Active mineral powder for asphalt concrete. Mineral powder (limestone) non-activated

mineral powder. For asphalt concrete mixtures, mineral powder is obtained by grinding limestone, dolomite (with a strength of at least 20 MPa), bituminous limestone and other carbonate rocks. The fineness of grinding powders should be such that during wet sieving, 100% of the powder passes through a sieve with holes of 1.25 mm, 0.315 mm - at least 90% and 0.071 mm - at least 70% of the powder. At the same time, their voidness when compacted in a special form with a load of 40 MPa should be no more than 35%.

Physical and chemical interaction of bitumen with mineral powder is approximately determined by the coefficient of hydrophilicity of powder particles with particles smaller than 1.25 mm. The coefficient of hydrophilicity is the ratio of swelling of a mineral powder in water (polar medium) to swelling in dehydrated kerosene (non-polar medium). More hydrophilic powders have a greater affinity for water and are characterized by a hydrophilicity coefficient of more than 1, and less hydrophilic - less than 1. For asphalt concrete. do not recommend powders with a hydrophilicity coefficient of more than 1.

A characteristic of mineral powders, reflecting their interaction with water, is the degree of swelling in water of a mixture of powder with bitumen. According to the technical requirements for mineral powder for asphalt concrete, the swelling of a mixture of powder with bitumen with a residual porosity of samples of 5 ... 6% should not exceed 2.5%.

Carbonate rocks used for the production of mineral powders should not contain more than 5% clay impurities.

In some cases, local materials are used as mineral powders - powdered industrial waste (fly dust from cement plants, ash, defecation waste from sugar factories, waste from asbestos-cement production). The quality of these powders is different, therefore, in each case, the properties of powders and prepared mixtures are checked. It is also important to establish the consumption of bitumen, the technological properties of the mixture on the accepted powder and the effect of the powder on the durability of asphalt concrete.

Due to the fact that mineral powders have a fine-grained composition, they have increased hygroscopicity and clumping during long-term storage in warehouses. Possessing a high surface energy, they react intensively with bitumen, quickly change its viscosity, which somewhat complicates the processes of mixing and especially the compaction of mixtures. The properties of mineral powders are significantly improved after preliminary hydrophobization, i.e., treatment with small doses of low-viscosity bitumen or other hydrophobizing substances (peat or wood tar, ferrolignosulfonate, etc.). Hydrophobized powders do not crumple during storage, do not spray during transportation, significantly improve mixing and compaction of mixtures; bitumen consumption at cooking asphalt mixes is decreasing.

A progressive way to improve the quality of mineral powder is the activation of the surface of grains with bitumen with surface-active additives during the grinding process, which combines physical and chemical processing with mechanical influences, developed by L.B.

Mineral powder is used as one of the components of organo-mineral mixtures, including asphalt concrete.

Substance characteristic

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 asphalt 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, in 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-carbonate rocks.

Powder activation

It 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 with a mixture of surfactants and bitumen is carried out.

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, it is the mineral powder that is chosen for activation, since it has a large specific surface (in the region of 4 thousand cm 2 /g). This is the most homogeneous component of the mixture.

The composition of which includes activated mineral powder, has several advantages:

• Increased density of the material.
• Stronger consistency.
• Resistant to moisture and frost.
• Improved crack resistance.
• Bitumen consumption is reduced by 15%.
• The laying of the mixture is carried out at a lower temperature.

How to obtain

The 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 it has high strength, it undergoes preliminary crushing 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 right quantities and mixed in. But other types of apparatus can 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 a storage bin or storage warehouse.

Storage and transportation

Mineral powder is stored in bunkers or silo-type storages. 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 on 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 wagons.

Powder mineral finely divided mineral material, consisting largely (at least 75%) of particles smaller than 0.071 mm, introduced into the composition of the asphalt concrete mixture in order to increase the heat and water resistance of bitumen, increase the density of the mineral skeleton and increase the mechanical strength and temperature stability of asphalt concrete.

Construction dictionary.

See what "Mineral Powder" is in other dictionaries:

mineral powder- mineral powder: Material obtained by grinding rocks or industrial solid waste. Source: GOST R 52129 2003: Mineral powder for asphalt concrete and organo-mineral mixtures. Specifications…

Mineral powder- - material obtained by grinding rocks or solid industrial waste. [GOST R 52129 2003] Mineral powder - a finely divided mineral material, consisting largely (at least 75%) of particles ... ...

activated mineral powder- activated mineral powder: Material obtained by grinding rocks or industrial solid waste with the addition of activating agents, by grinding bituminous rocks, including oil shale. Source: GOST R 52129 ... Dictionary-reference book of terms of normative and technical documentation

Activated mineral powder- - material obtained by grinding rocks or industrial solid waste with the addition of activating agents, by grinding bituminous rocks, including oil shale. [GOST R 52129 2003] Mineral powder ... ... Encyclopedia of terms, definitions and explanations of building materials

