Ballast stone or rock is the main part of railway structure and also it can be used wherever long stability and durability is meant.it has different sand types with various prices. It is also referred to as any gravel or broken stone used as bed for stability of railroad or any other roadway. The rock used to prepare the ballast must be exclusively from rock mined in mountain mines. The dimensions of the carcasses should be such that the ballast made from them is 100% broken and sharp-edged. Stones that form in broken rocks when the smooth surfaces are broken are not suitable for ballast. The rock used must have high hardness and igneous property such as basalt, diorite, quartz and granite. Limestone should not be used under any circumstances. (Granite, granodiorite, quartzlatite, diorite, etc.) Quartzite and hard traps are the most suitable stones for ballast. It should be noted that suitable natural limestone materials, only in exceptional circumstances where access to igneous quarries is not possible at reasonable intervals, after review and approval by a special expert commission will be commissioned by the employer, subject to the approval of the coat of arms. The employer will be acceptable (a representative of the High Supervision Authority must be present in the relevant commission). The stone to be used should be removed from the lower layers of the mine and the stones of the upper layers of the mine should not be used to the depth desired by the supervising engineer. Ballast storage should be done in such a way that the products whose samples have been sent to the laboratory can be separated from each other so that if the results are not acceptable, they can be decided. It is necessary that the ground of the warehouse is properly constructed, so that the soil does not mix with the loader when loading the ballast (It is better to do a concrete floor or the ballast should be removed from a little above the floor level). 
The shape of the depot should be regular and measurable to determine the volume of the ballast. The height of the ballast depot should be considered more than 2 meters. One special use of ballast stone is in railway production where long lasting stability and resistance is meant. The dimensions of the suitable grains for ballast for railways vary depending on the type of traverse used, for concrete traverse, the dimensions of the grains are between 20 and 60 mm. The seeds should be 100% broken, sharp-edged with rough surfaces, and not flaky or needle-shaped. The grain size of the sub-ballast particles must be in accordance with one of the valid regulations such as AREA.
Ballast stone specification
Ballast is a layer between the rail and the substructure which is composed of crushed stone aggregates, has a uniform granulation and usually has particle dimensions of about 3 to 3 mm. Tasks and role of the top layer: 1- Tolerating the vertical, horizontal and lateral forces on the sleepers in order to keep the line in its certain position 2- Providing part of the resilience and energy absorption of the line 3- Spreading and transferring loads to the lower layers 4- Surface water drainage 5- Adjusting and leveling the rail surface during rail laying and repairs 6- Damping and amortization of shocks, vibrations and sounds resulting from the movement of rail vehicles 7- Frost insulation for your sub-layer 8- Preventing the growth of plants in the line Suitable materials for ballast: The quality of the ballast layer depends on the type of materials used and their density. Ballast materials must have the following characteristics to perform their duties: - Resistant to abrasion, crushing and crushing. (High strength and hardness) - Resistant to weathering, have sufficient strength and uniform structure. (High durability) - In order to prevent the horizontal movement of the traverse, have enough grip, have sharp edges and even cubes if possible. In other words, they are broken stones. (Stability) - Good ballast should allow rapid infiltration of surface water. (Drainage) - It can be easily prepared and cheap. (Availability) - Its particles have a sufficient coefficient of elasticity. - The building stone has no pores, does not collect rainwater, and is free of soil and waste.
High-quality specifications
1) Specific weight and porosity of materials Ballast should be made of stone materials with suitable density and have the least impact against the presence of water. In this regard, the specific gravity of ballast materials according to 127ASTM-C should be at least equal to 2.6 t / mᶟ and the maximum amount of water absorption of materials according to ASTM-C127 is equal to 1% and in the worst case 2%. 
Also in the sheet test, the amount of scales created according to BS-812 should be less than or equal to 5%. 2) Frost resistance Since the use of the line is not interrupted in all seasons and rainy conditions, so the ballast material must have sufficient strength to maintain its quality during the change of different seasons. In this regard, the maximum weight loss of ballast rock materials per 12 glacial cycles should be less than 8%. 3) Abrasion resistance according to the Los Angeles test The percentage of high wear prepared based on the Los Angeles test should not be more than 30% per 1000 rounds. The test method is presented in ASTM-C535 for particles larger than 2.54 cm, and in ASTM-C131 for particles smaller than 2.54 cm. 4) Abrasion resistance according to microdaval test Since ballast materials are also affected by impact and vibration loads of trains in rainy conditions, on the other hand, given that in the Los Angeles experiment, granular materials fail due to impacts caused by falling steel bullets. Therefore, some good stone materials such as granite due to their constituent structure show a higher wear rate and are rejected, while in reality, they have good performance. 
But other stones whose poor quality has been proven in practice, due to the special crystal stone structure, show better performance in this experiment. Therefore, the best test to control the quality of materials against abrasion is a test that takes into account the presence of water without impacting the particles. The microdaval test, which is more common in European countries, applies the erosion agent in the presence of water to a 5 kg sample and uses the weight loss of the sample after the test (microdaval test is not common in our country.) Maximum weight loss in materials in the microdaval test in the presence of water should be less than 15 to 20%. 5) Material health testing Because the application of different periods of cold and heat or drying and wetting, as well as other chemical agents on stone materials, gradually causes them to erode, to control the health of the material, sulfate corrosion testing is usually recommended. This test is to measure the weight loss of materials against different periods of drying and wetting in a solution of sodium sulfate or magnesium sulfate. The amount of weight loss of materials for 5 consecutive cycles of drying and wetting in sodium sulfate solution should be less than 5% according to ASTM-C88 and the absolute maximum of 8%. 6) Dry and saturated compressive strength of stone materials Since the materials must have sufficient strength to withstand all the applied stresses, the amount of uniaxial resistance of the cylindrical core of the stone material is controlled. The minimum uniaxial strength of a cylindrical rock sample with a diameter of at least 5 cm and a height of 10 cm (H = 2D) in dry and saturated conditions should be more than 1200 and 800 kg / cm2, respectively. The loading of the rock core should be done at a speed of about 0.2 to 1 MPa per second and it should take at least 30 seconds for the rock to break. 
The entire use of ballast in industry as a stabilizer stone marks a turning point in stone piece use for the purpose of high durability and resistance. Specially its utilization in railway production has brought about a long-lasting guarantee of firmness and durability to railway industry and further any other areas of its usage. Honorably my company has been brilliant in supply and export of ballast stone product to all countries around the globe. In order to enjoy the best purchase of your life, press the link above to join our community in world trade.
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