucial when choosing crushed stone for M300 concrete. Superior crushed stone has less elongation and flakiness and is long-lasting. It must be devoid of contaminants like silt, clay, and organic materials, as these can gradually erode the concrete’s strength. For the stone to withstand the pressures and forces applied during concrete curing and service life, it should ideally be dense and hard.
Regarding the type of crushed stone, reliable vendors who follow quality guidelines are advised. Prioritizing should go to brands that are well-known in the building sector for offering consistent and trustworthy crushed stone. Reputable vendors frequently offer grading certificates that detail the crushed stone’s quality attributes and particle size distribution, guaranteeing that it satisfies the specifications needed for M300 concrete.
In summary, the amount of crushed stone (gravel) in M300 concrete has a big impact on how strong, long-lasting, and workable it is. Selecting the proper crushed stone in terms of size, quality, and brand guarantees that the concrete mix works as best it can to meet structural requirements and improve performance over time. When choosing crushed stone for concrete projects, engineers and builders can make well-informed choices by being aware of these factors.
Fraction of Crushed Stone | Recommendation for Concrete M300 |
Size | 5-20 mm |
Brand | Hard and durable types like granite or basalt |
- Why do you need crushed stone in concrete
- The main characteristics of crushed stone
- Classification
- Granite
- Gravel
- Limestone
- Slag
- Secondary
- Video on the topic
- OOO RBU No. 2 Video which concrete to choose on gravel or crushed stone
- Crushed stone: foundation device | Types of crushed stone | Application of crushed stone in road construction
- Which crushed stone to choose
- How to choose concrete, crushed stone, sand for a foundation or fence
- The difference between granite crushed stone and gravel
- Crushed stone: types, differences, characteristics
Why do you need crushed stone in concrete
Bulk material produced by crushing rocks, including boulders and gravel, is known as crushed stone. Stated differently, crushed stone is commonly interpreted as angular stones that may come from a variety of rocks.
There are a few things that need to be highlighted when answering the question of why crushed stone is added to concrete. Although it’s not always used when making concrete mix, adding this building material to the mixture helps you solve a number of issues:
- Increasing strength. Crushed stone particles have an irregular shape, due to which the adhesion of materials is enhanced and creep is reduced.
- Increased water resistance. Concrete mixtures with the addition of large filler are used if the finished coating will often come into contact with moisture.
- High strength. If such a filler is present in the mixture, it will take on the role of a frame. Concrete on crushed stone can be subjected to increased loads. For this reason, this technology is used in the construction of tunnels, bridges, hydraulic structures, foundations for buildings that have increased requirements.
- Reduced costs for construction work. When making a solution, the filler partially replaces cement, which is characterized by a higher price.
In the event that filler use is chosen, the following details need to be considered:
- Presence of several fractions of crushed stone in the composition. If the mixture contains only large stones, then air pockets may occur during the laying process, due to which the strength will decrease.
- The maximum size of stones depends on the design features. The fraction should be less than ⅔, than the smallest distance between adjacent reinforcement bars. Another calculation option is based on the width of the finished product – the stones should not exceed ⅓ of this indicator.
The main characteristics of crushed stone
After understanding the purpose of crushed stone in concrete, it is important to highlight a few key features that determine the technical indicators of ready-made mixtures:
- Density. Affects the strength of the finished product. The optimal density can be called one that varies within the range of 1.4-3 g / cm3.
- Flakiness. This term refers to the plane of the stones. Based on this indicator, several types of crushed stone are distinguished: cuboid, acute-angled, lamellar. Cuboid grains have maximum strength.
- Compressive strength. This indicator is determined in the process of compression and crushing of rock.
- Fraction. The characteristic is one of the main. It is customary to understand the size of stones (grains) by it. There are 3 main categories: large, medium and small. Knowing the main characteristics and features, you can choose the optimal fraction of crushed stone for concrete M300, M100 and any other.
- Radioactivity. Indicated on the packaging. It means what natural radioactive background the building material has. Class I can be used in any construction work, including the construction of buildings. II – for the construction of highways.
- Frost resistance. With the help of this characteristic, they indicate at what temperature conditions the strength of the finished concrete is maintained. This indicator is written with a letter. Next to it, a number is indicated – this means how many freezes and thaws the concrete crushed stone can withstand. For the climate of Moscow and most other regions of Russia, it is better to choose a material with an F300 indicator.
