RU2514069C1 - Raw mix for preparation of foam concrete - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: raw mix for preparation of foam concrete contains, wt %: portland cement 38.0 - 40.0, quartz sand 28.0 - 30.0, foaming agent 0.6 - 0.8, thermally modified peat additive, produced by heating peat up to 600°C with its further grinding, 1.9 - 2.8, water - balance.

EFFECT: production of foam concrete with higher strength and improved thermal properties.

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Description

The invention relates to the building materials industry and can be used for the preparation of non-autoclaved foam concrete used for small wall blocks of industrial premises and individual residential buildings.

The prior art compositions of the raw mix for non-autoclaved foam concrete, the advantage of which are low energy consumption for hardening products.

Known raw mix for the manufacture of lightweight concrete (copyright certificate SU No. 1588734, publ. 30.08.1990), consisting of Portland cement 12.0-20.0, slag pumice crushed stone 47.0-52.0; refractory production waste 8.0-13.0; ashes of power plants 5.0-9.0; wood saponified resin 0.035-0.45; waste metallurgical lime 1.0-3.0 and water - the rest.

Concrete obtained from this mixture has a high compressive strength of 6.3-10.4 MPa.

The disadvantage of this mixture is the high thermal conductivity λ = 0.146-0.166 kcal / m · h · ° C, since slag pumice gravel is used, which has a high density.

Known raw mix for the manufacture of foam concrete, including, wt.%: Portland cement 30.0-31.0, foaming agent PB-2000 0.3-0.35, ash TPP 10.0-12.0, expanded clay sand 20.0- 22.0, superplasticizer C-3 1.6-1.8 and water - the rest (RU 2415110 C1, С04В 38/10, publ. 01.25.2010). The compressive strength of foam concrete from the raw mix according to the specified patent is 1.5 MPa. The increase in strength is due to the use of S-3 superplasticizer. Along with an increase in strength, this admixture increases the average density of concrete, and hence the coefficient of thermal conductivity of foam concrete.

For the prototype of the inventive raw material mixture for the preparation of foam concrete, the raw material mixture according to the invention patent No. 2377225, IPC С04В 38/10, publ. 12/27/2009. The prototype feed mixture contains, wt.%: Cement 30.0-32.0, frother SDO 0.7-1 and PB-2000 0.6-0.7 (total content 1.4-1.6), aggregate in the form of silica dust 13.0-14.0 and water 36.0-37.0. The compressive strength of foam concrete from the specified raw mix is 1.3 MPa, approximately the same as that of the previous analogue. However, due to the large amount of foaming agent, it is possible to predict greater pore formation and better performance of the obtained foam concrete in terms of thermal conductivity in comparison with foam concrete from the raw mix according to patent No. 2415110.

An object of the invention is to obtain a raw material mixture for structural insulating products with higher strength and improved thermophysical properties.

The technical result consists in increasing the strength and lowering the coefficient of thermal conductivity of products from the inventive raw mix.

The task and the technical result is achieved as follows.

Like the prototype, the inventive raw material mixture for the preparation of foam concrete contains Portland cement, silica filler, foaming agent and water.

In contrast to the prototype according to the invention, the raw material mixture further comprises a thermally modified peat additive obtained by heating peat to 600 ° C followed by its grinding, and silica-containing aggregate contains quartz sand in the following ratio, wt.%:

Portland cement 38.0-40.0 quartz sand 28.0-30.0 foaming agent 0.6-0.8 thermally modified peat additive 1.9-2.8 water rest

Thermally modified peat additive, which is obtained by heating peat to 600 ° C with its subsequent grinding, and the use of quartz sand in the indicated quantities allowed to increase the strength of foam concrete in comparison with the prototype and to provide low thermal conductivity.

The data are obtained experimentally, outside the claimed composition, the specified result is not achieved. The introduction of the indicated thermally modified peat additives in larger quantities into the foam concrete mixture leads to a decrease in strength and an increase in the thermal conductivity of foam concrete.

