Experience of generations

experience of generations - non-explosive depleting substances (NRW)

staff VNIISTROM them. PP Budnikova in the mid 80's of the last century, developed and introduced non-explosive destructive means NRW and tested and implemented in more than 200 objects of technology of its application.

Principle NRW is to expand hardening aqueous suspension with pressure exceeds 80 MPa, which is higher than most of their foreign counterparts.

The property (concrete, reinforced concrete, granite, marble, etc.), subject to breakage (divided into blocks), drilled boreholes, which is filled with an aqueous suspension of NRW. NRW hydrated, hardening and increase in volume, which leads to the destruction of the object (divided into blocks). Failure occurs gradually, with a high level of security.

In 1989, the development of this team was awarded the Prize of the Council of Ministers in the field of construction and architecture.
1.1. Appointment
With HPB can be made directly to the destruction of the existing shops, towns, etc. and so on, with full safety for the environment, because the effect of HPB not accompanied by any fluctuations, release of solid or gaseous products.
1.2. Feature
NRW is a powder material often gray dusting, non-flammable, non-explosive, has:
alkalinity (pH-12, 5);
volumetric bulk density - 1.2: 1 , 3 t / m 3 ;
water demand - 28%;
developed pressure - up to 500 kg / cm 2 (50 MPa).
Due to the high hygroscopicity of NRW is packaged in moisture-proof packaging. Guaranteed shelf life (while maintaining sealing packing) in a dry place: at least 6 months.
1.3. The mechanism of action
When mixing the powder with water to form HPB fuel mixture (suspension), which, when filled in partially or completely closed cavity (for example, the trace) in an object, gradually, as a result of hydration powder hardens increases in the volume.
The increase is accompanied by the development of the pressure on the walls of the containing cavity (hole), the value of which in time of up to 500 kg / cm 2 (50 MPa). In the body of the containing object develop stress the importance of which can exceed its maximum tensile strength, which will lead to the destruction of the object.
Destruction effect is expressed in the body of the object formation of cracks and their development over time (see Figure 1). < br />

2.1. The process of destruction of the object consists of the following operations:

  • training facility to the destruction (removal of earth and debris obkopka, marking sites of destruction, and so on);
  • gadding as marked (the scheme);
  • Preparing the mix and filling her holes;
  • destruction facility (cracking);
  • design objects (and the subsequent exposure of the cutting valve, removal of parts of the destroyed object of fracture zone).

The most time consuming process in a set of works, mainly determined by the duration, cost and unit labor costs 1m3 destruction facility is to drill holes.
2.2. In preparation for the destruction of the object (for example, building structures) must be satisfied:

  • survey of the facility;
  • study of the conditions of works with the existing material handling equipment;
  • design flow chart (regulation) of the work;
  • staffing, training, and performance testing of equipment;
  • coaching personnel involved.

2.3. The composition process maps destruction of the object is:

  • description of the object of destruction (size, size, strength, porosity, fracturing, the nature and location of the valve), compiled from a survey of the available documentation;
  • list of necessary equipment,
  • scheme drilling holes;
  • INSTRUCTIONS Preparing the mix and sequence of its fill in the hole;
  • safety instructions.

2.4. Development schemes drilling holes based on the analysis:

  • characteristics of the object of destruction;
  • features available material handling equipment in the fracture zone,
  • tightness in the fracture zone (free surfaces at object destruction facilities not subject to liquidation, communication networks, etc.).
2.5. The main characteristics of the destroyed object, considered in the development schemes hole drilling are:
tensile strength of the material object (profile), and the parameters of its reinforcement (for concrete).
2.6. The basic principle in the design of the scheme drilling holes, ensuring the most efficient work, is the desire to meet, perhaps, less drilling in relation to a particular item.
Volume of drilling will be the smaller, the smaller the size of parts (units) formed in object is destroyed. The last is due, mainly, the characteristics of existing material handling equipment (see Figure 2).

2.7. Effective application of NRW in the facility requires a minimum of two vertical free surfaces arranged relative to each other at an angle (see Fig. 3). In the absence of the second free vertical surface it is necessary to form, using traditional methods.

3.1. Drilling holes in the objects to be destroyed, is carried out mainly through drills, machines can be used with the diamond ring drills.
3.2. With a large volume of drilling is recommended installing drilling string.
4.1. Recommended mainly to drill boreholes 32:42 mm diameter.
With holes 40 mm in diameter increases the probability of spontaneous emission of working fluid from the hole, especially if the object temperature exceeds + 25 0 C. The larger the diameter of the hole, the greater the damage, but consumes more NRW.
4.2. If the object is characterized by high porosity and, consequently, the water absorption, it is necessary to bore-holes (before filling them working mixture) to saturate with water.
4.3. Hole depth depends on the height of the destroyed object, its ability to splitting, but in all cases lower than its height at 5:10 see
From hole depth and inclination of the object depends on the direction of the cleavage cracks (see Fig. 5).

4.4. The direction is determined by the location of the destruction of holes in the object.
Usually cracks connect adjacent boreholes or go to the nearest hole on the free surface of the object (see Fig. 4).

4.5. With the destruction of the object, the height of which does not exceed 30-40 cm, it is recommended to drill boreholes inclined boreholes or use smaller diameter (see Fig. 6).

This is explained by the fact that the pressure created by the working mixture in the upper part of the hole (equal to h = 3d) less than in the lower part. The influence of low pressure in the upper part of the hole on the effect of the destruction of the smaller, the greater the depth of holes used.
4.6. Consumption NRW to destroy a particular object is determined based on the fact that the filling 1 cm 3 of the hole requires 1.8 g powder NRW.
4.7. For the detection of the valve (if you know the layout of reinforcement in the facility) hole drilling carried out in the immediate vicinity of the valve (see Fig. 7).

4.8. Location nearest to the free surface of the hole from the free surface should be two times less than the distance between the "internal" bore-holes (see Fig. 5).
5.1. Bore-holes, designed to fill the working mixture, must be clean, free of dust, debris, materials, water, etc.
5.2. Boreholes are filled with the working mixture to the mouth. No need to clog anything boreholes filled with the working mixture.
5.3. If the filling of the hole there is a bundle working fluid (water separation), we recommend 1-2 minutes after pouring the mixture to produce a working refilling working mixture in the already filled to drive out the detachable water.
5.4. After pouring the mixture of working to protect the mouth of the holes from the action of water (eg, rain).
5.5. Application NRW effectively if the temperature of the object being destroyed at least +2 +3 0 C and not more than +35 0 C.
The higher the temperature of the object, the cooler should be mixing water.
6.1. While cracking (from the moment of filling holes working mixture) in the destroyed object depends primarily on:

  • strength of the material object;
  • target temperature;
  • diameter holes;
  • distance between blast holes;
  • water content of the working fluid;
  • the temperature of the mixture.

6.1.1. The higher tensile strength of the material object, the greater the time to cracking.
6.1.2. Raising the temperature of the object (in specified in section 4 limits) helps speed up the process of cracking.
6.1.3. Reducing the distance between blast holes accelerates the formation of cracks, but causes increased consumption of NRW.
6.1.4. Increase the water content in the working mixture to slow the process of cracking.

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