RU2205813C2 - Sand blend for manufacturing cast-in-place foamed concrete - Google Patents

Abstract

FIELD: manufacture of building materials. SUBSTANCE: water-based sand blend for nonshrinking foamed concretes contains, wt %: Portland cement 42.3-43.8, foaming agent "Unipor" 0.2-0.4, stabilizing and air-entraining additive 0.3-0.6, and, additionally, quartz sand 26.5-27.4, said additive being composed of, wt %: industrial-grade lignosulfonate 39.1-41.2, caprolactam production alkali set- down 39,4-40.9, and potash 19.3-21.4. EFFECT: increased mobility and reduced dehydration and segregation. 2 tbl

Description

 The invention relates to the production of building materials, namely the manufacture of non-autoclave foam concrete for structural insulating products based on them.

 Foam concrete is known and widely used, where quartz sand is used as a filler, and hydrolysis blood, or a rosin emulsion, is used as a foaming agent. (K.E. Goreinov, K.N. Dubenetsky, S.G. Vasilkov, L.N. Popov, "Technology of heat-insulating materials and light concrete", p.234, M .: Publishing house of building literature, 1966).

 Higher requirements for the physicomechanical properties of foamed concrete at present require the creation of new blowing agents of the colloidal structure and protein-protein composition, which is treated with ammonia in order to prolong the pot life. To achieve increased durability and stabilization of the structure of products made of foam concrete produced in the factory, it was possible with the introduction of microdispersed fillers. (Korenkova S.F., Sukhov V.Yu., Verevkin O.A. "Principles of the formation of the structure of enclosing structures using filled foam concrete". M., Building materials 8, p.29-33, 2000).

 Monolithic foam concrete, as well as other types of monolithic concrete and products based on them, are made in stationary technology. (Yu.M. Krasny, D. Yu. Krasny "Monolithic housing construction. Textbook, Moscow, Yekaterinburg, 2000"). Monolithic foam concrete mixtures are fed over considerable distances both vertically and horizontally, and when unloaded from vehicles, they are discharged from a height of more than 1.5 m, laid into the formwork by concrete pumps and compacted by surface or depth vibrators. In accordance with this, the monolithic foam concrete mixture must have high water-holding ability and resistance to delamination, be conveniently pumped and easy to lay during transportation to the place of laying into the formwork and compaction.

 The above concrete mixtures have the same disadvantages - they do not have a sufficient degree of mobility and water separation, exfoliate.

Known raw mix for the manufacture of light concrete according to the author's certificate of the USSR 1514743, class. From 04 to 38/02, 1989, which includes Portland cement, lime, gypsum, coal ash, additives and water. The mixture contains ash with a bulk density of 500-600 kg / m ³ and a specific surface area of 1500-2300 cm ² / g, and technical lignosulfonates, oligodiethylsiloxane and industrial oil as additives.

 However, monolithic foam concrete must have high mobility (P3-P5 - cone draft of more than 10 cm) and water separation for these grades for workability not more than 0.4-0.8% (Concrete mixtures. Technical conditions. GOST 7473-94).

 The molding mixture according to this copyright certificate does not meet these requirements.

 To achieve such indicators for non-autoclaved monolithic foam concrete is impossible without the introduction of complex chemical additives and protein-protein foaming agent.

 Known molding mixture for the manufacture of monolithic foam according to the author's certificate of the USSR 1742271, C 04 B 38/02, 1992, adopted by the applicant for the prototype and containing, wt.%: Portland cement 18-30, coal ash 40-53, foaming agent 0.05 -0.15, aluminum sulfate 0.05-2.5, semi-aquatic gypsum 0.007-0.15, technical lignosulfonate 0.04-0.1, lime, providing an alkalinity of 2-5, water - the rest.

 However, it does not have sufficient mobility and water separation.

 An object of the invention is to prepare a molding mixture for non-shrinking foam concrete with improved technological properties: increased mobility, reduced water separation and delamination.

The problem is solved in that the proposed molding mixture for the manufacture of monolithic foam concrete, including Portland cement, a foaming agent, an additive containing technical lignosulfonate, and water, contains Unipor foaming agent and additionally quartz sand, and as a specified additive a complex chemical stabilizing-air-entraining KHSVD additive composition, wt.%: technical lignosulfonate 39.1-41.2, alkaline production of caprolactam 39.4-40.9, potash 19.3-21.4, in the following ratio, wt.%:
Portland cement - 42.3-43.8
Quartz sand - 26.5-27.4
Foaming agent "Unipor" - 0.2-0.4
KHSVD - 0.3-0.6
Water - Else
where the constituents of the molding sand mixture have their own purposes: Portland cement or cement is used as the bonding base of the mixture, quartz sand as a filler, Unipor foaming agent as a foaming agent for lightweight porous concrete, KHSVD is a stabilizing and air-entraining additive, providing maximum foaming and molding of a homogeneous porous structure of foam concrete.

