Mineral powder is used as one of the components of organomineral mixtures, including asph alt concrete.
Characteristic of the substance
Under the mineral powder is understood the material that is obtained after grinding rocks or powdered industrial residues. SNIP and GOST are used as a normative document. The mineral powder complies with the requirements of the state standard of the Russian Federation No. 52129-2003 "Mineral powder for asph alt concrete and organo-mineral mixtures."
It is made by grinding the following hard rocks: dolomitic limestone, dolomite, limestone. Non-carbonate raw materials and industrial wastes are also used as raw materials, in particular fly ash from various industries.
Two types of powder are used: activated and non-activated. For the first type of material, special activating agents are used. They are a mixture of surfactants with bitumen. Depending on the properties and raw materials used, the material is divided into two grades:
- MP-1. These are powders from carbonate rocks and bituminous rocks.
- MP-2. It is a mass of powdered residues from industrial plants and non-carbonaterocks.
Powder Activation
Asph alt mix will have better performance if the powders included in its composition are activated. To do this is quite simple. For these purposes, the so-called activation of powders is carried out with a mixture of surfactants and bitumen.
The essence of the process is as follows. At the stage of crushing, the raw material is processed by an activator. A strong bond is formed between the crushed material particles and the activator. Thus, the surface of the powders becomes hydrophobic, and the individual particles interact better with the bitumen. Of the entire composition of the asph alt concrete mixture, it is the mineral powder that is chosen for activation, since it has a large specific surface area (around 4 thousand cm2/g). This is the most homogeneous component of the mixture.
Asph alt mix, which includes activated mineral powder, has several advantages:
- Increased material density.
- Stronger consistency.
- Resistant to moisture and frost.
- Improved crack resistance.
- Reduce bitumen consumption by 15%.
- The mix is laid at a lower temperature.
Delivery method
Production of mineral powder occurs in several stages. It all starts with the preparation of the necessary raw materials. The starting material is dried in special drying drums. If limestone rubblehas high strength, it is pre-crushed on roller or hammer mills. In some cases, this step is skipped.
At the same time, the preparation of activating substances takes place. Bitumen and surfactants are heated to operating temperature. The mixture is being prepared for activation. The dried raw materials and the activating mixture are taken in the required quantities and mixed in paddle mixers. But other types of devices can also be used. When the mixture is well mixed, it is sent to the grinding plant for grinding to the required fineness. After that, the already prepared mineral powder is sent to the storage bin or storage warehouse.
Storage and transportation
Mineral powder is stored in silos or silos. In these cases, it is necessary to periodically carry out special measures that prevent the material from caking. It can be aeration, pumping and other processing methods. When packing in small containers (bags), the material is stored in warehouses. During production, the powder is transported along completely enclosed conveyors, conveyors, screws. Pneumatic transport is used for transportation around the territory of the enterprise.
It is necessary to transport the powder outside the enterprise in cement trucks, closed wagons (bunkers), containers. Small packing bags should be multi-layered paper or polyethylene. In this case, the mineral powder is transported in simple closed freight cars.