Material obtained by crushing limestone and dolomite and processed during their grinding. In order to hydrophobize the surface of its particles, an activating mixture is introduced (in an amount of 1.5 to 2.5% by weight of the mineral powder), consisting of a small ... ... Construction dictionary

GOST R 52129-2003: Mineral powder for asphalt concrete and organo-mineral mixtures. Specifications- Terminology GOST R 52129 2003: Mineral powder for asphalt concrete and organo-mineral mixtures. Specifications original document: activating agents: A mixture of surface active agents (surfactants) or products containing surfactants with bitumen ... Dictionary-reference book of terms of normative and technical documentation

mineral powder- 2.7. Mineral powder for SMA must meet the requirements of GOST 16557 78. It is allowed to use it as a mineral powder with an appropriate feasibility study for grain from rock crushing screenings smaller than 0.16 mm and ... ... Dictionary-reference book of terms of normative and technical documentation

mineral powder.- 0.10.2.5. mineral powder. Mineral powder for the preparation of hot asphalt mixes must meet the requirements of GOST 16557 78 and the requirements of clause 3.5.2. GOST 9128 84 when used as mineral powders crushed ... ... Dictionary-reference book of terms of normative and technical documentation

Paintings of pigment minerals on the yolk, a palette for icon painting (except for ocher). Selection and image: Viktor Slyotov, from http://mindraw.web.ru Main article: Pigments (technology) Natural mineral pigments, which have a special combination ... ... Wikipedia

Same as kartgeyser powder. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910 ... Dictionary of foreign words of the Russian language

The mineral powder offered by our company is the most important component of asphalt mixes. It is he who gives asphalt concrete the desired degree of plasticity, making it both durable and wear-resistant.

Mineral powder promotes the adsorption of most of the bitumen and increases the ability of asphalt concrete to withstand various plastic and elastic deformations. This leads to a significant improvement in the quality of the roadway, making it more durable and economical in operation.

Types of mineral powder

Mineral powder, in fact, is the dust of dolomites and limestones, which is obtained in the process of crushing these rocks. Mineral powder is used, as a rule, in the production of artificial asphalt, in which it is a filler that improves the adhesive and binding characteristics of bitumen.

At the moment, mineral powder is represented by several varieties that differ in their characteristics and composition. Based on this, it is possible to isolate the non-activated mineral powder and the activated one. Activated mineral powder differs from non-activated one in that special surfactants are added to its composition during production, which improve its properties and the final characteristics of asphalt concrete.

Mineral powder grades

In addition, the mineral powder is divided into grades, of which the most popular and widespread are MP-1 and mineral powder grade MP-2.

Mineral powder brand MP-1 can be activated and non-activated. It is actively used in the production of asphalt concrete mixtures and is obtained from carbonaceous rocks. Due to the fact that this brand of mineral powder has good swelling, bitumen capacity and porosity, it has a wide range of applications. Mark MP-1, in addition to the production of asphalt concrete, is used for the manufacture of dry mixes, in the chemical, metallurgical industries, in cardboard and roofing felt production. Also, the mineral powder of this brand can be used in the manufacture of heaters.

Mineral powder grade MP-2 is made from non-carbonate rocks, as well as secondary waste from industrial production, such as grinding of metallurgical slag, cement fly dust, fly ash from thermal power plants, etc. The composition of powder grade MP-2 is a mixture of magnesite and talc minerals. Thanks to this combination of mineral powder MP-2 has found wide application where increased plasticity, fire resistance, hydrophobicity and chemical inertness are required.

In addition to classification by grades, mineral powder also differs in hydrophobicity, grain composition, humidity, porosity, specific effective activity, swelling and other characteristics.

The choice of mineral powder is made taking into account the type and grade of asphalt concrete in which it will be used as an aggregate. The parameters of the substances that make up the asphalt concrete of a certain grade are regulated by the technological requirements of manufacturers. Based on these requirements, an order is made for a mineral powder of a certain brand.

Our company offers mineral powder of all popular brands. Our products meet all the requirements of GOSTs and can be used both for the production of asphalt concrete, and for the manufacture of dry mixes, animal feed, for soil deoxidation and for other purposes.

2.15. For the preparation of asphalt concrete mixtures, activated and non-activated mineral powders are used ( GOST 16557-78), obtained by grinding carbonate rocks - limestone, dolomite, dolomitic limestone, shell limestone, etc.

In addition, powder industrial waste is used as mineral powders: fly ash from cement plants, fly ash and ash and slag mixtures from thermal power plants, waste from asbestos slate production, ferro dust, tailings, etc.

Powder industrial waste should not contain contaminants (construction debris, soil, etc.). The properties of crushed basic metallurgical slags, fly ash and ash and slag mixtures, as well as fly dust from cement plants must meet the requirements GOST 9128-84, indicators of the properties of other powder waste - the requirements of technical specifications approved in the prescribed manner.