The composition of the inventive molding mixture for foam concrete was obtained for the first time and in known sources of information not identified, which confirms its novelty.

The use of thermally modified peat additives in the production of cement is known from the prior art (patent No. 2419592). Thermally modified peat additive, being chemically active, promotes the formation of new compounds in the process of cement hydration, improves its strength properties. The use of this additive for the production of foam concrete the applicant and the authors are not known from sources of information. Studies have shown that the use of thermally modified peat additives for foam concrete of the proposed composition leads not only to an increase in strength characteristics, but also to a new property - a decrease and uniform distribution of pores in the foam concrete, which in turn ensures a decrease in thermal conductivity. It was impossible to assume in advance that in foam concrete, in addition to strength indicators, thermal conductivity will improve. The amount, wt.%, Of each component of the foam concrete mixture and their relationship were obtained during the experiments, and not based on known dependencies and patterns. The resulting combination of distinctive features of the invention clearly does not follow from the prior art. Therefore, the invention meets the criterion of "inventive step".

For the preparation of the raw material mixture for foam concrete, it is possible to use any foaming agents - both synthetic and protein (Benotech PB-S, PB-2007, PB-2010, PB-Lux, GreeFroth, Addiment, Foamcem, Laston, Zelle-1, the Yabeton series ”, Etc.) produced by domestic or foreign industry. In a specific example, Benotech PB-S, a low-toxic synthetic foaming agent, was used as a foaming agent (foam multiplicity of at least 7, foam stability of at least 250 s, density 1.02-1.12, www.ecohim.spb.ru/Prod41.htm ), corresponding to GOST 24211-2003, TU 2481-010-58771162-2007. An already prepared mixture obtained by heating peat to 600 ° C, followed by grinding, was used as a peat additive. Foam concrete was prepared in a laboratory foam concrete mixer with a volume of 10 liters, which in its characteristics was close to the commercial production plant PBS 160 M. At first, thermally modified peat, sand and cement were mixed without adding water. The resulting mixture was poured into a concrete mixer and 60-70% water was added. Stirred for 2 minutes. Then a foaming agent was added to the remaining water and the composition was mixed for another 3 minutes.

The finished foam concrete mixture was placed in metal molds of 100 × 100 × 100 mm. The molded foam concrete samples were kept under normal conditions for 28 days. The test was conducted according to GOST 25485-89.

The compositions of the developed foam concrete mixture are presented in table 1, and the properties of foam concrete obtained on its basis for the compositions indicated in table 1 are presented in table 2.

Table 1 No. of
tava Components, wt.% Portland cement Quartz sand Frother Benotech PB-S Thermally modified peat additive obtained by heating peat to 600 ° C followed by grinding Water one 38,0 30,0 0.8 1.9 29.3 2 39.0 29.0 0.7 2.0 29.3 3 40,0 28.0 0.6 2,8 28.6

table 2 No.
composition Foam concrete indicators Thermal Conductivity, W / mK The limit of compressive strength, MPa The average density, kg / m ³ one 0.12 2,8 800 2 0.09 4.0 750 3 0,099 3,7 770 Prototype - 1.3 -

As can be seen from table 2, the optimal composition is composition No. 2. From table 2 it follows that the strength of the foam obtained from foam concrete mixtures prepared according to the claimed invention is higher than that of the prototype. At the same time, a low value of the coefficient of thermal conductivity was obtained, and cellular concrete in terms of average density met the requirements of GOST 25485-89 and belong to structural heat-insulating concrete.

Claims (1)

The raw material mixture for the preparation of foam concrete containing Portland cement, a silica filler, a foaming agent and water, characterized in that it further comprises a thermally modified peat additive obtained by heating peat to 600 ° C followed by grinding, and silica sand as the silica filler in the next the ratio of components, wt.%:
Portland cement 38.0-40.0 quartz sand 28.0-30.0 foaming agent 0.6-0.8 thermally modified peat additive 1.9-2.8 water rest