 "Unipor" is a protein-based dark brown liquid, is an environmentally friendly, chemically neutral product that does not contain chlorides, foam concentrate provides the highest quality foaming.

 The use of Unipor is regulated by the following regulatory and technological documentation: TU 653 RK 15259714 LLP 03-98, GOST 25485-89, GOST 21520-89. Developer of normative documentation Kunai - Stroyservis Company LLP, Kazakhstan, Kostanay.

 The preparation of the molding mixture is as follows.

Portland cement and quartz sand are fed dry to a concrete mixer. Separately, foam is prepared simultaneously on the basis of the Unipor frother in the foam generator. A complex chemical stabilizing and air-entraining additive is prepared separately: technical lignosulfonate, alkaline production of caprolactam and potash (K ₂ CO ₃ ), taken in the required proportions by weight. Moreover, technical lignosulfonate is present in the additive as a plasticizer, alkaline production of caprolactam is an air-entraining component, and potash (K ₂ CO ₃ ) is used as a hardening accelerator and to preserve the strength characteristics of concrete.

 In a special container, the additive is dissolved at a concentration of 1 kg of additive per 10 kg of water. Mixing the solution to completely dissolve the additive is carried out either by the supply of compressed air or by a mechanical stirrer. Then, the amount of additive required for the batch, established during the selection of the concrete composition, is supplied to the concrete mixer with the mixing water. Portland cement, sand and water are mixed together with the additive. Then the required amount of foam is added to the concrete mixer from the foam generator. The dosage of the complex additive, foam is carried out by weight or volumetric dispensers. Compressed air is supplied to the concrete mixer; the molding mixture is mixed. The finished mixture is piped with compressed air to the installation site.

 For experimental verification of the effectiveness of the inventive mixture, five formulations of molding compounds were prepared: two formulations - transcendental, in which values below the minimum and above the maximum specified in the claims were used, and three compositions were obtained using intermediate values of the components. All compositions, including the prototype, are given in table. 1.

 Test results: physicomechanical properties of each composition, namely air entrainment as a result of mixing of the additive components, shrinkage values of the mixture after holding the products in natural conditions for 24 hours, water separation, water-solid ratio, cone sediment mobility, expansion rate, average density in dry condition of the developed compounds, compressive strength at 28 days of age after natural hardening and thermal conductivity are given in table. 2. It subdivides the properties of the foam concrete mixture before the introduction of the foaming agent and after the introduction of the foaming agent, as well as the properties of the hardened foam concrete.

Results that meet the goal were achieved on the compositions of 1,2,3. From the analysis it follows:
- air intake increased, and water separation decreased;
- the mobility of the mixture increased at a constant W / T;
- shrinkage of the mixture decreased to 0;
- the rate of foaming has increased.

 Outrageous composition (1) does not meet the goal as a result of reducing air entrainment and water separation, as well as increasing shrinkage and lowering the strength of concrete.

 The composition is prohibitive (2) does not meet the goal due to a sharp increase in density and coefficient of thermal conductivity due to a decrease in the rate of foaming and a partial loss of mobility of the mixture.

 A significant increase in air entrainment and a decrease in water separation with a high mobility of the mixture and the rate of foaming, as well as an increase in the strength of concrete, allow us to conclude that the optimal amount of foaming agent is 0.2-0.4% by weight of cement, and a complex chemical additive is 0.6% by weight mass of cement.

 A complex chemical additive can be considered as stabilizing-air-entraining, providing maximum foaming of the mixture with the introduction of a foaming agent and the formation of a uniform porous foam concrete structure. The latter helps to increase the strength of foam concrete.

 The use of the proposed molding mixture for the manufacture of monolithic foam concrete allowed to increase the number of non-shrinkable foam concrete produced, to improve their technological properties: mobility, water separation and delamination.

Claims (1)

Molding mixture for the manufacture of monolithic foam concrete, including Portland cement, a foaming agent, an additive containing technical lignosulfonate, and water, characterized in that it contains a Unipor foaming agent and additionally quartz sand, and KXSVD, a complex chemical stabilizing-air-entraining additive, as an indicated additive composition, wt. %: technical lignosulfonate 39.1-41.2, alkaline production of caprolactam 39.4-40.9, potash 19.3-21.4, in the following ratio, wt.%:
Portland cement - 42.3-43.8
Quartz sand - 26.5-27.4
Foaming agent "Unipor" - 0.2-0.4
KHSVD - 0.3-0.6
Water - ElseP

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