CZ353191A3 - light-weight granulate for expanded concretes, process of its preparation and a mixing apparatus for making the same - Google Patents

Abstract

A granulate, for example vermiculite with a density of less than 1 and grain size more than 1.4 mm, it is processed by surface spraying particles with a mixture containing three additives, surface an active agent, a setting accelerator and a liquefying agent cement that are mixed with water. For his preparation it uses a mixing device that includes a center swivel a shaft (7) passing through a fixed feed hopper (1) of the particles with which the rotatable perforated plate is firmly attached (3). A fluid supply line (6) extends through the shaft (7), terminated by a spray nozzle (8).

Description

The invention relates to light artificial or natural; granulates, in particular for increased lightening of the concrete in the production of non-bearing lightweight concrete. It also relates to a process for preparing these coated granules and to a mixing device for carrying out the process.

BACKGROUND OF THE INVENTION

Light granules such as slate and expanded clay, pumice, pozzolan, perlite, vermicalite, expanded polystyrene, sawdust and cork are used in the production of lightweight concrete.

From these granulates, with a density of less than 1, a fine fraction, for example having a diameter of less than 1.4 mm, is first screened to avoid adsorption of excessively large amounts of additives, which would be detrimental to the desired material properties.

Said granules are basically characterized by a high porosity against traditional heavy aggregates. Porosity is very important, as it can cause undesirable properties in the production of lightweight concrete to be dense and mechanically strong and durable, high porosity allows lightweight aggregates to absorb the science needed in large quantities for proper cement hydration and good cement workability of concrete.

The use of a considerable amount of mixing water presents a number of other disadvantages, such as a deterioration of the mechanical properties, an increase in the setting time of the concrete, the average workability of the concrete and the risk of leaching cement.

SUMMARY OF THE INVENTION

The present invention makes it possible to obtain light granules which serve to significantly lighten non-loadbearing concrete. Their dosages per cubic meter of concrete are reduced, allowing the amount of cement used to be increased without changing the density of the hardened concrete and further improving the workability of fresh concrete for lower water coefficient values, i.e. the mixing weight of the mixing water and cement. This result is achieved by the synergistic action of a number of additives adsorbed on the surface of the granulates. The essence of the present invention is that the surface of the granulate is coated with a mixture of ingredients comprising a surfactant, a cement set accelerator and a fluidizing additive.

According to one embodiment of the present invention, the surfactant is preferably an anionic synthetic surfactant. It may consist of at least one of the following Reagents:

- sodium abietate,

- salts of ethanolamine, triethanolamine,

- fatty alcohol sulfonates,

- alkylarylsulfonates, sodium soaps of polyhydroxycarboxylic acids,

- alkaline soaps of natural fatty acids with a carbon chain from P ° θΐ8>

animal blood based surfactant protein derivatives.

This surfactant induces the release of air when mixing concrete and contributes both to lightening of the concrete and to its density by absorbing fine air bubbles acting as fine sand filling the gaps and greatly improving the workability of the concrete to the extent that it can be deposited drawing. The amount of this air can be controlled simultaneously by 3 amounts of mixing water and determined by the mixing time, particularly depending on the mixing speed.

In another embodiment of the present invention, the cement solidification accelerator is preferably 3 nitrate and / or sodium chloride. It may also consist of at least one of the following compounds:

sodium chloride,

- soda, potash, alkaline salts: carbonates, silicates, fluorosilicates, aluminates, borates, calcium nitrate, oxalic acid.

Any other cement setting accelerators capable of improving the mechanical properties in the initial phase of the process may also be used.

According to yet another embodiment of the present invention, the cementitious additive is preferably a polynaphthalene sulfonate with 40% dry matter or any other known higher molecular weight agent 3 suitable for this application, for example:

- sodium lignosulfonanera and calcium lignosulfonate,

- melamine-formaldehyde resin,

- sodium abietane and potassium abietane,

- resin soaps.

The main function of this additive is to improve the plasticity and mechanical properties of concrete while reducing the amount of mixing water.

The invention also relates to a process for the preparation of granulates, the surface of which is provided by adsorption of the 3 ingredients of the previously described specific ingredients, according to which granules are processed in the mixing device in the presence of this mixture of ingredients and water.

In the process of the present invention, 1000 or 1000 units of granulate of a mixture of three additives, a surfactant, a liquefying agent and a solidification accelerator are used in a ratio of 1000/1000/4000 by volume units.

The subject of the invention is also a mixing device or apparatus utilizing this method, which comprises a central rotating shaft extending through a fixed particle feed hopper supporting a rotatable perforated plate. A fluid supply line terminates through the shaft and terminates in a spray nozzle and opens into a spray chamber.

Overview of the drawings

The invention will be explained in more detail with reference to the drawing, in which an example of a mixing device according to the invention is shown.

DETAILED DESCRIPTION OF THE INVENTION

Further details of the invention will be elucidated in more detail in the following description and examples of its use, which are provided herein for purposes of illustration only, without limiting the scope of the invention.

