CS264230B1 - Process for preparing a foamed silicate composition - Google Patents

Abstract

The solution relates to the field of construction production. It consists in dry mixing cement clinker with a specific surface area of 5,000 to 10,000 cm2. g-1 with a nitrogen-releasing blowing agent, for example azobisisobutyronitrile in a ratio of 5 to 10:1 by weight, after which it is mixed with water containing up to 1% by weight of sodium lignin sulfonate and up to 0.5% by weight of anhydrous soda.

Description

The invention relates to a process for a foamed building material composition for building elements having a generally unsymmetrical weight distribution over the thickness of the building element using thermosetting cement, solidification regulator, blowing agent and water. The method belongs to the technology of production of expanded silicate building materials

Methods for producing foamed silicates using blowing agents in a mixture of cement, filler and water are based on the principle of gas evolution due to additionally applied energy, for example by heating with steam during autoclaving during product formation. The energy invested in the production of silicate binders in the process of their production is not used. The uniform foaming of the mass structure does not make it possible to use the strength characteristics effectively. The ultimate strength of the material is only achieved in limited cross-sectional areas. This fact, in view of the limited possibilities of increasing the strength, leads to an increase in the dimensions of the elements and thus to an increase in the amount of statically unused mass with an obvious impact on the high weight of the building elements. As a result, such components are generally unsatisfactory also from a thermo-technical point of view. Lightening of building materials solves the problem of thermal insulating properties, but with a great loss of strength and structural parameters.

The above drawbacks are overcome by the process for preparing a foamed silicate building composition for building elements with a generally unsymmetrical weight over weight of building element using thermosetting cement, solidification regulator, blowing agent and water according to the invention. It is based on the fact that cement clinker with a specific surface area of 5,000 to 10,000 cm ² g ^-1 is dry mixed with a nitrogen-releasing blowing agent, for example azobisisoburyronitrile, in a ratio of 5 to 10: 1 wt. %, and then mixed with water containing up to 1 wt. % sodium lignosulfonate and up to 0.5 wt. soda water.

The basic effect of the process according to the invention is to utilize the heat of hydration in the mass transition from quasi-liquid to solid state. Allow the thermosetting types of cements in which the traditional gypsum setting regulator is replaced with other types of ingredients and a large specific surface area of clinker minerals over 5000 cm ² .g ^_1 allows achieving the desired fluidity of the suspension at a lower water-cement ratio cement mixtures. By controlling the solidification of the mixture of thermosetting cement, the solidifying additives, the blowing agent and the water by changing their relative ratio and by temporally controlling the mold surface temperature, the shape of the distribution curve can be programmatically selected along the cross-section of the building element. In this way, it is possible to achieve optimal static and thermal technical parameters of the components according to the functional requirements of the structure or its part.

After mixing of thermosetting cement with water, very fine conversion of fine clinker particles to crystalline products takes place with the release of heat. At a suitable ratio of the solidification control ingredients, conditions for decomposition of the blowing agent are achieved in a closed mold space. The blowing agent is premixed in a fluidized bed mixer with dry cement so that the two substances are evenly distributed in volume. The solidification control ingredients are dissolved in the mixing water to prepare the cement slurry. The amount and type of ingredients influences the start of solidification, the rate of hydration and the amount of reaction heat released. The solid and liquid substances are mixed in a kneader. The water content is essential for foam formation. The viscosity of the cement slurry is a function of the specific surface area of the thermosetting cement used and the amount of mixing water.

The exothermic course of hydration must be correlated in time and temperature with the blowing agent decomposition. The curing process can be controlled in addition to the selected proportions of the components in the system by gradual cooling or, if necessary, additional heating of the mold surface. This process can be the same or different on both sides of the mold, which determines the shape of the weight distribution curve along the cross-section, the shape and size of the cavities, and the thickness of the rigid cementitious surface zone. As the production cycle length increases, the thickness of the cement stone increases and the difference between the minimum and maximum weight of the foam over the cross-section decreases. Characteristic features of weight distribution across the cross-section are the mass concentrations at both surfaces of the member and the generally unsymmetrical, and hence symmetrical, course of weight over the thickness of the member. The zone of cement stone, created on both surfaces, assumes mainly the static function, the light inner core then primarily the thermo-technical function. In addition, this zone creates a compact, durable surface of the element which can be reinforced and aesthetically plotted.

The process according to the invention is described in more detail below on two exemplary embodiments.

Example 1

Cement clinker with a specific surface of 7,800 cm ² . g ¹ was dry blended with azobisisobutyronitrile in a ratio of 10: 1 parts by weight. The second reactive component was water containing 1% sodium lignin sulphonate and 0.5% anhydrous soda based on cement. The water-based cement paste coefficient was 0.30. Hydration began within 30 minutes, during which time the mixture was pressed into a closed steel mold. The decomposition temperature of the blowing agent was 85-120 ° C. This temperature was reached within 3 minutes from the start of hydration due to exothermic heat generation by hydration of cement clinker. The resulting test sample exhibited a tensile strength of 10 MPa and a compressive strength of 100 MPa on the surface. At a foam density of 100kgm- ³ , the thermal conductivity coefficient was 0.02W / m ° K and at a density of 2600kgm ^-3 l, 0W / m ° K. The modulus of elasticity at the specified density ranges from 500 to 30,000 MPa.

Example 2

WT4m | P <> above. _ .yMnekfioJspe ^^^ - ^ ______ *? M <Wg Wi ™ is controlling 8 weight controls.Look>. reaktgmí.Jožkou «is water containing 1 ´% lignisulfonan; sodium and 0.25% anhydrous soda, based on cement The onset of hydration was 7 min.

Claims (1)

- SUBJECT A process for preparing a foamed building composition for building elements with a generally unsymmetrical mass over the thickness of the building element using thermosetting cement, solidification controller, blowing agent and water, characterized in that the cement clinker of specific CS 264 230 B1 is a factor of 0.32. The mixture was injected into the mold as in Example 1. The reaction was very rapid, the decomposition temperature of the blowing agent at 103 ° C was reached within 1 minute. The measured values of the test sample were the same as in Example 1. BACKGROUND OF THE INVENTION 5,000 to 10,000 cm ² . g ^-1 dry mixed with a nitrogen-releasing blowing agent, such as azobisisoburyronitrile, in a ratio of 5 to 10 g / ml. 10.:-1 wt. The mixture is mixed with water containing up to 1% by weight of sodium lignosulfonate and up to 0.5% by weight of anhydrous soda.