Black crushed stone: manufacturing technology

Black crushed stone is not always a natural raw material, extracted from rocks of the appropriate color by crushing and subsequent processing. Sometimes it is a loose material, which is covered with a special bitumen or tar composition. This treatment is necessary to obtain a product with higher wear resistance and adhesion (adhesion quality with other building compounds).

Kinds and fields of application

According to GOST, black rubble is classified according to the size of the fraction:

1. From 5 to 20 mm - gravel screening (crumb), which is the most fine-grained composition.
2. From 20 to 40 mm - medium-grained rubble. Most often used in construction.
3. From 40 to 70 mm - a coarse-grained material, with the laying of which is usually performed rasklintovka (redistribution of stone to remove voids).

The specific gravity of the black crushed stone is 2.9 t / m ³ , therefore it is transported only by heavy trucks.

Most often this material is used when laying pavements, urban avenues and sites. Also from it road asphalt concrete canvases are made. When building houses with basements or basement rooms, raw materials are used for waterproofing.

Sometimes this unusual material is used in the decorative decoration of suburban areas.

Bulk density of black rubble is 2900 kg.

Advantages and disadvantages

Among the advantages of this material is:

1. Reduced cracking. That is why the standard asphalt concrete is increasingly replaced with black rubble.
2. Increased shear resistance of coatings manufactured using this material.
3. Good resistance to slipping.
4. Long shelf life.
5. Easy compaction.
6. Possibility of laying the material in the cold state.

Of the shortcomings of black rubble, there are usually:

1. High water permeability of raw materials.
2. Too long term for pavement formation (up to 1 month). If the material is laid in late autumn at negative temperatures, the base will gain the required strength only after a year.

Also, when laying a new road surface, it will not be possible to exert strong pressure on it for up to 5 days.

The scope of this building material largely depends on the method of its production.

Technology of production by cold method

Such black rubble is used only for the repair of road surfaces. Cold production technology is performed in two ways: directly at the facility or in a special installation with subsequent transportation to the work site.

Such raw materials are being prepared using tar, bitumen and their emulsions at temperatures from +100 ⁰ C to +200 ⁰ C. The obtained material is laid in a cold form. At the same time, a necessary condition is the air temperature, which must be at least +5 ^° C.

Cold crushed stone has a low viscosity, so it can be stored in cold rooms for a long time.

Warm technology

In this case, the material is subjected to a temperature treatment from +80 ⁰ С to +120 ⁰ С. A warm crushed stone is used for laying new road surfaces with reduced mechanical load. Use the material at temperatures from +60 ⁰ C to + 100 ⁰ С.

Hot-process technology

Hot black crushed stone is made at a temperature mode from 120 ⁰ C to 180 ⁰ C. Tar and bitumen are also used for processing the material. Use it only when its temperature is within + 100-120 ⁰ C.

To lay warm and hot rubble it is necessary right after its manufacturing. That is why when installing road pavements, there is always a specialized asphalt laying technique.

In production conditions, expensive equipment is used to make black rubble.

It should also be taken into account that the raw material, produced under the influence of high temperatures, has very low resistance to fungus and mold formation. In order to eliminate this drawback, boric acid, diethanolamine and fatty acid suspensions are added to the crushed stone.

How to prepare yourself?

To make black rubble yourself, you need to mix the following components:

1. Crushed stone (most suitable for limestone) brand not lower than M600. It is better to use medium material (20-40 mm), since it has good absorbent properties.
2. An astringent component. As it is recommended to use bitumen BND 200/300. The amount of binder should be about 4-5% of the total mass of the gravel.
3. An aqueous solution of NaOH (this substance will be used as a bitumen emulsion).
4. Synthetic fatty acid in a volume of 3% of the total mass of bitumen.
5. Electric concrete mixer with a pear-shaped drum.
6. Device for extracting hot material.

The mixer needs to be equipped with a heating element, which will allow obtaining the temperature necessary for the processing of crushed stone.

The mixing time of all components in a concrete mixer directly depends on the volume of the raw material and on the size of the mixer.

With the help of black rubble, it is possible to pave all the tracks on the countryside, make the top layer of the blind area around the house or organize a reliable and durable parking place for your car. Nevertheless, it should be borne in mind that in private construction it is possible to use other materials that are much easier and cheaper to produce by oneself without the use of heating elements. In addition, the laying of black rubble is very difficult to produce alone.