When performing many types of repair or construction work, the use of crushed stone is required. In order to be able to apply it for certain purposes, crushed stone is produced in different fractions. The small material is used for decorative purposes, a large fraction is needed in the construction of important heavy objects.
The average fractional size is 20-40. Granite crushed stone of this size is the most demanded. For its production, quartz diorite or granite is used.
Material Composition
Granite is considered the hardest rock found on our planet. Due to its special strength, materials made from granite, including crushed stone, are used where heavy objects will be exposed during construction. And since granite is widespread in almost all countries, the cost of materials from it remains affordable and popular.
The color of the materials depends on what minerals granite contains, but usually it has a color from red to gray. If a small amount of dark minerals gets in, the material may have a mottled appearance.
Material benefits
Fraction 20-40 - crushed stone granite, which is considered the best filler for the construction industry. Thanks to its use, it is possible to fill out the necessary forms without difficulty, saving at the same time, and very significantly, expensive concrete mixes. Since granite grains have a rough chipped shape, excellent adhesion of the components occurs, which provides an excellent rate of adhesion of the material.
When compared with fractions of other sizes, it is medium grains that are produced at the lowest labor costs, which guarantees the most affordable cost of the material.
The properties
Performance indicators depend on the following properties:
- Fraction 20-40 - crushed stone granite, which has the highest wear resistance and compression.
- The material is able to withstand an infinite number of freezing / thawing and not collapse.
- The presence of low flakiness. In the total mass there are few grains that have needle and flat shapes, therefore, gravel is easily compacted in bulk structures and mortars.
- The density of crushed granite 20-40 depends on the rock from which it was made. For example, a cube of material from granite weighs about 1370-1400 kg, from limestone - 1280, gabbro-diabase - 1440 kg.
- Low porosity. The almost complete absence of pores contributes to high throughput and a low coefficient of moisture absorption.
- Low radioactivity. This quality is very important because it allows you to use the material in the construction of residential, household, public and industrial buildings. This number also includes kindergartens, schools, hospitals.
Compliance with GOST
On crushed stone granite 20-40 GOST number 8267-93 determines the following indicators:
- 5-23% flakiness;
- the composition should not be more than 0.5% of 5 mm grain and more than 10% of fractions whose size is less than 20 mm.
- clay dust should not exceed 0.3%;
- 1000-1400 brand strength;
- weight of 1 m3 of granite crushed stone 20-40 - 1.35 tons;
- the presence of lumps of clay - a maximum of 0.25%;
- the presence of particles of weak rocks - not more than 5%;
- bulk density of about 2.7 g / cm 3 ;
- wear resistance - indicator I1.
- the percentage of water absorption is a maximum of 0.4%.
In addition, the material must have the following properties:
- The indicator of frost resistance is F300.
- The level of radioactivity should not exceed 370 bq / kg.
During the determination of product quality, an assessment takes place according to these and other characteristics of crushed stone.
Scope of application
Granite crushed stone has such chemical and physical properties that provide the material with excellent performance characteristics. The scope of its application is determined by the size of the grain.
Fraction 20-40 - crushed granite, which is used:
- In concrete solutions.
- In the construction of reinforced concrete structures.
- During the laying of foundations.
- As a bulk material for the base under an asphalt surface.
- To strengthen or level the roads.
- When arranging parking for cars.
- For the manufacture of temporary sites where construction equipment will be located.
- In the construction of tracks for tram transport.
- For hardening the surface under the railway track.
Purchase Features
This is not about the acquisition process itself, but about the choice of material. The most important thing is that the material meets all the declared characteristics, and this is possible only when it meets the requirements of GOST. But are the characteristics described in this state document really important? What will happen if the gravel does not meet the requirements of GOST listed above?
As practice confirms, any changes will entail a decline in quality. For example, if there are more flat grains in the total mass than prescribed, the concrete obtained with their use will be of lower quality, and the quantity of concrete mix will need to be increased, which leads to an increase in cash costs.
If crushed granite 20-40 weight has less (or more) than it is necessary, it means that it contains grains of other fractions. So, the greater the weight, the greater the number of small grains in the total mass and vice versa: large particles take up more space, so such crushed stone will weigh less.
Therefore, in order not to purchase material that will not have the necessary characteristics, when buying, you must make sure that you have a certificate, a sanitary-epidemiological certificate, hygienic characteristics of the product and its passport.