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Manufacturing technology of paving slabs.

Posted by: Yuri Zarva
Source: trotuar.ru
E-mail: medbisnes@trotuar.ru

form preparation

concrete mix preparation

vibrotable molding

keeping the products during the day in the forms

dismantling products

packaging and storage

The process of manufacturing paving slabs includes several basic steps:

  1. form preparation;
  2. preparation of concrete mix;
  3. vibrotable molding;
  4. keeping the products during the day in the forms;
  5. dismantling products;
  6. packaging and storage.

PREPARATION OF FORMS

Forms for the manufacture of products can be used plastic, rubber and rubber-like (polyurethane). The number of molding cycles that the mold can withstand is: for rubber - up to 500 cycles, for plastic - 230-250, for polyurethane - 80-100 cycles.

Forms before pouring concrete into them are smeared with special compositions or concrete is poured without preliminary lubrication of the form. When working without lubrication, new forms are treated with an antistatic agent, after dismantling, the forms are inspected and, if necessary, washed with 5-10% hydrochloric acid solution.

Emulsol, OPL-1 (Russia) and SJA-3 (England) can be used for lubrication of forms. For the preservation of the surface of the form can not use lubricants containing petroleum products. The layer of lubricant applied to the surface of the molds must be thin, since pores remain on the surface of the finished product due to an excess of lubricant.

Emulsol and OPL-1 lubricants are applied with a brush before each pouring, CPA-3 lubricant is applied with a brush or spray. Lubricants CBA-3 is enough for 2-3 moldings. The temperature during application should be 18-20 ° C.

mix preparation
FIG. № 1

COOKING CONCRETE MIXTURE

For the preparation of decorative concrete is better to use a forced mixer. Basically, the procedure for preparing the mixture does not differ from the preparation of ordinary concrete (Fig. 1). The pigment is fed in about 30 seconds before the cement supply.

Optimum mixing mode:
sand + pigment - 15-20 s;
sand + pigment + crushed stone - 15-20 s;
sand + pigment + crushed stone + cement - about 20 s;
sand + pigment + crushed stone + cement + water + additives - 1-1.5 min;
total - 2-2.5 minutes

To increase the durability of concrete, its durability and impact resistance, it is also possible to add polypropylene, polyamide or glass alkali-resistant fibers with a length of 5-20 mm and a diameter of 5-50 microns in an amount of 0.7-1.0 kg per 1 m3 of concrete. The length of the fibers should correspond to the largest diameter of coarse aggregate in the concrete. Fibers with good dispersion form a three-dimensional grid in concrete, which significantly increases the bending strength, impact resistance and wear resistance of concrete.

Polypropylene and alkali-resistant glass fibers are injected with mixing water; polyamide fiber is injected into the finished concrete mix, i.e. at the last stage, the mixing time of the mixture is increased by 30-50 s.

When using silica fume supplements take the following schedule of concrete mix preparation:

sand + silica fume + pigment - 30-40 s;
sand + silica fume + pigment + cement - about 30 s;
sand + silica fume + pigment + cement + water + additives - 1-1.5 min.
vibrotable
FIG. No. 2 - Vibrotable

FORMING ON VIBROSTOL

The ready-mixed concrete has workability OK = 3-4 cm. Therefore, for its compaction, short-term vibration treatment is used. After preparation of the concrete mix, it is placed in forms and compacted on a vibrating table (Fig. 2).

In the production of colored tiles in plastic forms, one can use layer-by-layer molding to save pigment: the first face layer of concrete is prepared using pigment, the second layer of concrete without it.
For separate molding it is necessary to have two mixers for the preparation of concrete of the first and second layer.

FIG. No. 3 - Curbing in progress.

When molding, the face layer of colored concrete 2 cm thick is laid first and compacted for 40 s. After this, the 2nd concrete layer without pigment is laid and compacted by vibration for another 20 s. With a different mobility of concrete, it is necessary to select your own compaction time on the forming table.

SUPPORTING PRODUCTS

After molding, the products in the forms are installed in piles with a height of 3-8 rows, depending on the thickness and configuration of the tile. For example, square plates are placed no more than 3 rows. After that, the piles are covered with plastic wrap to prevent evaporation of moisture. The holding temperature must be at least 15 ° C. Additional heating is not required. After 24 hours of aging in the forms, you can make the form (release of products from the forms).


FIG. No. 4 - "Blockage" of paving slabs on a vibrating table.

Spreading

The dismantling of shaped articles is carried out on a special knock-out table with vibration (Fig. 4), while in order to facilitate the removal of the mold with the products, it is recommended to warm it up for 2-3 minutes in a hot water bath (temperature 45-50 ° С). It uses the effect of high thermal expansion of polymers compared to concrete.

The demolition of square slabs and facade tiles occurs without any special tools. It should be noted that stripping without preheating shortens the service life of the mold by approximately 30% and may lead to a marriage of the finished product, especially for thin products.


The process of knocking paving tiles. And its storage on pallets.


FIG. No. 5 - Tile is packaged and ready for sale.

PACKING AND STORAGE

After demolding, the tiles are laid on euro pallets "facing" to the "back", tying them with packing tape. To ensure further hardening of the concrete and preserve the presentation of the products, they must be covered with a polyethylene shrink or stretch film.

In the summer, the release of products is made when they reach 70% of the design strength, which approximately corresponds to 7 days of concrete hardening, counting from the moment of its manufacture. In winter, tempering is performed when 100% of the design strength is reached (28 days from the moment concrete is prepared).