Classification
It is common practice to classify loose filler into multiple categories while considering the rocks that were used to create it:
- granite;
- gravel;
- limestone;
- slag;
- secondary.
Granite
Crushed stone of this kind is produced by breaking up non-metallic rocks, which are typically monolithic rocks. GOST 8267-93 regulates the quality of granite used in construction. This filler material is stronger than other filler materials.
- fine-grained (fraction 0-5 mm and 5-10 mm);
- medium-grained (5-20 mm and 20-40 mm);
- coarse-grained (stones here reach 40-70 mm or 70-120 mm).
The medium fraction (5–20 mm) is most frequently utilized in construction projects. For laying roads, constructing foundations, and erecting reinforced concrete structures, this option is thought to be ideal.
Gravel
Such large-scale material is made of rocks. The technique of dispersing rocks after they are removed from a quarry is frequently used for extraction. Product quality needs to be up to GOST 8267-93 standards.
Though not as strong as granite, these stones nevertheless have a number of benefits:
- low price (relative to other types of crushed stone);
- minimal radioactivity.
- gravel for concrete – these stones are of river and sea origin;
- crushed – it can be obtained by crushing rocks.
- small – the size of the stone varies within 3-10 mm;
- medium – there are 2 options (5-20 mm and 5-40 mm);
- large – grains reach 20-40 mm.
Applications for gravel material include building sites, filling products made of reinforced concrete, and constructing pedestrian walkways.
Limestone
Crushed limestone is produced from sedimentary rocks. In this instance, the stones are carbonate rocks. The lowest possible cost is the benefit.
- 5-20 mm (the smallest fraction);
- 20-40 mm (the most popular);
- 40-70 mm.
Limestone has limited uses because of its low strength. It is appropriate for small-load path construction, glass and printing industry work, and cement mortar preparation.
Slag
When we talk about "slag crushed stone," we typically mean stones that come in various sizes and are made from slag that is used in manufacturing.
- large;
- medium;
- small;
- screenings.
Lightweight concrete can be prepared using this type of filler. Thermal insulation is the most often used application.
Secondary
Because this material is made from construction waste, such as leftover asphalt, bricks, and concrete, secondary crushed stone gets its name. These goods have to fulfill GOST 25137-82 requirements. Its affordability is its primary benefit.
One can list poor strength and resistance to frost as drawbacks. In spite of this, roads and weak soils are frequently strengthened with secondary raw materials.
For construction projects, it is essential to select the proper percentage of crushed stone for concrete mixtures, particularly for M300 grade, in order to ensure strength and durability. The workability, durability, and strength of concrete are all greatly impacted by the size and quality of the crushed stone used in its production.
The grading or size distribution must be taken into account when choosing crushed stone. Coarse and fine aggregates are usually mixed together to create concrete of M300 grade. Stones bigger than 5 mm in size are considered coarse aggregates, and they give the concrete mixture bulk and strength. In order to improve workability, fine aggregates—particles smaller than 5 mm—fill the spaces left by coarse aggregates.
The particular needs of the project and the accessibility of aggregates in the area should be taken into consideration when selecting crushed stone. Using crushed stone from reliable suppliers who uphold quality standards is advised. Dust, organic matter, and other impurities that can negatively impact the concrete mix should be removed from the stone.
Round stones are not as good as angular, rough-surfaced stones when it comes to crushed stone for concrete. The overall strength of the concrete is increased by the improved mechanical anchoring that angular stones provide within the cement paste. Furthermore, stones with a dense, hard structure work better in concrete mixtures, adding to their durability.
In the end, the percentage of crushed stone used in concrete M300 should strike a balance between guaranteeing the concrete mix’s good workability and sufficient strength. The grading, kind, and quality of the crushed stone should all be carefully taken into account in order to produce a concrete mixture that satisfies structural and construction specifications.
In the world of concrete, selecting the proper crushed stone is essential to building sturdy, long-lasting structures, particularly with grade M300 concrete. This article compares various sizes and brands to find the best performing ones as it investigates the ideal fraction of crushed stone. Anyone working in engineering or construction needs to understand how these factors affect the strength and durability of concrete. By the end, you’ll know exactly which features of crushed stone are most important to consider when aiming for premium concrete.