RU2148051C1 - Method of cellular concrete producing - Google Patents

Abstract

FIELD: building industry and materials. SUBSTANCE: invention relates to making building articles and monolith building. Method of mixture preparing involves additional addition of modified silica. At first, water and 40-60% of surface-active substance are fed into mixer followed by addition of siliceous component and cement. Then modified microsilica and remained part of surface-active substance are added and mixed to complete porosity for 2-10 min. Mixture has the following ratio of components, wt.%: cement, 35-42; siliceous component, 32-38; modified microsilica, 5-10; surface-active substance, 0.3-0.5; water, the balance. Concrete specific gravity is 810-860 kg/m³, strength is 40-53 kg/cm³. Method provides making high-strength nonautoclave hardening cellular concrete and protective-decorative layer of facing heating tiles. EFFECT: improved method of producing, high quality of concrete. 2 tbl

Description

 The invention relates to building materials, and in particular to methods for the preparation of cellular concrete for the production of building products and for monolithic construction.

 A known method of producing cellular concrete by mixing a surface-active substance (surfactant), water, a binder and aggregate, followed by foaming during transportation of the mixture with compressed air at a constant pressure of 0.5-3.0 MPa for 0.5-2.5 min The mixture is prepared in two separate mixers. (1).

 The disadvantage of this method is the complex technology of preparing the solution and the expensive operation of foaming under pressure.

 A known method of preparing a concrete mixture containing a surfactant and silica fume (MK), providing an increase in the physicomechanical properties of concrete, by sequentially mixing the cement first with aggregate for 1 min, then 3/4 mixing water, C-3 and MK are introduced into the mixer in the form pulps, mix for 5 minutes, and add an air-entraining additive with the rest of the water and mix for another 5 minutes. (2).

 The disadvantage of this method of preparing the mixture is the impossibility of obtaining high-strength cellular concrete due to the fact that during the mixing process, the cellular structure is destroyed and significant precipitation of the freshly formed product is observed.

 The closest is a method of producing aerated concrete, comprising preparing the mixture by sequentially supplying a surfactant, water, a siliceous component and cement to the mixer, mixing and porizing in a mixer made with a two-shaft with central and peripheral vertical shafts. (3).

 The disadvantages of this method is the limited scope, namely the impossibility of obtaining high-strength cellular concrete from a mixture with low water content.

 The technical problem is to obtain high-strength cellular concrete.

The problem is solved in such a way that in the method of producing aerated concrete, comprising preparing a mixture by sequentially supplying a surfactant, water, a siliceous component and cement to the mixer, mixing and porous in the mixer for 2-10 minutes, according to the invention, modified silica fume is additionally introduced into the mixture, first, water and 40-60% surfactant are fed into the mixer, then a siliceous component and cement, after which modified silica fume and the remainder of the surfactant are introduced and mixed until completely ization, in the following ratio of components of the mixture, wt.%:
Cement - 35-42
Siliceous component - 32-38
Modified silica fume - 5-10
Surfactant - 0.3-0.5
Water - Else
The proposed method differs from the known one by the additional introduction of modified silica fume into the mixture, the ratio of components and the mode of introduction of components into the mixer, which provides pores in concrete with a size of 0.1-0.5 mm. In this case, the separate introduction of a surfactant, first with mixing water, and then the remainder in the finished mixture, makes it possible to avoid the influence of mechanical factors on the mixture during mixing of the components of the concrete mixture and to prevent the mixture from settling.

 Mixing 40-60% surfactant with water for 0.5-1 min ensures uniform distribution of surfactant in water. Mixing the resulting solution with a siliceous component and cement contributes to additional air entrainment. The introduction of the remaining surfactant and silica fume in the finished mixture and subsequent mixing provides additional porosity to a given density. Violation of the mode of preparation of aerated concrete mixture leads to destruction of the structure and sediment of the mixture.

 The method is as follows.

 To prepare the cellular concrete mixture, Portland cement M 500 is used, silica component is quartz sand with a particle size of 1-1.5, surfactants are sulfonate powder TU-6-00-576-3650-86 or sodium lauryl sulfate TU-6-01-7- 89, modified silica fume TU-5743-049-02495332-96.

 Prepare a mixture with a water-solid ratio of 0.18-0.23. First, water and 40-60% surfactant are fed into the mixer and mixed for 0.5-1 min, then the silica component and cement are fed into the mixer and the mixture is mixed for another 1-2 minutes, after which the remaining surfactant and silica fume are introduced and mixed until complete porosity within 0.5 to 4 minutes.

 Examples of aerated concrete mixes, mixing modes and physicotechnical properties of aerated concrete are given in tables 1 and 2. In examples 1, 2, 6, sulfonate powder was used as a surfactant, and sodium lauryl sulfate in the remaining examples.

 As can be seen from the tables, the proposed method provides non-autoclaved aerated concrete with high physical and technical properties, which can be used as a heat-insulating layer for the manufacture of multilayer products, as well as a protective and decorative layer of facing insulation tiles.

Sources of information:
1. SU Copyright certificate N 1726459, C 04 B 40/00, 1992

 2. RF patent N2055034, cl. C 04 B 28/02, BI N6, 1996

 Z. RF Patent N2078749, cl. C 04 B 40/00, BI N13, 1997 (prototype).

Claims (1)

A method of producing aerated concrete, comprising preparing a mixture by sequentially supplying a surfactant, water, a siliceous component and cement to the mixer, mixing and porous in the mixer for 2-10 minutes, characterized in that the modified silica fume is additionally introduced into the mixture, first into the mixer water and 40-60% surfactant are supplied, then a silica component and cement, after which modified silica fume and the remainder of the surfactant are introduced and mixed until completely porous in the following ratio of components si, wt.%:
Cement - 35 - 42
Siliceous component - 32 - 38
Modified silica fume - 5 - 10
Surfactant - 0.3 - 0.5
Water - Else

Images