CS243852B1 - Production mixture for aerated concrete - Google Patents

Abstract

The solution relates to the production of aerated concrete. The aim is to achieve a compressive strength of over 5 MPa for products with a bulk density of 550 kg.m-3 and structural strength for products with very low bulk densities. This purpose is achieved according to the invention in that the casting mass contains 0.1 to 5% aminocaproic acid and/or its derivatives, the content of this additive being related to the weight of the dry matter of the casting.

Description

(54) Production mixture for casting aerated concrete mass

The solution relates to the production of aerated concrete. The aim is to achieve a compressive strength of over 5 MPa for products with a bulk density of 550 kg.m ^-3 and structural strength for products with very low bulk densities. This purpose is achieved according to the invention in that the casting mass contains 0.1 to 5% aminocaproic acid and/or its derivatives, the content of this additive being related to the weight of the dry matter of the casting.

(51, Int. CI. ⁴

C 04 B 22/08

243852 * 2

The invention relates to a production mixture for casting aerated concrete mass based on sand or fly ash with a cement-lime binder.

/The physical and mechanical properties of aerated concrete are determined by the micro- and macrostructural structure of their skeleton. Depending on the processing technology and specific consumption of binders for their production, average compressive strengths in the range of 3(0 to 4.5 MPa are achieved for the prescribed bulk density of 550 kg.m ^-3 . Reducing the bulk density of aerated concrete with the aim of achieving higher thermal resistance values of building envelopes has resulted in a decrease in compressive strength in such a way that aerated concrete with a bulk density lower than 450 kg.m ^- ^ can no longer be used for structural purposes, since the compressive strength of such components is already below the prescribed minimum limit of 2.5 MPa. At the same time, the use of aerated concrete with a low bulk density for reinforced production assumes a minimum strength of 3.0 MPa. In the case of aerated concrete lintels, which would correspond to the properties of perimeter structures with their thermal technical properties and show the required strength of 5 MPa, these properties are achieved with reinforced components with a higher bulk density of 700 to 800 kg.m ^-3 .

However, to achieve thermal insulation properties comparable to the perimeter structure, these elements need to be additionally insulated directly on site.

The above-mentioned shortcomings are eliminated in aerated concrete elements produced from the production mixture according to the invention, the essence of which is that the production mixture for casting contains 0.1 to 5% aminocaproic acid and/or its derivatives, the content of this additive being related to the weight of the dry matter of the casting.

By using this additive, the strengths prescribed for structural aerated concrete are achieved at very low bulk densities depending on the amount of additive used. In addition, this additive reduces the susceptibility of aerated concrete mass to cracking and contributes to reducing the thermal conductivity coefficient of aerated concrete products.

The above effects are achieved by the fact that the organic monomer additive in question, through its subsequent polymerization, creates its own microstructure in the skeleton of aerated concrete, which acts as a microreinforcement in the inter-pore mass. The actual use of aminocaproic acid and its derivatives for this purpose is due to the very good solubility of this substance in water, which guarantees its perfect dispersion in the casting, polymerizes in the temperature range of 50 to 70 °C, when, depending on the technology used, the formation of the aerated concrete structure is completed, and this polymerization takes place in an alkaline environment, without this environment degrading the resulting polymer and the resulting polymer is thermally stable during hydrothermal processing at temperatures of at least 200 °C, without its deterioration. No less important is the fact that the additive used is harmless to human health, even at elevated temperatures. It is also suitable for use in the production of reinforced parts, where it does not cause corrosion of the reinforcement.

The effects of the invention will be further documented on an example of its application. All the recipes given below apply to casting into a mold with a volume of 6.7 m ³ :

Product A B a) composition of the production mixture: cement 15% 40% lime 15% 10% ash 70% - sand - 50% b) outflow: production mix <kg) 2,450 1,050 overgrown sludge (1) 1,500 500 density of over-sludge <kg.l ^- Ď 1.3 1 water (1) 900 550

waste sulfate (1) 40 - density of sulfur sludge (kg.ll) 1.3 - aluminum additive (kg) 2.0 3.0 aminocaproic acid (kg) 8.0 20.0 c) physical-mechanical parameters finished product: volumetric weight (kg.m ^-2 ) 512 245 pevm .,t in pressure (MPa) 5.5 1.8

The product designated as A, with the same composition of the raw material mixture and casting, but without the additive according to the invention, had a compressive strength of only 4.1 MPa.

Product B with such a low bulk density would not be possible to produce under operating conditions without the use of the aminocaproic acid additive.

From the above, it is quite clear that the casting additive according to the invention increases the compressive strength of aerated concrete with a bulk density of 550 ^kg.m3 above 5.0 MPa, ensures structural strength in lightweight aerated concrete for both reinforced and unreinforced parts and enables the production of very lightweight aerated concrete parts with a bulk density of around 250 kg.m ^-2 .

Claims (1)

SUBJECT OF THE INVENTION Production composition for sand or fly ash based aerated cement binder, characterized in that it contains 0.1 to 5% aminocaproic acid and / or derivatives thereof, the content of the additive being based on the weight of the dry matter of the outflow.