The mixing device shown in the attached figure comprises in its upper part a conical dispenser or hopper 11 through which the rotary shaft extends in the axis of which the liquid supply line 6 is located. A perforated plate 11 is attached to the rotary shaft. The outer wall of the hopper 1 is provided with ribs 2.

A lower nozzle 8 is provided with a spray nozzle 8 disposed within the spray chamber 2. A funnel 8 is arranged between the perforated plate and the spray chamber 8, which narrows the diameter of the flow coming from the plate openings and converts it to the size of the spray chamber 2. the wall is provided with side blades 13 and is driven by a motor.

Example 1.

Preparation of the granulate according to the invention.

Use vermiculite with the following properties:

- bulk density ... about 60 kg / nP

- grain size ... 6 to 1.4 mm _5 ~

This plate 2 is perforated, thereby improving the already started turbulent movement of the granulate grains. The flow is then discharged through a fixed funnel 4 towards the inlet of the spray chamber 2.

The mixture of liquid additives and water is conveyed under pressure through line 2 ^and sprayed through a nozzle 8 into the center of the vortex vortex grain swirling stream. The swirling movement imparted to the particles particularly promotes their good contact with the atomized liquid.

The surface-treated vermiculite is then captured in the rotating chamber 12 and directed to the outlet opening 15 by means of a strip 16.

Three ingredients were sprayed onto 1000 liters of vermiculite in the following proportions:

anionic surfactant at 30% dry matter .....

... 1000 1 liquefaction agent (naphthalenesulfonate) at 40% dry matter .... ............................... 1000 1

- solidification accelerator / sodium nitrate / sodium chloride, 50 /

50% by weight / ................... 4000 g water ........................ .... 34000 g

Examples 2 to 4.

The vermiculite thus coated is used to prepare concrete having the following properties.

Example 2 shows a test sample wherein vermiculite has not been pre-treated by the method of the invention.

Example 2

Example 3

Example 4

Composition per m of laid concrete

Vermiculite not treated 1350 1

Vermiculite modified 10C0 1

Vermiculite modified 1000 1

-6 Cement CP 545 260 kg mixing water 370 kg

Water / cement ratio 1.423 wet concrete density 450 kg / m ^J concrete workability wet concrete mixture concrete appearance porous compressive strength after 7 days at

20 ° C and 50% relative humidity 0.4 MPa

Cement 545 Cement 545

300 kg 200 kg záměsová water mixing water 240 kg 220 kg 0,800 1.1

450 kg / m ^ 320 kg / m ^ liquid concrete compact concrete dense

MPa 0.4 MPa

As shown in the table, lightweight concrete with modified granulates is better than untreated vermiculite. At an equivalent density, the amount of mixing water is lower and the rheological characteristics of fresh concrete as well as the utility properties of hardened concrete are clearly better.

The present invention is not limited to the described and illustrated examples of a particular embodiment, but also extends to numerous other variations obtainable by one skilled in the art without departing from the basic principle of the invention.

Industrial applicability of the invention

The light granules, the process for their preparation and the mixing device for carrying out the process can be used for the production of non-lightweight lightweight concrete.

Claims (1)

7 E CLAIMS 3. 4. A lightweight granulate for lightweight concrete characterized in that it has a density of less than 1 and a grain size of greater than 1.4 mm and that its surface is provided with a coating comprising a mixture of a surfactant, cement setting accelerator and cementing additive, wherein the cement solidification accelerator additive consists of nitrate and / or sodium chloride. Lightweight granulate according to side 1, characterized in that it consists of one of the group consisting of slate and expanded clay, pumice, pozzolan, perlite and vermiculite, expanded polystyrene, wood sawdust and cork. Light granulate according to claim 1 or 2, characterized in that it is vermiculite. Light granulate according to Claims 1 to 3, characterized in that the surfactant is a surfactant anionic synthetic substance. Light granulate according to one of Claims 1 to 4, characterized in that the cementitious additive of the cement consists of a polynaphthalene sulfonate of 40% solids and a high molecular weight. Lightweight granulate according to one of Claims 1 to 5, characterized in that it is used for the production of lightweight non-load-bearing concrete intended for pumping application. 2. A process for the preparation of a light granulate according to any one of claims 1 to 6, characterized in that a mixture of said additives with water is sprayed on the granulate mixer. 7. The method of claim 7 wherein a mixture of three ingredients comprising a surfactant / liquefaction additive / solidification accelerator in a ratio of 10OC / 10OCC / 4COO is used to process 10,000 volume units of granulate. 8. 8. φ f of 7, passing through the fixed particle feed hopper (1), wherein a rotating shaft (7) which carries a rotatable perforated plate (3) passes the liquid supply line (6) terminated by a spray nozzle (8) which is discharged into the spray chamber (5). Mixing device according to Claim 9, characterized in that a funnel (4) is arranged below the rotary perforated plate (3), the inlet opening of which is situated upwards and has a diameter corresponding to the diameter of the perforated plate (3) and whose outlet below the aperture is located just above the spray chamber (5), the diameter of which corresponds to the diameter of the said rotary shaft nige