It should be taken into account that many powder industrial wastes are characterized by an excessively high degree of grinding (specific surface area up to 6-8 thousand cm3 per 1 g), which causes an increased porosity of such powders and an increase in the bitumen content in asphalt concrete mixtures.

Table 5

2.16. Test mineral powders and powder waste GOST 12784-78.

The choice of mineral powders and their substitutes, depending on the type and brand of mixtures, is carried out in accordance with GOST 9128-84 And table 5.

Physical and chemical activation of mineral materials

2.17. One of the ways to improve the properties of mineral materials that are part of asphalt concrete mixtures is their physical and chemical activation.

The essence of activation lies in the fact that the process of grinding, crushing or peeling grains of mineral material is accompanied by treatment with a mixture of surfactants with bitumen or another activator. Strong bonds arise between the surfactant (or activator) and the freshly formed mineral surface. As a result, the mineral hydrophilic surface turns into a hydrophobic one and the conditions for its interaction with bitumen improve. The greatest effect is achieved with the physical and chemical activation of mineral powders, since this component of the asphalt concrete mixture has the most developed specific surface (about 4000 cm 2 /g) and is more homogeneous in chemical and mineralogical compositions.

Due to such a change in the properties of the surface of the grains, activated mineral powders are better wetted by bitumen and not wetted by water, do not aggregate during storage and transportation, have a reduced porosity and bitumen capacity.

2.18. The high quality of activated, mineral powders makes it possible to prepare asphalt concrete with increased density, strength, water and frost resistance, and in some cases with increased shear and crack resistance.

Cold asphalt mixes based on activated mineral powder do not cake during storage; coatings from such mixtures are formed faster under the movement of cars.

The consumption of bitumen for the preparation of such mixtures is 10-20% less than mixtures on non-activated powder.

The use of activated mineral powders makes it possible to obtain asphalt concrete with the largest number of closed pores, which leads to lower water saturation at a given residual porosity and water permeability of the coating.

Preparation, laying and compaction of asphalt mixtures on activated mineral powder is carried out at a temperature reduced (compared to SNiP) by 20°C.

The raw material for the preparation of activated mineral powders can be screenings obtained after the primary or subsequent stages of crushing carbonate rocks in the production of crushed stone, or crushed stone that meets the requirements GOST 16557-78.

The activating mixture must consist of bitumen and anionic surfactant in the ratio indicated in GOST 16557-78. The total amount of the activating mixture should be 1.5-2.5% by weight of the mineral material.

2.19. The production of activated powder includes the following processes:

drying of mineral material (raw materials) in drying drums;

heating to operating temperatures of bitumen and surfactants;

preparation of an activating mixture;

dosing of dried mineral material and activating mixture;

mixing of the mineral material with the activating mixture in mixers of any type (preferably bladed ones);

feeding the mineral material combined with the activating mixture into the grinding plant;

grinding of mineral material to the required fineness of grinding;

supply of finished activated mineral powder to storage bins or to a warehouse (silo or bunker type).

The technological scheme of the installation for the preparation of activated mineral powder is shown on fig.1.

Plants for the production of activated mineral powder may also include hammer or roller crushers for pre-crushing crushed limestone before drying. The need for them arises if the crushed material has high strength.

2.20. To obtain activated crushed gravel, the crushing process is combined with treatment with an activating mixture. As a result of selective crushing (weak grains are crushed to a greater extent) and processing of freshly formed mineral surfaces with an activating mixture, a qualitatively new material is obtained, in which the grain composition, grain shape and surface properties are changed. The asphalt concrete plant must be additionally equipped with special units for the preparation of an activating mixture and a hammer crusher, which is included in the general technological scheme for the preparation of an asphalt concrete mixture between the dryer drum and the hot elevator.

For physical and chemical activation of gravel crushing products, a mixture of bitumen with cationic surfactants is used in a ratio of 1:5 - 1:10; the total amount of the activating mixture is 1.5-2.5% of the weight of the gravel.

Rice. 1. Technological scheme of the installation for the preparation of activated mineral powder:

1 - conveyor for feeding screenings or crushed stone into the storage bin; 2 - storage bin; 3 - conveyor for feeding the drying drum; 4 - container for volumetric dosing; 5 - drying and mixing unit; 6 - dosing tank for the activating mixture; 7 - conveyor for supplying material to the storage hopper; 8 - storage bin; 9 - feeder; 10 - ball mill; 11 - elevator for finished mineral powder; 12 - distributing hopper; 13 - auger for loading vehicles.

Asphalt concrete prepared using activated crushed gravel has higher heat, water and frost resistance.

2.21. Activation of natural sand is achieved by processing it with fluffy lime (activator) in the process of mechanical action in vibro-ball mills. Due to the change in the shape of the grains and the activation of newly formed surfaces, the interaction of activated sands with bitumen improves, and asphalt concrete based on them is characterized by higher shear and corrosion resistance.

The sand activation plant is assembled from mass-produced units and machines and is included in the general technological line for the preparation of asphalt concrete mixtures.